Talk:Redshift/Archive 5

This is an archive of past discussions about Redshift. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

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POV pushing section removed

===Frequency-dependent redshifts===
There are also a number of causes of frequency-dependent redshift of spectral lines. This use of the term 'redshift' is in less common usage, and will not be discussed further in this article. They include Brillouin scattering [1] , Compton scattering [2], Raman scattering [3] Wolf effect [4], and other theories such as tired light theories [5] These redshift mechanisms are sometimes called non-Doppler redshifts [6], non-Cosmological redshifts [7], or intrinsic redshifts [8].

This section was removed as the statements made about the citations are not verified. --ScienceApologist 02:30, 3 December 2005 (UTC)

RfC: Request for Comments

Wikipedia Request_for_comments page

Myself, user:iantresman is having a content dispute with user:ScienceApologist (previously User: Joshuaschroeder [9]) over whether to mention that some scientists use the term 'redshift' in a wider context than is used by that in astronomy to mean just Doppler, Cosmological or Gravitational redshift. I do not contest that the astonomical use of the term dominates. Details of the dispute may be read above, and on previous archive pages here and here.

I propose that the article includes something to the effect that (a) a 'redshift' means 'a shift in frequency' (ie regardless of the cause, such as in 'the spectral line is redshifted') (b) under the section "Causes of redshift": Some scientists recognsied a number of causes of frequency-dependent redshift of spectral lines. This use of the term 'redshift' is in less common usage, and will not be discussed further in this article. They include Brillouin scattering [10] , Compton scattering [11], Raman scattering [12] Wolf effect [13], Neutrino redshift [14], and other theories such as tired light theories [15] These redshift mechanisms are sometimes called non-Doppler redshifts [16], non-Cosmological redshifts [17], or intrinsic redshifts [18].

Evidence in support of the proposal (user:iantresman)

Over 500 peer-reviewed references (see list above) using the term 'redshift' in a non-Doppler-like manner.

You will note, please, that this "list" is not researched to support Ian's claim. It is only a list for keywords that he thinks supports his claim. Ian, however, has read not even 1% of the articles listed. This is not a form of evidence, rather it is the worst form of quote mine. --ScienceApologist 14:22, 3 December 2005 (UTC)

5 votes out of 5 in the Discussion on the Bad Astronomy Universe Today Forum in the thread "Spectral line redshift versus Doppler redshift", including supporting comments from Jet Propulsion Laboratory physicist Tim Thompson

Off-site polls should have no bearing on this community. Moreover, you will notice that the article phrases the question differently than the question here. It is asking if there should be two articles, one on redshift being associated with shifting frequencies and one on redshift mechanisms. Most people agreed that we should not have two articles and I agree too. What Ian conveniently left out was the question of whether scattering processes etc. as he outlines above should be included in the article. Tim Thompson, I would suspect, would not be pleased to see his name used here in support of the psuedoscientific POV-pushing of Ian. --ScienceApologist 14:22, 3 December 2005 (UTC)

Confirmation from three professors of physics that they use the term 'redshift' in a non-Doppler-like manner, including Prof. Daniel F.V. James [19], Prof. Emil Wolf [20] [21], and Prof. Theoretical Physics, Indian Statistical Institute, Sisir Roy [22]

Red herring point. the question is whether they are using redshift as the standard definition applies or as a placeholder for another form. --ScienceApologist 14:22, 3 December 2005 (UTC)

Contributing editors (a) User:Serjeant who writes regarding the Wolf effect "it certainly rates a mention" (b) Prof. Daniel F.V. James (mentioned above) who writes "The term "redshift" is not used just by astronomers. it refers to any process which increases the wavelength of light" (c) user:naasking who writes "the general "Redshift" phenomenon should in fact discuss all redshift (ie. all mechanisms of redshift,.." (d) User:Joke137 who also supported mentioning non-Doppler-like redshifts.

These editors both could not answer the basic points I outlined above as to why it does not belong on the page.

As one of the contributing authors in question, I should point out that I later had no objection to removing the Wolf Effect given that the Compton Effect and other frequency-dependent effects also had no place. However I am dismayed by the level of personal recrimination on both sides over what should be a simple parenthetical remark in the article.--Serjeant 16:45, 5 December 2005 (UTC)

The Wikipedia Neutral Point of View page requires articles to be "representing all majority and significant-minority views fairly and without bias."

The minority is represented very fairly in its own section of the article.

Evidence opposing the proposal (user:ScienceApologist)

User:Iantresman, very incompetent in this regard, has insisted that there is a different definition for redshift than that which is provided in the article itself. In particular, he apparently disagrees with the defintion of redshift as a proportional increase in the wavelegnth of an electromagnetic wave. This is a definition that can be found in any introductory physics or astronomy text dealing with the subject of redshift. Ian has not been able to find a resource that defines redshift in any other way. Indeed, there is an indication that Ian doesn't even understand this definitional constraint (see the archive). Instead, his advocacy extends to making lists of papers that use the term redshift but do not define it and ambiguously refer to effects which apparently do not conform with the definition we outline in the article. This is an unacceptable form of research. Redshift is rigorously defined by those who refer to the term directly in the resources on the page as a proportional increase in wavelength. It is not simply a "shift" of the wavelength of light to the red. Whether they realize it or not, scientists that use this term are appealing to such a distinction.

I see an argument for perhaps including on disambig the point that some people may refer to "redshift" when they mean just a shift in frequency to the red. This is not something that should be included in the body of the article as it is so rarely a mistake as to be almost impossible to find. User:Joke137 above may have found some articles that do this. It's not exactly clear. A sentence of clarification along the lines of "Some may have used the term redshift to a shift in a feature toward a longer wavelength that does not conform to the definition found on this page, but such usage is very rare." Indeed, it seems that the reference refering to the Stark effect may be due to a mistranslation!

What Ian fails to mention is the reason he wants to include the alternative mechanisms is because he has a chip on his shoulder against mainstream physical cosmology. In particular, he wants to see recognition of such problematic ideas as tired light and scattering processes as a mechanism for redshift. ~~Perhaps including a section in this article about such processes and why they do not account for redshifts would be in order.~~ There is currently a section in the article that outlines the points made by those who are involved in nonstandard cosmology. In particular, there are points about tired light and scattering processes. But a sentence/section as Ian sees it would be completely inappropriate and is giving undue weight to a minority pseudoscientific position that does not belong on the mainpage.

--ScienceApologist 14:22, 3 December 2005 (UTC)

Please Support or Oppose, together with a comment, and sign and date by either adding "--~~~~" (if you have an account), or your name and date if you don't.

Nominations

Support As proposed above, --Iantresman 12:20, 3 December 2005 (UTC)

~~Oppose~~ Weak support a disambig, but not of the character of Ian's paragraph. We should do it up front. --ScienceApologist 14:22, 3 December 2005 (UTC)

'Support' I agree with Dragon: don't try to make artificially narrow descriptions but instead distinguish between different uses. Also the featured Italian doesn't narrow the definition too much in the intro(Babelfish): "The movement towards the red one (also called with the English term redshift) is the phenomenon for which the frequency of the light, when observed in sure circumstances, it is lower of the frequency that it had when it has been emitted." (note the absence of the artificial "proportional increase") Harald88 22:32, 3 December 2005 (UTC)

~~Why do you say such is artifical? Do you know of alternative uses? I would like to see them.~~ See below. We've found the alternative. Now it's time to disambig. --ScienceApologist 02:22, 4 December 2005 (UTC)

Like everything touched by Joshua Schroeder, who changed his user name after his suspension, this article is a mess. It is flatly wrong to say that all non-Doppler mechanism for producing redshifts are frequency-dependent. The Wolf effect is just one that is frequency independent. CREIL is another.There are dozens of peer-reviewed articles about these and other plasma-based effects. As per usual grad student Joshua pretends to know things about subject that he has no knowledge of. A change in definition is not going to fix this article. But personally I have no interest in wasting more hours arguing with Joshua.Elerner 15:56, 3 December 2005 (UTC)

The Wolf Effect and Raman scattering both are dependent on the material through which the light is scattered. Basic electrodynamics tells us that there is no such thing as an index of refraction that is completely independent of frequency. This is another way of saying that all scattering processes are frequency dependent, though they may vary in degree. --ScienceApologist 02:55, 4 December 2005 (UTC)

Support - the definition of the observed redshift should not be controversial. The various mechanisms proposed to explain redshifts range from the standard explanations adopted by most astronomers to more controversial explanations that have little support among astronomers but are nonetheless published in the literature. I'd suggest that there should be a section for redshift in mainstream cosmology and a section for alternative proposed redshift mechanisms where mechanisms published in peer reviewed journals should be mentioned. Actually, I believe that was the way the article was structured, but all mention of those alternatives was expunged by Joshua. --DavidRussell 00:58, 4 December 2005 (UTC)

I'll grant you that Halton Arp said that redshifts have an intrinsic component, but does this criticism warrant an entire paragraph in the article? I removed the paragraph for the time-being as I'm not convinced that the current wording of the nonstandard section doesn't cover this issue (people can read more about it on the Halton Arp page). I guess the question should be, why should Halton Arp's criticisms be included beyond the point that there are people that criticize standard explanations of redshifts. Does Arp hold a special place amongst those that criticize? --ScienceApologist 02:19, 4 December 2005 (UTC)

Oppose. Just say that "Other physical processes affect the frequency of light, but do not in general give the same shift at all frequencies. Such processes include Compton Scattering, the Wolf Effect, ... These shifts are sometimes referred to as redshift or blueshift, although this may be considered incorrect by some as the shifts do not in general follow the equation above at all frequencies." Include links to Compton, Wolf etc and have done with it. Incidentally, the page has been updated with good figures but a poor text edit which removed much of the clarity and rigour.--Serjeant 16:45, 5 December 2005 (UTC)

Isn't that the point, that some scientists do not define redshift by the "full-spectrum" equation, and to suggest that this definition is the only accepted definition is incorrect? Surely that does not suggest that they are using the term redshift incorrectly, only that they are using the term differently? Even Joshua now recognises that chemists use the term 'redshift' in a different manner, and likewise for Compton & Brillouin scattering, and the Wolf Effect. --Iantresman 17:22, 5 December 2005 (UTC)

Hence "considered incorrect by some". Calling a Compton-scattered or Raman-scattered photon "redshifted" sounds clearly wrong to me, but other disciplines may be accustomed to using the word differently; QED. But this is issue much less important than deleterious recent edits.--Serjeant 18:26, 5 December 2005 (UTC)

Support. This dispute should be resolved by completely separating the conceptual definition from the mathematical definition. Redshift is used in both ways, so both should be included in the introduction. The mathematical definition is more rigorous. That doesn't make the conceptual definition bad or wrong. I would remove the word proportional from the definition of redshift as a word. This proportionality applies to the mathematical definition but not the conceptual one. Phenomena are important as observables without explanations attached and without equations or any quantitation attached. The beauty of the math, the explanations, the details, and the physics is that it makes sense of the concept and limits the concept in certain situations, adding rigor. That is why this information should not be part of the definition of the word. The proportionality of the shift is a separate observable from the observable of the shifting itself. I would also include the mathematical definition (first equation) in the introduction. Turning to peer-review journals won't help us with this dispute. Imagining what would be useful to someone who doesn't know the term and wants to learn about it for the first time will help us, and that takes the modesty to imagine ourselves lacking information instead of the pride of being familiar with so many details. Flying Jazz 19:45, 6 December 2005 (UTC)

After actually editing the article to make it look how I think it should look, I guess I've changed my vote to Partial Support. I support Ian's part (a) because people actually use and publish the word in this way. I oppose Ian's part (b) because a list of all the scattering mechanisms and effects and such is cumbersome and who is to say what "counts" and what doesn't? Let's say some sneaky postdoc sets up a machine in between my light source and my receiver. His machine emits red light when it receives yellow light. Now I would argue that I am observing a bona-fide redshift due to the sneaky-postdoc-effect because I agree with Ian's part (a), but if he starts listing causes of these redshifts then why won't the sneaky-postdoc-effect be included? Flying Jazz 06:34, 7 December 2005 (UTC)

500 peer-reviewed articles indicates what "counts" and what doesn't. And even if a sneaky post-doc contrives an experiment, he can still show a redshifted spectral line, and we know what he means, even if the cause is not confirmed. But we have to give peer-reviewed sources the benefit of the doubt. That's the way the "scientific method" is supposed to work --Iantresman 08:28, 7 December 2005 (UTC)

No, that's the way the politics of modern science work. Please do not conflate the two; it is depressing to imagine them being equal. :) —HorsePunchKid→龜 2005-12-07 08:34:17Z

I think you are missing my point. You are right that the term and the math are used for individual spectral lines without applying to the entire EM spectrum. That should be in this article. But your desire to take these 500 peer-reviewed articles that refer to subsets of the spectrum and separate out how some use the phrase or the math for this observed phenomenon and others use the phrase or the math for that theoretical possibility is misguided. And I wish I could agree with you because the guy on the other side of this issue has being unpleasant. A very limited number of phenomena (three as opposed to a long list) can explain the redshift that occurs throughout the EM spectrum (as opposed to one spectral line) and are refered to by many more than 500 articles. That's a good reason for nearly the entire article to be devoted to those three phenomena and the others to be mentioned collectively but not listed. I strongly support your (a) but strongly oppose your (b). Flying Jazz 12:00, 7 December 2005 (UTC)

I'm note sure I understand your point. Why would we not mention, for example, the Wolf Effect, which consistently refers to "redshift", and is not only demonstrated in the laboratory, but has been shown that under certain circumstance will also proudce a frequency-indpenendent redshift? Likewise scattering phenomenon which can be demonstrated, will redshift spectral lines? If I was researching 'redshift' why should I not be told that these various specific scattering phenomenon, tired light, and the Wolf Effect exist? We're talking about ONE sentence? How else would I discover that 'redshift' is connecting with, for example, Compton scattering? --Iantresman 14:36, 7 December 2005 (UTC)

You're right that the interaction of light with matter can cause a redshift in many different ways. You provided a long list in your proposal part (b), but that list is far from exhaustive. I'm reminded of the song "Roxanne, you don't have to put out the red light." Here's a woman who turns on a red light to advertise herself when the sun goes down. Analyze the spectrum near Roxanne's light and you'd see a redshift recurring every night. Now we have the sneaky-postdoc-effect and the Roxanne-effect. Both are covered by the current introduction to the article along with light scattering phenomena and photochemical phenomena by including the sentences "The terms redshift and blueshift may be used without mathematical rigor to empirically describe the reception of altered wavelengths. The ratio describing redshift may also be used in a variety of situations that only apply to individual spectral lines or a subset of the spectrum." If redshift due to interaction of light with matter can occur in a huge number of ways then we can't list only the ones that are supposedly important to someone or refered to by more than 17 peer-reviewed articles or the ones you like best or something. Please try to read the current introduction with an open mind. I think it really does address your first proposal (a) in a concise way that would be impossible if we tried to tackle (b). How would you discover that redshift is connected with Compton scattering? By learning about Compton scattering. Flying Jazz 03:52, 8 December 2005 (UTC)

Support Jerry Jensen A working definition of science is 'discovery through the recognition of patterns'. The peer review process is a sieve, accepting only patterns recognized by peers. If a new pattern, is not recognizable within the peer community, it is rejected. The peer review process fails when the mold is broken.

There is severe evidence the data reduction techniques used in peer reviewed evaluation of supernova breach reasonable data reduction norms, however the results are accepted because they are in agreement with the concordance model. This chain of logic has forced the physical science community into a blind acceptance of cosmic parameters which are not testable. The first step in correcting this systemic failure is recognition that the system is broken. Careful statistical analysis, without prior expectations, of supernova data does not support expansion redshifting. The cause of cause of cosmic redshift must be readdressed.

Some observations

First let me say that if one hears a chemist say "redshift" they will nearly never mean astronomical redshift and frequently mean Raman scattering, which is a common diagnostic tool in some branches of chemistry. So, yes, from a purely factual perspective there are scientists who say "redshift" and routinely mean something other than what this article is presently talking about.

Which may the crux of the problem. This article clearly centered on the astronomical redshift, so maybe it should be moved to astronomical redshift to discuss those observations and the possible explainations for them and then create a new redshift page that say something like:

Redshift refers to any one of a number of processes by which light can be moved to a lower ("redder") frequency. The astronomical redshift refers to a set of observations that ... Common causes for redshift in astronomy are ... Frequency shifting is also a valuable tool in diagnostic chemistry, where the most common causes of redshift are ...

However, just because I believe it would be appropriate to find a way to mention other uses of the the term redshift doesn't mean that one should stuff a laundry list of alternative views into an article on astronomical redshifts for the purposes of making the mainstream view appear scientifically controversial. Dragons flight 19:18, 3 December 2005 (UTC)

Dragons flight's suggestion has merit and while it may not put a complete end to this controversy, it would be a move in the right direction. DV8 2XL 19:48, 3 December 2005 (UTC)

I would agree with Dragons flight's suggestion if I could find a reference to a chemist text that used redshift in such a fashion. As it is, I cannot find any such reference. The closest we have are Joke137's citations above. None of those are chemist papers, though. Can either of you point me in the direction of somebody using "redshift" and not "red shift" in regards to Raman scattering? We could put the Raman scattering disambig on the Red shift page which is linked from the top. --ScienceApologist 02:08, 4 December 2005 (UTC)

Here [23]. Links 4, 5, 7, 8, and 9 are published papers using Raman "redshift". Most of the others look like preprints of papers, and I'm sure there are many more in the other 600 links. Dragons flight 02:24, 4 December 2005 (UTC)

Well, it looks like we're narrowing in on the culprit here. I am now firmly in User:Dragons flight's camp. We need to have a decent disambig while avoiding what the appearance of scientific controversy. Should we perhaps make the disambig on the top larger? We could make this page a different name, but there are a lot of articles that dynamically link here. I think this has taken us on the right path. --ScienceApologist 02:37, 4 December 2005 (UTC)

" ...a proportional increase in the wavelegnth of an electromagnetic wave. This is a definition that can be found in any introductory physics or astronomy text dealing with the subject of redshift." I found definitions limited to Doppler redshift only, and I found definitions limited to frequency independent wavelength increases, but I didn't find any definitions specifically mentioning and excluding frequency dependent wavelength increases. Did you find any? Thus, I found no guidance from formal definitions. The common usage of the term was quantified by Joke137's statistics, which show frequency dependent redshifts often enough to be mentioned in an article with 15,146 characters.

My point wasn't that there was an exlusory definition but that the definition of redshifts that was given never included frequency-dependent effects and indeed with further discussion excluded it by referring to the mathematical definitions we have on the page. --ScienceApologist`

"There is currently a section in the article that outlines the points made by those who are involved in nonstandard cosmology." But as I understand it, frequency dependent redshifts can't account for the redshifts of distant galaxies, so frequency dependent redshifts and nonstandard cosmology are two separate subjects.

Yes. That is why I propose to disambig at the Red shift page if there are no objections. --ScienceApologist 14:30, 4 December 2005 (UTC)

"...a minority pseudoscientific position..." If so, then sometimes a scientific attitude, like other virtues, is best taught by example, and maybe ScienceApologist's belated recognition will change things for the better. Art LaPella 07:43, 4 December 2005 (UTC)

Photochemist's opinion

First, let me say that I am not yet a professional scientist. I am an undergraduate doing an honors thesis in a photochemistry lab. We throw the terms redshift and blueshift around all the time to talk about changes in fluorescence spectra. We are referring to a chemical redshift, where the a polymer changes the wavelength at which it emits most intensely in response to certain experimental conditions. This redshift has nothing to do with the astronomical redshift. I have never seen a photochemical paper use the term redshift, and I'm strongly under the impression that it is an informal photochemical term, not one used in the literature. (However, being an undergrad, I'm not particularly well-read.) I would be happy to help develop an article on (photo)chemical redshift, if we decide to make this redshift a disambig. -- stillnotelf has a talk page 03:01, 7 December 2005 (UTC)

You make a good point that many fields use redshift in an informal way. Ian makes a good point too that many fields use redshift in a formal way but still without matching the mathematical definition that applies at all wavelengths. That other guy makes a good point that we should define redshift with mathematical rigor. I've added the statement "The terms redshift and blueshift may be used without mathematical rigor to empirically describe the reception of altered wavelengths in a variety of situations that only apply to part of the spectrum. However, most references to redshift—including the remainder of this article—utilize a mathematical definition that is uniformly applicable at all wavelengths." Having another disambig or additional articles on all the flavors of non-rigorous redshifts would be a mistake I think. Flying Jazz 06:54, 7 December 2005 (UTC)

The redshift equation is used by all scientists to work out the redshift of a single spectral line, regardless of the cause, and regardless of whether the redshift is Doppler-like or not. The redshift equation may be used as a rigorous definition, but it applies to an idea situation, in the same way that Boyle's law applies to an ideal gas. --Iantresman 09:10, 7 December 2005 (UTC)

Statements including the phrase "...is used by all scientists" are generally wrong. All scientists are not using mathematical definitions all the time. But you're right that the redshift equation may be used to quantify a redshift even in cases where it involves phenomena that apply to single lines or only part of the spectrum. Perhaps there are three definitions of the phrase. One is qualitative: "the light has experienced a redshift" requires no math. One is quantitative with application to a single spectral line or a portion of the spectrum. The most common definition is the one implying a uniform redshift over the entire spectrum. Your analogy to Bolye's Law is off base because Boyle's Law doesn't define anything and because (I think) it can be demonstrated in the lab that the Doppler-like effect of redshift really does follow the math as precisely as we can determine for huge regions of the spectrum while Boyle's Law can be demonstrated in the lab to always be an idealization of reality. I've edited the introduction to reflect these three possible distinctions. Flying Jazz 12:03, 7 December 2005 (UTC)

We generally don't use the given redshift equation at all, we just take the difference of two peaks. We're looking at the movement of peaks in a molecular spectrum, which doesn't have definable lines, but rather broad (dozens of nm wide) peaks. So, yeah, "single spectral line" never applies to chemical redshift, because molecules that shift colors don't have line spectra, and atoms (which do have line spectra) do not shift colors (that I know of). I don't want to get too embroiled in this, but like I said, someone please let me know if you decide you want a blurb on photochemical definitions of redshift. -- stillnotelf has a talk page 17:48, 7 December 2005 (UTC)

Yes please. Can you give (a) a descriptive definition of 'redshift', and if you use one, (b) a mathematical description too, (c) In a chemisty context, what cause or causes produce such a redshift. --Iantresman 18:03, 7 December 2005 (UTC)

I think Stillnotelf is talking about the fact that when a molecule changes its shape slightly due to a change in solvent or another molecule binding to it, peaks in its absorption spectrum will move a little. If an absorption peak moves from 300 to 350 nm then this might be called a redshift of 50 nm. The math is something like redshift = peak_wavelength_after - peak_wavelength_before. The cause is a different spacing of atoms in the molecule before and after a chemical or physical change. These values are an extension of the qualitative usage of redshift as any shift to a larger EM wavelength. Chemists want to know where to set the spectrophotometer so they aren't interested in the ratio. The oxygenation of hemoglobin causes a change from blue to red color because peaks in the transmittance spectrum of that molecule increase in wavelength. This could be called a redshift too. So could someone painting a house. Flying Jazz 06:22, 8 December 2005 (UTC)

Photochemistry added to article

I did a little research on photochemical redshift in addition to what I know already, and I added information on it to the article because there's a lot of science out there that assigns a length scale to something called a redshift. Stillnoteelf was right that IUPAC calls this usage informal. Nevertheless, I guess that IUPAC accepts it as proper usage for pure and applied chemists. See redshift here-- http://www.iupac.org/reports/1996/6812verhoeven/R.htm . My hope is that by explicitly stating definitions that are not formal and rigorous, the bulk of the article that uses the formal and rigorous definition will be stronger, and people who come here with the informal usage in mind will find what they came here for. Flying Jazz 22:51, 8 December 2005 (UTC)

I spoke with my advisor today - she tells me that she does indeed see "redshift" and "blueshift" in the literature, although some authors still prefer more formal terms. The link to bathochromic shift is perfect, because it keeps this article focused on more formal terms and redirects the chemistry discussion to a chemistry page. Thanks, Flying Jazz, I'd've probably gotten around to that in a week or two (I'm in the middle of final exams), but you made just the right link. -- stillnotelf has a talk page 01:42, 9 December 2005 (UTC)

I have updated bathochromic shift and its partner hypsochromic shift. Without wanting to open a can of worms, why is there no discussion over blue shift, and why is it titled in a different style? -- stillnotelf has a talk page 02:02, 9 December 2005 (UTC)

Red shift opens a can of Wikipedia worms because, as an astronomical observation, it is consistent with the Big Bang theory of origins but not with most other theories of origins that a few folks like better. If we observed blueshifts way out there in space then maybe we'd think we live in a collapsing universe...but more importantly the poor neglected Blueshift talk page would be getting all the attention! Flying Jazz 02:21, 9 December 2005 (UTC)

Oh, I understand the cosmology issues - I was just wondering why it's being ignored. I guess since it's rarer, it's less important. I notice that blueshift even re-uses the redshift graphic, even though the phenomenon should be reversed! -- stillnotelf has a talk page 02:38, 9 December 2005 (UTC)

That's a mistake. Thanks for pointing it out. --ScienceApologist

The meaning of proportional and its consequences

OK, this subsection is about math definitions for 12-year olds which a lot of very good scientists forget around age 23, but it appears to be critical for this debate. If a is proportional to b then a/b is constant. This means that the present article saying redshift is "defined as proportional to wavelength emitted" is incorrect. I've changed this to "redshift is defined as the proportionality between the change in wavelength and the wavelength emitted" which is correct.

This also gets to the heart of the deeper issue under debate. A proportionality is not just a ratio. A proportionality is an equality between multiple (at least two) ratios. If redshift is measured for one spectral line for the situations that Ian describes, we can say z=change/emitted and get a redshift. However, this is no longer a proportionality because there is only one ratio involved. Therefore it is a different mathematical definition of redshift (a ratio but not a proportion) even though the same equation is used to obtain the same a value with the same name. I don't think any of this should be in the article because it is esoteric minutae about the way science uses words and equations mixed in with 12-year old math. But I hope it clarifies some of the debate here and justifies my recent edits. Flying Jazz 13:15, 7 December 2005 (UTC)

Surely it's not esoteric minutae. Doesn't every redshift measurement begins as a measurement of a single spectral line. This is the more general use of the term. The special case is where full-spectrum prortionality is either assumed, or subsequently demonstrated. And then it's only astronomers who claim that the special case, full-spectrum redshifts are the only 'true' redshifts. Physicists studying scatting phenomenon, the Wolf Effect, tired light theories, do not. Indeed, the very fact that we have to qualify the word 'redshift' with a prefix (such as Doppler, full-spectrum, frequency-dependent, etc) demonstrates that the word 'redshift' is a general term, even though context may allows us to use it more specifically? And consequently, an article on 'redshift' should provide a list of the different kinds (and usage) of redshift. --Iantresman 14:48, 7 December 2005 (UTC)

The paragraph you wrote, Ian, is a unique point-of-view, but isn't based in fact. Claiming "general" and "specific" uses for redshift is like claiming that there are "general" and "specific" uses for energy since there are some scientists who use energy to mean things other than a quantity which has units of kg m² s^-2. The vast majority of physicists who would bother would define redshift as what we have currently on this page. --ScienceApologist 19:59, 7 December 2005 (UTC)

Some of my 500 references say otherwise. For example, when Wolf and James write [24]:

"Fig. 2. Redshifts and blueshifts of a spectral line as predicted by (3.4)..." and,
S_V(ω) = (2/R²) S_Q (ω) [1 + R_e μ_Q (P₁, P₂, ω)] (3,4)
"It will be shifted towards the lower frequencies (redshifted)" (note their definition)
"In one of the experiments the observed spectrum C was redshifted"
"This expression shows that the relative frequency shift is independent of the central frequency ω₀ of the incident light and thus imitates the Doppler effect."

In other words, Wolf and James emphatically use 'redshift' in a DIFFERENT way to the fequency-dependent usage, and this demonstrates not only that a frequency-indepenedent redshift as the only definition is erronous, but examples should be given.

And yes, there are general uses of the word "energy". As you can see, I'm full of energy, as any dictionary will tell you, and I agree that physicists have a more rigorous definition too.

--Iantresman 10:46, 8 December 2005 (UTC)

general and specific

The terms "general" and "specific" are tricky here. On the one hand (maybe Ian's hand), there are more phenomena that can be related to a less rigorous definition of redshift (the qualitative observation or the ratio) than there are phenomena that can be related to the more strict definition (the proportionality), so the less rigorous definition is more "general." On the other hand (maybe ScienceApologist's hand), the less rigorous definition doesn't apply at every wavelength, so in this mathematical sense, it is more "specific" and only people who use the proportionality are using the "general" case. I think it's best to avoid the terms general and specific entirely in a situation like this. Flying Jazz 04:57, 8 December 2005 (UTC)

Ian's points

1) Every redshift measurement doesn't have to begin with the measurement of a single line. The bands in the color redshift next to the introduction could be apportioned among a group of undergrads. Each undergrad could measure the shift of one line all at the same time and then all the data could be collated simultaneously to find they all have the same redshift (or don't).

2) We don't have to qualify the term redshift with a prefix, but if someone comes across the term with a prefix and turns to wikipedia for help then the articles are already out there on doppler and compton and other phenonema for people to find out what the qualifier means.

Then the same argument should apply to Doppler-like redshifts. Recall:

Wikipedia does NOT have a scientific point of view: "There is a minority of Wikipedians who feel so strongly about this problem that they believe Wikipedia should adopt a "scientific point of view" rather than a "neutral point of view." However, it has not been established that there is really a need for such a policy" [25].

".. articles should be written from a neutral point of view, representing all majority and significant-minority views fairly and without bias." [26]

In other words, if you mention specific examples of frequency-dependent redshift, then to be fair and unbiased, frequency-independent redshift should at least be mentioned too. There's perhaps half a dozen frequency-independent redshifts (plus the Wolf Effect which will also produce frequency dependent redshifts).

--Iantresman 10:46, 8 December 2005 (UTC)

I think you mixed up the words "dependent" and "independent" throughout that last post. Your statement that there are perhaps a half-dozen redshifts that don't use the proportionality at all wavelengths is just plain untrue. That number of half-dozen is based on subcategorizations that you want to make. The very good reason that the article doesn't discuss these redshifts is that there are not "perhaps a half dozen" of them. There are an unlimited number based on subcategorizations that other people want to make. Any event, process, or activity that increases EM wavelength could be called this type of redshift because "redshift" is being used as a synonym for "increase in EM wavelength". Why do you only want to select six and how will you justify the six you select and the millions you don't select? As for photochemistry, will you include redshifted peaks in transmittance spectra? The redshift in the transmittance spectrum of hemoglobin when it becomes oxygenated is what turns blood from blue to red. Will you include redshifted peaks in reflectance spectra? This is what happens when I paint my house a different color and when an octopus changes the pigments in its skin. Do these individual usages fall into your half-dozen or will you lump them into "photochemical redshifts" or will you lump photochemical and other redshifts into "non-cosmological redshifts"? Every subcategory of usage will have similar sub-subcategories.

This entire debate is about usage and semantics because that was what you asked for in your request for peer-review. I agree with you that non-proportional redshifts are still redshifts. These redshifts are mentioned in the introduction to the article now. But picking and choosing which non-proportional redshifts to discuss as examples will always be an exercise in non-neutral POV and will always be inherently biased. The neutral POV is to present all of them together in one category as is done now. Flying Jazz 14:40, 8 December 2005 (UTC)

Surely painting your house red does not shift the frequency of light. Paint absorbs all but the red wavelengths. Likewise octpuses changing colours.

Sorry to sound facetious, but I can't find any peer-reviewed usage of "house-paint redsfhift" nor "octopus redshift", nor to the alledged effect causing it. However, I do find frequent reference to Brillouin scattering, Compton scattering, Raman scattering and the Wolf Effect with regard to redshift. I don't find "dozens" of other kinds of frequency-dependent redshifts mentioned by name,

The Wolf Effect, (a) produces an actual frequency-dependent redshift (b) may produce a frequency independent redshift that is indistinguishable from the Doppler redshift. See my extract immediately above the sub-head "general and specific". --Iantresman 17:15, 8 December 2005 (UTC)

Can somebody tell me under just what conditions the Wolf Effect does and doesn't give a frequency independent aka Doppler redshift? --Curious in Munich 20:08, 8 December 2005 (UTC)

You may only be reflecting the facetiousness that I may be emitting. Please read the first few sentences here about the redshift that occurs when cooking a lobster. http://www.ch.man.ac.uk/people/academic/RelatedDocuments/JRH/Lobsterphysicstodayoct2002.pdf

This lobster-cooking redshift (like angry-octopus redshift and painting-a-house redshift) is an example of a reflectance spectrum that has peaks at increased wavelengths. It's REAL! It's so real, your own eyes SEE it! The frequency of reflected light is shifted because the molecules in the material have been altered. Reflectance, transmittance, and absorption redshifts due to chemical change are three subcategories of terrestrial non-cosmological photochemical perhaps-biological perhaps-nutritional (insert adjective here) redshifts that don't involve emission. Then there are subcategories of photochemical redshifts that do involve emission and then there are a gadzillion other things that might not be photochemical redshifts but are other kinds of redshifts that might not be found in your abstract query from the Nasa Astrophysics Data System because there are no angry octopuses or cooked lobsters in space.

If you insist that I find peer-reviewed articles that use the term "reflectance redshift" or "angry-octopus redshift" or "biological redshift" then you are the one who is forcing this article into a scientific POV instead of a neutral one. Now it's time for me to cook a steak. I like my steak medium-well. Here's a test question for anyone who might be following along. Does cooking a steak cause a redshift or a blueshift in what my eyes see and do I need to consult a peer-reviewed journal to know when it's done just the way I like it? Flying Jazz 18:35, 8 December 2005 (UTC)

3) I didn't mean to imply that certain usages of redshift were minutae. I added these usages to the introduction of the article because I agree with you that they occur often and are NOT minutae. I meant that this debate about semantics and word-usages is minutae. Still important to have I guess.

My argument is that the introduction as it is now provides a list of the different usages of redshift. Usage 1 is qualitative. Usage 2 is a ratio. Usage 3 is a proportion. This satisfies your proposal (a). I think your proposal (b) is not so much about word usage as it is about selecting some of the many physical processes that involve word usage 1 and/or 2 (but not 3) as more important and more "listable" than other physical processes that do the same thing. Flying Jazz 04:57, 8 December 2005 (UTC)

It seems that the article is becoming less to do with Doppler-like redshifts, and more to do with the variety of uses of the term redshift in science. But I think that if we mention "bathochromic shift" we ought to give examples, just as we do with Doppler-like redshifts. For your average person, "bathochromic shift" means nothing; but pigments in lobsters changing colour (if indeed this is related), gives people something to relate it to. --Iantresman 22:37, 8 December 2005 (UTC)

You might be right. The bathochromic shift article could be spruced up a bit. As for the redshift article, my main purpose in adding photochemical usage is to add clarity so readers know what formal redshift isn't. Giving examples of bathochromic shift in a redshift article would be pretty dumb when there's a bathochromic shift article out there already ready and waiting. Flying Jazz 22:59, 8 December 2005 (UTC)

There's already a Gravitational redshift article page, so why not a Doppler redshift article, and Cosmological redshift article, or even "Doppler-like redshifts" page? I still think this Reshift page should be comparing and constrasting all types and possible causes of redshift, and not detailing Doppler-like redshifts. We are readily discussing "Non-Doppler-like redshifts", but where do I find out what this means? Why do people discuss Brillouin scattering and the Wolf Effect in the context of redshift? What is the significance of 500 peer reviewed articles that mention non-Doppler-like redshifts? If I go to the page on, for example, Galaxies there is little detail on any paricular galaxy, or type of galaxies; but at least I can find out what options there are. --Iantresman 23:25, 8 December 2005 (UTC)

I've already addressed these questions once because I took them seriously. See #2 in the discussion above. Now I'm starting to realize that they may just be rhetorical questions to you because when I answered them up there you just started asking them again down here. Flying Jazz 00:27, 9 December 2005 (UTC)

At the time that the questions were answered originally, there was no bathochromic shift mentioned in the article. Now that this has been added, it seems reasonable to wonder why mention of Brillouin scattering, Compton scattering, Raman scattering, the Wolf effect, and other theories such as tired light theories, are still excluded? The Wolf Effect, for example, has NOTHING to do with bathochromic shifts, NOTHING to do with scattering, but will also produce a redshift. --Iantresman 08:41, 9 December 2005 (UTC)

The Wolf Effect is the analog for Raman scattering in a plasma. --ScienceApologist 15:19, 9 December 2005 (UTC)

As far as I know, the different between them is that Raman scatting will produce multiplets, Brillouin scattering will produce triplets, whereas the Wolf Effect may produce a simple frequency-independent, Doppler-like redshift. --Iantresman 16:01, 9 December 2005 (UTC)

So what is the mechanistic difference between Raman scattering and the Wolf Effect? --ScienceApologist 16:08, 9 December 2005 (UTC)

There are numerous peer-reviewed articles that will explain it so much better than I can. Here are 6000+ peer-reviewed articles on Raman Scattering, and, 100 peer-reviewed articles that cite Emil Wolf's orginal article on the Wolf Effect. I'm only a nonscientist layman.--Iantresman 16:51, 9 December 2005 (UTC)

Since the two mechanisms are due to resonance within energetic relationships between constituents in molecules or ions in a plasma, then it is clear that they are mechanistically the same. --ScienceApologist 17:41, 9 December 2005 (UTC)

Bathochromic shift is not really a theory about anything. It's a tool or at most a raw observation that's used for information about things here on Earth. The addition of bathochromic shift was in response to your request for comments part (a). Having it here does not impact the reasonableness of including most of the effects you mentioned in (b) in one direction or the other.

Bathochromic shift is used astronomically, but fairly rarely I think, in this way: If there are two astronomically observed spectral lines that are near each other and if someone on Earth suspects that these lines may be due to two closely related molecules that exist in interstellar space, they can add a substituent to one molecule to obtain the other causing a bathochromic shift here on Earth and if the two spectral lines they get here match the ones out there, then it's evidence that those spectral lines out there might be due to the molecules. That usage (astronomical but not cosmological) occurs in this article: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11145341&dopt=Abstract This is astrochemistry. Not astrophysics.Flying Jazz 15:47, 9 December 2005 (UTC)

Redshift and Arp

This page has a section titled "Redshift interpretations in non-standard cosmologies" - That section is a perfectly valid place to put the following summary of Arp's interpretation of redshift:

Another critique of the standard interpretation of cosmological redshift has come from Halton C. Arp, who has claimed to find empirical support in the existence of apparently connected objects with very different redshifts. Arp has interpreted these apparent connections to mean that these objects are in fact physically connected. He has further hypothesized that the higher redshift objects (usually Quasars) are ejected from the lower redshift objects - which are usually active galactic nuclei (AGN). In Arp's model the large observed redshifts of these objects is dominated by a non-cosmological (intrinsic) component. Conventional cosmological models regard these as chance alignments and Arp's hypothesis has very few supporters within the research community.

Before I re-insert the paragraph I will wait for specific comments by others that actually have demonstrated a neutral POV on this page with regard to the neutrality of the paragraph. Joshua Scroeder's opinion is not the final say on this matter and I will not defer to it. Wikipedia is supposed to be a worldwide community resource and it is absurd that a single individual is persistently allowed to vandalize the efforts of others.

Personal attacks aside, my problem with the paragraph is that it gives a lot of credit to Arp without making it clear that a) his research is based on limited observations and has its roots in the quasar controversies of 30-40 years ago, b) why do you include a sentence about ejection and physical connection of quasars when the article is about redshifts? Isn't this a bit of a red herring? c) is there anything wrong with keeping the nonstandard section very short and having people who are interested link over to that article?

-ScienceApologist 02:29, 4 December 2005 (UTC)

Gives Arp a lot of credit? The paragraph includes the following phrases: "has claimed to find", "has interpreted", "has hypothesized" - and the paragraph concludes with a statement that he has very few supporters in the research community. You can't get any more neutral and factual than that. Its a simple statement of what he says and why he says it.

In response to your lettered points:

(a) The quasar controversy has been going on for 40 years. And the inclusion of the last sentence makes it clear that in that 40 years, he has gained very little support from other researchers.

When is the controversy going to be over? Arp doesn't seem to want to admit that he has been wrong about anything. Observations of host galaxies don't even seem to phase him. I don't accept that this is an ongoing controversy anymore than the Shapley-Curtis debate. --ScienceApologist 18:51, 5 December 2005 (UTC)

(b)First, the ejection is part and parcel of Arp's interpretation about redshift. Since the article is about redshift a sentence stating why he has concluded that there are intrinsic redshifts is necessary for context. But if we want to apply your criteria, then we should toss out the whole section on expansion of space - because the "article is about redshifts" - not about expansion of space.

Arp's critique represents an arguably narrow part of the entire redshift phenomenon. It applies only to Arp quasars. This seems a bit myopic for a broad article on "redshift" in general. --ScienceApologist

(c)Again, by that criteria, we should make the expansion of space section very short and refer people to the Big Bang or an entirely separate expansion of space article.

No, I think we should give in to notability in how something is reported. How notable is Arp compared to the Big Bang? --ScienceApologist 18:51, 5 December 2005 (UTC)

It is inconsistent of you to make arguments such as those in b and c but not apply the same argument to the portions of the article you like.

And you have to keep in mind that while Arp disputes the Big Bang, there are advocates of intrinsic redshift that think intrinsic redshifts are a phenomenon superposed upon the cosmological redshift from expansion. Those ideas would be most appropriate in this article. There really should be a section on Causes of redshift and another section on Alternative proposals for causes of redshift. --DavidRussell 15:18, 4 December 2005 (UTC)

What I don't understand about the comparison of intrinsic redshifts to a metric expansion is that an intrinsic redshift component smacks of unfalsifiability. It isn't a model for redshifts but it's an argument that there are other mechanisms for redshift that haven't been discovered yet. There is no formula to point to that describes an intrinsic redshift. This is different from the expansion of space which directly relates the scale factor to the redshift.

Reporting Arp here in an entire paragraph gives him proportionally more space than that which he is generally dealt with by those who study the phenomenon. I'm not convinced that Arp's ideas represent a significant enough of a minority to be portrayed in this way on this page. This is an editorial opinion, of course. --ScienceApologist 18:47, 5 December 2005 (UTC)

As a digression from our current RfC, I think this is quite an interesting point, but in a slightly wider context. Reading the redshift article, I note that the cosmic microwave background radiation has a redshift value of z = 1089. It would also seem to make sense that this redshift may be a commbinations of (a) Cosmological (b) Doppler (c) Gravitational (d) Other unspecified Doppler-like mechanisms. Since all possible causes are indistinguishable, is it possible to (a) estimate the proportion of each cause (b) Falsify anyone of them as contributing to the overall redshift? And then having said also this, isn't this very discussion of "intrinsic redshifts", whether real or not, a very real area of discussion, in which case a cursory summary of (a) why it is considered, and (b) rejected, must be worthy of comment? --Iantresman 19:06, 5 December 2005 (UTC)

Yes: (a) Cosmological. Almost 100%. (b) Doppler: 10⁻³. It is mainly responsible for the dipole, due to the peculiar velocity of Earth (c) Gravitational. Arguably the same as cosmological, but the Sachs-Wolfe effect is the main source of gravitational redshift. Probably about 10^-5. (d) None that I know of. There is a very carefully worked out theory that agrees with the data for all these. –Joke 03:27, 9 December 2005 (UTC)

Arp has been reinstated pruned down and ready for action. I'm not convinced we should include him, but in fairness to the fact that Zwicky's Tired Light gets a mention it's only fair that Arp's pathological skepticism gets a mention as well. --ScienceApologist 07:55, 9 December 2005 (UTC)

I guess that the word "pathological" is a bit outrageous, ScienceApologist, doesn't it?

Red shift or redshift?

In astronomy, redshift is most often used, but "red shift" is also acceptable. What is it like in chemistry? Do the chemists use "red shift" or "redshift" more often? This is of vital importance to the disambiguation. --ScienceApologist 02:43, 4 December 2005 (UTC)

I am not a chemist, but I believe the situation there is the reverse, that "red shift" is most common but that "redshift" and "red-shift" are acceptable alternatives. Dragons flight 04:16, 4 December 2005 (UTC)

From what I can gather this is true. So perhaps the disambiguation should go on the Red shift page instead of here? We already link to this page at the top of the article. We can just make it clearer that this is the redshift associated with astronomy. --ScienceApologist 04:19, 4 December 2005 (UTC)

Redshift proposal clarification

I just wanted to clarify what is being proposed. The way I read the suggestions is as follows:

The current Disambiguation page, "Red shift" (two words), summarises scientific and non-scientific uses of the word Redshit and redshift, pretty much as it does now.
It is proposed that the current page on "Redshift" becomes a Disambiguation page summarising scientific uses of the word redshift such as (a) Astronomical (Doppler-like) redshifts (b) Non-Doppler-like redshifts (c) Any other scientific uses of the word redshift.
It is proposed (by Dragons flight's) that a new page be created called something like "Astronomical redshift", which will describe all Doppler-like redshifts.

To which we should add that:

All scientific redshift pages should include a fair and prominent mention to the other redshift pages. eg. The Astronomical redshift page would mention something like "See also other scientific uses of the term redshift.

--Iantresman 10:42, 4 December 2005 (UTC)

The proposal I laid out is different: disambig on the Red shift page and expand the dynamic disambig link at the top of this page. --ScienceApologist 14:26, 4 December 2005 (UTC)

As I see it, there are now three options on the table:

1. My original Request for Comments described above

2. Dragons flight's suggestion of a compromise "Astronomical redshifts" page, as I have described in the section "Redshift proposal clarification".

3. And now your suggestion to expand the existing "Red shift" Disambiguation page.

The problem I have with the last suggestion is that the use of the term 'redshift" as used by scientists in peer-reviewed journals regarding Brillouin scattering, Compton scattering, Raman scattering, the Wolf effect, neutrino redshift, and other theories such as tired light theories, tend to use the word 'redshift' without a space.

--Iantresman 15:17, 4 December 2005 (UTC)

Actually, there seem to be more articles that use "red shift" with the space in terms of the Raman scattering, for example. The chemists that use "red shift" in this sense are referring to a "shift to the red". That's not to say there are no examples of chemists using "redshift", just as there are examples of astronomers using "red shift". It's simply a matter of what seems to be common practice. If we could get an optical chemist to weigh in, that would probably be the best. --ScienceApologist 15:49, 4 December 2005 (UTC)

Raman scatting is just one cause out of several others mentioned. Looking at Google Print, I find:

"Compton Scattering" + redshift = 133 refs 10-fold usage over + "red shift" = 13 refs
"tired light" + redshift = 65 refs 9 fold usage over + "red shift" 7 refs
Brillouin + "redshift" = 5 refs slightly less than + "red shift" 8 refs
"Non-cosmological redshift" 11 refs exclusively over "Non-cosmological red shift" [0 refs]
"Intrinsic redshift" 55 refs almost exclusively over ::::*"Intrinsic red shift" 1 ref

So whereas Raman and Brillouin scattering seems to use "red shift" slightly more than "redshift", all other uses I've mentioned heavily use the single word "redshift". --Iantresman 16:40, 4 December 2005 (UTC)

This confirms what I suspected. Compton Scattering as a mechanism for redshift is promulgated by one disgruntled, retired NASA scientist and isn't studied outside of this. Tired light is Zwicky's idea, and intrinsic/non-cosmological redshifts are all Arp promotions. Since Birllouin and Raman scattering are well-known as the "other sort" of red shift, I say we include them on the red shift page. That removes them from discussion here.

Now we need to discuss the notability of Compton-scattering, tired light, intrinsic redshifts. The section at the bottom of the page should cover that.

Does this satisfy? --ScienceApologist 17:12, 4 December 2005 (UTC)

As far as I can tell from the previous discussions:

The only person in favour of your proposal is yourself.
The only person in favour of your defintion of redshift is yourself.
The only person who does not accept other uses of the term redshift (except in respect to Raman scatting) is yourself.
The only person who rubbishes 500-peer reviewed references to other uses of redshift (except in respect to Raman scatting) is yourself.

But the original Request for Comments is still in its early days yet, and I anticipate at least some criticism of my proposals from someone other than yourself. --Iantresman 18:01, 4 December 2005 (UTC)

Perspectives

The issue here is the definition of redshift. I see no reason for any particular controversy here. Use of the term "Redshift" in science literature predominantly refers to astronomical redshift, this is pretty obvious. In astrophysics, the cause is mostly assumed to be cosmological, i.e. Hubble expansion. This is also not in dispute. However, other uses of the phenomenon in science are notable and should be included.

Redshift is a shift (towards the red) in the absorption or emission spectra of a light source, when compared to fixed well-known chemical spectra. The term was first used in astronomy and astrophysics, where it almost always refers to galactic redshift and is assumed to be caused by expansion as inferred by the Hubble relation ... blah blah. This is not in dispute, regardless of whatever your personally preferred explanation for the observed redshift is.

However, redshift has also found applications in other fields, such as analytical chemistry. Subsequent investigations have found several physical and chemical processes that can cause redshift in materials, some of which are frequency dependent. Such effects are ... blah blah.

Given this, I'm not sure what the fuss is about. I don't think we need a separate Astrophysical redshift page, if people are willing to be sensible. Sadly, there is one troublemaker here on some strange personal vendetta. Jon 08:44, 5 December 2005 (UTC)

There are a few nitpicks I have with your comments:

Redshift is not always cosmological. It is sometimes due to gravitational or Doppler velocities as shown in the article.
Redshift is a shift to lower frequency not just "toward the red". I'm assuming you know this though and just glossed it over. However, it's important we get it right in the article.
The redshift term does not "almost always" refer to galactic redshift. In cosmology it may, but there are plenty of stellar astronomers who never refer to galactic redshifts.
The redshifts in analytical chemistry are often termed "red shift" with the space. As such, why not include those on the disambig page?
That Iantresman is on some strange personal vendetta may be true, but that's beside the point.

ScienceApologist 08:57, 5 December 2005 (UTC)

I was glossing somewhat. Unfortunately I was talking about you, but I'm assuming you have a wry sense of humour. In particular, what is your problem with mentioning non-astrophysical redshifts? The current article launches straight into astrophysics without first covering a general definition.

I remember from my geochemistry that redshift came into XDF analyses. Interestingly, while searching for crystallogrphy and redshift, I came across this curiousity - Arxiv which is probably not hugely relevant yet still interesting. Jon 09:04, 5 December 2005 (UTC)

I have no problem mentioning analytical chemistry red shifts whatsoever. However, as I pointed out above, I think they more often use "red shift" as opposed to "redshift". --ScienceApologist 09:12, 5 December 2005 (UTC)

I think it's a mistake to put too much emphasis on the presence or absense of a space. I think we have seen that the usage is not universal, neither is it logical, and I wouldn't count on a Wiki reader choosing the right one. That might mean redirecting from "Red shift" to "Redshift" and sorting out the other issues with one page less, but I don't have a comprehensive suggestion so I'll duck and cover again. --Art Carlson 10:33, 5 December 2005 (UTC)

I think Wikipedia needs a pub. Everything gets settled one way or another at a pub. - Roy Boy ⁸⁰⁰ 17:44, 5 December 2005 (UTC)

I agree, make mine a double Jon 00:52, 6 December 2005 (UTC)

Criticism

From above:

Incidentally, the page has been updated with good figures but a poor text edit which removed much of the clarity and rigour.--Serjeant 16:45, 5 December 2005 (UTC)

Ouch. Can you point to an example? --ScienceApologist 19:04, 5 December 2005 (UTC)

OK. To be fair the graphics are really very good - I just have a problem with some of the new text. Here are some quick comments, working down.

The first comment is one of style. The article starts out with a lengthy description of the context of redshift; I believe it should immediately define the thing (with an equation). Context can come later.

In the causes section, it starts by suggesting that the expansion of space "creates new space between the source and the observer". This is incorrect, and in any case contradicts expansion as described - is it stretched old stuff or new stuff?

Good catch. The sentence has been reworded. --ScienceApologist 18:57, 6 December 2005 (UTC)

A bit further down, the Doppler effect is described using a Taylor series, which is by definition approximate. This is an encyclopedia definition, so either the full equation or the low-v limit should be quoted.

Full equation instated. Low-v limit quoted. --ScienceApologist 18:57, 6 December 2005 (UTC)

Much nicer :) --Serjeant 19:34, 6 December 2005 (UTC)

In the next section we have "metric expansion of a vacuum can occur faster than the speed of light". Later we have "the effect is Galilean invariant with physical movement of the galaxies". Both of these are pretty nebulous if they mean anything at all.

The first comment I think is important considering the present dark energy issues of expansion and also cosmic inflation. Perhaps it should be reworded with reference to horizons?

I completely understand your enthusiasm to communicate exciting advanced ideas, but we must avoid losing the reader. To do this carefully and rigorously we would need to introduce too many extra concepts, such as proper distance (as opposed to comoving), time-like hypersurfaces and so on. In the interests of succinct and accessible definitions, perhaps it's best to say simply that distances increasing due to expansion of space is a physically different situation to things moving inside that space. There's nothing stopping us linking to other pages though.-Serjeant 19:34, 6 December 2005 (UTC)

I think I agree with this, however since we quote redshifts that are far greater than 1 there is a natural tendency for people to ask the question of how you can get velocities faster than the speed of light. --ScienceApologist 18:33, 7 December 2005 (UTC)

I'm not sure why you think the second comment is nebulous.

The situation is better described by the original text: "Nevertheless, astronomers (especially professional ones) sometimes refer to 'recession velocity' in the context of the redshifting of distant galaxies from the expansion of the Universe, because they all know it's only an apparent recession. This can sometimes be confusing to the intelligent lay person who does not realise the astronomers are just talking in a shorthand, and aren't in fact ascribing this redshift to a real recession movement of the source."--Serjeant 19:34, 6 December 2005 (UTC)

I think that this statement is a bit weasely and slanted. For one, it bifurcates the population into intelligent lay people (who defines their intelligence) and "the astronomers" who form a cadre of jargon-using closed-shop misers of terminology (a characterization that Iantresman may agree with, but isn't NPOV). Anymore, most cosmologists I know don't speak of the Hubble Flow as representing a recessional velocity since the scales have increased enough to allow for redshift space up to 6,7,(10). Recessional velocities in those instances make little physical sense. Recessional velocities tend to be used when referring to high velocity clouds, for example. In those cases, they are due to actual recessional velocities and not the Hubble Law. Maybe we should dispense with the connection between the Hubble Flow and recessional velocities altogether. --ScienceApologist 18:33, 7 December 2005 (UTC)

All disciplines, including astronomy, have techincal terms which use words in a more specific and restricted sense than their general use outside the field. This is a genuine bifurcation, as you put it, and it is not in any sense contentious to portray it as such. I'm afraid you're mistaken if you think professional astronomers never use the term "recession velocity" in the knowledge that it is not Doppler. It is even implicit in the term "Hubble flow"; this "flow" is clearly not a flow, but no professional is confused.--Serjeant 15:34, 8 December 2005 (UTC)

I think what I'm trying to say is that the distinction may be broader than the sentences you proposed. Astronomers say a lot of things about redshift space in different contexts. I wasn't claiming that astronomers "never use the term", only that it has started to fall out of use a lot more in the last decade or so. --ScienceApologist 20:36, 8 December 2005 (UTC)

--ScienceApologist 18:57, 6 December 2005 (UTC)

Further down, space is not expanding DUE TO a time dependent scale factor. The latter is a description, not a cause.

I disagree. I think the Friedmann Equations provide a cause for space expansion by allowing for a scale factor. If general relativity didn't describe cosmological scales, we would have no notion of expanding space. --ScienceApologist 18:57, 6 December 2005 (UTC)

So the time dependent scale factor causes the expansion of the Universe? I still contend that the former describes the latter, rather than causing it. The causes of the expansion of the Universe are better given as the initial conditions (but what caused them?) combined with the requirement of obeying the Einstein field equations.--Serjeant 19:34, 6 December 2005 (UTC)

Well, it depends on whether you think that "due to" implies causality and whether causality is in the sense of the arrow of time. The redshift of light is due to the scale factor in the same way that the ratio of force to acceleration is due to the inertial mass. Isn't this a bit nitpicky? Inflationary theory, of course, demands a scale factor as the (roughly) linear remnant of the inflaton exponential expansion and in some sense can be thought of as the set for "initial conditions". So is this statement really so problematic? ScienceApologist 18:26, 7 December 2005 (UTC)

"Due to" can easily be taken to mean a causal link. In any case, the article is not saying that redshift is "due to the [changing] scale factor", but that space is expanding due to the scale factor, which is tautological. Really, the phrasing needs a lot more care I'm afraid.--Serjeant 15:34, 8 December 2005 (UTC)

But tautology is often employed in physics vis-a-vis Newton's Second Law. How would you rephrase it (or would you simply omit it)? --ScienceApologist 20:36, 8 December 2005 (UTC)

Then it describes "a coordinate shift in the electromagnetic wave to lower energies". Have we just moved into phase space?

Perhaps poorly worded. I'm not sure how to reword it though. --ScienceApologist 18:57, 6 December 2005 (UTC)

It's not a coordinate shift (transformation?).--Serjeant 15:34, 8 December 2005 (UTC)

How is it not an affine transformation? --ScienceApologist 20:36, 8 December 2005 (UTC)

It's not a coordinate transformation in the sense that GR uses the term; i.e., it's not referring to choices of reference frame. You're right that you can, somewhat imaginitively, regard all physics as a mapping of a past phase space position onto a future phase space position. When this mapping is linear, you can call it an affine transformation. However this is taking us well outside the realm of defining redshift in the most accessible and accurate way. I think we would be best keeping to the conventional use of "coordinate transformation" in the context of general relativity.--Serjeant 10:27, 9 December 2005 (UTC)

I'm trying to think what the difference is between a general relativity transformation and the redshift due to the expansion of space. My favorite set of transformations in GR are those dealing with the Schwarzchild metric. You can switch back and forth between different sets of coordinates to gain perspective on the hypersurfaces of the black hole. I cannot for the life of me see how this is any different than taking two timelike hypersurfaces and transforming between the two of these. In fact, if I remember correctly, that's how the redshift is defined in relativity. --ScienceApologist 15:28, 9 December 2005 (UTC)

Joshua, one is a co-ordinate transformation, which is arbitrary, and one is a physical change. To say that redshift is the result of a coordinate shift is to risk implying redshift is not a physical effect. The energy density of the CMB photon gas *is* decreasing; it is not the result of a coordinate transformation.--Serjeant 17:35, 9 December 2005 (UTC)

I've had this argument before and it may be intractable. What is the difference between a "physical change" and a change in the observer's frame of reference in this regard? After all, the energy density of the CMB isn't really decreasing if you use comoving coordinates, it's the same as it was the time it first freely streamed. All that's changed is rulers in relation to microphysics. Coordinate transformations in GR correspond to different perspectives that lead to different "physical changes". If you follow the geodesic or you stay a given proper distance away from a black hole, the "physical properties" of the black hole change. This is parametrized by the coordinate transformation. Is that indicative of physical effect? Likewise while a redshift corresponds to an actual "observation", what it may not correspond to is an actual "physical change" since this is really an artifact of the integration over the scale factor through proper time. --ScienceApologist 18:36, 9 December 2005 (UTC)

Here is a proof that I am immortal. Let t0 be the time which I die. Change time coordinates from t to t'=t*(1+(1/(t0-t))). As t tends to t0, t' tends to infinity. Why am I not reassured? --Serjeant 13:31, 12 December 2005 (UTC)

Because whether someone observes your immortality is immaterial as you, as a massive particle, have your own Lorentz frame worldline to worry about. However, the only form we have for dealing with redshift is in an observer's frame (because there is no such thing as a photon rest frame). So it really can be said that the physical change and the change in the frame of reference are equivalent. --ScienceApologist

"Such an effect is exactly analogous to a redshift caused by a recessional velocities that increase with the distance away from the observer." Plain wrong, I'm afraid.

There are subtle differences, but I think saying that this statement is "plain wrong" is a bit overkill. How would you modify it? --ScienceApologist 18:57, 6 December 2005 (UTC)

It's different; therefore it's not "exactly analagous". It's nothing to do with overkill , it's about an encyclopedia entry being correct.--Serjeant 14:35, 8 December 2005 (UTC)

If we remove "exactly" does that satisfy? --ScienceApologist 20:36, 8 December 2005 (UTC)

My feeling is that we would be best avoiding all claims of analogy between space expansion and Doppler shift.--Serjeant 10:27, 9 December 2005 (UTC)

Can one of you tell me what the difference is? How can I operationally distinguish between recessional velocities and expansion of space? --Art Carlson 11:02, 9 December 2005 (UTC)

The biggest difference I can think of is that you can see physical objects that have a "recessional velocity" (in the proper distance versus time sense) greater than the speed of light. ScienceApologist 15:23, 9 December 2005 (UTC)

Does that translate into an upper limit for z due to physical velocities? If so, then I can distinguish the source of some but not all redshifts. If not, I still don't know what observations I can make that would rule out one effect or the other. --Art Carlson 16:22, 9 December 2005 (UTC)

There is no upper limit for z since there is no upper limit on γ. Observationally, the cosmological redshift and the Doppler redshift are indistinguishable, but because they are mechanistically different for a z larger than a certain value for the right cosmology, the object will be outside of a physical horizon (though not an observable horizon). This is different from the Doppler interpretation. --ScienceApologist 16:39, 9 December 2005 (UTC)

Then they are "exactly analogous" in the sense of being observationally indistinguishable? Is it only a question of the "interpretation" of the observations? --Art Carlson 20:36, 9 December 2005 (UTC)

That's about as much as I have time to do for now. I don't want to sound like we shouldn't be grateful for people putting in their time for free for the public good here, but at the moment we have an article which has quite a few loose ends. The figures are super though.--Serjeant 15:13, 6 December 2005 (UTC)

I'd like to disagree with one point. I don't think the article should start with an equation.

Wikipedia is aimed at all, not just scientists. Equations mean nothing to the vast majority of people.
Redshift primarily is an observation; I think that's the one thing everyone agrees upon: a movement of a spectral line. Its alledged causes, and formal description using maths are secondary.

--Iantresman 15:22, 6 December 2005 (UTC)

The redshift entry in my old Penguin Dictionary of Physics has a two-sentence description in words, then a less ambiguous algebraic definition of the same, which seems the right balance to me. I'm afraid that most knowledge of the physical universe is closed to someone for whom equations mean nothing at all.--Serjeant 15:31, 6 December 2005 (UTC)

Exactly. Description first, maths later. And arguably the maths only quantifies the redshift, it says nothing about the cause, nor how the phenomenon manifests itself. --Iantresman 17:01, 6 December 2005 (UTC)

Both of which can come later. The equations should come very early on because they are the most succinct and unambiguous definition.--Serjeant 18:19, 6 December 2005 (UTC)

Wikipedia:WikiProject Physics

I just found the RFC associated with this page. A really good place to announce such things, and ask for help, is at Wikipedia talk:WikiProject Physics. That is the place where most of the physicists hang out, and in particular, the people with the PhD's. However, you don't need a PhD to participate -- its just a good place where physics topics can be discussed and announcements/requests can be made. linas 06:14, 8 December 2005 (UTC)

NPOV removal

Since we've resolved the issues with respect to photochemistry (which umbrellas Raman scattering, Brillouin scattering, etc) and we've established a consensus intro, the NPOV tag is not appropriate. --ScienceApologist 07:12, 9 December 2005 (UTC)

Maybe. Photochemistry requires chemistry, not physics. I'm pretty sure that Bathochromic redshifts only apply to the physicochemical state changes of molecules. Never atoms. That's not chemistry, so the umbrella of photochemistry isn't big enough. The additional parts of the article about z that isn't proportional at all wavelengths provide this umbrella I think. However, the main problem that Ian had with this article still exists in most ways. The article has a POV that doesn't mention the specific physical (whether chemical or not) redshifting that he wants to be mentioned in here. Flying Jazz 15:47, 9 December 2005 (UTC)

I've restored the Neutral Point of View tag. As far as I can see, we're still in the middle of a Request for Comments. I disagree that we have developed a consensus intro. We have had some great discussion and contributions from FlyingJazz, yet we have completely ignores support from Harald88, David Russell and a contribution from Eric Lerner. --Iantresman 08:41, 9 December 2005 (UTC)

Being in the middle of an RfC does not mean that the NPOV flag needs to stay. The NPOV flag should come down when it is clear there is no longer an issue of NPOV. So far, I have not seen any indication that there are any outstanding issues. --ScienceApologist 08:45, 9 December 2005 (UTC)

Ian's proposal part (b) included a list of causes of redshifted lines in an astrophysical context, not a photochemical context. Ian is right that some astrophysical redshiftting (in the qualitative not-z-proportional sense) is caused by effects that are not specificly mentioned in this article at the moment. They aren't photochemical effects either. The question is should they be mentioned? To me, the answer is entirely dependant on whether they can be described and compared in a way that is rational, doesn't seem arbitrary, and doesn't refer to cosmology. It seems like some crap like tired light theory obviously shouldn't be in such a list. But I honestly don't know enough about some of the others. ScienceApologist...from a purely empirical perspective without any reference to cosmological theories, are some astrophysical spectra observed with shifted lines that aren't completely accounted for by one value of z or molecular interaction? Maybe I am talking about the difference between "the redshift" meaning z-proportional and "a redshift" meaning a line or lines that don't exactly follow "the redshift." I'm more of an expert on terrestrial chemistry and I freely confess to still being confused about the main issue. Flying Jazz 15:47, 9 December 2005 (UTC)

oops. I've been paying so much attention to the introduction, I didn't see the last section of the article. There is still something unusual going on in this article though. If individually shifted lines in a spectrum that vary from "the redshift" of the entire spectrum are still called "a redshift" by physicists then I'm not so sure they should be only mentioned in a section on non-standard cosmologies. Just because a few people misuse these redshifts to create poor cosmological theories, is that a reason to only mention them here? Flying Jazz 16:05, 9 December 2005 (UTC)

500 peer-reviewed scientists MISUSE the term? They use it correctly in their context, just as chemists use the term correctly in a bathochromic context. It seems that the only people who assume "redshift" has only a cosmological-related meaning, are astronomers.

The article already mentions tired light, at least giving people the opportunity to find out more elsewhere. There should be at least a sentence explaining why the theory was suggested and why it was rejected. Currently the article just says that it was, with no substantiation. I also feel we should mention Greenberger's theory of variable mass particles (yet another peer reviewed reference: [27])

And still we do not mention the other types of frequency-dependent redshift, all of which have been demonstrated to work in the laboratory (except for neutrino redshift), including the Wolf Effect that will produce a frequency-independent Doppler-like redshifts too. --Iantresman 16:39, 9 December 2005 (UTC)

The "500 peer-reviewed scientists" aren't proposing alternative cosmologies when they talk about redshift in the context of this effect or that one. They're mostly just discovering or reporting interesting empirical phenomena. People who point to their usage as evidence for alternative cosmologies are misusing the sceintists and the term redshift when they are not as exact as possible about what those scientists are discussing. As soon as I added the photochemical definition, you wrote a post in talk saying that this addition was justification for other theories to be introduced and ScienceApologist added this content to the article itself, "There are also advocates of nonstandard cosmologies which claim that certain bathochromic shifts can account for redshifts" after the article itself says bathochromic shifts ARE redshifts! You and ScienceApologist both want an unneutral POV skewed towards one cosmology or the other using anything found in this article.

Redshift is an empirical observation with certain causes that point towards certain cosmologies. There are demonstrated and undemonstrated causes. The undemonstrated causes like tired light should not be discussed in the article in my opinion. The cosmologies are two steps removed from the topic of the article. Only the standard cosmology should be mentioned and that should only be in passing. Cosmology seems to be the motivating factor for both of you to contribute anything to this article. I hope that changes. Flying Jazz 17:28, 9 December 2005 (UTC)

Sounds good to me. --ScienceApologist 17:39, 9 December 2005 (UTC)

Section removal

Since there are policies regarding the inclusion of extreme minority positions at Wikipedia:Neutral point of view#undue weight and Wikipedia:Neutral point of view#Giving "equal validity" ~~and according to the suggestion of User:Flying Jazz above~~, the section on non-standard cosmologies has been removed. --ScienceApologist 17:48, 9 December 2005 (UTC)

Please do not take actions in my name. It is uncivil. I agree with your action, but it is something I would not have done immediately without further discussion first. In the future, say something like "I agree and did this" instead of the sneaky nasty passive "according to the suggestion of...this has been done." Flying Jazz 18:14, 9 December 2005 (UTC)

Sorry, I didn't mean to imply you endorse my actions, I just was inspired by your comments. I take full responsibility for my own edits. --ScienceApologist 18:18, 9 December 2005 (UTC)

An absolutely appalling unilaterial decision. It makes a mockery of "Request for Comments". And to suggest that it is taken regarding Wikipedia's "neutral point of view", is a joke when the very first line of the policy says that articles should be written "representing all majority and significant-minority views fairly and without bias." The article now implies that there are NO minority views, and that non-cosmological redshifts are not even considered by anybody. Stalin would have approved. Disgusted. --Iantresman 21:00, 9 December 2005 (UTC)

Protected

This article has been protected due to edit-warring. When consensus on how to proceed has been reached (hopefully with the help of the RfC), please place a request for unprotection at WP:RFPP. ≈ jossi fresco ≈ t • @ 21:13, 9 December 2005 (UTC)

Can you refer to the difference links that refer to this being an edit war? --ScienceApologist 21:13, 9 December 2005 (UTC)

If you disagree with the page protection, you can make a request at WP:RFPP. ≈ jossi fresco ≈ t • @ 21:18, 9 December 2005 (UTC)

I asked Jossi to intervene as I felt there were edits being made that had not fully discussed and agreed upon. You'll notice that I have not made ANY edits to the article since putting in the "Request for Comments" (RfC) since I feel it has not run its course and no consensus has been reached.

You'll note that after receiving positive support from Harald88, David Russell and Eric Lerner, I didn't jump in and implement my proposal --Iantresman 21:38, 9 December 2005 (UTC)

I have this page on a watch, and I have to say I was shocked SA wiped such a big chunk of the article. Non-standard cosomologies pop up fairly often in science magazines, and several pages on WP essentially apologize for the cosmological red-shift not being among the kinds of red-shift you first encounter when you study the topic. As such, the deleted text stands as an explanation of why you can develop a non-standard cosmology from first principles. That a non-standard cosomology relies on these principles does not invalidate the principles. I'm okay with protection until wholesale destruction of the article is under control.Jok2000 21:48, 9 December 2005 (UTC)

Unlocked, as the revert immediatly preceding the lock by the locking admin seems a bit questionable. An Rfc does not mean editing must stop. Vsmith 23:29, 9 December 2005 (UTC)

There is editing, and there is wholesale, unilateral removal of an entire section. That's not consensus, nor cooperation, nor in the spirit of the Request for Comments. --Iantresman 00:37, 10 December 2005 (UTC)

Proposal part (b)

I think (although I'm not 100% certain) that much of the support for Ian's proposal is because he's right that there are many astrophysicists who do work on redshifts that have demonstrable causes which are not mentioned in this article right now and they should be mentioned. Ian's list:

Compton scattering, Raman scattering, Wolf effect, Neutrino redshift, tired light theories, non-Doppler redshifts, non-Cosmological redshifts, intrinsic redshifts

has two closely related problems.

1) It contains a mixed bag of actual causes, classifications of causes lumped together, and unproven theory. He makes a good point with his journal articles. The actual causes of astrophysical redshifts and some mention of how they are categorized should be in this article because the word is used by astrophysicists in that context, but the bag should be unmixed by someone familiar with the field so that proven causes are included, lumped classifications are formalized, and unproven theory is discaded. Why discard unproven theory from this list? For the same reason that "Big Bang theory" or standard cosmology or whatever it's called should not appear on the list of causes that is in the article currently. "Big Bang theory" is not exactly synonymous with "expansion of space." Expansion of space is a commonly used cause to explain redshift. The standard theory is one step further removed. It's a theory that's consistent with this cause.

2) It contains causes for redshifts which do not have z as a proportionality constant at all wavelengths, and so they are different from the causes that are mentioned in this article right now. Just because they're different, that doesn't mean they shouldn't be included. I think they should be included along with the reasons why they are different. Ideally, I think there should be a table of with column headings of "effect," "wavelengths applicable," "proportional z?" "comments" and one or two other column headings that people want. For the three currently in the article, the entries would be wavelengths applicable: all and proportional z: yes. For Compton scattering, the entries would be whatever wavelengths correspond to 0.5 MeV to 3.0 MeV (if those values are right) and no. The Compton scattering equation could even be put into the table here. This will take work from a skilled person who cares about astrophysics.

A table like that would help everyone no matter what cosmological theory they are proposing. Flying Jazz 23:13, 9 December 2005 (UTC)

Isn't the problem more to do with how to present the variety of causes, rather than whether to include them? I envisage something along the lines of the following (together with references):

Redshift type
Name(s) Date
Discovered
(or predicted) Frequency
independent?
(ie. ∝ Z) Full
spectrum? Spectral
Distortion? Laboratory
Demonstrated? Main area
of study Notes &
References

Doppler-like redshifts

Doppler redshift 1750? Yes Yes No Yes Astronomy

Cosmological redshift
(Hubble redshift) 1920 Yes Yes No No Astronomy

Gravitational redshift
(Einstein shift) 1950 Yes Yes No Yes Astronomy

Scattering redshifts

Brillouin scattering ???? No Yes Yes Yes Chemistry/Physics

Compton scattering ???? No Yes Yes
(Doublets) Yes Chemistry/Physics

CREIL ???? No Yes Yes Yes Chemistry/Physics

Raman scattering ???? No Yes Yes
(Multiplets) Yes Chemistry/Physics

Other types

Bathochromic shift 19?? No No No Yes Chemistry

Wolf effect 1985 Yes/No Yes No Yes Physics/Optics

Theoretical redshifts

Plasma redshift 1920 No Yes No No Astronomy

Tired light 1920 No Yes No No Astronomy

Variable mass 1970 ??? Yes No No Astronomy

Neutrino redshift 1970 Yes Yes No No Astronomy

--Iantresman 23:59, 9 December 2005 (UTC)

OK. That's a start. Looking at that "Laboratory demonstrated?" column makes me think it's a start that makes your agenda laughably obvious! But it's still a start and I hope other people build on it. Actually, I hope people subtract from it. I'd get rid of the "Date Discovered" column. Why? People can go to the indivudual effect for that. I'd only include examples in astrophysics and eliminate the "Main area of study" column. Why? Because z and spectral distortions are irrelevant for photochemical applications (bathochromic) where emitted wavelength doesn't even appear in the equation. These should be redshifts that represent a change between emitted and received. And of course, I'd eliminate the "Theoretical redshifts" because redshift is an observed phenomenon. I can't comment on the category names because I'm not familiar enough with the field. Numbers (like wavelength ranges for Compton and widths for Wolf) would be good because we're trying to teach people about redshifts here. Flying Jazz 00:49, 10 December 2005 (UTC)

Can we have a citation to someone who looks at scattering and considers it a redshift? Apparently there are chemists that view it as a bathochromic shift, but it is highly aberrant to conclude that there are people studying Compton scattering who call the frequency change in photons a "redshift" other than John Kiernan. This is a problem for Wikipedia:Netural point of view#Undue weight. The table should be reduced to four rows, one each for the three kinds of physical redshift and one for bathochromic redshifts, as far as I'm concerned. --ScienceApologist 02:26, 10 December 2005 (UTC)

I have provided 500 peer reviewed articles. See my comments below on how you can double-check yourself. Your comment on undue weight would be accurate if the article was about "Doppler-like redshifts". It's about "redshift". You wouldn't exclude "pluto" from an article on planets because it is less significant that the rest. The Wikipedia article even includes "Other candidates" when they are clearly not planets; but at least they are listed, and an explanation is provided as to why they are mentioned. There are even sections on "Suggested wide definitions" (of 'planet'). --Iantresman 12:04, 10 December 2005 (UTC)

Reread the first sentence of the article and get your mind off of cosmology and chemistry for just a minute or two. Are you reading the first sentence of the article? Good. Read it again. Has it sunk in yet? Good. Now then, imagine an effect due to atoms or electrons or interference or scattering or something and it causes an increase in wavelength between light emitted and light received. It doesn't involve molecules in a spectrophotomer so it's not chemistry and it can't be a bathochromic shift. Is this increase in wavelength between light emitted and received a redshift? Quick! Yes or no? Are you reading the first sentence of the article?

You might be right that almost no physicist would call these wavelength increases redshifts because they don't shift the entire spectrum in a proportional way like z should. I don't know if you're right or not. Ian goes on about 500 articles talking about these things. I don't know if he's right or not. But both of you seem to be putting the cosmology first and working backwards through the causes to the observables you want or don't want to call redshifts instead of dealing with this article about observables. Red shift is an observable. There really do seem to be a lot of people who look at compton scattering and call it a red shift of a spectral line because what we receive is different from what was emitted. I don't know if they're all wackos or not. You can imagine a physicist saying, "Oh that wavelength change? That's just Compton scattering. That's not a redshift." You can't imagine anyone saying, "Of that redshift? That's Compton scattering. That's not a the kind of redshift we're interested in" without declaring their usage to be wrong. The problem may be with your imagination.

If you conceded that astrophysical events that increased any spectral wavelength in any way between emission and reception could all be called redshifts, how would you change Ian's table? Flying Jazz 04:05, 10 December 2005 (UTC)

Discovery/prediction date is not vital, but interesting. A table of planets might give discovery date. I see no reason to remove it, unless the table is short of space.
Frequency independent I think helps define the different kinds of redshift.
Spectral Distortion? helps characterise the different kinds of redshift, in particular the unique properties of Doppler-like redshifts.
Laboratory Demonstrated? This is important for ALL kinds of redshift. (1) It differentiates the redshifts from each others, (2) Tells you if, for example, CREIL is demonstrated or not. You're right that I do have an agenda: to fairly describe all types of redshift.
Theoretical redshifts - I don't see why incuded these are a problem. (a) Yes, redshift is observed; is the cause due to X, Y or Z? It doesn't matter, but let people find out that certain theories don't work for whatever reasons (b) Prediction is a cornerstone of the scientific process. (c) Some of them, like 'Neutrino redshift' provide an independent means of testing Doppler-like redshifts.
Perhaps we also need a column "Full spectrum?" as this also differentiates the different kinds of redshift.
"Reread the first sentence of the article and get your mind off of cosmology and chemistry"
And more importantly, read the title of the article: "Redshift"! There are already articles on Gravitational redshift and Wolf effect etc., and there should be an article on "Doppler-like redshifts" where it can be discussed more fully. But this is an article on just "Redshift".
"Ian goes on about 500 articles talking about these things. I don't know if he's right or not."
This disappoints me. I provided the peer-reviewed reference so that they can be checked. Nearly every item listed includes an online abstract so that you can double-check the usage of the word. Joshua has quibbled my selection, though he has not been able to show any examples where I was incorrect.... and there are some, but I rounded my numbers down to exclude them. Simply click the links I provide, and then click on the dated reference number in the left-hand column, or the letter "A"; Here are some examples of peer-reviewed articles titles (culled from the links just mentioned, one from each redshift type), which uses the term 'redshift' in a variety of contexts:

"The origin of the redshift in Brillouin spectra of silica films containing tin nanoparticles"
"AGN Jets at High Redshifts: Inverse Compton Scattering of the Cmb?"
"Quantized Redshifts of Galaxies: Stimulated Raman Scattering in Cold Intergalactic Rydberg Matter"
"Redshifts via "Coherent Raman Effect on time-Incoherent Light" "
"The Wolf effect and the redshift of quasars"
"Noncosmological Redshifts"
"Lab Experiments Revealing Non-Doppler Redshifts with Possible Cosmological Applications"
"Neutrino Redshifts -- A Search for Information"
"Further Evidence for Intrinsic Redshifts in Normal Spiral Galaxies"
"Curvature pressure in a cosmology with a tired-light redshift."

I would still be content with my original proposal of a sentences in "causes" mentioning Brillouin scattering, etc., but a table would be much better, and much more informative.

--Iantresman 12:04, 10 December 2005 (UTC)

Here's why your 500 articles might be crap. You point to articles that say in the abstract something like "We model...the redshift z=1.187 quasar PKS 1127-145. We propose a scenario in which the high-energy photons are produced via the Compton scattering..." and then you wave around a flag like a systematically mistaken person saying "LOOK! Here's one of the 200 articles talking about Compton scattering as a redshift!" when the article is modeling photons without calling Compton scattering a red-shift. Shame on you for misusing other people's work that way and trying to deceive someone like me who isn't familiar with the field. It almost makes me physically ill when I think about the possiblity that someone might abuse something I do in the future in a similar way just because I include certain words in an abstract. Nevertheless, if systematically mistaken editors like you use the term "redshift" in a non-standard, incorrect, wrong, pseudoscientific, unconstructive way often enough, then I support an article with a table that points out precisely why this usage is wrong. And I only support the inclusion of such a table if it includes the phenomena you point to but not the theory you believe that misuses the phenomena AND if the entire non-standard cosmology section is removed. Flying Jazz 13:22, 10 December 2005 (UTC)

This is exactly what I've been saying all along (since time memorialized in our archives). I'm not trying to be "astronomically" or "cosmologically" hegemonic, I'm merely pointing out that Ian's references do not show what he claims they show and that as far as I can tell there are only four uses of the term "redshift" that I've read which are verifiable as uses which seem to conform to the standards of Undue weight. --ScienceApologist 14:15, 10 December 2005 (UTC)

It's even more ridiculous than that. A huge number of the articles he claims support his position actually are very explicit in their opposition to his position by explicitly stating redshift is synonymous with an object at constant z. So now I know. He's wrong. But I don't know that you're right. And even if you are right and there is only one physicist who calls Compton scattering a redshift, there are obviously a lot of non-physicists who call it that too. OK. Maybe astrophysics textbooks are explicit that redshift IS z and is only due to three known causes and maybe every physicist except one uses it that way. But even if everything you're saying is right, wikipedia isn't a physics textbook. You've GOT to admit that the idea that some lines received on Earth that are at increased wavelength from when they were emitted AREN'T called redshifts by nearly all physicists is still very interesting to non-physicists and worthy of comment. Would you support something like Ian's table if there were a column labeled "proper usage" or "standard usage" that had "Yes" in some places and "No" in other places? Flying Jazz 14:39, 10 December 2005 (UTC)

I don't think I agree with your assertion that just because something is interesting to laymen it should be included on a page that tries to rigorously define a subject. At some point we have to be judicious in our selection of sources. Otherwise we'd be including painting a house red as a redshift. I doubt very much that there are a lot of non-physicists out there who would be confused if we didn't include Compton scattering on the redshift page. In fact, I suspect just the opposite, that inclusion of such is likely to be more confusing. I have no objection to stating something along the lines of "redshift is frequency-independent and coherent" which effectively eliminates the need for Ian's list. --ScienceApologist 15:11, 10 December 2005 (UTC)

That "frequency-independent and coherent" statement ignores informal bathochromic usage. For photochemistry, it's just wrong. For other fields outside of astrophysics, it's probably too limited. If a chemist has two pigment solutions of a complex polymer solution and says "changing from A to B caused a redshift of 25 nm in the reflectance spectrum of the air-dried adduct," they are using the term redshift in its often-used informal bathochemical sense. And they may also be describing painting a house. Painting a house and cooking lobster really does cause a redshift, and grilling a steak causes a blueshift. These are already covered by the article. You are showing very little faith in the ability of readers to take information and reach their own conclusions by recognizing that different fields use words in different ways. Flying Jazz 16:50, 10 December 2005 (UTC)

I agree that the informal bathochromic usage is different from the formal physics usage. So, why don't we include painting a house and cooking a steak on the table? --ScienceApologist 16:53, 10 December 2005 (UTC)

Because painting a house and cooking a steak are examples of photochemical redshifts. The table (I think) is supposed to show usage? or causes? But definitely not examples or it could be filled with a gadzillion objects. One problem with a table showing "causes" is that it begs the question "causes of WHAT?" and maybe we're back to astrophysics bickering. Does Ian's list only contain wavelength-increasing phenomena that have been seen on spectra from astronomical objects? Would it be better if the table were labeled "usage" instead of "causes"? Flying Jazz 17:29, 10 December 2005 (UTC)

Brillouin scattering & Redshift references

You are absolutely right that some of my references are incorrect. But lets do this one redshift type at at time. Here are some abstract extracts from Brillouin scattering references at NASA the Astrophysics Data System (ADS) [28] (my highlights):

"Spectra of the back-reflected light show redshifts indicative of Brillouin scattering." [29]
"A prompt stimulated Brillouin scatter (SBS) signal [..] The SBS signal was red shifted by approximately 51 A" [30]
".. 1% of the incident power, was found to be redshifted by 80-100 A, the shift expected for stimulated Brillouin scattering from a plasma.." [31]
".. the red shift signature of Brillouin scattering was observed." [32]
".. the spectra of the backscatter light were obtained and show the red shifts characteristic of Brillouin scattering." [33]
"Stimulated ion-Compton or Brillouin (in the strong ion damping limit) backscattering explains the red-shifted backscattered spectrum.. " [34]
"Observed red-shifted back-reflected light shows that Brillouin is operating..." [35]
"...oblique forward scatter' is conducive to large redshifts, while outward backscatter yields lower redshifts." [36]
"The redshifted scattered light shows the characteristic temporal and spectral features of stimulated Brillouin scattering. " [37]
"The origin of the redshift in Brillouin spectra..." [38]

Please check the context of each extract, and indicate whether any of these fit into either the (a) three Doppler-like redshifts, or (b) Bathochromic redshift?

"Deluded wacko nonscientist layman" --Iantresman 16:02, 10 December 2005 (UTC)

Ian, your quotes don't serve to illustrate anything other than people use redshift and Brillouin scattering in the same sentences. The last citation, for example, is clearly about a Doppler shift, but you wouldn't know by your quotation. I don't have time to fact check all of your proposed citations. --ScienceApologist 16:31, 10 December 2005 (UTC)

You need to provide more than your opinion. If you look at the abstact for the last entry (ie. click on the little number at the end), you will find this particular article is about "The origin of the redshift in Brillouin spectra of silica films containing tin nanoparticles". So unless the silicon film is moving very fast, this is not due to a Doppler redshift. I'll give you three more guesses. --Iantresman 16:39, 10 December 2005 (UTC)

The abrupt change of velocity in surface acoustic waves in thin films of amorphous SiOx containing nanometre scale -Sn crystals is shown to be directly associated with the size-dependent melting of the nanoparticles, confirming preliminary experiments. -- First sentence. --ScienceApologist 16:49, 10 December 2005 (UTC)

I don't know if this is possible, but if I measure a Brillouin redshift for a piece of thin film mounted in a stationary holder, and I assume the shift is due to the Doppler effect, will I be able to infer a Doppler velocity for the sample? --Iantresman 18:06, 10 December 2005 (UTC)

Good job, Ian. Obviously, there are some physical effects that increase wavelength between the source and the observer (and so aren't bathochromic), and people refer to the effect as redshift without any reference to z. It seems unlikely that an astronomer would ever call these effects redshifts, so I'm also starting to see your point for including "Field of study" in the table. I'm sure glad you aren't refering to that 500 number any more and you are talking about specific instances. ScienceApologist...engineers in particular use whatever short cut word they want to describe an effect and don't give a damn about what some astrophysicist says. By not conceding the point that many people call a wavelength-increase a redshift, you are fighting a losing battle and the wrong battle I think. Better to devote time to thinking about how that usage can be distinguished from the constant-z usage and keeping that "theoretical redshift" junk out. Flying Jazz 17:12, 10 December 2005 (UTC)

This request on the Physics Project made my attention wander over here, so I've spent some time this morning looking over the talk and the article. Here are my comments:

Redshift {and blueshift} does indeed have two distinct meanings

1) Any decrease in frequency, e.g. e due to temperature changes, backing scattering or environmental effects. {Though I don't know of anyone who uses redshift to refer to compton scattering}.

2) Astronomical {doppler} Redshift

Personally, I only use redshift in the first sense since I am not an astrophysicist, and I have colleagues who do the same. I, however, agree that is not the predominate useage of the word, rather the doppler astronomical effect is. Furthermore, the first usage doesn't have a phenomena or field of study connected with it; it is just shorthand for "the frequency decreased", the second usage is an active area of study. If I were looking at an article about redshift, I would expect it to be on astronomical redshift.

The list of "500 peer-reviewed articles" is suspect as it was not collated carefully. I skimmed through the list and a few dozen abstracts and found:

1. "peer-reviewed articles" that are conference abstracts and so neither articles nor peer-reviewed.

2. articles, especially in the compton scattering list, which happen to mention redshift in the abstract, but do not connect scattering and redshift.

Even if most of the 500 are articles that use redshift in a non-doppler sense -- which it isn't clear to me is true -- that is a small fraction of the scientific literature.

I did my own search in Web of Science for red shift, and it found 13657 articles {out of 24171224 indexed}, and from skimming through the first few pages of articles, it appears that only a few percent are using redshift in the first sense.

I suggesting treating redshift as an article with a predominate meaning and some minority useages {such as how PDX is treated}, so add to the top "For redshift as shift in frequency due to environmental coupling see Bathochromatic shifts ", "For redshift as a shift in frequency due to scattering, see scattering, Compton effect, etc... Salsb 17:31, 10 December 2005 (UTC)

This is very agreeable to me. I think the table is just overkill considering the fact that the majority of the uses is to a z. --ScienceApologist 18:01, 10 December 2005 (UTC)

I think the table is quite a useful summary. If it does not belong here, in what kind of article should it be placed? --Iantresman 18:22, 10 December 2005 (UTC)

I don't find the article table useful for at least two reasons. 1) it doesn't actually have much content 2) the astronomical use of redshift is so dominate in science that I think the table could lead to a false impression Salsb 18:33, 10 December 2005 (UTC)

I liked the idea of a table that shows detailed information about what can cause an increase a wavelength between the source and the observer and how those causes differ without including extraneous information. I haven't seen the kind of table yet that I was hoping to see. Flying Jazz 18:43, 10 December 2005 (UTC)

Just to be clear, not all of these examples are about changing wavelengths between a source and observer. In photochemistry, a redshift {or blue shift} is when the emitted wavelength is different in one environment vs. another, and in scattering the wavelength doesn't change from scatter to the observer {although the scattering changes the wavelength relative to the original source}. That's why this usage is a distinctly different and why this table might lead to confusion. Salsb 18:51, 10 December 2005 (UTC)

Yes. But a good table might lead to clarity. Flying Jazz 18:54, 10 December 2005 (UTC)

BTW this in antedotal, but the last time I submitted a paper with "redshift" it was changed to "red shift", as I was using it in the photochemical sense. Of course, that is just one journal. Salsb 18:33, 10 December 2005 (UTC)

This suggestion is reasonable, and it seems to describe where we are heading, but the critical issue is what's included in "etc"? I'm not sure about what environmental coupling is. It seems to be using a physics term to describe a photochemistry concept, but that is relatively minor compared to the details of what is included in the "etc." Flying Jazz 18:31, 10 December 2005 (UTC)

Oops. I think I may have advocated two entirely different things within 15 minutes of each other earlier today! This is the first time I've contributed to a discussion like this one here. Please forgive. Ideally, I would like to see a table that includes demonstrated causes of observed wavelength increases due to scattering effects and interference effects (if that's what Wolf is) in addition to the three effects already in the article. In an ideal world, this could be done in a way that is rational, includes the absolutely critical differences between them like the size limitations for the scattering effects, maybe includes an equation for each one, excludes non-standard theory, and includes a comment that redshift is identical to z in the astrophysics community and only refers to the the three constant-z effects.

Such a table would obviously not resemble the one presented above in most ways. I don't have the knowledge or the time to build one. My background is in chemistry. But I'd like to see it done. I think many non-physicists would because we would learn a lot. I hope the physicists reading this regard it as a challenge. If it can't be done or shouldn't be done for some reason, I'm for Salsb's proposal except I'd like to see the photochemistry stay in the article as it is now for reasons explained by Dragons_flight above. But I'm not willing to fight hard for keeping photochemistry here, and including more detailed photochemical stuff in bathochromic and hypsochromic shift is certainly something that will be done eventually anyway. Flying Jazz 01:17, 11 December 2005 (UTC)

Many thanks for your contribution. I accept that the 500 peer-reviewed references are not to a very high standard. This seems mainly in the section on Compton scattering, since the list of references to "Brillouin scattering and redshift", seem to mention the term 'redshift' in a "scattering" context almost exclusively.

I wonder if you have come across the Wolf effect, since this is neither a scattering phenomenon, nor is it Doppler, Comoslogical nor Graviational redshifts? --Iantresman 17:59, 10 December 2005 (UTC)

The Wolf Effect is a type of absorption process which is very similar to scattering. --ScienceApologist 18:04, 10 December 2005 (UTC)

Prof. Daniel F.V. James writes that "The Wolf effect is the name given to several closely related phenomena in radiation physics dealing with the modification of the power spectrum of a radiated field due to spatial fluctuations of the source of radiation. [..] The discovery of coherence-induced spectral shifts grew out of work investigating the connection between optical coherence theory and the empirical laws of radiometry, in particular, the dependence of radiative transfer on the wavelength of light." [39] --Iantresman 18:33, 10 December 2005 (UTC)

My understanding of the Wolf effect is that its due to scattering off of a random surface. The actual paper describing the Wolf effect for the first time is :Physics Letters A Volume 146, Issue 4 , 21 May 1990, Pages 167-171: "Correlation functions of random scattering media are introduced, which generate scattered light whose spectrum is shifted with respect to that of the incident light in a manner which mimics the Doppler effect in its essential features. " We don't subscribe to the journal so I can't point to details, but the abstract does refer only to numeric simulations, not observations or simulations. Though I'm sure more work has been done since then. Salsb 18:44, 10 December 2005 (UTC)

Actually Emil Wolf's first paper was "Non-cosmological redshifts of spectral lines (1987) Nature 326 363–5". He writes: "Here, we demonstrate that under certain circumstances the modification of the normalized spectrum of the emitted light caused by correlations between the source fluctuation within the source region can produce redshifts of spectral lines in the emitted light." He goes on to write: "There is, however, quite a different mechanism, which can be described at the macroscopic level, and which can imitate effects of source correlations; namely effects of correlations between refractive index at pairs of points in a spatially random but statistically homogenous, time-invariant medium." I can't find a mention of scattering, nor of surfaces. --Iantresman 19:06, 10 December 2005 (UTC)

Different context {Re: Surfaces}

The Nature article is a letter elaborating on a previous paper in PRL, 56:13 p1370 (1986) on the "Invariance of the Spectrum on Light on Propagation". Although this is a minor point in the context of this article, I'll look through it when I get a chance. 19:25, 10 December 2005 (UTC)

Actually its a pretty easy article, and just shows that while in general the spectrum can change upon propagation, for most sources it would not, so never mind Salsb 19:29, 10 December 2005 (UTC)

Redshift, the edit war?

How can anyone have an edit war over redshift?--152.163.100.203 14:40, 10 December 2005 (UTC)

Good question. It's not about redshift. It's about the stubborn and blind scientific establishment vs. bold and brilliant rebels. Or about careful and honorable professionals vs. anti-enlightenment crazies. --Art Carlson 17:48, 10 December 2005 (UTC)

I wonder where a "Deluded wacko nonscientist layman" fits in :-) --Iantresman 18:39, 10 December 2005 (UTC)

I apologize for the name calling. When I saw that you wrote "Over 500 peer-reviewed references (see list above) using the term 'redshift' in a non-Doppler-like manner," I replied with, "He makes a good point with his journal articles," and when I learned otherwise I felt a bit foolish and lashed out. However, this is ultimately my fault for not performing due diligence, and it is certainly no excuse for losing my temper. I may be out of my league in this debate for several reasons involving my lack of experience with Wikipedia, with cosmology controversies, and with the content itself. Redshift is not a subject I feel particularly passionate about, so I thought I might be a pair of "fresh eyes," but now I think it may be best if I withdraw from commenting further about your proposals. Flying Jazz 06:24, 11 December 2005 (UTC)

No problem. I still consider your contributions valuable. The 500 references were acquuired rather quickly, and their quality was not as good as they could be. The Compton scattering references look the poorest quality, but the rest seem pretty good; 30 out of 31 references to Brillouin scattering and redshift look good, and I suspect that the other scattering redshifts are good too.

My concern with the article is that it will turn into a scientific article on Doppler-like redshifts, whereas it should be a more general article aimed at 12-year-old, explaining why Doppler redshifts are used in astronomy, and why other kinds of redshifts have been considered and possibly rejected. A more scientific article in its own right is still relevant, but called "Doppler-like redshifts" (or similar).

I don't know why theoretical redshifts should be excluded. Tired light and scattering theories and redshift were also important in the history of redshift, and neutrino redshifts could be a vital distinguising factor between different kinds of redshift. Theory is a vital pillar of the scientific method, and an explanation of why Cosmological redshift is better than, for example, tired light and Compton scattering, demonstrates the scientific method better than pretending that tired light is insignificant and should be excluded. --Iantresman 10:31, 11 December 2005 (UTC)

My concern with the article is that it will turn into a scientific article on Doppler-like redshifts, whereas it should be a more general article aimed at 12-year-old, explaining why Doppler redshifts are used in astronomy, and why other kinds of redshifts have been considered and possibly rejected -- We must have different ideas about Wikipedia. We should not aim at 12-year-olds but we should aim for accuracy. We're not writing a children's book here. We could write this article as a children's non-fiction book explaining all of waves, particles, energy, etc. so that 12-year-olds could understood what we meant by "frequency" or "wavelength" or "Doppler". Yes, a really great children's book could be written here, but that's not the point of Wikipedia. The point of Wikipedia is that we have repositories of accurate and verifiable information. There is no need to dumb down or extend artificially the content of the article to conform to some stereotype invented by Ian of what a 12-year-old can understand. --ScienceApologist 11:22, 11 December 2005 (UTC)

That you see article "accuracy" and "aimed at 12-year-old" as mutually exclusive is telling. I suspect that most adults have a scientific understanding of a 12-year-old. The job of an editor is to make the subject accessible to all. No, you don't have to predefine all technical terms (since Wiki links can do that), but you do have to the describe the effect unscientifically FIRST without using scientific jargon. As the Wiki NPOV says: "a minority of Wikipedians [..] believe Wikipedia should adopt a "scientific point of view" [..] However, it has not been established that there is really a need for such a policy..."

I'm not the one who brought aiming at 12-year-olds into the conversation. That was you. Your contention was that certain ways of writing were incompatible with some made up 12-year-old's understanding. The fact is, it would be dishonest of us to present an article here that a 12-year-old could understand independently on first reading without doing other research on the subject. It's not that accuracy and a 12-year-old audience are mutually exclusive, it's that we are not writing an encyclopedia for 12-year-olds! The goal of Wikipedia is to provide the information; it is not to dumb-down articles. You're absolutely right that we don't have to predefine technical terms, but my "technical terms" (yay!) are apparently your "jargon" (boo!). Your insinuation that my contributions are jargon belie the fact that I had a major hand in developing the featured article Big Bang article which relied on a similar style. Just because Wikipedia does not adopt SPOV does not mean you are free to edit an article on a scientific subject to conform to that which your own tastes dictate. NPOV does not rule over Wikipedia, the mission as an encyclopedic repository of information does. The fact is the information is all there, if you have the chance to read it. --ScienceApologist 12:34, 11 December 2005 (UTC)

This is the first two sentences from the Neutral Point of View page (my emphasis):

Wikipedia policy is that articles should be written from a neutral point of view, representing all majority and significant-minority views fairly and without bias.
According to Wikipedia founder Jimbo Wales, NPOV is "absolute and non-negotiable".

--Iantresman 13:24, 11 December 2005 (UTC)

Non-sequitor. --ScienceApologist 12:32, 12 December 2005 (UTC)

A more scientific article in its own right is still relevant, but called "Doppler-like redshifts" (or similar). Absurd. The distinction here should not be between Redshift (technical) and Redshift (pop sci). That's a contrived excuse for a POV-fork that I think would be very bad. --ScienceApologist 11:22, 11 December 2005 (UTC)

I don't know why theoretical redshifts should be excluded. -- Maybe you should clarify what you mean by "theoretical" here. I think what you mean to say is "hypothetical" or even "conjectured" or "contrived". Please read up on what a scientific theory is. You lump together tired light with neutrino redshifts with other redshifts of your own (or some fringe scientist's) invention. The commonality between them is hardly that they are "theoretical". In fact, they are of such a disparate class, I don't even know how to begin evaluating your contrivance. --ScienceApologist 11:22, 11 December 2005 (UTC)

Tired light and scattering theories and redshift were also important in the history of redshift -- Where do you make up this knowledge of the "history of redshift"? Have you read a book on the history of redshift or something? How did you ever come under the misconception that "tired light and scattering theories" were "important" in such a "history". --ScienceApologist 11:22, 11 December 2005 (UTC)

neutrino redshifts could be a vital distinguising factor between different kinds of redshift. -- Another example of including material you apparently don't understand and passing it off as simple fact. First of all "neutrino redshifts" aren't a special kind of redshift. They represent mechanistically the same phenomena talked about above. They are only different in terms of the particle physics origin of the radiation. Second of all, there are no serious scientists proposing that measuring the redshift of primordial neutrinos or neutrino fluxes from supernovae would give us any information on whether other mechanisms for redshift were possible except maybe in the Foucault's pendulum sense of proving the Earth rotates. But taking an argument like that seriously by mainstream scientists is like arguing that we didn't know until 1851 that the Earth moved as Galileo said. --ScienceApologist 11:22, 11 December 2005 (UTC)

That you suggest that "there are no serious scientists proposing that measuring the redshift of primordial neutrinos", and implying that Chuck Gallo is not a "serious scientists" disgusts me, just as you label "Plasma comology" as pseudoscience, and label Halton Arp's work as "pathological skepticism". --Iantresman 12:05, 11 December 2005 (UTC)

Let's add another thing to the list: taking another user's comments out-of-context. You took my comments so far out of context that I have no trust in any of your references whatsoever because the context is clear to anyone who read my comments. I made the following statement: There are no serious scientists proposing that measuring the redshift of primordial neutrinos or neutrino fluxes from supernovae would give us any information on whether other mechanisms for redshift were possible except maybe in the Foucault's pendulum sense of proving the Earth rotates. -- This is absolutely the case. Those scientists that do want to measure neutrinos from cosmic events to look for their redshifts want to do so for a variety of reasons, but to claim that it is to test whether plasma cosmology is correct or that there are no such things as intrinsic redshifts is beyond absurdity. The only comparisons that would be made by legit mainstream scientists are those that would be using the idea as an added point based on the settled physics of the observations. Just like Foucault's pendulum in 1851. --ScienceApologist 12:17, 11 December 2005 (UTC)

Chuck Gallo says of Neutrino redshifts [40] "If the photon and neutrino redshifts are similar, then a Doppler and/or Space Expansion interpretation is justified. If the neutrino redshift is much smaller than any corresponding photon redshift, then an interpretation via a cumulative energy-loss mechanism is justified. This is a very definitive experimental test of redshift interpretations.". I would have thought that any "serious scientists" would welcome such a test. --Iantresman 13:24, 11 December 2005 (UTC)

End scene. Ian has completely missed the point. --ScienceApologist 12:32, 12 December 2005 (UTC)

Theory is a vital pillar of the scientific method, -- Theory is a branch of science. It involves models. It is not a part of the scientific method. --ScienceApologist 11:22, 11 December 2005 (UTC)

and an explanation of why Cosmological redshift is better than, for example, tired light and Compton scattering, -- is like trying to explain why creationism is better than evolution. Tired light has a page. So does Compton scattering. They don't explain redshifts. That is made clear on the tired light page which is simply a story that often gets told in science about mistaken ideas. Intrinsic redshifts due to Compton scattering is a contrivance of a disgruntled NASA engineer from what I can gather. Compton scattering definitely does not belong in this Wikipedia article. It seems clear to me that this excuse is only to further the agenda of a rather disgruntled POV-pusher who takes seriously his disdain for mainstream scientific explanations of the universe. --ScienceApologist 11:22, 11 December 2005 (UTC)

demonstrates the scientific method better than pretending that tired light is insignificant and should be excluded. -- Tired light is on the tired light page. It is an alternative explanation for an observation of redshift. It might be described as a competitor to the Big Bang or the Hubble Law understanding of an FRW universe. It is not part of the observation of redshifts. --ScienceApologist 11:22, 11 December 2005 (UTC)

Compton redshifts

Just to continue my evidence that redshift is used in a Compton scatting context (see my extracts regarding Brillouin scatting above), here are some specific extracts:

"A study of Beta Orionis spectra suggests the possibility that a rather large Compton redshift is present in the spectrum of this star." [41]
"The line is identified as a Compton-redshifted iron K line..." [42]
"Each outgoing quantum observed at frequency ω' and wavevector k'=k'n' is quattered from an incoming quantum frequency ω'/η' where [equation] is the Compton redshift ratio..." Sec 3.1
"The spectrum of synchrotron radiation is strongly suppressed relative to the classical spectrum at high frequencies, and that this is a consequence of the Compton redshift effect..." [43] (Same article as above).
"The function Φ includes all three essential components of Compton scattering ie. Compton redshift of scattered photon due to electron recoil." [44]
"For Compton scattering [..] where [equation] is the Compton redshift." [45]
"Additionally an iron emission line at 6.2keV was discovered and identified as a Compton-redshifted iron K line and may come from recombination in an optically thick photoionized corona..." [46]
"For complete scattering by heavy particles -- atoms or molecules, the Compton redshift is even less than 10^-9... [47]
"Missana (1983) suggested the possibility of a large Compton redshift in the spectra... [48]
"They interpreted this feature as being a Compton-redshifted iron K-line..." [49]
"From the study of the spectra of eighteen O-type stars can be argued that a large Compton redshift is present... [..] The measurements of velocities and Compton redshift made by the writer.." [50]
Title: "Compton Effect Interpretation of Solar Red Shift" [51]
"In a recent paper, Kierein and Sharp have proposed that the solar redshift arises from Compton scattering... [52]
Title: "Variations of the Generalized Compton Red Shift in the Sun" [53]
Title: "Implications of the Compton effect interpretation of the red shift" [54]
Title: "Inverse Compton scattering and the alignments observed in high-redshift radio galaxies" [55]
Title: "The Compton Effect as an Explanation for the Cosmological Redshift" [56]
Title: "Compton Scattering Can Explain Redshifting" [57] (Peer reviewed?)
Title: "AGN Jets at High Redshifts: Inverse Compton Scattering of the Cmb?" [58]
"The redshift in this expression is due to the Compton effect" [59]
"...arising from a Maxwellian distribution of thermal velocities, the red shift of the "Compton effect"..." Part I Part II
".. lines of the solar spectrum formed in the reversing layer are subjected to a redshift due to multiple Compton scattering..." [60]
"The line broadening and redshift may arise from either Compton scattering in a cool plasma..." [61]
"The redshifts may be due to either the ionized gas of the warm mirror receding at a radial velocity of 4000-5000 km s^-1 or to effects of Compton scattering in a complicated geometry." [62]

--Iantresman 12:12, 11 December 2005 (UTC)

What a quote mine. I made it through the first reference which is using redshift in the sense that is defined in our article, but it straddles the quantum and classical worlds by beautifully mixing metaphors involving redshift which is just a ratio as defined in our article and scattering which is uniquely solved for a single particle, a single scattering, in a narrow limit of phase space. So to truly explain this reference we'd have to provide this as an explanation, and that's for just one article! --ScienceApologist 12:51, 11 December 2005 (UTC)

Can you give show where the article is using term 'redshift' as you have defined it? Phrases I don't see in your article are the term 'Compton redshift', 'Compton effect', nor 'Compton scattering' as used in these 24 peer-reviewed articles. --Iantresman 13:24, 11 December 2005 (UTC)

The definition used in their article for η is the same as our z as I described above. Since the microphysical uses for single photon frequency-shifts due to Compton scattering are used not in an observational sense but rather in a theoretical derivation (which is not saying that this is a "theoretical redshift", only that the ratio was used to obtain a result derived from theory) this is not a reference which has any bearing on this article. In fact, someone reading that particular article who didn't understand what they were talking about would be well-served by this article. --ScienceApologist 12:36, 12 December 2005 (UTC)

Yes I agree that their η is the same as your z, showing that the Compton effect is a cause of redshift. Other giveaway signs are quoted extracts (above) such as:

The line is identified as a Compton-redshifted iron K line.
"The Compton Effect as an Explanation for the Cosmological Redshift"
"Compton Scattering Can Explain Redshifting"

The last one is pretty unambiguous. The ONLY PERSON ON THE PLANET that I know that disagrees, is you Joshua.

--Iantresman 13:29, 12 December 2005 (UTC)

And Ian continues to ignore my explanation. The Compton effect can be described using our formula just as any potential reshift could be (including painting a house red). This is beside the point. --ScienceApologist 13:33, 12 December 2005 (UTC)

The point is that:

"Compton Scattering can Explain Redshifting" (see reference above)
Likewise I have several other commonly put-forward causes of redshift (all peer reviewed)
Several of these have been DEMONSTRATED in the laboratory (all peer reviewed)
Indeed, I have 500+ peer reviewed references offering alternative causes of redshift to those you have listed
You have presented NO peer-reviewed evidence against
Under any other circumstances, one or two peer reviewed references would be sufficient to back-up an arguement.
That 500+ peer-reviewed references (see below) are not good enough for you makes "preponderence of evidence" a bit of a joke.
And that YOU (one person) won't allow ONE SENTENCE (insignificant) summarising 500+ peer-reviewed references and evidence (not insignificant) is quite disgusting.

--Iantresman 14:23, 12 December 2005 (UTC)

Well OK. So I'm back. You both did say you valued my contribution after all! ScienceApologist...you also are not using sufficiently specific terminology to make your points. The fact that a house is a certain color could be described using the formula for z. You shine one (emitted) color on the house. You get (observed reflected) a different color due to Raman scattering or Stokes scattering or something else in physics that I don't know about and that Ian maybe wants to be included in the article because it can increase wavelength. Painting a house red cannot be described using the formula for z. It could be used twice I suppose, to describe a before and after, but of course, the informal photochemical equation for redshift would be the way to go to describe a difference between two closely related pigment molecules. Bathochromic shifts can't really can't help either of you in the points you are trying to make. Separate equation. Separate field. Flying Jazz 00:53, 13 December 2005 (UTC)

750 Peer-reviewed "Untrivial Redshifts"

"Untrivial redshifts - A bibliographical catalogue" (1981) by Reboul, H. J. in Astronomy and Astrophysics Supplement Series, vol. 45, July 1981, p. 129-144.

Seven hundred and seventy-two coded references, covering 70 years of study of anomalous, i.e., untrivial redshifts (NTZ), are presented. Definitions are given for trivial Z and for the classical theories, and lists are presented for 17 classes of NTZ and 19 classes of unclassical theories. [Full abstract | Full text]

Quote from article: "We arbitrarily define as trivial a redshift which can be easily explained by a combination of the three following effects: Doppler, Schwarzschild, Friedmann." [Do we mention Schwarzchild or Friedmann?]

Summary

Number of classes of nontrivial redshift: 17+19 = 36 (excluding the Wolf Effect).
Number of references acribed to gravitational/classical explanations ~210
Number of peer-reviewed references supporting iantresman's position = 500+ (edited from 700+ 19:35p)
Number of peer-reviewed references supporting Joshua Shroeder (ScienceApologist)'s position = Zero

What a horrible and biased summary. I think this about closes the case on our dealings with Ian. --ScienceApologist 12:38, 12 December 2005 (UTC)

Joshua Shroeder's evidence against me:

I am "getting all [my] information from very biased sources" [63]
I am "doing searches in very round-about way" [64]
I need to "get a handle on the basics of redshift" [65]
I "haven't demonstrated even a cursory understanding of the subject" [66]
I am a "nonscientist layman" [67]
My "POV pushing is out of control." [68]
I have a "refusal to read introductory astronomy texts" [69]
I "refuse to address the real concerns about the article representing consensus in the field." [70]
Because of my "insertion of nonsense" [71]
That when I "claim that [i] are getting [my] information from adsabs, I know this to be false..." [72]
I "have not demonstrated a cursory understanding of the subject" [73]
I am "content to naysay and bring in irrelevent material." [74]
I "haven't made a thorough evaluation of the sources you wish to consider" [75]
I haven't "taken the advice of myself and others to read the Italian page" [76]
I make "a claim that is not backed up even by the papers you cite and do not read. [77]
My "first citation is to a poorly written (from the English standpoint)" [78]
"The second paper I cannot make heads-or-tails of." [79]
"I'm not sure we've demonstrated that there are people who use redshift to mean something other than the definition we have here" [80]
"...the citations are not verified." [81]
"User:Iantresman, [is] very incompetent in this regard, " [82]
"Ian has not been able to find a resource that defines redshift in any other way." [83]
"Ian doesn't even understand this definitional constraint " [84]
"This is an unacceptable form of research. " [85]
"Ian fails to mention .. the reason he wants to include the alternative mechanisms.. because he has a chip on his shoulder..." [86]
"The paragraph you wrote, Ian, is a unique point-of-view, but isn't based in fact." [87]
"The vast majority of physicists who would bother would define redshift as what we have currently on this page" [88]
"That Iantresman is on some strange personal vendetta may be true, " [89]
"I have no problem mentioning analytical chemistry red shifts whatsoever." [90]
"I have not seen any indication that there are any outstanding issues" [91]
"Ian, your quotes don't serve to illustrate anything other than people use redshift and Brillouin scattering in the same sentences." [92]
"I don't have time to fact check all of your proposed citations." [93]
"I don't even know how to begin evaluating your contrivance." [94]
"Tired light has a page. So does Compton scattering. They don't explain redshifts." [95]
"Intrinsic redshifts due to Compton scattering is a contrivance of a disgruntled NASA engineer" [96]
"the first reference which is using redshift in the sense that is defined in our article, but it straddles the quantum and classical worlds by beautifully mixing metaphors involving redshift which is just a ratio as defined in our article and scattering which is uniquely solved for a single particle, a single scattering, in a narrow limit of phase space." [97]

--Iantresman 16:28, 11 December 2005 (UTC)

The Wolf Effect and Hubble's Law

Having read (or at least scanned) The Wolf effect and the Redshift of Quasars, I think I can now say something about these mysterious special conditions. The model that James has in mind is a special geometry in the immediate neighborhood of quasars involving a dust torus, line-emitting clouds in the hole of the torus and an inisotropic scattering medium capping the hole. It's a pretty special model which has a lot of loose ends (as discussed in the article), but is not patently absurd. The point is that no one is proposing that space is permeated by a medium that redshifts everything. If the Wolf effect can explain any redshifts at all, it can only explain those from quasars. Many researchers apply Hubble's Law to quasars to get an estimate of their distance and brightness as a starting point for speculation on their nature. Quasars are not used at all to establish Hubble's Law, so the existence of the Wolf Effect in no way weakens the case for the Big Bang. Some of the versions of this article that have come and gone in recent weeks left a different impression. --Art Carlson 13:15, 12 December 2005 (UTC)

I agree with this summary and would like to add that now that we have nearly 100,000 quasar redshifts, it seems unlikely that they are all oriented the same way so as to invalidate a d=zc/H calculation for distance. Peculiar velocities can be shown to be orders of magnitude more important. --ScienceApologist 13:20, 12 December 2005 (UTC)

The facts are that (peer-reviewed references provided previously):

The Wolf effect will produce a redshift (demonstrated in the laboratory)
The Wolf effect may produce a Doppler-like redshift
Peer-reviewed scientists have suggested that the Wolf effect could play a part in Quasar redsifts
Whether this weaken the Big Bang theory or not, is irrelevant.
Wolf's original paper is cited by at least 100 other peer-reviewed papers.
Evidence against: Joshua Shroeder's opinion.

--Iantresman 13:44, 12 December 2005 (UTC)

When one models spectra, one tries to take into account all possible sources for the differences between observed and emmitted spectra. To this end the Wolf Effect is important. It's not at all clear that this is a mechanistic form for redshift. Why not include a link to frequency changing processes in physics in a See also section and be done with this? --ScienceApologist 13:47, 12 December 2005 (UTC)

The only person who believes "it is not clear", is yourself (one person).
The peer-reviewed evidence says IN PRINT that the Wolf Effect will produce redshifts
One of the authors (Prof. Daniel James) of a couple of the articles has CONFIRMED this here a month or so ago.
I have confirmation (via email) from TWO other Professors (Emil Wolf and Sisir Roy), also confirming that the Wolf Effect will produce redshifts.
Peer-reviewed evidence against, presented by yourself = ZERO
That YOU (one person) won't allow ONE SENTENCE (insignificant) summarising 500+ peer-reviewed references and evidence (not insignificant) is quite disgusting.

--Iantresman 14:42, 12 December 2005 (UTC)

Redshifts are observed for essentially all astronomical objects. I just want it to be clear that the Wolf Effect applies to at most one category of objects, namely quasars. Fair enough? --Art Carlson 15:05, 12 December 2005 (UTC)

Spot on. Cosmic Wolf Effect Doppler-like redshifts are indeed proposed only for quasars. But a general redshift (with distortion) is also demonstrated in the laboratory. --Iantresman 15:34, 12 December 2005 (UTC)

The article currently states: redshifts are observed in the spectra from ... quasars ... to increase proportionally with the distance to the object. Is this true? How is the distance to a quasar determined independently of its redshift? On the same topic, I don't understand ScienceApologist's comment above (beginning "I agree with this summary"). --Art Carlson 16:15, 12 December 2005 (UTC)

That's a very good question. Some object's distances can be measured independently, for example, by measuring their parallax. Other factors are also used to infer distance, such as brightness; the brigher an object, the closer it is. I'm sure that Joshua will confirm that it's a lot more complicated than this, but the reason there is a cynicism over redshift = velocity/distance is that basically it is an assumption. For a recommended overview, see Arp's book, "Seeing Red", or I am sure that Joshua can recommend a CRITICAL book on redshift. --Iantresman 16:39, 12 December 2005 (UTC)

That's the sort of statement that gets you justifiably in trouble with Joshua. The Hubble realtionship may be an assumption for quasars, but it is an experimentally determined relationship (albeit a complex one) at least as far out as we can resolve supernovae and spiral galaxies. --Art Carlson 17:15, 12 December 2005 (UTC)

Every statement gets me in trouble with Joshua. And I have no interest in questioning the Hubble relationship in the redshift article. --Iantresman 17:26, 12 December 2005 (UTC)

The nature of quasars was a controversy settled decades ago. Arp cannot bring himself to admit that he was wrong even though we've seen host galaxies around quasars. Quasars are simply AGN at large distances. --ScienceApologist 17:47, 12 December 2005 (UTC)

"..settled decades ago.." According to Joshua.
Yet a 2005 paper [98] seems less certain, except that it is written by Arp. And his fellow colleagues: Pasquale Galianni, E. M. Burbidge, V. Junkkarinen G. Burbidge, and Stefano Zibetti. And its peer-reviewed, and appears in the dodgy journal The Astrophysical Journal, Volume 620, Issue 1, pp. 88-94.

What a convenient game. So Arp claims that the quasar is "interacting" with the foreground galaxy. Dubious at best, but this is an interesting observation of a quasar nonetheless. --ScienceApologist 18:35, 12 December 2005 (UTC)

And Arp and collegues have over 50 other papers published since 1985 (decades ago) [99] on quasars and redshift, and some of them even seem peer reviewed.

Arp is an admired observer, no doubt. We don't have to take all of his ideas as gospel. --ScienceApologist 18:35, 12 December 2005 (UTC)

Joshua, are all of Arp's colleagues "pathological skeptics" too (to quote one of your earlier comments on Arp)? How about the peer-reviewers?

Some of Arp's colleagues undoubtably are. Some are not. Some peer-reviewers may be, but as we don't know who they are, how are we to tell? --ScienceApologist 18:35, 12 December 2005 (UTC)

But we digress. --Iantresman 18:19, 12 December 2005 (UTC)

Notice that Ian conveniently avoids the fact that host galaxies around quasars have been observed. Appeal to authority is his game. --ScienceApologist 18:31, 12 December 2005 (UTC)

I merely provided peer-reviwed evidence to show that the issue has not been "settled decades ago". --Iantresman 19:07, 12 December 2005 (UTC)

Still silent on the issue of observed host galaxies, I see. No matter, this is a page on redshifts, not on quasars anyway. --ScienceApologist 19:14, 12 December 2005 (UTC)

Not all quasars have host galaxies - some are too small and faint to resolve that conclusively. Jon 13:21, 13 December 2005 (UTC)

Do I understand correctly that galaxies have been resolved around some (presumably largish) number of (presumably low z) quasars, and that the galaxies have been observed to have the same redshift as the quasars? So the argument is that these quasars are observed to have no intrinsic redshift, so presumably other, higher z quasars don't either and their redshift corresponds quantitatively to their recessional velocity. (The distance determination of high z quasars still requires an extrapolation of Hubble's Law.) --Art Carlson 22:16, 12 December 2005 (UTC)

More specifically, the Wolf Effect cannot plausibly apply to any objects except quasars. These observations show that it does not apply to low z quasars, so presumably it doesn't apply to high z quasars either. Therefore the Wolf Effect has been shown to play no significant role in producing cosmic redshifts. Other known sources of line-shifts can be ruled out because z is not independent of wavelength. And thus we are left with only the three effects listed in the article. --Art Carlson 22:23, 12 December 2005 (UTC)

That's a pretty good summary of the way it shapes up. Here is a reference to a host galaxy survey done by HST, for example. Host galaxies for high-redshift surveys have also been looked for and found. Doing a search for "naked quasar" on ADSABS will turn up a few hits from the 1990s about quasars that supposedly do not have host galaxies and there is a Nature article about a quasar with a host galaxy that may have few to no stars, but these are all easily interpretted in the Seyfert-quasar continuum. --ScienceApologist 22:35, 12 December 2005 (UTC)

Untrivial redshifts - A bibliographical catalogue

Ian was right that this paper http://articles.adsabs.harvard.edu//full/seri/A%2BAS./0045//0000130.000.html (even though it's a little old) is very relevant to the debate about what should and should not be in the wikipedia article. It seems to be a very good list of references for relevant work performed before the 80s. But if you read the content, not only does the article not support Ian's view about what should be included, it explicitly opposes them repeatedly. The 17 classes discussed are empirical observations, not effects that cause wavelength increases. Each of the 17 classes is correlated to references that explain the phenomena using classical theory, not other theory. And the 19 unclassical theories presented also are not presented as effects that cause wavelength increases or as alternate usage of the word redshift. These unclassical theories would be best described in a non-standard cosmology article in my opinion. The authors' separation of z into proportional-z and non-proportional-z is similar to what's in the Wikipedia article right now in the mathematics section. They simply call proportional-z-at-all-wavelengths "trivial" and the non-proportional empirical observations untrivial. I think it would be a mistake for this wikipedia article to use those terms. I still hope a physicist somewhere makes a table that shows all the different effects that can change the wavelength of light from emission to the observer (like raman, compton, stokes, brillioun, wolf and others) so they can be compared and contrasted. But I withdraw my support for such a table here. Or for a list. Flying Jazz 02:18, 13 December 2005 (UTC)

I think I see where you are coming from.

I agree that we should not use Reboul's terms. As he writes in the article, "we arbitrary define as trivial..", and I can find perhaps only one or two other articles that use the terms "trivial redshift" and "non-trivial redshift".
Are Reboul's first group of 17 classes "proportional-z"? He says that they are Nontrivial ie. not Doppler, nor Schwarzschild (gravitional), nor Friedmann (Cosmological), and his second group of 19 classes are Unclassical, ie. theories that are NOT "widely ascertained by laboratory experiments" (my emphasis), not trivial, and not the consqeuence of relativity, nor black holes, nor the Big Bang.
Rouboul does ascribed some of the catalogues items to proporional-z theories, as indicated by his "Third digit: favoured interpretation" label (p.131 [100]), in which three of the 16 digits represent gravitational, or classical interprations.
So my main point is that here is a group of papers that largely discuss "redshift" in a non-Doppler, non-Cosmological and non-gravitational manner. The current article on redshift ascerts that "Redshift according to various physical models can be due to three different effects"; that is an absolute that is at odds with the 500+ references, since the current articles does not even acknowledge that other interpretations exist.

--Iantresman 10:33, 13 December 2005 (UTC)

You are confusing usage, effects, and interpretations in a way that leaves me puzzled about exactly what you are saying. There are non-proportional z observations out there. Some people might call them non-trivial, others might call them intrinsic or non-intrinsic, others might call them not-Doppler-like. All of those terms are ambiguous because (like "general" and "specific") they can be used to mean other things in a different textual context. What is intrinsic to the universe as a whole? This would be a cosmologically intrinsic redshift. What is intrinsic to a specific object? This would be entirely different. What is intrinsic to a specific effect? This would be different again. "Intrinsic" vs "non-intrinsic," "general" vs "specific," and "trivial" vs "untrivial" are all context-dependent terms and none of them should be included in the article. The current article on redshift says:

The ratio z may be used in a variety of situations that only apply to individual spectral lines or a subset of the spectrum without representing a proportionality. However, most references to redshift—including the remainder of this article—utilize a proportionality that is uniformly applicable at all wavelengths.

Not only does this statement incorporate everything you want to be incorporated, it also does so in a way that removes ambiguity about the usage of other terms. Reboul's paper is interesting because of that third digit you are refering to. Is he lumping all of the scattering effects into a category called "photon-photon/photon-boson interactions?" I really don't know. But I don't see any of the specific categories and effects from your table in his list of interpretations. His specific categorizations are arbitrary because ANY specific categorizations would be arbitrary, including yours. That's the nature of language. Mathematics isn't arbitrary and has already adressed the issue. Flying Jazz 13:24, 13 December 2005 (UTC)

In that case, that's where I shall agree that we disagree, that "..the remainder of this article — utilize a proportionality that is uniformly applicable at all wavelengths".

If I was looking for something about redshift, and didn't know that there were (a) Proportional-Z (b) Non-Proportional-Z, then the statement is useful in telling me that there are two broad kinds of redshift, but it doesn't help me find out any more information about the latter.

The Wikipedia page on Planets, for example, confirms which bodies we identify as planets; but it is also helpful in providing "Other candidates". We acknowledge that there are also Non-Proportional-Z redshifts, then tell the reader that they won't be discussed, and then won't tell them some examples to enable them to find out more information.

I would also argue that many of Reboul's references have also been put forwards as "Proportional Z" redshifts. Again, the Planets page discusses "Definition and classification of planets", but we won't even acknowledge that, for example, the Compton effect and the Wolf effect have also both been suggested (many peer reviewed references) as a cause of proportional Z redshifts. If we were applying the same criteria to the Wikipedia Planets article, article, we would delete all but two sections... and not tell the reader where the information has gone.

The main definition of the Redshift article page is in the title: "Redshift", and this contradicts the arbitrary designation that the main focus will be about Proportional-Z Redshifts. And this goes against Wikipedia NPOV policy that an article should be "representing all majority and significant-minority views fairly and without bias"; Not only do we not mention them fairly and without bias, we don't mention them at all!

--Iantresman 15:10, 13 December 2005 (UTC)

Planets are a poor analogy because they are objects out there. You look at the object and you can define whether it's a planet or not depending on certain traits it might have. Redshift is very different because it's an observation. And there are multiple questions about observations.

1) What is the observation?
2) What causes the effect that is observed?
3) What theory can be put forward to explain these effects from #2?

The division of redshift into proportional and non-proprtional z addresses #1 because these two broad classes are what is actually observed. Your request for comments was a great idea because #1 was not addressed properly before then. You are also absolutely right that the article as written right now stops addressing non-proportional z immediately after it is defined. This is where the articles and the "number of articles" you keep mentioning come into play. Does a significant minority use the term for effects and theory describing non-proportional redshift?

Every time you intend to show #2 or #3 applies to your argument by posting specific articles (or numbers of articles), the content of the articles themselves seems to show the exact opposite of your point and this is why I've changed my mind on this issue. The articles that describe non-proprtional z as a redshift (#1), stop this usage and begin to talk about the specific effect (#2) without refering to it as a redshift any longer. For instance, in the third digit of Reboul's paper, he makes a distinction between "Gravitational redshift " as an effect (#2) from "photon-photon, photon-boson interactions" as an effect (#2). He explicitly does not call the interactions a redshift or any other effect a redshift that is not included in the current article. Nevertheless, the observations themselves (#1) are redshifted wavelengths in both cases. When someone says "That redshift observation is due to the compton effect," they are talking about usage as an observation (#1). I accept that this is a significant minority usage and it is covered under non-proportional. If someone says "The compton effect causes redshift," they are talking about usage as a cause (#2), and the references you've provided show that this doesn't seem to happen. An article that uses redshift the way you want would be biased towards a tiny minority viewpoint based on the evidence you yourself have presented. Again, this is all about semantics and splitting hairs when it comes to usage. Still important I guess. Flying Jazz 16:08, 13 December 2005 (UTC)

Sure the observation of redshift is more important than "cause", in the sense that the observation is measured, and the cause is potentially theoretical. But where there are articles on "Doppler redshift", an article is suggesting that this observed redsfhift is caused by the Doppler effect.

Likewise, an article on "Compton redshift" implies that the cause is due to the Compton effect. Just because Reboul's ONE article does not implicitly specify that the "Compton effect" causes "redshift", does not take away that there are peer-reviewed articles that do. Some of the Compton redshift references above are even more specific, such as (my emphasis):

17. Title: "The Compton Effect as an Explanation for the Cosmological Redshift"
18. Title: "Compton Scattering Can Explain Redshifting"
20. "The redshift in this expression is due to the Compton effect"

I believe that if we accept that "Doppler redshift" implies a redshift that is caused by the Doppler effect, then although we may not agree that "Compton Scattering Can Explain Redshifting", the references show that Compton scattering is one of several causes that have been put forward over the years for redshift. Likewise Brillouin and Raman scattering, and the Wolf Effect.

Consequently, I believe that the inclusion of ONE SENTENCE giving examples of possible alternative causes of redshift, is not unreasonable since it satisfies:

1. Wikipedia Neutral Point of View Policy that "articles should be written from a neutral point of view, representing all majority and significant-minority views fairly and without bias. According to Wikipedia founder Jimbo Wales, NPOV is "absolute and non-negotiable""' (my emphasis).
2. That I have cited credible sources, as suggested by Wikipedia Cite Sources page
3. That according to Wikipedia, the information is verifiable "Articles in Wikipedia should refer to facts, assertions, theories, ideas, claims, opinions, and arguments that have been published by a reputable or credible publisher. The threshold for inclusion in Wikipedia is verifiability, not truth."[101]

--Iantresman 16:37, 14 December 2005 (UTC)

Removal of nonstandard cosmology section

So are there objections (other than Ian) to removing the nonstandard cosmology section in this article? --ScienceApologist 02:30, 13 December 2005 (UTC)

We can paste the relevent material on the nonstandard cosmology page. --ScienceApologist 02:32, 13 December 2005 (UTC)

Let me weigh in on this question and others.

I favor keeping Red shift as a disambiguation page, and Redshift as the page for all physics/optics information.
Redshift should include information about (non-Doppler) shifts in individual lines because
1. There is a reasonable chance that a reader will come to the page looking for such information. This requires only a brief mention with links to the detailed articles.
2. It is interesting to learn why they are not a candidate for explaining cosmic redshifts, especially if one is interested in alternate cosmologies. Mention should be made of non-proportionality with wavelength, blurring, and broadening.
3. It helps emphasize the highly significant observation that cosmic redshifts are always Doppler-like.
Redshift should mention proposed alternative explanations of the observed proportionality of redshifts involving known physics (Wolf effect) or new physics (Tired light). The inadequacy of these explanations should be made clear, but the details should probably be left to those pages.
Redshift should likewise explain why gravitational effects are a minor and well-undstood (Aren't they?) perturbation in cosmic redshifts.
What's left over is recessional velocity and the expansion of space, which are indistinguishable. At this point we have explained why redshifts can be equated with velocities. The rest is cosmology, which should be left to Physical cosmology and Non-standard cosmology.

--Art Carlson 09:47, 13 December 2005 (UTC)

I think I largely agree with that. --Iantresman 10:47, 13 December 2005 (UTC)

Where did you find out recessional velocity and expansion of space redshifts are indistiguishable? I rather thought that their non-equivalence was a cornerstone to the whole big-bang theory. I know why they're not, but I'd hate to pollute wikipedia with accusations of original research or common sense. :)Jok2000 12:01, 13 December 2005 (UTC)

The current dismbig works for me. The current distinction between z as a proportion at all wavelengths and z as a ratio used in other contexts works also. For cosmology, I would

reorder the three causes to place Expansion of Space last (switch 2.2 and 2.3) so the reader sees the first two causes before arriving at the cosmological one.
move the non-standard cosmology section to the Expansion of Space section as 2.3.1 because this will tell readers who think there is a fuss exactly what the fuss is about.

Readers who think there is a fuss should be told there is no fuss. The current wording doesn't do this. Sometimes the best thing to do is to not give undue weight. --ScienceApologist 01:00, 14 December 2005 (UTC)

move all references to the Big Bang (meaning the last paragraph in the extragalactic subsection) into the Expansion of Space section and include no references to cosmology in any other part of the article. Flying Jazz 14:25, 13 December 2005 (UTC)

Why are you singling out cosmology for your objections? --ScienceApologist 01:00, 14 December 2005 (UTC)

It's like I've been saying. Redshift (in the proportional-z sense) is an observation. That's why it's so valuable. The three effects that cause it are important, but they are of secondary importance to saying what redshift is. The theory developed using those effects is of tertiary importance in a redshift article. My goal with those changes would be to not single out cosmology. As for a fuss, discussions of origins will always cause a fuss. That's just human nature. If the fuss is to remain, why not localize the fuss in the subsection that makes people fussy? Flying Jazz 02:36, 14 December 2005 (UTC)

I object to the assertion that cosmology is somehow intrinsically more "fussy" than, say, exoplanet studies. --ScienceApologist 13:09, 14 December 2005 (UTC)

I want to do a moderate reorganization along the lines of my comments above:

The relative change in wavelength z - Simple renaming of "Mathematical definitions"
Redshift due to scattering - This is the place to mention that the term sometimes refers to the shift of individual lines. A list of individual effects is not necessary because they are (or should be) listed in the article on scattering. The fact that scattering is invariably associated with a non-proportional z, blurring, and line broadening will be mentioned here, in preparation for discarding it as an explanation of astrophysical observations.
Doppler-like redshift - Formerly "Causes of redshift"
1. Relative motion -
2. Expansion of space -
3. Gravitation -
4. The tired light hypothesis - I don't know if I like this here, since it isn't on a par with the other three topics, but I would like to get it out of the way. Mention will be made of supernova light curves and the CMB.
Astronomical observations - Here is the place to emphasize that astronomical observations are all constant z and therefore, once gravitational effects are accounted for, can only reasonably be interpreted as recessional velocities. In fact, z is so constant that the constancy of the fine structure constant can be determined to great accuracy. (I.e. the existing section on "Redshift and the variation of the physical constants" will be incorporated here.)
1. Local -
2. Cosmic -

Speak now or forever hold your peace. --Art Carlson 16:44, 14 December 2005 (UTC)

Since this is an article titled "Redshift", and not "Astronomical redshifts", nor "Proportional-Z Redshifts", I think we should list (a) some of the suggested Scattering mechanisms (b) the Wolf Effect which is not a scattering mechanism. Some my earlier references suggest that these mechanisms are also associated with proportional-Z redshifts too, including the Wolf Effect, as are some of the Compton redshift references above. This would satisfy (1) Wikipedia NPOV to include "significant-minority views fairly and without bias", (2) that the information has citations, and (3) that the information is verifiable. --Iantresman 17:28, 14 December 2005 (UTC)

I don't think a list is necessary, but I don't object to one. The form of the Wolf effect proposed to imitate the Doppler redshift is a form of scattering. As such, I strongly suspect, though it isn't entirely clear to me yet, that it must also be associated with massive line broadening, which would rule it out as an explanation of astrophysical redshifts. If you have access to a copy of Doppler-like frequency shifts generated by dynamic scattering we might be able to settle the question of line broadening. Excuse me if I didn't follow all of your references. Could you point me to the one that talks about a proportional-z Compton redshift? --Art Carlson 17:55, 14 December 2005 (UTC)

I don't have a copy of that particular paper, but you might want to try one with a similar title published in the same year, though I have not read it: "Shifts of spectral lines caused by scattering from fluctuating random media" (1990). I think a couple of the Compton effect articles assume proportional Z since they are comparing to Cosmological or Graviational redshifts. For example, "The Compton Effect as an Explanation for the Cosmological Redshift" (1995). And likewise for the Wolf Effect, see "Correlation-induced spectral changes" (1995, Wolf and James), Section 6.3.Doppler-like shifts of spectral lines. --Iantresman 19:48, 14 December 2005 (UTC)

Art, your proposed reorganization is well-thought out and acceptable. I think a list would be problematic. An exhaustive list of scattering processes can be included at the scattering page and need not be rehashed at the redshift page. Instead, make note that "scattered" photons can lose or gain energy and link to the page on scattering processes. It doesn't belong on the redshift page. --ScienceApologist 18:50, 14 December 2005 (UTC)

I don't see a list as problematic; indeed, I am sure I could even produce one for you. But the problem with linking to a page on Scattering is that this page does not even mention redshift, whereas providing a link to, for example, the page on the Wolf effect DOES mention redshift, unless you've removed it YET AGAIN. --Iantresman 19:48, 14 December 2005 (UTC)

Scattering encompasses far more processes than simply frequency shifts. Linking to the Wolf Effect is an argumentative POV. A vanishingly small number of astrophysicists think the Wolf Effect is a source for quasar redshifts, for example. As such, links to that article are a definite case of POV-pushing. Scattering can result in frequency shifts and so linking to the scattering category would be good as it includes processes that you have conveniently left out of your POV-pushing such as Rayleigh scattering and Thomson scattering (to name only two). --ScienceApologist 20:47, 14 December 2005 (UTC)

My very limited understanding of the issue is that redshift due to movement of the source can be demonstrated in the lab and is very non-controversial, Einstein redshift is a simple case of "here's why massive objects do that." I personally don't know if it can be demonstrated in the lab, but I remember that it was demonstrated first with Mercury. And (according to Ian's table at least) redshift due to the expansion of space is what the standard theory calls the effect that we can ignore nearby but seems to predominate with objects that are very far away so we might never really be able to experiment with it. In terms of local-->far away, this argues for a reordering to place cosmological redshift last, and in terms of least disputed-->most disputed the same ordering would occur. If we are going to give scattering a heading and use the Doppler-like terminology, I would rather see:

Doppler-like redshift - Formerly "Causes of redshift"

Relative motion -
Gravitation -
Cosmological -
1. Expansion of space
2. ~~Other~~ Non-standard (or inconsistent?) theories

If something like tired light is included (which would surprise me if I came across this article for the first time), why include it as a #4 when it's really only meant as an explanation to compete with expansion? And if some of these are included, which should be excluded? Just as "Redshift due to scattering" was proposed to largely consist of a link to scattering, "Other theories" in my view should largely consist of a link to non-standard cosmology. I don't hold this view very firmly, but I would appreciate a comment about it. Flying Jazz 21:12, 14 December 2005 (UTC)

There are no other theories in cosmology for the origin of redshift other than the expansion of space. That's why Iantresman is fighting tooth and nail here. It is not NPOV to claim that there are "other theories" when really the fact that the only consistent explanation for the cosmological redshift is the expansion of space as predicted by FRW cosmology. That's akin to claiming that there are "other theories" that explain observations that point to an Earth that rotates. The fact is, they are not accepted theories and as this is a scientific page we need to stick to scientific theories. What no one can point to is a notable source that makes the claim that the redshifts seen in the Hubble Law are due to something other than the expansion of space. I don't mind including tired light as an excluded example as it is of some historical interest, but it probably should be excluded. --ScienceApologist 21:26, 14 December 2005 (UTC)

First of all, from the little I do know, I agree with your interpretation that they are not accepted theories. My using the word "other" is a result of lack of experience with the discipline. I really am not here to discuss cosmology, but the placement of cosmology in this article does interest me. I don't understand why you don't mind including one example of an unaccepted theory and not others that are equally wrong. And if they are all equally wrong, it seems better to me to include none rather than one and to refer the reader to the non-standard cosmology article in the exact location that calls for the reference. I particularly don't understand including tired light as a #4 instead of subcategorizing it under the particular cause of redshift that it was meant to explain and failed to explain. Do you have an opinion about my proposal for reordering? It seems unsual to me to order them the way they are right now. Is there a reason to put the expansion cause in between the other two? Flying Jazz 22:01, 14 December 2005 (UTC)

I don't understand why you don't mind including one example of an unaccepted theory and not others that are equally wrong. -- Mostly for historical and notability reasons. Tired light is an idea that was suggested as a Zwicky whimsical alternative to the steady state-Big Bang wranglings before the discovery of the CMB and is arguably the last time somebody seriously proposed that redshifts could represent "new physics". There remains a common misconception in many people's minds that light somehow "loses energy" as it travels through space. The fact that this does not occur is an important point to make to clear up misconcetions. --ScienceApologist 22:19, 14 December 2005 (UTC)

I don't object to excluding tired light as we know it is incorrect. It is the one "incorrect" interpretation that makes the most sense to include, in my mind. Arp's "variable mass" suggestions and plasma cosmology's "scattering" insistences are considerably less notable than tired light. --ScienceApologist 22:19, 14 December 2005 (UTC)

There is some justification for putting expansion of space behind Doppler redshifts since metric expansion is Galilean invariant with physical velocities. That's fundamentally different than a metric curvature causing a redshift. --ScienceApologist 22:19, 14 December 2005 (UTC)

Joshua, the title of this article is "Redshift". It is NOT "Hubble redshift", nor "Cosmological redshift", nor "Doppler-like redshift", nor "Astromoical redshift". That you keep mentioning redshift in a cosmological or astronomical context, TO THE EXCLUSION OF ALL OTHER DEFINITIONS, contravenes Wikipedia NPOV policy "... that articles should be written from a neutral point of view, representing all majority and significant-minority views fairly and without bias. According to Wikipedia founder Jimbo Wales, NPOV is "absolute and non-negotiable". There is no other interpretion. By all means, create a page on "Cosmological redshift", but don't appropriate "Redshift" in the name of Cosmology.

I am "fighting tooth and nail" for fairness. I have no interest in implying other redshift are "cosmological". But the verifiable peer-reviewed citations say there are other laborartory-demonstrated redshifts: most are distorted in some way; the Wolf Effect may be Doppler-like. But the information is verifiable. That you have provide nearly no peer-reviewed references, and no verifiable information, is telling.

That you can't include ONE SENTENCE to say this in a fair way is appalling. That the mere thought of the idea of non-Doppler-like is so abhorent to you that you must wipe it out of the literature also appalls me. That's suppression. That you challenge that ANYBODY has even mentioned non-Doppler-like redshifts, contrary to the evidence apppalls me. The rest of us talk about, discuss it, consider it, test it, write about it, and RECORD it. That's science. --Iantresman 22:29, 14 December 2005 (UTC)

Do you have anything new to add, Ian? --ScienceApologist 22:32, 14 December 2005 (UTC)

To be clear this is my point for why Ian's advocacy should be excluded: What no one can point to is a notable source that makes the claim that the redshifts seen in the Hubble Law are due to something other than the expansion of space. Does making the sentence bold mean that it is more important? ;) --ScienceApologist 22:34, 14 December 2005 (UTC)

Look at what you just wrote in bold and how it makes the issue so specific by limiting the discourse down to exactly the cosmological. There are redshifts. Then there are the doppler-like redshifts that are wavelength-invariant. Then there are the Hubble redshifts which are not due to velocity or gravity. And then there is the fact that there is no theory to explain them successfully by any method other than by the expansion of space. I'm arguing for that exact structure in the article itself and mentioning other theory in that precise context. I think the ordering of the three causes based on Galilean invarience is way over the top obtuse. Like most non-physicst scientists, I learned general relativity and then forgot much of it and now I just understand that gravity warping space and other "relativistic stuff" isn't needed for velocity and space expansion effects. But I think going from local to cosmic is a better ordering for a wikipedia article. Flying Jazz 23:16, 14 December 2005 (UTC)

Except that the order you outline is not "from local to cosmic" as there are peculiar velocities observed in the Hubble Flow and the gravitational redshift has been observed on the surface of the Earth. I think that the order we have now is best from the perspective of discovery. Doppler was discovered first, then the expansion of the universe, then came Pound-Rebka. --ScienceApologist 23:25, 14 December 2005 (UTC)

To me and to the common reader, the issues you are discussing are details and cosmological redshift is best found from stuff very far away, gravitational redshift is best found from stuff that is massive, and doppler redshift can come from any old thing that's moving fast. Of course stuff that is far away is also big and moving. But conceptually, there are critical differences to the common reader that argue in favor of the order I am proposing. Flying Jazz 23:44, 14 December 2005 (UTC)

Yes, there are references, which have already been cited, but which YOU don't find noteable. I actually don't know whether the references hold true, but Wikipedia's policy on verifiability says "The threshold for inclusion in Wikipedia is verifiability, not truth". (my emphasis)

Whether the non-Comologicl redshifts such as Wolf, Compton, etc etc, have anything to do with Hubble's Law is irrelevent. Once again, this is an article about "Redshift", not about "Cosmological redshift". Redshift and Hubble are NOT synonymous, and I've never promoted the incusions of suggesting that these redshifts demonstrate, suggest, or even hint at being responsible for the Hubble redshift. --Iantresman 23:05, 14 December 2005 (UTC)

If it is irrelevent as to whether they are cosmological or not, then clearly making a reference to the fact that scattering can result in frequency shifts and leaving it at that is enough. No need to link directly to Wolf, Compton, etc, because all scattering can do this (including Tyndall effect). --ScienceApologist 23:08, 14 December 2005 (UTC)

Ian would do well to reread Wikipedia:Verifiability. Inaccurate sources are intrinsically not verifiable. As such, something like Don Scott's page is not verifiable. Ian's interpretations of certain peer-reviewed articles are also not verifiable. --ScienceApologist 23:08, 14 December 2005 (UTC)

I've not used Don Scott's page as source in the redshift article. Why bring it up?

My references, by definition, are verifiable peer-reviewed citations, eg:

A peer-reviewed article title: "The Compton Effect as an Explanation for the Cosmological Redshift". Interpretation?
Joshua Schroeder: "In "certain" circumstances (read "special" there or "contrived") you can get Compton Scattering to mimic the Doppler Effect. " [102]
Emil Wolf's article title on the Wolf Effect: "Noncosmological redshifts of spectral lines". Interpretation?

Your opinions are neither referenced, and hence are not verifiable. QED

--Iantresman 00:35, 15 December 2005 (UTC)

You use Don Scott as a starting point for many of the sentences and "information" you include. Relying on the advocacy of people like him is part of the reason so much of your work is so unverifiable. Your references are not verifiable since you pick-and-choose points and reinterprety them to fit your own agenda. That you do not realize this is part of the problem. You have not bothered once to check out any references that refer to redshift in any form other than the few culled abstracts and papers which you enjoy. Check out, for example, the references at the end of the article. --ScienceApologist 15:55, 15 December 2005 (UTC)