Wikipedia:Reference desk/Archives/Science/2009 May 10

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May 10

Microwave oven question

So I'm watching the Food Network and this lady is trying to soften up a big block of chocolate in a microwave oven so she can make chocolate curls and she goes overboard and melts the inside of the block, which happens to me all the time when I try to soften butter - those extra four seconds make all the difference.

My question here is about pre-loading. I believe you're always supposed to put some load into the oven, i.e. if you run the oven empty, you can ruin the magnetron. So if you put a cup of water in with something else, does the presence of the extra EM-absorber influence the other thing?

Put another way - if she'd put a cup of water in the oven at the same time, would the block of chocolate turn out more uniformly heated or would it have melted internally the same way and just taken longer to get ruined? And would it make any difference if it was a static or rotating-tray oven? If I can figure out those questions and world peace, I'll be a happy man! :) Franamax (talk) 01:30, 10 May 2009 (UTC)

Putting a cup of water would have been a bad idea with chocolate. The steam from the heating water would have caused the chocolate to "seize". Basically, if small amounts of water get into chocolate as its melting, all the fat clumps together in rather annoying ways. Chocolate should be kept scrupulously dry during melting. The water may slow down the melting of the chocolate, but is also is likely to mess up the process itself... --Jayron32.talk.contribs 04:29, 10 May 2009 (UTC)

For melting Chocolate you should not set your microwave to full power. Most (all?) microwaves regulate the "power" setting by switching the unit on and off at certain intervals. That gives the heat time to dissipate during the "off" cycle. Water takes a lot of energy to heat in a microwave. It's unlikely to produce any significant amount of steam at the settings needed to melt chocolate. (20% to 30% should do for most microwaves.) What you are going to get at full speed is some components of the chocolate starting to boil and separating out of the mixture. (Even if you don't try to boil water at the same time.) It's like trying to melt it in a hot frying pan instead of in a bowl suspended in a pot of hot water. A cup of water in the microwave would have created an uneven heat distribution in the oven. That would not really change with a rotating tray, because the relative position of water mug and chocolate would not be affected. You'd just get less of an effect on the side not directly facing the cup. So just lower your setting or heat the chocolate in short intervals and you should be fine. 71.236.24.129 (talk) 04:52, 10 May 2009 (UTC)

the real answer to the question is don't use the microwave to melt chocoloate. It's lazy and unprofessional. And gets bad results, as you've discovered. Melt it over water you put on the stove. —Preceding unsigned comment added by 94.27.208.52 (talk) 10:27, 10 May 2009 (UTC)

There is one reason to melt chocolate in the microwave. SteveBaker (talk) 13:55, 10 May 2009 (UTC)

has there ever been a double-blind study of any of the claims of the bible?

Have there ever been a controlled, double-blind study of any of the claims of the bible?

I'm thinking things like breaking a group of sinners into control and test groups and having only one group repent and seeing the results, etc. Obviously we can't tell which subjects would go to Heaven, but are there any claims in the bible that we can tell, and which have been tested in a controlled double-blind experiment? 94.27.208.52 (talk) 10:19, 10 May 2009 (UTC)

Not exactly what you ask for, but the article Efficacy of prayer may be of interest. --NorwegianBlue ^talk 10:32, 10 May 2009 (UTC)

There are no claims of the efficency of prayer in the Bible. There are no claims in the Bible that could be verified in the manner you suggest. Generally, the Bible doesn't contain many claims except of the kind "this guy said such-and-such", or historical accounts of the kind of "this tribe slaughtered another tribe, and then the Assyrians enslaved everybody". People unfamiliar with the Bible, or religion, generally tend to confuse claims made by specific churches or clergies with "the Bible". It is very simple to dispel such confusion, all you need to do is actually read the book. Reading the Bible doesn't mean you are automatcally a pious Christian, it simply means you want to check for yourself what these people keep talking about. --dab (𒁳) 10:49, 10 May 2009 (UTC)

It might be worth to add that some of the historical claims of the bible have been verified, but likewise that many are incompatible with our current knowledge of history. And many again are neither independently verified nor refuted. History does not use double-blind studies, but other methods, of course. --Stephan Schulz (talk) 11:21, 10 May 2009 (UTC)

I happen to agree with dab that actually reading the bible is the quickest way to convince one of its nonsense. However, I wonder if he has been taking his own advice, I think the bible is littered with references to prayers being answered. A quick random trawl through just one book (1 Kings) came up with numerous examples, for instance;

• Yet have thou respect unto the prayer of thy servant, and to his supplication, O LORD my God, to hearken unto the cry and to the prayer, which thy servant prayeth before thee to day (8:28)
• Then hear thou in heaven their prayer and their supplication, and maintain their cause. (8:45)
• And the LORD said unto him, I have heard thy prayer and thy supplication, that thou hast made before me: I have hallowed this house, which thou hast built, to put my name there for ever; and mine eyes and mine heart shall be there perpetually. (9:3)

By the way, is double-blind referring to Saul and Onan? SpinningSpark 12:00, 10 May 2009 (UTC)

Unless you're taking the fundamentalist approach to interpreting the bible, the bible makes *no* claims. The bible is a written expression of people's faith, much like a poem or a song can be an expression of a person's love. If you're reading the poem looking for verifiable claims, you've missed the point. Wikiant (talk) 13:20, 10 May 2009 (UTC)

Of course, if everyone who was "into religion" took that view - the world would be a very different place. Sadly, I'd guess that at least 99% of religious people are either:

1. People who DO take the fundamentalist view that every word in that crazy book is true...OR...
2. People who haven't actually read the book from cover to cover and who are taking their view of the subject from what they are told by the people in group (1).

The book itself is mostly self-contradictory gibberish. SteveBaker (talk) 13:47, 10 May 2009 (UTC)

The trouble with this thought experiment (and one of the major reasons that science says that religion is unfalsifiable) is that if such an experiment were to disprove some hypothesis that's stated in the Bible, the religious folks out there would undoubtedly say something like "But God wants to test our faith and therefore made your experiment come out that way." - there is no way on earth they'd say "Huh! Wow! Well, I guess you atheists were right all along - I won't bother repenting anymore."

So there is no experiment you can do that would falsify what's stated in the bible because it says that god is literally omnipotent - and all rational thought on the subject ends right there. When some hypothesis is unfalsifiable, it's beyond the realms of experimentation and generally regarded as (at best) irrelevant and (typically) something that Occam's Razor says we should simply ignore.

Moreover, the experiment you suggest (where one group of sinners repents and the others do not) cannot be perfomed blind - yet alone double-blind. Again; if the repentant group were not to gain any benefits, the religious crowd would merely claim (with some justification perhaps) that they weren't truly repentant - or that the "unrepentant" group were secretly repentant after all. Of course if the experiment did show some benefit for the repentant group - I would claim (with a good deal of justification) that the results were merely consequences of the placebo effect. Without a true double-blind study (which seems impossible in this case), none of this would tell you anything useful at all.

I suppose the best you could do would be to raise a bunch of children from birth, half randomly assigned to "conventional" religious teachings and with the other half being taught some entirely fake religion. As they grow older, find the sinners amongst them (and one group has the traditional 10 commandments to sin against while the other group has things like "thou shalt not run with scissors" and "thou shalt not exceed the speed limit, even in a 55mph zone") - sort both groups into those who repent and those who do not and follow their progress. If repenters of both religions do better - then it's placebo effect - if only repenters of the "real" religion do better then maybe we're on to something here. However, the religious people would doubtless come up with a whole bunch of weak excuses to explain any results that disproved their position - so it's still unfalsifiable. Of course it wouldn't be enough to have just the children not knowing whether their given religion is real or faked - the whole society in which they grew up would have to be similarly double-blinded...so this isn't in any way a practical experiment.

SteveBaker (talk) 13:47, 10 May 2009 (UTC)

Statements such as for I the LORD thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me seem to me to be very much making a claim. Unless as you say, you are reading it like a poem or a song can be an expression of a person's love (although there is precious little love in that quote). But in that case the Bible cannot be held to be the "word of God" since it is now, according to your view, "an expression of people's faith" (not God's word) and I cannot see how it can be held to be one's moral authority with that outlook. You have a nice book of poems but not an authoritive source of belief. SpinningSpark 14:09, 10 May 2009 (UTC)

I wouldn't say a "nice" book of poems...most of it is exceedingly nasty when compared to modern standards. SteveBaker (talk) 15:01, 10 May 2009 (UTC)

In reply to Spinningspark, I did not claim the Bible contained any "nonsense". It is a compendium of Iron Age to Roman Era texts, no more nor less "nonsensical" than any other text of the same category or genre.

I did also not dispute that the Bible relates incidents of God answering prayers. It does not contain any claim that God answers prayer with any frequency or predictability. He answers them whenever he bloody pleases. Hence the verses you quoted, which portray God's reaction to prayer as a remarkable exception, not the statistical rule. You will also note that then hear thou in heaven their prayer and their supplication is the subjunctive mood, i.e. the expression of the wish that he may hear, not the statement that he does hear. Obviously, the Bible implies that God is in control. But it does not make any prediction as to when or how he isgoing toexertthat control next time you pray, it is only presenting a collection ofanecdotes of how he (allegedly) did react in the past. I would be interested in your proposal for a double-blind study for that. This would be similar to offering a prediction of what my next edit is going to be based on my edit-history, but with the requirement that this prediction is made where I can see it. I would then be completely at liberty to either confirm your prediction or to prove it wrong. In reply to SteveBaker, if you think the Bible is "self-contradictory gibberish", I trust you have never tried to read a Buddhist sutra or a Hindu Purana. If you're going to read a 2000 year old text, you'll need to be prepared to make some philological effort. You cannot read ancient texts like you do the NYT. The problem with the Bible seems to be that many people assume that they can, while nobody would dream of approaching a Pali sutra or an Ugaritic hymn like that. --dab (𒁳) 12:00, 11 May 2009 (UTC)

Yeah - I've tried to read some of those other religious texts and I have to agree that they are vastly worse than the Bible. I use the bible as an example because it's the only book of that genre that I've ever managed to read all the way through...and even then, it was a struggle! Talk about turgid! Once you get away from the well known stories, there is an awful lot of pointless waffle about who begat who and junk like that. Also, the Bible isn't a 2000 year old text - it's been hacked about by countless generations of people who were not acting to preserve the meaning of the text - many parts of it are less than 1000 years old. However, it's very clear that there is no effort made to preserve consistency or direction - you are told to do some thing on pain of eternal damnation on one page - then 10 pages later we're told the exact opposite. If this book (in it's present state) were regarded as a mere historical curiosity - then that would be very different from a book that well over a billion people claim to be the core of their belief system. I'm pretty sure though that less than one in a thousand of them has actually read the book from cover to cover (which is REALLY surprising - I mean - if you're going to define your entire life according to some book - you'd really want to read it at some point!)...right now, nobody I know (including one priest, two rabid fundamentalists and one missionary) has ever actually sat down and read it from start to finish. SteveBaker (talk) 13:17, 11 May 2009 (UTC)

tangent on atheism

And herein is the problem. If you want the bible to stand as "an authoritative set of beliefs," then you must live with the circular argument: The bible is authority because the bible says that it is the word of God and the word of God is authority. Thus, you are left with a choice. Either (1) The bible is, fundamentally, a circular argument and so is relevant only to those who, a priori, believe it to be relevant, or (2) The bible is an expression of the God-human relationship and so is relevant to everyone. Option (1) makes the bible, in effect, completely meaningless. Wikiant (talk) 17:34, 10 May 2009 (UTC)

I fail to see either the logic of that statement or its relevance to the question we are supposed to be answering. If the Bible is an expression of the God-human relationship (option (2)), it is only relevant to me if it conforms, a priori, to my beliefs in what the God-human relationship consists of. That sounds awfully similar to option (1) in my book. Supposing I accept option (2), it is not relevant to me (and I would guess a lot of other people) because I have no intention of having anything to do with a God-human relationship that has God sending a bear to rip apart children who have merely called his prophet "baldy" or who strikes a man blind for refusing to fuck his dead brother's wife. (edit) Thus your claim that option (2) is relevant to everyone is false by at least one. SpinningSpark 19:15, 10 May 2009 (UTC)

You're suggesting that, under option (2), the bible is not relevant to atheists. But, wrt assumptions, atheists are simply the flip side of fundamentalists. The former assume that everything in the bible is true (ergo double-blind studies cannot satisfy them). The latter assume that everything in the bible is false (ergo, again, double-blind studies cannot satisfy them). WRT the original question, applying double-blind studies to biblical claims is like applying double-blind studies to poetry -- one misses the point from the very start. Wikiant (talk) 22:42, 10 May 2009 (UTC)

Atheists don't believe everything in the Bible is false. We believe those parts that are supported by evidence, disbelieve those parts that contradict evidence and are generally indifferent to the rest (most of us use Occam's razor when we need to decide something on those issues, which doesn't happen very often). --Tango (talk) 23:41, 10 May 2009 (UTC)

(@Wikiant) You assume too much, I made no statement about whether or not I was an atheist, and my reasoning on (2) does not apply only to atheists; it is perfectly possible to believe in God and at the same time discard the Bible. You are making straw man arguments. It is certainly not true that a double-blind experiment could not possibly satisfy a scientifically minded atheist. Regarding us missing the point, the question asked was not what is the point of the Bible (not a suitable question for the Science Desk anyway), but whether it can be tested, which is most definitely answerable. Arguing that the Bible is poetry and so is untestable is really just trying to avoid the issue. Even if that is accepted, the Bible is still being used as a moral reference and it is valid to ask if its moral claims make sense. SpinningSpark 06:59, 11 May 2009 (UTC)

You aren't describing an atheist, but an agnostic. The atheist believes that God does not exist. If you can be swayed by a double-blind experiment, then you aren't an atheist. Wikiant (talk) 11:21, 11 May 2009 (UTC)

No, that's nonsense. I believe that when I tumble down the stairs I will fall, so I'm a gravitist. But that does not mean that I would keep that position if I managed to miss the floor and waft away. Of course positions can and do change in response to evidence. --Stephan Schulz (talk) 11:39, 11 May 2009 (UTC)

See Weak and strong atheism. What you describe is strong atheism, which I consider just another religion (generally an unorganised one, but still characterised by the same rejection of the scientific method). Most atheists are weak atheists (a category which includes (at least some) agnostics, but is larger). I consider myself a weak atheist and not an agnostic. I am certain that, given the evidence I have available to me, I can confidently reject (at any commonly used confidence level) the hypothesis that there is a god. I am, however, open to the possibility that new evidence will turn up to support that hypothesis and I will need to change my beliefs accordingly. I think most people that describe themselves are atheists hold similar views. --Tango (talk) 11:54, 11 May 2009 (UTC)

Who is "you"? Anyways, that's still not quite right. Strong atheism is a believe that there is no god, weak atheism is the lack of a believe in god, agnosticism is the belief that either we don't know, or that we cannot know, depending on whom you listen too. But even my belief in gravity or no god can be changed by proper evidence. There is a difference between belief and dogma. --Stephan Schulz (talk) 12:16, 11 May 2009 (UTC)

"You" is Wikiant, the person that wrote the message above mine and one indentation less. "Lack of belief in god" would describe agnostics, weak atheists and strong atheists - by definition, it describes anyone that isn't a theist. The difference between those categories is the level of certainly that there isn't a god. A strong atheist is absolutely certain that there isn't a god and nothing will change their mind. A weak atheists think it is possible, but very unlikely that there is a god. Agnostics aren't sure either way (they may err to one side or the other, but will be somewhere near the 50/50 mark). (Precise definitions vary depending on who you ask, by some definitions the categories overlap (see agnostic atheism, for example [by my definitions, that would probably fall under weak atheism]).) --Tango (talk) 13:08, 11 May 2009 (UTC)

Well, we have to be a little careful here. My personal position is that the "God hypothesis" is unfalsifiable. That means that I know for an absolute fact that proof of the non-existance of God (as defined by almost all religions) is impossible. That's not quite the same thing as total disbelief...but it's very, very close. I know for a fact that there are an infinite number of unfalsifiable hypotheses (Russell's teapot for example) - and that the probability that any particular one of those is true is arbitarily close to zero...but not zero. Technically, that makes me an agnostic. However, that word is generally understood by the religious fraternity as someone who has genuine conflicted doubt about the existance of God...which could not be futher from the truth. I am as certain that there is no god as that there is no tooth fairy and that there is no Santa Claus. I am as certain that there is no god as that you have not just transformed into a pink bunny rabbit while reading this post. That's a very high degree of certainty indeed. However, it's not 100% - nor can it be because we have an unfalsifiable hypothesis here. What matters is that I act and behave in every way as if I'm certain that there is no god. The almost infinitely small amount of doubt is of interest to mathematicians only! 1/infinity is pretty damned close to zero!

So I am the strongest kind of atheist there can possibly be...because logically, nobody can be 100% certain that an unfalsifiable hypothesis is actually false - although they can be arbitarily close to 100% certain. If the word "atheist" has any meaning at all - then a lot of people are atheists. If it has no meaning then there are dramatically different kinds of agnostics. There are the kind who (like me) put the probability of god(s) existing at the 1/infinity level - those who think it's a 50/50 thing - and the totally rabid fundamentalists who have a 1/infinity level of doubt in their chosen god. If you choose to apply those terms then absolutely everyone is an agnostic...which makes the word useless.

Considering atheism to be "just another religion" is the entire topic of this thread. If you still believe that to be true - then you have not read a single word of my first two posts to this thread. There is a huge difference here. To be a strong atheist (or even a weak one, I think), you have to want logic, proof, verifiability and falsifiability in all things. To be in any kind of religion at all - you have to be prepared to believe without question what someone else has told you - with no possibility of there ever being proof. That's a really dramatic difference. Calling atheism a "religion" is profoundly upsetting to me - and a contradiction of the very meaning of the word: a-theism...no theism...no religion. Religious people would dearly love for the atheists to be labelled as "religious but just in another way" - but that's totally untrue.

SteveBaker (talk) 13:17, 11 May 2009 (UTC)

Steve, you seem to have misunderstood either me, or the concept of strong atheism. I said that strong atheism is just another religion, and I stand by that. Strong atheism is the belief that there is absolutely no chance of a god existing (not a very very small chance, literally zero chance). That isn't based on logic or the scientific method, it's an absolute assertion which is not (and cannot be) supported by empirical evidence - sounds pretty religious to me (I don't think it is a belief actually held by many people, though). What you describe as your own beliefs is weak atheism, which is not religious. As a mathematician, I must object to your abuse of "infinity". Infinity is not just a very large number, it is larger than any number can be. 1/infinity is precisely zero (for the appropriate concept of infinity, it is undefined for other concepts of infinity). If I interpret you correctly (ignoring your bad maths!), you believe the probability of the existence of a god is a finite, positive real number. A very small one, but still finite and positive. (There are no infinitesimals in the real numbers - that's why 0.999...=1.) --Tango (talk) 16:08, 11 May 2009 (UTC)

By Wikipedia's definition of a strong atheist (ie someone for whom the probability that gods exist is zero), I don't think anyone is a strong atheist. The older version of the article had a more useful distinction:

Strong atheism - belief that there are no gods

Weak atheism - no belief that there are gods

There might be utility in Wikipedia's current definition to contrast with the people for whom the probability that (their) god exists is one. There are people with that stance. Zain Ebrahim (talk) 14:39, 11 May 2009 (UTC)

As I've said above, defining weak atheism as the lack of belief in a god is useless. Someone that believes there are no gods also lacks a belief in a god (tautologously). Weak atheism is the view that the existence of a god is extremely unlikely (to the point where you can just assume there isn't one), but with the acceptance that one can never be 100% certain. --Tango (talk) 16:08, 11 May 2009 (UTC)

Sorry, but that is not the standard definition. There is a difference between "I believe there is no teapot in orbit around Mars" and "I don't believe there is a teapot in orbit around Mars", although it requires a decent supply of nits. The one is active disbelief, but the other is just a lack of positive belief. As an example, someone may not have any opinion on the topic, be it for lack of information or lack of interest. --Stephan Schulz (talk) 16:50, 11 May 2009 (UTC)

I'm pretty sure it is the standard definition. Either way, your definition is certainly wrong. I know there is a difference between those two statements, but they are not mutually exclusive (a belief in the lack of a god is a lack of belief in a god, as I've said 3 times now [the converse obviously doesn't hold]). If you wish to categorise people by their beliefs in this fashion, those beliefs need to be mutually exclusive. --Tango (talk) 16:57, 11 May 2009 (UTC)

Ah. There is the beef. No, they do not need to be mutually exclusive. Of course a strong atheist also is a weak atheist, just like a communist is left-wing, or an obese person is overweight. --Stephan Schulz (talk) 19:20, 11 May 2009 (UTC)

I don't think that is the standard definition. It certainly isn't the definition use in our article, which starts: "Strong atheism is a term generally used to describe atheists who accept as true the proposition "gods do not exist". Weak atheism refers to any other type of non-theism." (emphasis mine) --Tango (talk) 19:29, 11 May 2009 (UTC)

The odd thing about these definitions is that they describe only three qualitatively dissimilar groups: theists (i.e., probability that god exists = 1), strong atheists (i.e., probability that god exists = 0), and weak-atheists-and-agnostics for whom the probability that god exists is positive but strictly less than 1. Within this group, one might draw a continuum from weak atheist to agnostic to (weak?) theist, but the difference among these is quantitative, not qualitative. Wikiant (talk) 20:13, 11 May 2009 (UTC)

I don't think that to be a "strong atheist" you have to think the existence of God is actually impossible. You just have to believe that it's possible to derive reliable conclusions from God's nonexistence.

So for example a strong atheist who believes "if the Sharks someday win the Stanley Cup, then there is a God" will also believe "the Sharks will never win the Cup".

On the other hand, a weak atheist who believes "if there is a God, then the Sharks will someday win the Stanley Cup" will simply decline to conclude that the Sharks will someday win.

As for me, I believe in God, but I don't actively hold to very many specific propositions about God. So God is there, but our beloved los tiburones are still going to have to find a way to suck it up in March. --Trovatore (talk) 20:44, 11 May 2009 (UTC)

I guess that depends on what you mean by "reliable". If you mean "certain", then those two definitions are equivalent. If you allow a little uncertainty then I would disagree. I conclude from the lack of a god that there is no harm in me not going to a church every Sunday, a mosque every Friday and a synagogue every Saturday (isn't is nice of the Abrahamic religions [I regret, I don't know when the various non-Abrahamic religions like to meet up] to have their main prayer meetings on different days? It makes everything so much simpler for those that like to hedge their bets!). I consider that conclusion reliable enough to follow it. I don't consider myself a strong atheist and I don't think I count as one under any common definition of the term. --Tango (talk) 22:53, 11 May 2009 (UTC)

Yes, it's all pretty qualitative. You might be able to add a dividing line at the 50/50 mark quite easily. I describe a weak atheist as someone that believes the chance of there being a god is very very low, but I don't attempt to quantify "very very low", I don't see anything to be gained by arbitrary dividing lines. --Tango (talk) 22:53, 11 May 2009 (UTC)

Personally, I would only use the word "atheist" of someone who was fundamentalist in their disbelief in God. Otherwise agnostic is fine and can happily include non-fundamentalist Christians too since we are all open minded. I think very few people can actually define what they mean by the statement "God exists" anyway (I tried at [1]). But the initial point in this thread is important. There can be no notional of authority or infallibility without first cracking the notion of "intent". And from an information technology point of view no finite set of words can stand as truth (description is only convergent to the real world because of the size of the data sets). Anyway for goodness sake if you learn nothing else from Richard Dawkin learn that people who explain religion to you are a selection biased set and instead make up your own mind and arguments. Most of purported religious "logic" is rubbish even to hairy old Christians like me. But a lot of claimed "science" is rubbish to so as long as I don't buy a magnet for my car fuel inlet why should these other claims bother me? --BozMo talk 11:28, 13 May 2009 (UTC)

This was a very interesting discussion about probabilities, but I think most people don't look at theism and atheism as a mathematical formula. For example, most religious people call those people strong atheists, who actively fight against theists, seeking arguments against them or just bullying them, while weak atheists or just nontheists are those who don't care. --131.188.3.21 (talk) 08:19, 13 May 2009 (UTC)

I've never heard the terms used like that. --Tango (talk) 10:54, 13 May 2009 (UTC)

Nor have I. I like to use the term "evangelical atheist" to describe the former. But according to our disputed article on Antitheism, it's a pejorative term used by Christian apologists and one or two atheists. A Quest For Knowledge (talk) 20:26, 13 May 2009 (UTC)

@Tango: Looking through google, I see that both definitions of strong atheism are fairly common. Imo, the definition I outlined above is better than WP's because it distinguishes between actual atheists. If we accept that atheists are all rational reasonable people, then there won't be any strong atheists by the WP definition (to claim any absolute knowledge about unfalsifiable hypotheses is irrational) but there are people who actively believe that there aren't any gods.

Regarding the mutual exclusivity, I don't understand your concern. Why is the distinction useful iff it's mutually exclusive? Sure, according to that definition, strong atheists are also weak atheists but I don't see this as being a problem in practice: if someone tells me they're a weak atheist, I'll assume they're not a strong atheist. Of course, if you wanted to, you could tweak the definition to make it mutually exclusive. Zain Ebrahim (talk) 09:38, 14 May 2009 (UTC)

Quark strangeness and charm

No, not the Hawkwind album. Strangeness and charm quantum numbers are preserved in strong interactions, as are the (less commonly used) bottomness and topness quantum numbers. The natural extension of these properties to first generation quarks would be "upness" for up quarks and antiquarks and "downness" for down quark and antiquarks. However, "upness" and "downness" do not seem to be identified as separate quantum numbers; instead, they are merged into the isospin quantum number. Is this purely a historical anomaly (isospin was introduced a long time before the discovery of quarks), or is there a more fundamental reason - e.g. are "upness" and "downness" not actually preserved in all strong interactions ? Gandalf61 (talk) 10:50, 10 May 2009 (UTC)

Upness and downness are as good flavor quantum numbers as strangeness, charm, bottomness and topness and are indeed preserved by the strong interactions. But it is conventional (and convenient) to replace them by two other flavor quantum numbers, namely isospin and baryon number. It is not uncommon to also replace strangeness by flavor hypercharge. The reasons for doing so are twofold.

Firstly, as you guessed, historically baryon number and isospin were identified as important quantum numbers much earlier then the existence of quarks and their flavors became accepted. Secondly, there are practical reasons for using baryon number and flavor isospin. For instance, unlike upness and downness, baryon number is preserved by all known interactions including week interactions.

Also, the energy scale of the strong interactions as given for instance in terms of the pion decay constant $f_{\pi }\approx 93MeV$ is much bigger than the up and down quark masses and roughly the same order of magnitude of the strange quark mass, but much smaller than any of the other quark masses. That means that the symmetry operation that replacess the up quark with a down quark and vice-versa is a good symmetry and the charge associated with that SU(2) symmetry (which happens to be flavor isospin) is a valueable theoretical tool. For instance, there are two different kinds of nucleons (protons and neutrons) and three different kinds pions, which means there are six different ways pions can interact with nucleons. Flavor isospin symmetry tells us that if we can understand and describe one of those interactions, we have automatically understood and described the other five. It pays to use the symmetries of the theory to organize the description of the interactions.

The mass of the strange quark is not entirely negligible but is still small enough that the symmetry operation that replaces the up quark, the down quark and the strange quark among themselves is a fair symmetry and the charges associated with that SU(3) symmetry (which happen to be the flavor isospin we already talked about plus the flavor hypercharge) are still somewhat valueable tools. That's why sometimes it is usefull to replace strangeness with flavor hypercharge. All the other quarks are too heavy and enlarged symmetries that also include those heavier flavors are bad and their charges are essentially useless. That's why charm, bottomness and topness are used instead.

Notice that I have carefully described those quantum numbers as flavor isospin and flavor hypercharge in order to avoid confusion with weak isospin and weak hypecharge which are entirely different quantum numbers. The latter ones are gauged symmetries and are preserved by all known interactions. Beware that folks in the Nuclear Physics crowd use unqualified isospin and hypercharge to refer to the former ones while folks in the High Energy (Particle Physics) crowd use those unqualified terms to refer to the latter, which unfortunately adds a lot to the confusion. Dauto (talk) 19:41, 10 May 2009 (UTC)

Thank you for that very clear and comprehensive answer. Gandalf61 (talk) 06:15, 11 May 2009 (UTC)

Submarine hull breach

In numerous films and books, both fictional and factual, it's said that a pressure hull breach in a submersible at great depth would happen so fast the occupants wouldn't know it had happened, and that a pin sized hole would create a beam of water that could cut a person in half. Can you tell me fast the water is actually moving? I appreciate there are a huge number of factors to consider (cabin pressure, water pressure, cabin size, size of breach and probably a host of others) but roughly how fast would the water be moving? In a (hypothetical) much larger vehicle with much greater internal space, would people potentially be able to witness and even avoid such an event (closing a hatch that can resist the pressure, for example)?81.129.229.14 (talk) 12:44, 10 May 2009 (UTC)

Well, submarine says that "When submerged, the water pressure on submarine's hull can reach 4 MPa (580 psi) for steel submarines and up to 10 MPa (1,500 psi) for titanium submarines like Komsomolets," - so we can be pretty safe in saying that 1500psi is the most pressure we have to consider here. I looked on the website of FlowCorp who make machines that cut anything from cardboard to titanium using high pressure water streams. According to their site, a machine that can cut through a few inches of cardboard requires a stream that's about one hundredth of an inch in diameter with a pressure of 20,000 psi - and to cut through steel, they use 40,000 to 60,000 psi. So it seems unlikely that a 1500 psi stream from a pinhole (which is around a hundredth of an inch in diameter) would cut a person in half if it has less than a tenth of the pressure needed to cut cardboard. Flowcorp's machines produce a Mach 2 flow at 40,000 psi and a Mach 3 flow at 60,000 psi - so at 1500 psi, the speed would probably not be all that fast.

Actually, we can work it out - the Hagen–Poiseuille equation should pretty much apply here:

$\Phi ={\frac {\pi R^{4}}{8\eta }}{\frac {|\Delta P|}{L}}$

Where:

$\Phi$ is the volumetric flow rate

$R$ is the internal radius of the tube (meters)...0.000125 meters

$\Delta P$ is the pressure difference between the two ends (pascals)...10,000,000 pascals

$\eta$ is the dynamic fluid viscosity (pascal-second (Pa·s)), 1.3 × 10⁻³

$L$ is the total length of the tube (meters) - say 5cm??

So the flow rate is .000014 m³s^-1 - which (through a hole with a cross-sectional area of our pinhole) is 285 meters per second - which is about 640mph. That's quite a bit more than I'd suspect from the FlowCorp numbers...but it depends sensitively on the diameter of that "pinhole" - if the hole is half that diameter then the flow rate is 1/16th as much and the speed of the jet is 1/4th as much. That sensitivity on the size of the hole means that this story can be as true or as false as you want it to be!

SteveBaker (talk) 14:56, 10 May 2009 (UTC)

The water would presumably start to spread out and slow down as soon as it came through the hole, so it would be going slower once it reached the person that was going to be cut in half by it. I'm not sure how much slower, so it may or may not be significant, but I do observe that the video clip on that website shows the high pressure stream only travelling a few millimetres before hitting the target. What we are discussing would, presumably, be orders of magnitude further (unless the person was leaning about the side of the sub at the time, but even that seems unlikely - they are double-hulled, aren't they?). --Tango (talk) 19:01, 10 May 2009 (UTC)

The Russian submarine Kursk suffered a torpedo explosion that ripped a 2 square metre hole in its hull at a depth of 100m. Nevertheless, 23 members of the crew at the other end of the submarine survived long enough for an officer to take a roll call and write a list of their names. Sadly, they all died before a rescue could be attempted.

In an incident with a happier outcome, a seawater hose failed on the Australian submarine HMAS Dechaineux (SSG 76) when it was at its maximum diving depth. The engine room was flooded, but the crew managed to control the flooding just in time to allow the submarine to surface. Gandalf61 (talk) 15:56, 10 May 2009 (UTC)

Check out Cecil Adams' answer to a similar question here. --Sean 13:12, 11 May 2009 (UTC)

The volume of ice at the north and south ice caps and Greenland?

I seem to recall that the rise in sea level is suppossed to be 50 metres if both ice caps, the ice over Greenland, and all other ice melted. But I am sceptical. The world is a big place. The oceans have an area of about 360 million square kilometres. If they rose by 50 metres, then the extra volume would be 18000 million million cubic metres. What is the total above-sea-level volume of ice at the north and south ice caps, Greenland, and other glaciers and ice? 84.13.171.69 (talk) 14:39, 10 May 2009 (UTC)

Well, your skepticism is easily debunked given some numbers:

Firstly: be careful - not all of the sea level increase predicted from Global warming comes about from melting ice. Remember, as objects heat up, they expand - and that will happen to our oceans if we don't stop the temperatures from increasing. However, the rate at which the warmth from the atmosphere heats the deep oceans is hard to estimate (I got told off about that the last time this question came up!) - so let's ignore that for the moment - bearing in mind though that it's certainly not an insignificant part of this process.

The ice over the antarctic is way more than a kilometer thick in places - remember that a cubic kilometer is a thousand million cubic meters - so 18000 million million cubic meters sounds impressive - but that's "only" 18 million cubic kilometers.

According to antarctica the antarctic ice sheet covers 13.7 million square kilometers and averages 1.6 kilometers thick...which is 22.4 million cubic kilometers - significantly more than the 18 million you need to make your math come out right. Which means that a 50meter sea level rise can easily be accounted for by the melting of antarctica alone...that's forgetting all of the ice and snow on mountains and glaciers in the rest of the world and the effect of the expansion of the volume of water due to the overall warming trend. There are even worse consequences possible here...as the ice melts from the continent of antarctica, the quadrillions of tons of pressure of all of those cubic klicks of ice goes away and the continent will rise upwards as the pressure is relaxed. This will allow the continental shelf in the region to rise up - displacing yet more water to the rest of the planet. To add insult to injury - the increasing water depths pressing down on the continental shelves (and further inland as flooding begins) will press downwards on the other continents making them sink a little - making it seem like the water is rising even faster (although in reality, it would be the land sinking - that's little comfort to someone living on the coast!) Some estimates for the worst case sea level rise go as high as 70 meters...and given these numbers, you can see why! SteveBaker (talk) 15:26, 10 May 2009 (UTC)

Of course to melt so much ice, it would take about 6x10²⁴ joules to overcome the enthalpy of fusion of ice. Given that the relevant solar constant in Antarctica is well below the 300 watts per square meter average for the planet, it would take a long time to melt. (My back-of-the-envelope calculation suggests that if we could convert 100% of the solar radiation in Antarctica into 100% efficient ice-melting, we could melt that much ice in just 50 years, though!) Of course, this calculation is not a realistic model of climate-change - I haven't accounted for albedo, let alone convection and weather! - but it does put some perspective on the size of the numbers involved. Nimur (talk) 15:54, 10 May 2009 (UTC)

There are also factors that go in the other direction, though, including geothermal heating and heat transfer between the tropical and polar regions, as well as increased ice flow rates as the ice thins and its temperature rises. Looie496 (talk) 16:36, 10 May 2009 (UTC)

A couple of things I missed:

Melting ice at the north polar ice cap doesn't directly affect the sea level because it's already floating - which means that it's already displacing the same amount of water it'll create when it melts. That's good news - but along with it comes bad news. As Nimur points out, it'll take a long time to melt all of the antarctic ice...however, it doesn't actually have to melt - if it merely slides into the ocean and floats - that's enough to produce a problem. It has been noted that there are mechanisms that accelerate the destruction of glaciers when the meltwater from the top of the glacier finds it's way through crevasses to the underlying ground and produces a lubricating layer between the ice and the ground beneath. This allows the ice to slide much more rapidly down to the ocean where it can first form "ice shelves" and then break up into icebergs (which displace water even before they melt).

Greenland contains only about 2 million cubic kilometers of ice - less than a tenth the amount of antarctica - but it's melting much more rapidly - so in the short term, it's a bigger problem.

SteveBaker (talk) 17:08, 10 May 2009 (UTC)

Your first point directly above is not quite correct (as was pointed out to me the last time I answered a similar question - isn't it great that we can learn from new material as we come across it?). Don't forget that the water is salty, but the ice is fresh, so the displacement is not nearly as exact as we might hope. Antarctica is a huge multiple whammy due to the reasons mentioned above, but the arctic will also be a significant source of sea level rise. Matt Deres (talk)

Well - it's true - seawater is about 2.5% denser than distilled water - so there would be a tiny difference due to the arctic ice cap melting - but it's not enough to make much of a difference to global sea level. The arctic ice is only 4 to 5 meters thick on average - so even if 100% contributed to sea level rise, it would be negligable compared to the antarctic glaciers at 1600 meters thick...but you're right, technically that 2.5% density difference makes a tiny difference to the ocean depths. SteveBaker (talk) 12:24, 12 May 2009 (UTC)

Half right. The salinity makes a huge difference to the current flows and speed of mixing. Which in turn drives the rate of rise. I see we do not have an article on Double diffusive convection yet.--BozMo talk 12:33, 12 May 2009 (UTC)

Time Travel

Wouldn't time travel be undesirable? Besides the grandfather-paradox and everything else about going back in time (which is really impossible considering you need a 'receiver' which wasn't built years ago), consider this scenario. Some time in the future the world is going to face a calamity, e.g. the sun expanding into a super giant and enveloping the earth. All those people in the future (who are still on this planet) would want to find the fastest way to get out of the situation. Assuming they all choose to go back in time. The population of the planet at the time they choose to go back to would increase immensely. But the calamity in the future is still going to happen. Assuming all those people living there at the time of that calamity also decide to go back in time, and this keeps happening, sooner or later we'd have an infinite number of refugees on the planet. Maybe we should make some rules and regulations on what times in 'history' (which will be our future anyway, until the receiver is built) you are allowed to send billions of people back to, to prevent ridiculous overcrowding.--KageTora (영호 (影虎)) (talk) 15:22, 10 May 2009 (UTC)

As long as you go back far enough that you won't live to see the calamity a second time, and you don't have any children, there isn't a loop to worry about. As long as you spread people out over a millennia or two, there shouldn't be able real problem. (Assuming such a thing is possible, which it probably isn't. Also, if you can invent a time machine you can probably use similar methods to invent a spacecraft that travels faster than light, in which case you could evacuate to another solar system instead.) Incidentally, the sun will turn into a red giant, not a supergiant. --Tango (talk) 15:27, 10 May 2009 (UTC)

If you accept the repugnant conclusion, this would likely be a very, very good thing. — DanielLC 15:31, 10 May 2009 (UTC)

Yeah - there have been countless sci-fi stories about the undesirability of it...and few (if any!) that make it sound in any way desirable. However, time-travel is impossible - so it's not really something we have to be concerned about. However if you'd like food for thought:

• Let's dump all of our CO2 emissions and other garbage back into the Triassic era.
• Temporal tourism results in huge crowds of time travellers with fancy holographic cameras gathering just before momentous events in history. It becomes virtually impossible for any historic event to go "as planned".
• Stock markets collapse, banks fold, casino's can do no business as future travellers do the "deposit a penny in 1800 and collect the compounded interest in 2800", sending back in time copies of almanacs and horse-racing results.
• Temporal anomalies (if your version of time travel allows them) make life hard to lead.
• Business collapses as each one attempts to patent all of the products of their competitors before that product was even invented.
• Businesses realise that they can manufacture goods in one time and send them back or forwards to a time when they were either vastly more expensive or insanely desirable.
• The movie business collapses as people travel forwards in time until their copyrights have expired and watch new movies (and the sequel that hasn't even been made yet) for free.

Pretty soon, you realise that it all becomes very silly! SteveBaker (talk) 15:35, 10 May 2009 (UTC)

(EC)If they didn't have any children, they would all die out in, say, a hundred years or so (assuming life-span hasn't increased dramatically), but that would leave a block of about a hundred years which would be uninhabitable, because of the huge population. This would keep happening until all the 100-year blocks would be gone. Also, presumably it'd be the same people coming back every time, if their 'history' (our future) is not changed by all these people coming back (which would actually be the grandfather paradox).--KageTora (영호 (影虎)) (talk) 15:49, 10 May 2009 (UTC)

True, Steve. Nice answer. I could imagine the Battle Of Agincourt, with all the French and English soldiers suddenly surrounded by millions of people, and they'd be thinking, 'where did all these people come from? Shall we postpone the battle?', which would probably end up just not happening. Nice one.--KageTora (영호 (影虎)) (talk) 15:55, 10 May 2009 (UTC)

As long as your time machine doesn't allow for travel back to before it was invented (which, to my knowledge, all serious ideas for time travel don't - unless you can find a naturally occurring time machine that has existed for a while), a lot of those problems disappear (or can, at least, be solved). Time limited copyright and patents would obviously be pointless, you would to change those laws so they make more sense. Just like we have the Berne convention and similar agreements to handle copyrights in different countries, we would need agreements between different time periods (I'm not sure what they would say, though... the idea of limited monopolies to encourage creativity without stifling progress is a good one, limiting in terms of time is an excellent way to do it but we would need some other limitation if time travel become commonplace). Economics would change drastically once the time value of money becomes zero. The underlying principle of trade would still function perfectly well. Intertemporal trade would be very similar to international trade - things like Comparative advantage would still apply, just within a very different framework. Google suggests several people have given the matter some thought. Seeing as I'm supposed to be revising, I'll go and read some of their conclusions! --Tango (talk) 16:50, 10 May 2009 (UTC)

Sadly, not my original idea. There is at least one SciFi book that describes this idea. JFK's limo sets out through the streets of Dallas - but before it can pass the school-book repository, the whole of Dealy Plaza is suddenly crammed full of bizarrely dressed people clutching their tiny, white iTimeMachines. The presidential Limo can't even make it along the street and is forced to turn back and find a different route. As Oswald emerges, confused, from the repository, hundreds of happy tourists surround him demanding autographs and asking him to pose for their holo-snaps. One inexperienced temporal tourist offers Mr Zapruder $100 for his camera. Sadly, when they return to their own time, nobody has any clue what they are talking about and nobody has even heard of Oswald. SteveBaker (talk) 16:54, 10 May 2009 (UTC)

I generally assume the Novikov self-consistency principle, so such problems don't exist. --Tango (talk) 17:52, 10 May 2009 (UTC)

Exactly what I am talking about, Steve. Consider the combined populations of both any single point in the future and all possible points in the future. It would be possible even to go back to the same point in time you've visited before multiple times and see many versions of yourself. It's a ridiculous thing. Plus, you could even go back in time, live your life there, and so long as you didn't alter the path of your parents meeting (Cf. Back To The Future), you could be safe in the knowledge that even when you die, you'll be born again, anyway.--KageTora (영호 (影虎)) (talk) 18:00, 10 May 2009 (UTC)

I don't see any problems with any of that. It's rather different to how we generally consider existence to work, but it is all perfectly consistent with itself and the assumption that time travel is possible. --Tango (talk) 18:22, 10 May 2009 (UTC)

Seems to me though the Novikov principle might result in incredibly constrained existences for those people who travelled to the past. You wouldn't be able to buy that particular loaf of bread, because it has the folate needed for the neural development of the fetal ancestor who then is smart enough to go to the school where he meets the woman with whom he parents a child whose descendant eventually introduces your grandpa and grandma. You wouldn't be able to chop down the tree whose descendant eventually falls across a creek and allows your mother to escape a lava flow just in time. That would be some strange existence. Franamax (talk) 20:46, 10 May 2009 (UTC)

Yes, but you probably wouldn't notice anything strange. You probably wouldn't even try and chop down that tree. You just have to get rid of this purely religious notion of "free will" - you are part of the universe, your decisions are part of the universe. If you universe is "conspiring" to prevent paradoxes, it will probably do so simply by you not thinking of causing them. The only time you would observe anything strange would be if you consciously tried to cause a paradox. Accidental paradoxes would just not happen with no particular reason required for them not happening. --Tango (talk) 20:53, 10 May 2009 (UTC)

Apart from being undesirable it would be a complete disaster, im thinking about the Butterfly effect...:) —Preceding unsigned comment added by 84.64.16.41 (talk) 20:46, 10 May 2009 (UTC)

It's interesting that a descendant of H.G.Wells, who first put down the idea of a time machine in one of his books, called, funnily enough, The Time Machine, was on Discovery a few weeks ago discussing the grandfather paradox. He extrapolated that if he went back to kill H.G.Wells before he came up with the idea of the book, the universe (which tries its best to eliminate paradoxes - except in the quantum realm) would make the gun not go off. He would then be asked why he tried to kill H.G.Wells during his police interrogation, and he would say he was testing the grandfather paradox, which, in turn, according to his theory, might actually cause H.G.Wells to write the book.--KageTora (영호 (影虎)) (talk) 21:43, 10 May 2009 (UTC)

It's a fun thought. I'm not sure I'd call it "interesting", though. It is too highly contrived to be interesting. --Tango (talk) 23:36, 10 May 2009 (UTC)

Time Travel is one of those technologies that everyone wants to have, but nobody wants anyone else to have. See also Invisibility Devices, Mind Reading, Flying Cars, etc.

I think this is an essential quality of a good science fiction technology. APL (talk) 03:54, 11 May 2009 (UTC)

The original poster's idea has been done I think rather definitively, albeit in the opposite direction, in The Restaurant at the End of the Universe. --Trovatore (talk) 04:04, 11 May 2009 (UTC)

I wouldn't say any of steve baker's..er... examples are problems which we would face if there is time travel... Rather, since none of these has already happened, we can say these are pieces of evidence. Which, of course, leads us to one of two conclusions : a) As has been pointed by many, time travel is impossible. b) Even if time travel is invented in the future, we, for whatever reason, won't be able to do these things. Maybe because there is some superstrict board which monitors us and forbids us to do anything of that sort... maybe it has already been invented but the scientist is just too scared that people will misuse it in the above mentioned ways that he has just kept it mum... Maybe we didn't understand properly... a different interpretation which satisfies all these problems... Who knows... My point is that don't count your chickens before they hatch.. Anything is possible in Science and Religion... Rkr1991 (talk) 11:43, 11 May 2009 (UTC)

What does religion have to do with it? --Tango (talk) 11:46, 11 May 2009 (UTC)

Hey that was just a general comment... like all's fair in love and war... Like the joker says, why so serious ? Rkr1991 (talk) 11:54, 11 May 2009 (UTC)

"All's fair in love and war" is a well known idiom with a clear metaphorical meaning. "Anything is possible in Science and Religion" isn't. --Tango (talk) 16:12, 11 May 2009 (UTC)

Isn't the OP's question the exact plot of the Star Trek episode All Our Yesterdays? Astronaut (talk) 18:25, 11 May 2009 (UTC)

I hadn't seen that episode, but after reading the article, it would appear that it is, basically, yes.--KageTora (영호 (影虎)) (talk) 04:56, 12 May 2009 (UTC)

There's probably a book about this, I just don't know what it is. It occurs to me that you cannot travel through time to change the past in any pre-meditated way because after you'd made the change it would have always been, removing the reason for you to go back in time in the first place and therefore creating a paradox. Has anyone seen this in a book before? I'd like to have something interesting to read. -Pete5x5 (talk) 05:16, 14 May 2009 (UTC)

Psychokinesis

I would like to make a BIG POINT in Psychokinesis subject.

here is your link http://en.wikipedia.org/wiki/Psychokinesis

I have red the hole thing and i find you have forgotten a BIG BIG DEAL....

You talk about Psychokinesis and telekinesis ect... most of your subjects are american peoples, how and who ever made Psychokinesis happen and possible and some articles and facts of government and scientists opinions....

But you HAVEN'T EAVEN ONES SPOKEN ABOUT " the Chinese techniques in martial art" Or what they compare Psychokinesis to is :::::::"CHI ENERGY":::::::: the power of CHI or QI or KEE or other various names, as The Yin and The Yang .... I mean you have your links for all of this but (((( MY PROBLEM IS THAT YOU DON'T LINK THE TWO SUBJECTS TOGETHER!!!!!!! ))))

Psychokinesis is a word to replace the believe of the The Yin and The Yang..... Moving objects by the Chi Power, Deep Meditation and Chi exercises, You can develop your "Psychokinesis" Powers by doing QI GONG Exercises every day!

This is a big point , if you read your own articales you will realise that both subjects talk about the same effect but both are not linked together....

'I would STRONGLY recommend to make more researches and add an IMPORTANT article that connects the two subjects together !!!!''''Bold text

Chi Power or as some call Psychokinesis IS a NATURAL Effect of the Human being....

If Article added, It would be cool to add my Name as the person who reminded this fact to you. —Preceding unsigned comment added by 70.53.148.72 (talk) 15:35, 10 May 2009 (UTC)

Sheesh! Where do we start here?

1. What is your actual question?
2. Please don't post your message twice - please don't include your email address (I've deleted it).
3. Psychokinesis has NEVER not once, ever been demonstrated under proper scientific conditions - it's bullshit. If you can do it - or know someone who can - talk to the Committee for Skeptical Inquiry people or the James Randi Educational Foundation and they'll give you a million dollars (literally!) if you can prove it under rigorous conditions. The fact that nobody has yet done that - despite this lucrative offer - speaks volumes.
4. This is not the place to soapbox your favorite ideas.
5. This is not the place to discuss changes to Wikipedia articles - use the article's own Talk: page.
6. Be aware that telekinesis is considered "pseudoscience" and Wikipedia has some increasingly strict rules about how we portray such things. If it's bullshit (and this is), we're going to say so.
7. Nobody's name is "attached" to an article - take a look at any of them - no accreditation is ever given.
8. Wikipedia is "the encyclopedia you can edit" - which means that if you find a mistake or see something that needs fixing, you have to do it yourself. However, I'll go out on a limb here and say that every edit you make along the lines you describe will be deleted again within a lot less than 24 hours.

SteveBaker (talk) 15:44, 10 May 2009 (UTC)

Steve, can you package that response into a suitable template format, for quick re-use? I've been on pseudoscience patrol often enough to need it... Nimur (talk) 16:09, 10 May 2009 (UTC)

I have it on a hot-key. :-) SteveBaker (talk) 16:37, 10 May 2009 (UTC)

And (9) Please don't SHOUT. It will only serve to destroy what little credibility you might gain.--86.25.193.89 (talk) 16:52, 10 May 2009 (UTC)

"UN-altered REPRODUCTION and DISSEMINATION of this IMPORTANT Information is ENCOURAGED, ESPECIALLY to COMPUTER BULLETIN BOARDS." —Tamfang (talk) 20:52, 10 May 2009 (UTC)

I think he's complaining that the Psychokinesis article doesn't mention the Chinese concept of Qi. Astronaut (talk) 18:09, 11 May 2009 (UTC)

I tried placing it on a computer bulletin board with telekinesis, not touching the keyboard, sadly without any results. What am I doing wrong? Should I have used a Mac instead of a PC? Edison (talk) 14:02, 12 May 2009 (UTC)

I think Linux is the only OS that supports telekinesis, and also FreeBSD if I recall correctly --BiT (talk) 15:27, 12 May 2009 (UTC)

Why do males have nipples?

- Most male mammals have nipples like female mammals. Why do the males need nipples? Is it a kind of rain check, to be used later if the females become unable to suckle for some calamitous reason? ~~ —Preceding unsigned comment added by 59.93.8.216 (talk) 15:41, 10 May 2009 (UTC)

ava looke at Nipple#Nipples_on_male_mammals a little bit maybe

ncal43 —Preceding unsigned comment added by Ncal43 (talk • contribs) 15:44, 10 May 2009 (UTC)

The male nipple actually carries a very nice lesson about how evolution works. The only genetic difference between male and female mammals (well, for most mammals) is the Y chromosome, which marks an animal as male. Because there is only one copy of the Y chromosome in a cell, it cannot evolve in the same way as other chromosomes, which have two copies each. The consequence is that the Y chromosome is very small -- nature keeps as few genes as possible on a chromosome that can't evolve in the usual way. This means that the genetic difference between males and females is tiny -- basically just a few genes that control the expression of other genes. Since the genomes are so similar, every structural difference between males and females requires complicated gene-programs, so it pays for nature to keep the differences as small as possible. It's easier to reduce an organ to a small, nonfunctional form, like the male nipple, than to eliminate it completely. Looie496 (talk) 16:52, 10 May 2009 (UTC)

I would maybe reword that last sentence to say that it is easier for an organism to use the same body-development plan for as long as possible before coming to rely on genes on the sex-linked chromosomes. Looking at the link Ncal43 supplied, it seems that rather than the "organ" being "reduced", it is actually the further development of the mammary gland which is suppressed. And the Y chromosome is actually full of a startling amount of junk. Franamax (talk) 20:09, 10 May 2009 (UTC)

It only takes a tiny bit of female hormone to make the male breast start producing milk. The normal male breast is indistinguishable from the immature female breast. See Gynecomastia and Male lactation. Edison (talk) 23:00, 10 May 2009 (UTC)

There is only really one relevant gene on the Y chromosome - SRY. It determines the production of male hormones, everything else follows from that with exactly the same genes as females have. --Tango (talk) 23:32, 10 May 2009 (UTC)

I should clarify - there are other sex-linked genes, but they don't determine sex. They happen to be on the part of the Y chromosome that doesn't cross-over with the X chromosome, but that is just coincidence. --Tango (talk) 23:34, 10 May 2009 (UTC)

Further to the above, I would like to question the implicit assumption invariably accompanying this question, that nipples only have one function. Many organs in many organisms have dual or multiple functions, and the nipples are no exception. Apart from their primary role as efficient interfaces between maternal breast and infant mouth (which is not indispensable, as Monotremes lack nipples), they are also, at least in H sapiens, erogenous zones, being erectile and sensitive during sexual arousal. This applies to male as well as female nipples. Any mature and sexually active male unaware of this must have a very unimaginative partner. 87.81.230.195 (talk) 03:53, 12 May 2009 (UTC)

Physical error in Star Trek?

In the new Star Trek film, Kirk and Sulu are falling in a free fall toward the surface of Vulcan, when they are beamed up in mid-fall to the Enterprise, and they are shown falling on the transported pad with an audible thud, and then merely brush it off. Now, when falling on the ground from the sky, isn't what kills you that the deceleration happens too fast, causing all the kinetic energy in your body being transferred in one go? In this case, it doesn't matter what Kirk and Sulu are falling on, or from what height. If they aren't gently slowed down in advance, they'll die anyway when they suddenly stop falling. In fact, they don't even need to hit anything - merely stopping in mid-air would be fatal if it happened too fast. Have I got this right? JIP | Talk 17:06, 10 May 2009 (UTC)

It's fiction. Try not to worry about it. Transporters don't really exist so issues of whether they are depicted realistically are quite utterly unanswerable. (When Time Magazine asked "How does the Heisenberg compensator work?", Star Trek technical adviser Michael Okuda responded, "It works very well, thank you.") SteveBaker (talk) 17:12, 10 May 2009 (UTC)

I was expecting this kind of answer. Merely replying this way is, in fact, equal to saying Kirk could have simply waved a magic wand and caused Nero's evil rogue ship to disappear and make everyone happy, when after all, it's fiction. What I would have wanted, is an answer to whether I have understood the physics thing in falling down correctly. Just because something didn't really happen is no excuse to throw all pretense of realism out of the window. JIP | Talk 17:16, 10 May 2009 (UTC)

Actually, that's why the transporter needs a Flux_capacitor. It adjusts the speed of incoming bodies to match the inertial frame of the receiving station. In the old series, Scotty is doing this manually with those levers he operates. If the relative speed is high, he may not compensate the movement completely - and rather than risking to have them fly up and then down again, he errs the other way. Alternatively, look at the concept of a Bergenholm in the Lensman series, which operates by temporarily suppressing the inertia of a body, allowing it to accelerate without picking up kinetic energy (and to revert to the old velocity once it's disabled again). --Stephan Schulz (talk) 17:33, 10 May 2009 (UTC)

Yes, you are essentially correct, if they impacted the transporter at the same speed they were going to impact the ground at, it would have the same effect. We'll have to assume the transporter changed their speed when it changed their position (I see no reason why it couldn't do that - if you can rematerialise matter you should be able to choose its momentum pretty freely) - let's assume the small drop is because whoever was transporting them (I haven't seen it yet) was afraid he wouldn't get the position exactly right (perhaps due to them falling in an unpredictable way) and didn't want them to materialise halfway through the pad. As for what would happen if you just stopped in mid-air, it would depend on what stopped you. The reason rapid deceleration is bad is because different parts of your body decelerate at different rates (the bit that impacts first stops almost immeadiately and the rest of your continues moving, so you get crushed). If whatever stops you stops you in a similar fashion, it will be just as bad, if it stops all of you at the same rate (using artificial gravity, or something), then it would be harmless. --Tango (talk) 17:43, 10 May 2009 (UTC)

I'm sorry - but you can't expect a scientific answer for something that IS magic. Transporters do not - nor cannot exist...period. What they do or do not do with residual momentum when the source and destination are moving at different speeds is quite utterly unknowable. I could say - "Well, the StarTrek transporter perfectly removes the difference is speed and direction between source and destination - and all you saw in the movie was due to the transporter placing the center of gravity of the humans at an appropriate distance above the deck. The problem was that they were lying flat at the time and thus fell two feet to the ground on arrival"...but it's fiction...it doesn't exist...it doesn't matter. When you watch a StarTrek movie, you turn off your brain and enjoy the ride. SteveBaker (talk) 17:47, 10 May 2009 (UTC)

Nonsense, it's still entirely possible to apply a modicum of scientific thought to the process. After all, science is a way of approaching problems. So long as we accept that A) These are not real-world facts we're dealing with. and B) If we go too deep we'll eventually hit either an unknowable, or a contradiction. Then why couldn't this question be approached in a completely logical, scientific way?

We have observed transporters moving individuals from planet surfaces up to a ship in orbit. (In fact, that's their primary purpose.) The speed difference between the ship and the planet surface can be massive. (They usually show the Enterprise entering orbit against the planet's rotation, for whatever reason.) Since they can complete these planet-to-ship transports without splattering anyone against the side of the transporter room, we have to assume that the transporter is adjusting the away team's speeds to match the ship's speed. So the physics of this dramatic beam-out in the new movie is nothing special, the transporter must do that for every single transport. (Luckily, obscure transporter physics is not what makes the scene dramatic.)

So why did they crunch against the floor? Easy. They beamed in on their sides instead of the usual boots-down orientation. Even if they were perfectly lined up with the floor of the transporter you'd still fall a little. Imagine the difference between beaming in with both boots flat on the deck, and beaming in with one elbow just barely touching the deck at a weird angle.

We've seen this sort of thing before, where someone beams up in a weird position and then falls when they beam in. Not so much in the original series, but in TNG, Voyager, etc. Another fun thing is when they beam someone up who's running, but they beam in stationary and have to 'catch themselves'. I'm sure we've seen that once or twice. APL (talk) 03:47, 11 May 2009 (UTC)

Tango's reply answered my original question about physics. As for SteveBaker's comment, you are essentially right, but your original reply came out as a simple handwave, rather than the detailed explanation you now gave. Stephan Schulz provided a good reply while keeping in mind that Star Trek is fictional: "Yes, if they weren't slowed down, they'd die. That's why Scotty used a flux capacitor to slow them down. How does a flux capacitor work? By magic." I wasn't asking about the internal workings of flux capacitors or transporters, but about simple everyday physics that happen outside the transportation. JIP | Talk 18:04, 10 May 2009 (UTC)

(EC - twice)Transporters could not exist and would be a dangerous thing anyway even if they did. We all know about the 'got transported inside a physical object by accident and died' thing. Well, that would happen in any place that has an atmosphere. You'd be transported into that air, and oxygen atoms are physical objects. You'd end up meshed up with the air.--KageTora (영호 (影虎)) (talk) 18:23, 10 May 2009 (UTC)

That problem could perhaps be solved by having the transporter transport the air out of the way first, by having the transported object and anything at its destination simply exchange places? How would it do that, then? The same way it would already work: by magic. We aren't interested in how transporters work, we are interested in what effects they have. JIP | Talk 18:27, 10 May 2009 (UTC)

Even that seems tedious and dangerous, not speaking about the heisenberg compensator magical plot device. The only possibility that I can think of for a transporter to work would be the existence of a forth spacial dimension which we learned to access somehow. Anyone who knows about Flatland knows how it could be used for teleportation. --131.188.3.20 (talk) 23:32, 12 May 2009 (UTC)

Well, just as a side note, for a transporter to work, it would have to dismantle all the atoms in the person's body, then reconstruct the body at destination. This would mean that the actual scene where they suddenly appear in mid air would be silly, considering they never did that before in any other scenes. As for the rapid deceleration thing, yes. There is an advert on British TV warning against bad driving where two cars have a head on collision. And it warns (very graphically) that even if you have air-bags you can still be killed because your internal organs keep moving even when you and the car have actually stopped suddenly, and they can all be ruptured.--KageTora (영호 (影虎)) (talk) 18:35, 10 May 2009 (UTC)

Which, I think answers your question. It would be an instant dismantling of every atom in the body, therefore causing no movement of internal organs caused by any rapid deceleration, and then reconstructing the person at destination.--KageTora (영호 (影虎)) (talk) 18:41, 10 May 2009 (UTC)

So, when they reappeared above the transporter pad, they would have zero velocity, and then they would just drop down the half a metre or so onto the transporter pad, leaving them essentially unscathed? That makes sense. How the transporter is going to change the velocity to zero without going through deceleration is a question of quantum physics, not mechanics, and therefore outside the scope of this topic. JIP | Talk 18:47, 10 May 2009 (UTC)

Teleportation is generally described in terms of transferring information - you examine the object at its source, destroy it, transmit the information about it to the destination, and rebuild it. There is no reason why you should have to rebuild it with the same momentum it started with (although to momentum of parts of it relative to the others would need to stay the same - you don't want your heart to stop mid-beat, or anything, who knows what would happen then?), since it isn't the same object. It is a new object that is created to be identical to the first. --Tango (talk) 18:52, 10 May 2009 (UTC)

"There is no reason why you should have to rebuild it with the same momentum it started with" No reason? Except that simple, point-by-point subtraction of the free-fall momentum is not going to work! Every atom is so confounded by thermal noise; macroscopic displacements of organs are going to throw the tissues out of place; molecular vibrations; statistical trends of gas-flow in the lung and fluid in the blood.... I don't think you could just "subtract" a scalar speed from every atom in a body and have everything "be okay." (Imagine what making an enormous change to the net velocity of every single atom will do to the instantaneous temperature and pressure of the material?) SteveBaker is correct to hand-wave this off as magic. If we had a scientific explanation for these "small details", we would have already figured out transporter technology. We do not have any explanation for these details (probably because it is fundamentally physically impossible; at the very least, we have at least got a technological limitation). Therefore, every time you make a "science-like" statement, as a "flux capacitor that resets the momentum", you are just moving the bar up a notch in terms of where you stopped caring about the magic. You can't explain the flux capacitor scientifically, so it's just technobabble for a "magic-wand". I don't see why you should even bother pretending that this has solved the physical incongruity. Nimur (talk) 19:06, 10 May 2009 (UTC)

Well in TNG, they replaced the flux capacitors with pattern buffers, so they must have been working on the science. :) Possibly helped by the Stargate SG-1 team. I'd like to know about a few more of the small details though, such as why a phaser vanishes the person, their clothing and anything they're holding - but not one scrap of ground or the building they're holding onto. Also why no-one ever thought of installing seatbelts when they upgraded the Enterprise. The TV/film industry is truly a strange land. At least the old-time SF writers had to try to explain the miracles. Franamax (talk) 19:47, 10 May 2009 (UTC)

That isn't a problem with removing the momentum, that's a problem with teleportation itself. We have to suspend disbelief at some point. In my opinion, good science fiction requires us to only suspend disbelief for a very small number of things (they can be extremely unbelievable, though) and then everything else follows logically from those assumptions. If you assume that teleportation is possible and just ignore all the problems with it, then it requires no further suspension of disbelief in order to accept that you can remove the momentum from a teleported object. Star Trek is reasonable sci-fi by that definition, but they do tend to resort to technobabble a little more than they ought. X-Files is terrible sci-fi (well, "speculative fiction" is probably a better term, it isn't strictly sci-fi, but the same point applies) - it requires you to suspend disbelief separately for each episode (which is particularly bad considering it is meant to be about solving mysteries and there is no way you can possibly solve the mystery before it is revealed [and trying to do so is part of the fun of watching such shows] since you don't know what unbelievable thing is going to turn out to be true this week). Stargate is good, once you accept the premise of the show there is very little that is unbelievable in each new episode (nothing at all in many episodes). --Tango (talk) 20:24, 10 May 2009 (UTC)

Yes, also, laser weapons would be viewed as a constant stream of light, not a bolt that flies along much slower than the speed of light, considering they are made of light.--KageTora (영호 (影虎)) (talk) 19:54, 10 May 2009 (UTC)

Funnily enough, transporters DO exist, at least in some form. I saw something on Discovery about one that has been built, but it can only transport a single atom at this point in time. I have no links for this. Anyway, there was some question about it being the same atom or a replication of the one the machine just destroyed. The scientists who created it, however, said it was the exact same one, but didn't provide any proof. To transport a human, however, would require (obviously) a bigger machine and much more power to store all the information during the 'transportation' process. But this is a problem, because we have no way of knowing whether it is the same person that has been 'transported' or an exact replica of one that has been utterly destroyed, which is, in fact, terrifying if you are the one going through the process. The reason we have no way of knowing is because, being an exact replica, they will say they are the same person.--KageTora (영호 (影虎)) (talk) 19:51, 10 May 2009 (UTC)

Is this] what you're talking about? They're not claiming to have moved the physical atom though. Franamax (talk) 19:54, 10 May 2009 (UTC)

... and even if one atom could be "transported" (or re-assembled as an identical copy), there are bandwidth limits that mean it will never be possible to "transport" anything nearly as complex as human by any technology imaginable at present. It's fun to pretend, though. Dbfirs 20:27, 10 May 2009 (UTC)

Quantum teleportation. It's quantum information (qubits) that gets moved, so it's not really teleportation. It's the same as this message making its way from my computer to yours—there are no electrons or other particles that make the trip. I'm not teleporting electrons even though there happen to be electrons on both ends. Furthermore you can move qubits around by using a quantum channel, you don't need the quantum teleportation protocol. So really it's not a big deal, and I wish these articles wouldn't be so sensationalistic about it. -- BenRG (talk) 22:14, 10 May 2009 (UTC)

A moderate fall to the floor is a moral lesson by the transporter. Falling at high speed can be dangerous when there doesn't happen to be a transporter with a helpful operator around. The transporter doesn't compensate completely for the speed difference in order to give the fallers a scare so they will try harder not to fall another time. That's my theory anyway. Seems at least as good as technobabble. Some parents use a similar principle when warning/punishing their children for doing dangerous things. "Son, you could have drowned by swimming less than an hour after eating so I'm pulling out the waterboard to show you how it feels". What, your parents didn't do that? PrimeHunter (talk) 20:55, 10 May 2009 (UTC)

But it would be exceedingly unusual for the velocity of an orbiting transporter room to exactly match the velocity of the place they're beaming from/to. There are at most two locations moving with a given velocity on the surface of a rotating sphere. Only dramatic license can explain the observed behavior of Star Trek transporters. -- BenRG (talk) 22:14, 10 May 2009 (UTC)

Back to the workings of the flux capacitor, which JIP asked about, I'm thikning that what might have happened (and I'll grant you I haven't seen the movie) is that the atoms were not just snatched fromt he air like, say, a baseball player catching a ball. Instead, couldn't they have been slowed down at a rate allowing them to suffer minimal damage, then "beamed in" when they were slow enough to avoid the harmful effects?

In other words, if velocity was lethal limit, all the atoms were slowed down while continuing to go ythrough the air, with a "transporter lock" on them. They were slowed gradually, then, even moved back up a ways if they had to be. Then, when they were going slow enough, they could then be safely brought to a place where they could land.

This may just be explaining the "magic" a little more, but at least it sounds more plausible than some things. After that, I'll just use the line fromt he parody I wrote in college once:

Scotty: I can't defy the laws o' physics, Cap'n.

Kirk: Sure you can, Scotty, this is Star Trek, we do it all the time. :-)Somebody or his brother (talk) 01:12, 11 May 2009 (UTC)

That wouldn't fit with how transporter beams are usually described, it would need to be a tractor beam. There is no reason why they couldn't write a story in which a tractor beam and a transporter beam are used together for such a purpose, but I see no reason to assume that's how it worked unless they say so. As I've said above, there is no reason to think momentum has to be preserved during teleportation. (And, as BenRG points out, there is going to be relative velocity between the source and destination anyway whenever the ship is in orbit.) --Tango (talk) 10:16, 11 May 2009 (UTC)

Actually - the things that bother me most about that movie in particular are the ways that the computer interacts with people. Like when the computer politely informs the captain that the autopilot has been damaged...surely the autopilot is a piece of software that runs in the computer? If it has enough working processors to perform speech recognition and to drive all of those fancy displays - why the heck can't it run the 7 lines of code you need to implement an autopilot?

 while ( the autopilot is engaged )
 {
   if ( you're too far to the left ) steer to the right a bit ; else steer to the left a bit ;
   if ( you're pointing too far up ) steer down a bit ; else steer up a bit ;
   if ( you're going too fast ) slow down a bit ; else speed up a bit ;
   sleep ( 1 millisecond ) ;
 }

You could argue that the computers sensors were damaged - yet they appear to be giving the captain realtime on-screen data of time to collision - you could argue that the computer's control over the engines and steering are broken - but then we'd have to believe that there is a hard-wired connection between the joystick on the captain's chair and the actual engine controls, which seems really unlikely.

If he hadn't kicked the engineering team off of the ship he could have had them write those 7 lines of code (it took me less than 30 seconds) then had the last of them beam off the ship. Anyway - what's wrong with "Computer: Transfer control to the shuttlecraft"? Or just aim the ship in the right direction and say "Computer: Don't touch the engine controls" - then run to the transporter bay and beam yourself to the shuttlecraft?

Then, when Scotty is trying to "get a transporter lock" on the falling crewmembers, he's looking at a display with dots on it showing the position of the two crewmembers and frantically trying to line up a couple of cursors on top of them. Aside from the fact that he only seems to have to do this in two dimensions(?!?) - the fact that computer knows their positions accurately enough to draw the graphics on the display means that it would be TRIVIAL to have it 'snap' the aim cursor to the nearest dot...making it a simple matter for any unskilled transporter officer to snatch people out of the air like that.

Conclusion: The Federation's computer programmers are utterly useless!

Anyway - we should listen to the wise words of Arthur C. Clarke: "Clarke's Third Law: Any sufficiently advanced technology is indistinguishable from magic." - which is what we have here. Magic - with all of it's capabilities and arbitary limitations. SteveBaker (talk) 12:30, 11 May 2009 (UTC)

There are some minor problems with the code given for the autopilot. In reality it's not that simple. What you just described was the most simple proportional controller, which will oscillate horribly even in the most ideal conditions. For control systems at least a PID controller is required, and if not all of the system's parameters are known, or there can be measurement errors (which they always are), than even that's not enough and you have to combine them with predictors and parameter estimators, or use more advanced and complicated controllers. However, I still agree that if the voice recognition works, the autopilot should also work, except for some required hardware accelerators burning out (you know one of the most important starship design rules: no fuses in the cockpit), but even then there should be backup software solutions available. But I am sure it's a lot more than just 7 lines of code.

Science fiction means, that it can contain devices or events which are not possible by our current understanding and/or technological level. You can invent your own rules, but you have to stick to them. So if you have a flux capacitor and you use it by your own rules and without contradicting yourself, it's fine. You can use any crazy science you want, if the connections in it are logical, the consequences are well described, and all the gadgets are explainable under the rules you use. Look at Stanislaw Lem for example: in the novel Fiasco he uses giant walking robots, cryogenics, some kind of pseudo-FTL space travel, gravity-altering devices and weapons, nanofungus, but it still remains scientific: the miraculous gadgets are not just plot devices, their functionality as well as their shortcomings are presented in detail and, logically, seem plausible. Or, a more modern example, Fine Structure [2] has every crazy thing even thought about by science fiction authors: alternate dimensions, teleportation, FTL, time travel, superpowers, universal constructors, telepathy, etc., but is still amazingly scientific and realistic.

Star Trek is, by the way, not science fiction in the strict sense. Science is always just a background or a plot device. The problem of these kind of "flux capacitors" is, that they usually do not follow even their own rules. If it really worked, would it make sense? - that's the question we should ask. In the Back to the Future, for example: Why would anyone have a newspaper article about a photo of an empty place in the graveyard? How do Marty's parents not freak out when they realize their son looks exactly like the mother's previous lover? How does doing just nearly similar things lead to the nearly same future? How can Marty possibly take the place of a completely different child (as he altered his parent's marriage quite a lot)? - These are the questions that make it unrealistic, and not the "how does the flux capacitor work?". --131.188.3.20 (talk) 14:23, 12 May 2009 (UTC)

Plot devices aside, there is actually an awful lot of considerations embedded in the auto-pilot's concern "Where should the ship be and how fast should it be moving?". It would start with knowing what course was entered, knowing current position and velocity relative to something (what reference frame does one use on a starship?), and being able to adjust for potential obstacles, etc. I don't see a huge problem with a ship being able to predict time till collision and yet not having enough guidance for a full autopilot to know where it should be going, etc. Your point about simply having the ship maintain constant velocity in a predetermined direction is a good one though, I don't see why that should be a problem. Dragons flight (talk) 16:29, 12 May 2009 (UTC)

I know I'm coming late to the party, having only just seen the movie, but I have to but in with the obvious answer. <assume star-trek meta-physics>The transporters always have to compensate for a large velocity difference, since the ship is in orbit, thus has a significant velocity in the frame of the "stationary" person being transported from the planet surface (this has been mentioned above). As for their horizontal orientation upon arrival, the same point applies: being in orbit, the ship is almost never in the same "upward" orientation of the person being transported, so the transporter must compensate for this always. So, if you are talking about consistancy with previous and subsequent events (which I can only assume represent the physics of the Star Trek universe), their velocity upon arrival is not an error, but their orientation is.</assume star-trek meta-physics> Ew I feel dirty, let's not talk about hypothetical future physics anymore :-D -RunningOnBrains 16:55, 12 May 2009 (UTC)

Also, it seemed to me that near the end of the movie when they beam Spock off the little future ship, he's sitting down when he gets transported but arrives standing up. I guess the plot wouldn't have benefited from slapstick "chair pulled out beneath him" humour at that part of the script, but the nebulously defined transporter serves its role as a charmingly flexible plot device yet again. TastyCakes (talk) 17:14, 12 May 2009 (UTC)

Star Trek transporters (and the equivalent technology in other si-fi) have always been able to straighten people's legs, there are plenty of examples of it. I don't see anything that function would contradict, so we just need to suspend disbelief for it. --Tango (talk) 17:57, 12 May 2009 (UTC)

My point is that the transporter apparently couldn't change the orientation of Kirk and Sulu when they were falling, but it could change Spock's orientation when his ship blew up. TastyCakes (talk) 18:50, 12 May 2009 (UTC)

Perhaps the sudden change in gravity would be harmful? As it is, they went from about 1g (presumably they were at terminal velocity, I haven't seen it) to 0g (they would have been in free fall once they appeared above the pad). Perhaps changing from 1g in one direction to 1g in another would be too much (it would be a change of about 1.4g in magnitude). It's not a particularly good argument, but it will do if you would rather that than just calling it creative license. --Tango (talk) 17:57, 12 May 2009 (UTC)

If transporters worked by creating some kind of wormhole, then momentum, velocity, gravity and all these would have a great effect. However, by the use of Heisenberg compensators, I thing it's very clear they work by deconstructing the target and reconstructing an identical copy. So they could reconstruct the copy when and where and facing whatever direction as they wanted. The only question that remains is why are they not using it for "saving" people and reconstructing them in case of death, or just healing injuries by replacing damaged body parts. Maybe a protocol forbids it? --131.188.3.20 (talk) 23:20, 12 May 2009 (UTC)

Why not? BECAUSE IT'S FICTION. It doesn't suit the storyline for there to be no danger. They continually walk the fine line between making things ridiculously easy for everyone - and yet keeping the technology seeming fresh and exciting. SteveBaker (talk) 01:37, 13 May 2009 (UTC)

I think you still do not understand what I was saying. I have no problem with creating crazy rules, so no need for shouting; the fact that they don't even stick to their own rules is what was bothering me. I was not saying "it's impossible for it to function", I'm rather saying "even if it functioned like described, there would be huge plot holes". And I'm not speaking just about Star Trek, but all kind of "light" science fiction. --131.188.3.21 (talk) 07:59, 13 May 2009 (UTC)

One of the things you need to be careful of when building a fictional world is to keep it self-consistent. Star Trek isn't particularly good at that, which tends to strain the suspension of disbelief at times. --Tango (talk) 11:00, 13 May 2009 (UTC)

Because "their patterns degrade in the buffer" over time. There are plenty of times when this is mentioned. The amount of information required to reconstruct a human body would be enormous, so presumably they have some kind of specialised storage medium that doesn't work for long periods of time. --Tango (talk) 11:00, 13 May 2009 (UTC)

There was an entire mini-series in the Star Trek: The Next Generation spin-off book series where Montgomery Scott is transported in an emergency situation, and then kept in the transporter buffer for seventy years, so when he reappears in Captain Picard's time, he's still as fresh as he was in Captain Kirk's time. JIP | Talk 19:22, 13 May 2009 (UTC)

Running, There's no error in their arrival orientation. It was the safest orientation for them to materialize in. If I wasn't in a strictly standing position I sure as heck wouldn't want to be beamed in upright. That would just give me farther to fall before I wanged my head against the deck! APL (talk) 04:29, 15 May 2009 (UTC)

On a side note, About 20 years ago, I read an interesting book by an author called Simak - can't remember the title (it's on my bathroom bookshelf, but I can't be bothered going and getting it) about a guy who was transported to some planet on the intergalactic transportation network, and through some error, two copies of him were made, one arriving at the destination intended and the other in some place that nobody knew existed. The one that arrived at the correct destination is subsequently killed in an accident, while the other somehow manages to get back to Earth (doesn't say how, because that's actually when the book starts - loophole alert!). The book goes on to discuss the legal implications of him being 'dead', yet still alive. Interesting book.--KageTora - (영호 (影虎)) (talk) 02:23, 16 May 2009 (UTC)

Ha! Wikipedia has an article on him, and saved me the trouble of going to the bathroom. The book is called 'The Goblin Reservation'. Wikipedia is wonderful ! --KageTora - (영호 (影虎)) (talk) 02:26, 16 May 2009 (UTC)

the sun's limb

There's an old joke:

"Your cough sounds better."

"I've been practicing."

Well, I have forty-some years' practice in making myself misunderstood. So this is a paraphrase of my question of April 28 (I didn't see the replies until today).

Given:

• The sun, being gaseous, has no discrete surface. (I got clear agreement on that point, but that's not what I was looking for.)
• It sure looks as if it had one.

What is it that looks like a surface? When astronomers speak of the limb of the sun, e.g. to define the four 'contacts' of a transit, what do they mean? —Tamfang (talk) 19:10, 10 May 2009 (UTC)

It is a gradient, it's just hard to see it very clearly. In some cases, especially eclipses, it shows up very nicely as a gradient. Have you looked at photosphere and chromosphere and solar corona? Depending on your astronomical need, and your area of research interest, any of these might be considered "the surface" of the sun. Specific definitions with specific radii will be suitable for particular cases, but as you already realize, there is not a clean radius at which there is total consensus to call the "edge". Nimur (talk) 19:32, 10 May 2009 (UTC)

Gradient. The central region has been blocked out to prevent saturation of the imager, because the contrast difference between the photosphere and the corona is pretty huge. Nimur (talk) 19:32, 10 May 2009 (UTC)

In the eclipse picture, I see a gradient in the outer corona, yes. I don't see a gradient in the part of the picture that is relevant to the question. —Tamfang (talk) 20:37, 10 May 2009 (UTC)

Would one definition be the point where an object behind the sun is no longer visible at a given (or any) wavelength? Franamax (talk) 19:51, 10 May 2009 (UTC)

Perhaps, but I don't think that would give you a firm boundary. Objects would just get harder and harder to see (as more and more of the photons from them get blocked). There would be no point where suddenly all the photons are blocked when none of them were before. --Tango (talk) 20:58, 10 May 2009 (UTC)

There is no precise boundary to the Sun, just a gradual fade to nothingness.

The reason it looks like it has a clear boundary when you look at it with the naked eye (or, more advisedly, through a solar filter!) is because the range over which it varies from dense enough to be easily seen to sparse enough to be impossible to see is quite small (from this far away, at least). If you look at it through a telescope you can see that it does fade out gradually, as seen in this picture. --Tango (talk) 20:04, 10 May 2009 (UTC)

Sun#Photosphere: The change in opacity is due to the decreasing amount of H^- ions, which absorb visible light easily. That's a start, anyway. —Tamfang (talk) 20:37, 10 May 2009 (UTC)

I'm not sure of this, but it seems to me that clouds could be seen in a similar way. From a distance they can look opaque and sharply defined, yet the closer you get the less distinct their boundaries appear to be. I am not a meteorologist nor an expert on the sun - just wondering if it's an apt analogy. --Scray (talk) 01:48, 11 May 2009 (UTC)

Sounds like a good analogy to me. There are quite a lot of difference between small droplets of liquid suspended in a gas and a large ball of plasma held together by self-gravitation, but neither has a clear boundary. --Tango (talk) 10:18, 11 May 2009 (UTC)

As I recall, the apparent sharp "surface" is an optical illusion caused not so much by decreasing opacity as by the changing index of refraction. Supposedly in this situation there is a discontinuity, a well-defined limiting angle from which light rays can appear to come. I've never actually worked through this in detail. --Trovatore (talk) 09:08, 12 May 2009 (UTC)

Lightning Photographs

hi,

how do people take pictures of lightning? I mean its obviously not someone with super quick reactions, so how is it done? Constantly taking photos during a storm and hoping to get something? Computer detectors that can take a pic instantly?

thanks, --84.64.16.41 (talk) 20:35, 10 May 2009 (UTC)

Long exposure with a pinhole aperture? —Tamfang (talk) 20:40, 10 May 2009 (UTC)

Lots of photographs of empty sky will eventually yield a few photographs with good lightning. Especially in the era of digital cameras, this is becoming increasingly common. I know some people who attempt to do automated shutter triggering, but this is difficult. Nimur (talk) 20:55, 10 May 2009 (UTC)

All the pictures on lightning seem to have been taken at night, which supports the "long exposure" theory. (If you take a long exposure shot during the day it would just be overexposed all over unless you had a special lens with a minute aperture.) --Tango (talk) 21:08, 10 May 2009 (UTC)

Actually, I'm not sure even a really small aperture would work - it would probably have to be so small as to not pick up the lightning. The key things are the difference in brightness between the sky and the lightning and the length of time the lightning is there relative to the length of the exposure. The latter has to be very short if you don't want to have to take a crazy number of shots before you get a good one (if you have a 1/100 second exposure, you would probably have to take thousands of shots, if you have a 1s exposure you might be able to get away with a few dozen during a big storm - the exposure being 100 times longer essentially makes the lightning 100 times shorter). If the latter is very short, then the former needs to be very large to make up for it. --Tango (talk) 21:13, 10 May 2009 (UTC)

Yes that's right, all the really spectacular pictures are taken with long exposure, that is, fix the camera down and lock the shutter open. Not much good for anything other than to look pretty as often there is more than one strike in the shot (but makes for a better picutre). It is perfectly possible to capture lightning with a hand-held camera and a "normal" shutter speed, I've seen it done several times, but be prepared for a lot of failures. With high speed cameras it is possible to capture the ascender strike followed by a frame of the descender. This is more scientifically useful, but not so pretty. SpinningSpark 21:27, 10 May 2009 (UTC)

If you wanted to do that, though, wouldn't you use a high speed video camera? --Tango (talk) 23:30, 10 May 2009 (UTC)

Lightning strikes up?--KageTora (영호 (影虎)) (talk) 00:27, 11 May 2009 (UTC)

See Lightning#Leader formation and the return stroke. --Tango (talk) 00:52, 11 May 2009 (UTC)

You could "just" set up a digital video camera, aim it at the sky in night or daylight, and push "Record", then grab the one or two or three frames that recorded the strike. By digital video camera, I don't mean MiniDV or anything that records in PAL or NTSC, because the frame will look awful; but rather a camcorder that records to an MPEG stream of some sort. Tempshill (talk) 02:33, 11 May 2009 (UTC)

I've only shot lightning at night, as others have discussed above, but there are lightning triggers that will detect the lightning flash and release the camera's shutter. These can be used in daylight. Here's an example, no endorsement implied. I've also seen plans based on an Arduino. -- Coneslayer (talk) 12:08, 11 May 2009 (UTC)