Introduction to LIGO & Gravitational Waves
Stochastic Gravitational Waves
Diagram showing different stages in the
evolution of the universe since the Big Bang and when gravitational
waves and the CMB came into existence. [Image: NASA]
 |
Stochastic gravitational waves are the relic
gravitational waves from the early evolution of the universe.
Much like the Cosmic Micro-wave Background (CMB), which is likely to be
the leftover light from the Big Bang, these gravitational waves arise
from a large number of random, independent events combining to create a
cosmic gravitational wave background. The Big Bang is expected to
be a prime candidate for the production of the many random processes
needed to generate stochastic gravitational waves (and the CMB), and
therefore may carry information about the origin and history of the
universe. If these gravitational waves truly originated in the
Big Bang, these waves will have been stretched as the universe expanded and they can tell us about the very beginning of the
universe—they would have been produced between approximately 10
-36 to
10
-32 seconds after the Big Bang, whereas the CMB was produced
approximately 300,000 years after the Big Bang. The sound these
gravitational waves would produce is a continuous noise (much like
static) and will be same from every part of the sky (just like the
CMB). Similar backgrounds could be produced by a combination of many
simultaneous inspirals, bursts, or continuous signals from throughout the Universe.
An example signal from an stochastic
gravitational wave source. [Image:A. Stuver/LIGO]
 |
Listen to this stochastic signal.
