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]

Big Bang and Gravitational Waves
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 be 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]
Example Stochastic Waveform

Listen to this stochastic signal.

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