In 2015, astrophysicists for the first time detected gravitational waves, ripples in space-time that occur when neutron star or black hole mergers disrupt the cosmos. The observation of these waves confirmed Einstein’s theory of general relativity, which predicted such waves would occur if space-time worked as he believed it did. In the seven years since, nearly 100 merging black holes have been detected by observing the gravitational waves that these extraterrestrial events emit. Now, Caltech researcher Keefe Mitman and colleagues have modeled such collisions in more detail and revealed so-called nonlinear effects.
“Nonlinear effects are what happens when waves on the beach crest and crash,” said Mitman, first author of a paper published in the journal Physical Review Letters.
“The waves interact and influence each other rather than ride along by themselves.”
“With something as violent as a black hole merger, we expected these effects but had not seen them in our models until now.”
“New methods for extracting the waveforms from our simulations have made it possible to see the nonlinearities.”
“In the future, the new model can be used to learn more about the actual black hole collisions that have been routinely observed by LIGO observatory ever since it made history in 2015 with the first direct detection of gravitational waves from space.”
Columbia University’s Professor Lam Hui used an analogy to describe the information that gravitational waves can provide:
“If I give you a box and ask you what’s in it, the natural thing to do is to shake it. That would tell you whether inside the box are candies or coins. That’s what we’re trying to do with these models, is gather a sense of the inner contents of a black hole by listening to the sound that’s emitted when it’s shaken.”
“The shaking in the case of black holes is the disruption that occurs when two collide and merge.”
“By listening to the harmonics that it emits,…
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