By Rafi Letzter
The universe might “remember” gravitational waves long after they’ve passed.
That’s the premise of a theoretical paper published April 25 in the journal Physical Review D. Gravitational waves, faint ripples in space and time that humanity has only in the past few years managed to detect, tend to pass very quickly. But the authors of the paper showed that after the waves pass, they might leave a region slightly altered — leaving behind a sort of memory of their crossing.
These changes, which the researchers termed “persistent gravitational wave observables,” would be even fainter than the gravitational waves themselves, but those effects would last longer. Objects might be shifted slightly out of place. The positions of particles drifting through space might be altered. Even time itself might end up slightly out of sync, running briefly at different speeds in different parts of Earth.
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