Unproven Einstein theory of 'gravitational memory' may be real after all, new study hints

By Andrey Feldman published 25 minutes ago

Einstein's theory of general relativity suggests that the "memory" of ancient events, such as black hole mergers, may be etched into the fabric of space-time by gravitational waves. New research shows how this theory of gravitational memory could finally be proven.



an illustration of two black holes swirling together
When black holes spiral toward collision, they emit gravitational waves that ripple across the universe. New research suggests that evidence of the earliest black hole mergers in the universe may be imprinted on the fabric of space-time. (Image credit: VICTOR de SCHWANBERG/SCIENCE PHOTO LIBRARY via Getty Images)


A team of theoretical physicists has proposed a new way to test one of the most intriguing predictions of Einstein's theory of general relativity: gravitational memory.

This effect refers to a permanent shift in the fabric of the universe caused by the passage of space-time ripples known as gravitational waves. Although these waves have already been detected by observatories such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo interferometer, the waves' lingering imprint remains elusive.

The researchers suggest that the cosmic microwave background — a faint glow left over from the Big Bang — might carry the signatures of powerful gravitational waves from distant black hole mergers. Studying these signals could not only confirm Einstein's prediction but also shed light on some of the most energetic events in the universe's history.

"The observation of this phenomenon can provide us with more knowledge of different fields of physics," Miquel Miravet-Tenés, a doctoral student at the University of Valencia and a co-author of the study, told Live Science via email. "Since it is a direct prediction of Einstein's theory of general relativity, its observation would serve as a confirmation of the theory, much like the observation of gravitational waves by LIGO, Virgo and KAGRA [the Kamioka Gravitational Wave Detector] has done! It can also be used as an additional tool to study some astrophysical scenarios, since it can contain information about the type of events that generate memory, such as supernovae or black hole collisions."

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