Astronomers regularly observe gravitational waves (GW)—ripples in space and time—that are caused by pairs of black holes merging into one. Einstein’s theory of gravity predicts that GW, which squeeze and stretch space as they pass, will permanently distort space, leaving a “memory” of the wave behind. However, this memory effect has not yet been detected, as it would be extremely small, leaving only the faintest traces.
Click here for original story, Astronomers search for gravitational-wave memory
Source: Phys.org