https://www.quantamagazine.org/gravitati...-20211208/
Gravitational Waves Should Permanently Distort Space-Time
"The “gravitational memory effect” predicts that a passing gravitational wave should forever alter the structure of space-time. Physicists have linked the phenomenon to fundamental cosmic symmetries and a potential solution to the black hole information paradox."
I knew that headline and summary had to be utter nonsense, but YouTube vids on it either disagreed among themselves or were full of GR arcane math lingo to wade through. Wikipedia proved to be the best, but still only as a brief summary:
https://en.wikipedia.org/wiki/Gravitatio...ory_effect
"Gravitational memory effects, also known as gravitational-wave memory effects are predicted persistent changes in the relative position of pairs of masses in space due to the passing of a gravitational wave....
Detection
The effect should, in theory, be detectable by recording changes in the distance between pairs of free-falling objects in spacetime before and after the passage of gravitational waves...."
So not at all a 'permanent distortion of spacetime', but simply a bit surprising residual displacement - i.e. effect of GW jigglings do not exactly cancel out after the wave has completely passed through.
Presumably a reflection of the highly unsymmetric generation of GWs owing to final stage inspiral of BH-BH, NS-NS etc. binary pairs. And 'memory effect' persistence strictly applies only to free-falling test masses very far from any perturbing effects of net gravitational attraction from other masses. Hence the test masses themselves must be sufficiently small and well distanced from each other.
Gravitational Waves Should Permanently Distort Space-Time
"The “gravitational memory effect” predicts that a passing gravitational wave should forever alter the structure of space-time. Physicists have linked the phenomenon to fundamental cosmic symmetries and a potential solution to the black hole information paradox."
I knew that headline and summary had to be utter nonsense, but YouTube vids on it either disagreed among themselves or were full of GR arcane math lingo to wade through. Wikipedia proved to be the best, but still only as a brief summary:
https://en.wikipedia.org/wiki/Gravitatio...ory_effect
"Gravitational memory effects, also known as gravitational-wave memory effects are predicted persistent changes in the relative position of pairs of masses in space due to the passing of a gravitational wave....
Detection
The effect should, in theory, be detectable by recording changes in the distance between pairs of free-falling objects in spacetime before and after the passage of gravitational waves...."
So not at all a 'permanent distortion of spacetime', but simply a bit surprising residual displacement - i.e. effect of GW jigglings do not exactly cancel out after the wave has completely passed through.
Presumably a reflection of the highly unsymmetric generation of GWs owing to final stage inspiral of BH-BH, NS-NS etc. binary pairs. And 'memory effect' persistence strictly applies only to free-falling test masses very far from any perturbing effects of net gravitational attraction from other masses. Hence the test masses themselves must be sufficiently small and well distanced from each other.