A reader also wonders about recalibrations of LIGO:
I was about to say “no” because the distortions from gravity waves cause the 2.5 mile LIGO arms to compress and stretch around one-ten-thousandth the diameter of a proton — tiny fractions of femtometers. And after stretching and compressing, you’d be back to normal. But this article (http://www.pbs.org/wgbh/nova/next/physics/gravitational-wave-memory/) mentions that spacetime might be distorted by gravity waves, so normal might not be the same normal again. Maybe that’s why I don’t fit into my old jeans anymore…
Fascinating stuff! I (being a lowly software engineer) had never thought of this:
Now that gravitational-wave detection is likely becoming a regular occurrence—we’ll probably find evidence of many more in the next few years—physicists are again pondering an obscure detail about gravitational waves that was once also thought virtually impossible to observe—gravitational-wave memory, which involves permanent changes in the distance between two objects.
And then that leads to this:
“In the last few years, we have discovered that ‘empty’ space, as described by Einstein’s theory of gravity, is not as empty as we once thought,” [Andrew] Strominger says. “It actually has a lot of hidden structure which can store information. The information is stored at the edges of space such as infinity or the horizon of a black hole. We [c]all this structure ‘soft hair.’ ”
“The gravitational-memory effect measures the soft hair,” Strominger says. “It would be most interesting to directly measure it.”
“This is indeed a very exciting prospect,” [Paul] Lasky says. “It is fantastic that people are thinking about the implications of such a detection, and it is especially wonderful to hear that it could have an influence on such fundamental questions as the black hole information paradox.”
Amazing thoughts. I wonder how all this theorizing impacts the mathematical universe hypothesis – that is, what the hell does the merging of two neutron stars mean in terms of the hypothetical mathematical entities of which we’re merely a reflection? (I think.)
Oh, and maybe this has something to do with virtual particles? Sure wish I hadn’t been such a slowpoke in college….
