On Sunday, March 23, 2025 at 10:52:00 AM UTC-6 John Clark wrote:
On Sun, Mar 23, 2025 at 11:18 AM Alan Grayson <[email protected]> wrote: *> Generally speaking, what are the wave lengths of those space variation waves, and how are they measured? * *LIGO is able to measure the distance between two mirrors 2 1/2 miles apart to an accuracy of 1/10,000 the width of a proton. And you need that sort of accuracy if you want to detect gravitational waves. They achieve this astounding level of precision by measuring the interference effects between two laser beams. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* So they measure an interference pattern. How do they know it's a gravitational wave? AG *> What exactly is waving, space or spacetime,* *Spacetime. So if you detect a variation in space caused by a gravitational wave** then you can use Einstein's equations to figure out what the variation in time must've been, and if you detect a variation in time you can figure out what the variation in space must be. **As Einstein's teacher Hermann Minkowski said*:* "Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of both will retain an independent reality".* Interesting. I keep thinking of spacetime as one thing which is measured, but that's really not the case. AG -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/a1c1e7c6-96b8-4d8d-8ee3-265e0b76792fn%40googlegroups.com.
