On Sunday, March 23, 2025 at 1:06:06 PM UTC-6 John Clark wrote:
*Correction: the two LIGO installations are in Louisiana and Washington state. not Oregon as I originally said. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* What do you mean by L shaped, if there are two separate detectors? AG n0w e3b On Sun, Mar 23, 2025 at 2:47 PM John Clark <[email protected]> wrote: On Sun, Mar 23, 2025 at 2:36 PM Alan Grayson <[email protected]> wrote: *>> 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. * *> So they measure an interference pattern. How do they know it's a gravitational wave? AG* *LIGO is L shaped with each leg being 2 1/2 miles long, theory says gravitational waves should shrink the distance between one leg at the same time it's expanding the distance in the other leg, nothing else could do that. And to make sure they have two identical facilities, one in Louisiana and the other in Oregon, if it's a gravitational wave then the two detectors should measure the same thing at almost the same time because gravitational waves move at the speed of light, any slight delay between the two can help them figure out the direction the gravitational wave is coming from. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* e3b -- 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/95dc35bf-ae36-496d-9fbd-859e230b0f35n%40googlegroups.com.
