On Saturday, February 1, 2020 at 6:49:40 AM UTC-7, John Clark wrote: > > On Sat, Feb 1, 2020 at 7:41 AM Alan Grayson <[email protected] > <javascript:>> wrote: > > *>But what if the CMB is the local clock? * > > > I'm not sure what you mean by that, but if all the hemispheres of the CMB > look about the same to you then you'd know you're motion was about the same > as the average motion of matter in the universe, if the hemispheres looked > radically different then you'd know you were moving at a different speed > than most matter in the universe. But so what? If you and I want to compare > our local clocks the only relevant factors are our relative speed (Special > Relativity) and the relative gravitational fields (General Relativity) > we're in, how the CMB looks to either of us is irrelevant. As Brent said > "*it's > called relativity theory for a reason*". > > Einstein and even Galileo said if you're in a sealed room moving at a > constant velocity you can't tell if you're moving or not, but you don't > need to invoke the CMB to know that if you look out a window on a moving > train you can see that there is a lot more stuff outside that window than > inside the train, and so you could determine you're moving relative to most > of the stuff around you. And if I was in a smaller train than you on a > parallel track that was moving even faster than you compared to most of the > stuff around us then the only thing you would need to know to figure out > the time dilation is our relative motion. And both of our local clocks will > be different not just from each other but also different from the clock on > the station platform. > > *> How could it manifest time dilation, compared to a clock in some moving >> frame, if its "clock" reading doesn't change? AG * > > > I don't understand the question. You never see your local clock rate > change, you observe other people's local clock rate change. Everything > always seems normal to you, it's other people's clocks that behave oddly. > > John K Clark >
When you use the Lorentz transformation to calculate the slower clock rate in another frame, what you get is the real clock rate in that frame. It's what the other observer measures, even though that observer notices nothing different. IOW, the calculation of the other observer's clock rate is not just an appearance, but what is experienced by the other observer. Now suppose we have an observer moving wrt the CMB, and the other observer at rest wrt the CMB, what I was calling the local clock. The local clock rate never changes, but it should according to relativity, from the pov of the observer in motion wrt the CMB. 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 on the web visit https://groups.google.com/d/msgid/everything-list/eba45b13-dcbf-48e7-971b-6f728eccad51%40googlegroups.com.
