On Tue, Jan 28, 2020 at 9:04 PM Alan Grayson <[email protected]> wrote:
*> By "objective" I just meant that when the clocks are compared, the > elapsed time differs between the clocks being compared, and the effect is > NOT just an appearance. It's like the case of comparing an orbiting clock > with a ground clock.* > It's a real effect and as I've mentioned before you prove it every time you use your car's navigation system to find a new grocery store. The GPS satellite is moving very fast so due to Special Relativity the satellite's clock will LOSE 7210 nanoseconds a day, but the satellite's clock is in a weaker gravitational field than the clock on the ground because it is further from the Earth's center, so due to General Relativity the clock will GAIN 45850 nanoseconds a day. Taking these 2 factors into account the satellite's clocks gains 45850 −7210 = 38,640 nanoseconds a day relative to a clock on the ground. If this were not taken into account the GPS system would drift off by 6 miles every day, the error would be cumulative. > *>* *there's a problem IMO. Will the far away galaxy's clock, be slower > than, say, the Earth's clock, from the pov of the Earth observer?* > YES! > * > But the reverse is also true, as seen from the observer in the far > away galaxy.* > YES! *> Seems like a contradiction. Each clock runs slower than the other > observer's clock. * > Welcome to Special Relativity, a phenomenon discovered by Einstein in 1905, but it took him another 10 years to come up with General Relativity, an effort so difficult it nearly killed him. * > I had a long discussion about this with Brent awhile ago, and he > claimed that the resolution involved simultaneity,* > And Brent was 100% correct. If I start my stopwatch when I see the hand of your clock point to 5 and stop it when it points to 10 I will find that your clock is running slower than my clock. And when you do the same thing you will find that my clock is running slower than your clock. It's odd but there is no paradox because we will disagree about when to start and stop the stopwatch. > *>* *but I never resolved it. AG * > If you can't resolve an issue in Special Relativity that has been resolved by the physics community for 115 years then perhaps you should have a little humility before you make grand pronouncements about cosmology which at the very least requires General Relativity which is far more complex mathematically and difficult to conceptualize than Special Relativity. > *> Doesn't a hyperbolic geometry have negative curvature?* > Yes. > *> If so, this is not what is measured for our universe. AG* > What you measure when you count how many degrees the angles in a triangle have is the 3D curvature of space, I'm talking about the 4D curvature of spacetime. John K Clark -- 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/CAJPayv3N9Y1VRQqkZJHJsC32fw7H87ryzn3OjAS4JWDVoz%3DqLg%40mail.gmail.com.
