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But as far as I know, Einstein never addressed the question of simultaneity-at-a-distance, according to the person who sometimes accelerates (the AP).

But as far as I know, Einstein never addressed the question of simultaneity-at-a-distance, according to the person who sometimes accelerates.

I'm now thinking that Einstein DID address the question of simultaneity-at-a-distance

Quote from: MikeFontenot on 11/04/2021 01:05:01But as far as I know, Einstein never addressed the question of simultaneity-at-a-distance, according to the person who sometimes accelerates.I'm now thinking that Einstein DID address the question of simultaneity-at-a-distance, according to a person who sometimes accelerates. I remember that Einstein predicted that for two clocks stationary in a gravitational field, the clock higher in the field (farther from the source of the field) will run faster than the clock lower in the field. He got this result long before he published his paper on his GR theory (and long before he arrived at his GR theory). He got it by solving an SR problem, and then invoking his "principle of equivalence" between acceleration and gravitation.The SR problem he solved was for a rocket, not in the presence of any gravitation field, with a clock at the front and a clock at the back, that is undergoing a constant acceleration. He determined that the clock in front will run faster than the clock at the back. So he DID determine what an accelerating observer at the rear of the rocket will conclude about the current time at the front of the rocket.I've heard that Einstein wrote a paper in 1907 (2 years after his SR paper, and 8 years before his GR paper) that may have discussed the above result. I'm currently trying to find that 1907 paper (translated into English, of course). I'd like to know if he used CMIF (co-moving inertial frame) simultaneity in getting his result, and whether he made any assumptions in justifying that choice.

So if I follow that logic correctly if the clocks were in sync at departure they would be in sync once they/the rocket came to rest in reality ?.

Given they have undergone the same velocity and gravitational potential is not a factor.

I'm now thinking that Einstein DID address the question of simultaneity-at-a-distance, according to a person who sometimes accelerates.

I remember that Einstein predicted that for two clocks stationary in a gravitational field, the clock higher in the field (farther from the source of the field) will run faster than the clock lower in the field. He got this result long before he published his paper on his GR theory (and long before he arrived at his GR theory). He got it by solving an SR problem, and then invoking his "principle of equivalence" between acceleration and gravitation.

He determined that the clock in front will run faster than the clock at the back. So he DID determine what an accelerating observer at the rear of the rocket will conclude about the current time at the front of the rocket.

I've heard that Einstein wrote a paper in 1907 (2 years after his SR paper, and 8 years before his GR paper) that may have discussed the above result. I'm currently trying to find that 1907 paper (translated into English, of course). I'd like to know if he used CMIF (co-moving inertial frame) simultaneity in getting his result, and whether he made any assumptions in justifying that choice.

But why should that fact - that we can't see them doing it - mean that they aren't simultaneously doing it?

It seems to me, if I may interject an impertinent and possibly ignorant comment, that "simultaneity" is not ruled by the fact that light travels at a fixed speed.All it means, is that we can't see two events happening at the same time.

All our interpretations are therefore dependent on the properties of "light".

All it means, is that we can't see two events happening at the same time.

Quote from: charles1948 on 14/04/2021 17:00:16All it means, is that we can't see two events happening at the same time.No it doesn’t. It’s not due to the time taken for light to travel, that is a separate effect.

Mike F wants to make it about people, but it's not. Per Einstein, it's about the choice of coordinate system, and anybody is free to choose any coordinate system they like.

Quote from: Colin2B on 14/04/2021 18:40:51Quote from: charles1948 on 14/04/2021 17:00:16All it means, is that we can't see two events happening at the same time.No it doesn’t. It’s not due to the time taken for light to travel, that is a separate effect.I don't quite follow you. We can only tell if two events happen at the same, by looking at them.Our "looking" is dependent on light. So what's the "separate effect" that we can employ without using light?

Charles1948 said:"Is this not Capitalism in action - profit from Science by selling books."The monograph is 18 pages long. So at $5, that's a cost to the purchaser of about 28 cents per page ... not much more than it would cost you to photocopy it. My royalty, per monograph sold, is 85 cents. Obviously, I didn't do it to get rich. I provided the information for anyone who wants to understand that new alternative simultaneity method, especially those readers who don't like the negative ageing that the CMIF method can produce.

Quote from: charles1948 on 14/04/2021 18:57:42Quote from: Colin2B on 14/04/2021 18:40:51Quote from: charles1948 on 14/04/2021 17:00:16All it means, is that we can't see two events happening at the same time.No it doesn’t. It’s not due to the time taken for light to travel, that is a separate effect.I don't quite follow you. We can only tell if two events happen at the same, by looking at them.Our "looking" is dependent on light. So what's the "separate effect" that we can employ without using light?It doesn't matter what the speed of light is in the train experiment. What is important is the order that you see the flashes in. Since the light from one flash necessarily travels the same speed as the light from the other flash, then the order that you see the flashes in tells you the order that the events occurred in.

Surely not. The order in which you see the flashes, only tells you the order in which you see them.Not at all when the flashes actually happened.

If two flashes occurred simultaneously, and you were watching from a distance of (say) 1,000,000 miles from one flash, and 10,000,000 miles from the other, you'd see the two flashes as occurring at seemingly different times. Because the light from each flash would take a different time to reach you..