The twin Paradox revisited

[martillo]

9 hours ago, Boltzmannbrain said:

I read that you did not want the distance from B to A to equal the distance from A to C, but this diagrams shows exactly that. 

Thinking that is not the case now. The discussion in this thread made me change my mind. I'm convinced now that in the case we analyzed the travelers don't age differently at the end. Actually I'm thinking that may be just travelling at high velocities does not produce any difference in age ever except possibly for the case of accelerations present and this is case for pure GR theory which is an area I don't pretend to enter. That's what some physicist are arguing now, that the difference of age is caused by the accelerations only. Actually my problem was with the idea of travelers aging less and the idea has vanished now. I'm speculating now that may be in some future is demonstrated that also accelerations actually would not produce any difference in age and in all cases the twins will reunite with the same age. That's what I'm thinking now. The twins' paradoxes would be solved at the inverse now: that at a first approach in Relativity Theory travelling twins could age less while actually that is not the case.

Edited February 20, 2023 by martillo

[Markus Hanke]

9 hours ago, martillo said:

the case of accelerations present and this is case for pure GR theory

No, that’s a common misconception. GR only comes into play if there is non-negligible gravity involved; the case of acceleration in a flat spacetime is handled perfectly well by SR.

9 hours ago, martillo said:

I'm speculating now that may be in some future is demonstrated that also accelerations actually would not produce any difference in age

We already have plenty of direct evidence from particle accelerator runs that accelerated particles behave exactly like SR says they do. Perhaps the best demonstration of this is Fermilab’s “Muon g-2” experiment, where unstable muons are introduced into the ring and accelerated to a \(\gamma\) of ~30. And as expected, their average life time really increases by the expected amount as compared to a reference sample that remains stationary in the lab frame. And this is only one example - literally every accelerator run we do demonstrates the reality of time dilation and length contraction, in exactly the way SR predicts it will.

[Boltzmannbrain]

12 hours ago, martillo said:

Thinking that is not the case now. The discussion in this thread made me change my mind. I'm convinced now that in the case we analyzed the travelers don't age differently at the end.

Yes, that is true.

Quote

Actually I'm thinking that may be just travelling at high velocities does not produce any difference in age ever except possibly for the case of accelerations present and this is case for pure GR theory which is an area I don't pretend to enter.

By "accelerations" do you mean gravity?

Quote

That's what some physicist are arguing now, that the difference of age is caused by the accelerations only. Actually my problem was with the idea of travelers aging less and the idea has vanished now. I'm speculating now that may be in some future is demonstrated that also accelerations actually would not produce any difference in age and in all cases the twins will reunite with the same age. That's what I'm thinking now. 

Are you saying that you don't think time dilation exists from either velocity or acceleration?

[Genady]

14 hours ago, martillo said:

I'm convinced now that in the case we analyzed the travelers don't age differently at the end.

Of course, they don't. That's why we tried to point out the wrong assumptions in your calculations which led to the wrong conclusion that they do.

[martillo]

2 hours ago, Genady said:

Of course, they don't. That's why we tried to point out the wrong assumptions in your calculations which led to the wrong conclusion that they do.

And you succeeded. My calculations were wrong. I admit it now.

3 hours ago, Boltzmannbrain said:

By "accelerations" do you mean gravity?

Any acceleration. Gravity, vehicles' accelerations, whatever.

3 hours ago, Boltzmannbrain said:

Are you saying that you don't think time dilation exists from either velocity or acceleration?

I think time dilation and length contraction exist as observed on different frames in Relativity Theory but also the relativity of simultaneity. I'm thinking the things could run such a way that different aging is something that could actually not take place ever. I mean, as Genady said some at some post, the timestamps in the clocks of each traveler is always the same so aging actually would not actually take place. That's what happens in the problem we analyzed with constant velocities and no acceleration so valid between inertial frames only. Now I'm speculating on the possibility that something similar could happen with accelerated frames. Just speculating with the idea now. As Markus Hanke said there's some experiments showing time dilation in accelerated frames but may be, just may be, aging could be something different that could actually not take place in this case too may be due to the relativity of simultaneity. I mean time is affected by accelerations but simultaneity too and so may be the timestamps (clocks' readings) could always be the same...

Edited February 20, 2023 by martillo