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Quote from: Halc on 22/09/2023 17:37:25Nothing you do at a given moment in time can effect what your own clock says at that moment in time. Can it change what a relatively moving observer see on our accelerating clock?

Nothing you do at a given moment in time can effect what your own clock says at that moment in time.

Quote from: Halc on 22/09/2023 17:37:25All that matters is that you pick a frame and figure out the speed of each clock in that frame, and for how long it travels at that speed. The one formula that is needed (quoted several times above) takes speed as an input, and makes no reference to acceleration.Change of reference frame requires acceleration.

All that matters is that you pick a frame and figure out the speed of each clock in that frame, and for how long it travels at that speed. The one formula that is needed (quoted several times above) takes speed as an input, and makes no reference to acceleration.

It's the cause of asymmetric time dilation in twins paradox.

Without it, no twin can conclude that the other twin is older than himself.

The acceleration is irrelevant other than providing the SPEED at which relativistic effects occur.

Halc kindly did the calculation for you and the method he used gives any answer you could possibly need. Acceleration does not occur in the equation he used and is irrelevant.

This is also incorrect since the conclusion is abstract (mental, not physical) unless they are in each other's presence, in which case it is called 'differential aging', which is the unequal comparison of clocks physically in each other's presence.

Yes, one can remove any parameter from any equation. However, the equation then loses it's integrity and any answers obtained will be utterly meaningless.

In your initial query you specified a speed of 40% the speed of light. Obviously acceleration is needed to achieve these speeds but acceleration does NOT figure in the subsequent calculation. This has been explained to you several times and at this point I give up-i'm out.

This is a slightly modified twin paradox to distinguish the effects of relative speeds and acceleration. Twin A started a journey to Alpha Centauri 4 light years away in a space ship moving at 0.4c. He is expected to arrive 10 years later, according to earth observer. Twin B stayed home to improve the space ship, so he can go to Alpha Centauri 5 years later at 0.8 c. Classical physics calculation predicts that they'll arrive at Alpha Centauri simultaneously. Does special theory of relativity predict the same? How old are they when they meet up at Alpha Centauri?

Most people have no difficulty in using earth earth reference frame to calculate relativistic effects. But they start to disagree when they are asked to make the calculation from the travelling twin's frame of reference.

For sanity check,

People who have even a basic understanding of relativity don't disagree.

Why do you need a sanity check?

Are you sure?

According to A, twin B and C only change their frame of reference once.

Quote from: hamdani yusuf on 25/09/2023 14:14:31Are you sure?Yes. You received the correct answer to your question, so I don't really understand where your confusion is coming from.

In your scenario twin A starts in the earths inertial frame and then accelerates to a new inertial frame. He then decelerates to Alpha Centauri's inertial frame, so in your example there are 2 inertial frame changes. Twin B does exactly the same number of inertial frame changes. Observer A, B and C all agree on the number of changes in inertial frames of A and B.I am not going to address observer D since this was not part of the original scenario, it is unnecessary and it only is going to cloud the issue.

What makes you think that they are correct?

The confusion comes from asymmetrical results produced by symmetrical situations.

So, you are not confused if the problem can be simplified to 0 or 1 inertial frame change, but you start to get confused with 2 or more inertial frame changes.

No, your scenario is a very straight forward relativity problem and not confusing at all. You are the one that is claiming this is confusing and unclear. So just let me repeat; the correct answers were given in reply #1 and reply #3. Do you agree that these answers are correct or do you see a problem with the answers?

You don't seem to understand the core problem in twin paradox situations. Time dilation observed by a relatively moving observer is just half of the problem. The other half is asymmetrical results between the twins, which means that one of them will observe time contraction of the other twin, instead of time dilation. It's the cause of this supposed asymmetry which created disagreement among physicists.

The asymmetry is due to one twin changing reference frames.