Twin Paradox in 3-sphere (S^3)

In summary, the conversation discusses a scenario where X and Y reside in the 3-sphere and Y is accelerated to near the speed of light along a great circle before meeting X and giving each other high-fives. The two are identical twins at this moment, but Y continues alone on the great circle while X remains in an inertial frame. When they meet again, it is unclear which twin is younger as neither has undergone any accelerations. The conversation also mentions the Twin Paradox in compact spaces and the concept of elapsed proper time, as well as discussions on the cosmological twin paradox and the role of acceleration in determining differential aging in special relativity.
  • #106
I simply can't make it any clearer for you. If the fundamentals of relativity theory are still hazy to you, I can recommend some excellent references. Also, consult the arXiv (and my earlier posts) if you need clarification.

So again, I must ask: any ideas? To quote pervect:

"There is a general agreement about the broad details, which is that the two twins won't be the same age.

The disagreement as I read it is how to explain the age difference, i.e. to point to a particular mechanism. The first papers say that it can be addressed in terms of winding number (which is a topological property that doesn't even need a metric). The second papers say that this is not correct, that one needs more than the winding number to properly explain the age difference, that one needs the metric information.

Everyone agrees that there should be an age difference AFAIK."

So: what is the proper resolution? Is the 'winding number' approach right, despite its apparent refutation in the literature? Or do Barrow and Levin have the right idea? Is there perhaps another idea we're missing? And please: I can't explain it any better than I already have; consult the literature if you're unsure about why the paradox may persist in the complex cases.

Any ideas?
 
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  • #107
If you are not willing to entertain the possibility that you are misunderstanding, then you can never learn. In that case, it is pointless to even try to have a discussion about this with you. Is this what you are telling us?

I truly hope not. So please go back and answer the questions asked here:
https://www.physicsforums.com/showpost.php?p=1269327&postcount=105
 
  • #108
JustinLevy, I simply can't make it any clearer for you. If the fundamentals of relativity theory are still hazy to you, I can recommend some excellent references. Also, consult the arXiv (and my earlier posts) if you need clarification.

So again, I must ask: any ideas? To quote pervect:

"There is a general agreement about the broad details, which is that the two twins won't be the same age.

The disagreement as I read it is how to explain the age difference, i.e. to point to a particular mechanism. The first papers say that it can be addressed in terms of winding number (which is a topological property that doesn't even need a metric). The second papers say that this is not correct, that one needs more than the winding number to properly explain the age difference, that one needs the metric information.

Everyone agrees that there should be an age difference AFAIK."

So: what is the proper resolution? Is the 'winding number' approach right, despite its apparent refutation in the literature? Or do Barrow and Levin have the right idea? Is there perhaps another idea we're missing? And please: I can't explain it any better than I already have; consult the literature if you're unsure about why the paradox may persist in the complex cases.

Any ideas?
 
  • #109
KingOrdo said:
Any ideas?
Yes, to close this topic, it's going nowhere.
 
  • #110
MeJennifer said:
Yes, to close this topic, it's going nowhere.

Indeed; but not for want of trying on my part. I've been extremely patient, to the tune of five pages of posts. . . .
 
  • #111
KingOrdo said:
JustinLevy, I simply can't make it any clearer for you.
Why do you insist on evading the questions? That would make your position abundantly clear. Which currently it is not as you keep stating things that contradict GR as well as the papers you are referring to.

The previous questions and related points have been brought up by other posters and you continue to ignore them or resist acknowledging them. In doing so you ignore the very discussion you repeatedly seek. So if you do not answer those questions, it will be nearly impossible for any poster to help you.

This is a simple request, and the questions are not difficult or time consuming. So please answer the specific questions previously given to you.
 
  • #112
JustinLevy, I simply can't make it any clearer for you. If the fundamentals of relativity theory are still hazy to you, I can recommend some excellent references. Also, consult the arXiv (and my earlier posts) if you need clarification.

So again, I must ask: any ideas? To quote pervect:

"There is a general agreement about the broad details, which is that the two twins won't be the same age.

The disagreement as I read it is how to explain the age difference, i.e. to point to a particular mechanism. The first papers say that it can be addressed in terms of winding number (which is a topological property that doesn't even need a metric). The second papers say that this is not correct, that one needs more than the winding number to properly explain the age difference, that one needs the metric information.

Everyone agrees that there should be an age difference AFAIK."

So: what is the proper resolution? Is the 'winding number' approach right, despite its apparent refutation in the literature? Or do Barrow and Levin have the right idea? Is there perhaps another idea we're missing? And please: I can't explain it any better than I already have; consult the literature if you're unsure about why the paradox may persist in the complex cases.

Any ideas?
 
  • #113
KingOrdo said:
MeJennifer said:
Yes, to close this topic, it's going nowhere.
Indeed; but not for want of trying on my part.
How can you possibly say that? It is going no where directly because of your lack of trying.

I have asked repeatedly for you to answer some simple questions. You refuse to acknowledge questions were even asked of you, let alone actually try to answer them.

So stop avoiding the questions, as these relate to the heart of the matter.
Please answer the following:

1) As pervect mentioned, even in a non-closed universe, two distinct inertial paths can cross in two places.
a] So before moving onto closed spaces, do you understand that there is no paradox about how much proper time elapsed on these two world lines?

b] If so, please explain your understanding of the resolution of this "paradox" to give others a starting point to build explanations from.

2) Do you agree that the question of how much proper time elapsed requires a geometry, ie. that until a geometry is defined we cannot ask for the distance between spacetime points? If not, please explain why.

3) Do you agree that specifying a geometry does not specify a coordinate system (ie. the description is still coordinate invarient)? If not, please explain why.

4) Do you agree that once the geometry is specified, there is a unique answer to how much proper time elapsed along a path in spacetime? And therefore there is no "paradox"? If not, please explain why.
 
  • #114
JustinLevy, I simply can't make it any clearer for you. If the fundamentals of relativity theory are still hazy to you, I can recommend some excellent references. Also, consult the arXiv (and my earlier posts) if you need clarification.

So again, I must ask: any ideas? To quote pervect:

"There is a general agreement about the broad details, which is that the two twins won't be the same age.

The disagreement as I read it is how to explain the age difference, i.e. to point to a particular mechanism. The first papers say that it can be addressed in terms of winding number (which is a topological property that doesn't even need a metric). The second papers say that this is not correct, that one needs more than the winding number to properly explain the age difference, that one needs the metric information.

Everyone agrees that there should be an age difference AFAIK."

So: what is the proper resolution? Is the 'winding number' approach right, despite its apparent refutation in the literature? Or do Barrow and Levin have the right idea? Is there perhaps another idea we're missing? And please: I can't explain it any better than I already have; consult the literature if you're unsure about why the paradox may persist in the complex cases.

Any ideas?
 
  • #115
You have now repeated that last posting 6 times.
To me that is trolling. Hopefully a moderator can take some action here.
 
  • #116
I've asked for moderators to intervene pages ago. I ask a simple question and get only evasion. I can explain myself no better than I already have. Any insult/evasion/irrelevance/etc. will be met by boilerplate. You should expect that. I am asking a serious question about a serious topic.
 
  • #117
KingOrdo said:
I ask a simple question and get only evasion.
You did not get evasion. You got answers from several posters which you preceded to ignore or misunderstand. When people took the time to help resolve this misunderstanding you refused to help in anyway.

KingOrdo said:
I can explain myself no better than I already have.
Yes you can. You can answer the simple questions directly addressed to you to help others understand where the common ground lays and where the disagreement occurs.

The questions are not an insult, nor an evasion, nor irrelevant.

The are simple, reasonable, and relevant. Your evasion of them makes me question your motives here. If you are not here to just troll, please stop evading the questions.
 
  • #118
Obviously, this thread is going nowhere. Questions have either been answered, or not been addressed, or issues not clear, etc.. etc.

After 8 pages of responses, I believe it is time to stick a fork into this one. Please do not repost this question in another thread.

Zz.
 

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