Twin Paradox

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Main Question or Discussion Point

Who is older? The one who rides at the spaceship or the one who is left on earth?
 

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  • #2
phinds
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Who is older? The one who rides at the spaceship or the one who is left on earth?
What do you think? What has your research into the "paradox" turned up so far?
 
  • #3
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What do you think? What has your research into the "paradox" turned up so far?
It may vary. The one who rides at the spaceship may be older or younger than the person left on earth.
 
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phinds
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It may vary. The one who rides at the spaceship may be older or younger than the person left on earth.
No, that's not correct. You need to do some reading on the basics of Special Relativity. Just asking questions on a forum really isn't going to teach you much.
 
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No, that's not correct. You need to do some reading on the basics of Special Relativity. Just asking questions on a forum really isn't going to teach you much.
I've read a lot already. I've seen some video from NASA about the twin astronaut. And I think their study about this one is not yet done.
 
  • #6
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I've seen some video from NASA about the twin astronaut
Which twin did the NASA video identify as being older at the reunion?
 
  • #7
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Which twin did the NASA video identify as being older at the reunion?
The person on earth. But based on what I have read their research is not yet finish.
 
  • #8
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Mark Kelly to be exact.
 
  • #9
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The person on earth.
There you go.

But based on what I have read their research is not yet finish
This is not an active area of research for NASA. However, other researchers have done this experiment. Not with humans but with radioactive particles.

The ones that stay in place age more than the ones spinning around the accelerator ring. Just as predicted by relativity.
 
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  • #10
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I've read a lot already. I've seen some video from NASA about the twin astronaut. And I think their study about this one is not yet done.
Watching internet videos is a remarkably ineffective way of learning this stuff. Some videos are OK, most are awful, there's no way of knowing which is which if you don't already understand the subject.

The Twin Paradox isn't really a paradox at all; it was described by Einstein in his very first paper on relativity (1905) as a surprising but logical consequence of the theory. It's often presented as a "paradox" as a pedagogical tool, a way of getting people to challenge their natural but wrong intuitions about time, but in fact there is no logical inconsistency and no question about which twin ages more.

A good layman-friendly introduction can be found here: http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_paradox.html
 

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