Which twin is younger in a spaceship race at 0.8c?

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Discussion Overview

The discussion revolves around the twin paradox in the context of special relativity, specifically focusing on a scenario where two twins travel in spaceships at relativistic speeds (0.8c) and how their aging is perceived relative to each other. The conversation explores the implications of time dilation, the effects of acceleration, and the relativity of simultaneity in different reference frames.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that if both twins are moving in a circle at the same speed, they would age the same, as time dilation is a function of speed in inertial frames.
  • Others argue that while each twin sees the other aging slower due to relativistic effects, this perception does not reflect the actual aging process in their respective inertial frames.
  • A later reply questions the assumption that both twins must be in the same location to observe each other, suggesting that their relative positions affect their observations of aging.
  • One participant illustrates the relativity of simultaneity by describing a scenario with buoys in space, indicating that different frames can disagree on the simultaneity of events, impacting the perceived ages of the twins.
  • Another participant expresses confusion about the implications of acceleration and how it affects the aging of the twins, particularly when they stop and observe each other.
  • There is a discussion about whether one twin would "catch up" to the other in terms of age during acceleration, referencing the classic thought experiment of the Earth twin's age jump during acceleration.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the question of which twin is younger, as multiple competing views remain regarding the effects of acceleration, the relativity of simultaneity, and the interpretation of observations made by the twins.

Contextual Notes

The discussion highlights limitations in understanding due to the complexities of relativistic effects, particularly in non-inertial frames and the implications of acceleration on perceived aging.

  • #31
JesseM said:
I don't actually understand the diagram that you drew...is it just meant to be a rotated version of this one that you posted earlier, or is it actually "skewed" in the sense that the angles between different lines wouldn't be the same as the wikipedia diagram?

I haven't read the rest of your reply yet (I'm running back and forth from my computer to wrapping paper) but to answer this question real quick: the former option is right. It's the same as that link, only rotated (it just seemed to be the easiest way to draw it, considering that my drawing tools consist of a pen, folded paper, and an old birthday card).
-DT
 
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  • #32
Oh, alright, the fact that mine was rotated and you referring to "vertical and horizontal" threw me off. That makes complete sense. Thanks again.
p.s. my diagram is only "skewed" relative to a "standard" diagram (the 2nd link you posted). The difference is I skewed t relative to t' and x' relative to x, whereas the first link you posted (the rotated version of mine) has t and t' skewed relative to t'' and x and x' skewed relative to x'' (where t'' and x'' the vertical/horizontal axes; the "standard" axes in C's reference frame).
 
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