Who Ages Faster in the Twin Paradox?

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    Paradox Twin paradox
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Discussion Overview

The discussion revolves around the Twin Paradox in the context of special relativity, specifically addressing the question of which twin ages faster after one travels at relativistic speeds and returns. Participants explore the implications of different reference frames, the effects of acceleration, and the interpretation of time dilation.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants express confusion about why one twin ages more than the other, questioning the symmetry of the situation from different reference frames.
  • Others argue that the traveling twin experiences acceleration during the turnaround, breaking the symmetry and confirming that they are not in an inertial frame throughout the journey.
  • A participant suggests that one must choose a single inertial frame to analyze the situation consistently, noting that in the Earth's frame, the rocket twin's clock runs slower.
  • Another participant discusses the Lorentz transformation, explaining that the distance and time experienced by the traveling twin are foreshortened, leading to less elapsed time for them compared to the Earth-bound twin.
  • Some contributions highlight the use of spacetime diagrams to visualize the different paths taken by the twins, indicating that the lengths of these paths correspond to the proper time experienced by each twin.
  • There are discussions about the term "paradox," with some participants clarifying that it is used ironically and that the situation can be resolved through proper understanding of relativity.
  • One participant raises a concern about the interpretation of the "Time Gap Objection," questioning whether the perceived aging differences during the trip are indeed an accounting error or if they hold validity in the context of time dilation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretation of the Twin Paradox. While some agree on the role of acceleration and the necessity of choosing a reference frame, others continue to question the implications of time dilation and the nature of the paradox itself.

Contextual Notes

Limitations in understanding arise from the complexity of switching reference frames and the effects of acceleration, which are not fully resolved in the discussion. The interpretations of time dilation and the implications of the "Time Gap Objection" remain points of contention.

  • #61
indirachap said:
Thanks. How is it that the law of physics is the same in every FOR when in the spacecraft FOR the astronaught clearly is not experiencing the same law of physics behaviour as that being experienced in the Earth FOR?
In the spaceships FOR clocks that move fast time dilate also. The law is the same in all inertial frames.
 
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  • #62
indirachap said:
How is it that the law of physics is the same in every FOR when in the spacecraft FOR the astronaught clearly is not experiencing the same law of physics behaviour as that being experienced in the Earth FOR?

They both use the same laws of physics. But the results they get from those laws depend on whether or not they are accelerating. The person back home never accelerates, but the astronaut does accelerate, at the turnaround.

Anytime the spacecraft is traveling at a constant velocity with respect to the inertial person back home, the astronaut will say that the person back home is aging more slowly than she is. But while the astronaut is reversing course at the turnaround (which requires her to accelerate), she will say that the person back home is aging much faster than she is.
 
  • #63
GrammawSally said:
They both use the same laws of physics. But the results they get from those laws depend on whether or not they are accelerating. The person back home never accelerates, but the astronaut does accelerate, at the turnaround.

Anytime the spacecraft is traveling at a constant velocity with respect to the inertial person back home, the astronaut will say that the person back home is aging more slowly than she is. But while the astronaut is reversing course at the turnaround (which requires her to accelerate), she will say that the person back home is aging much faster than she is.


Well said, GrammawSally.
 
  • #64
indirachap said:
Would it be fair to say that during a journey at the the near speed of light a second would still be a second but it would take longer to pass due to time dialation?
There is a way that statement could be interpreted to make it correct, so I would say "yes", though I am not sure that you understand yet.

Let's say you have a spaceship with a lab onboard that has an array of different science experiments, each designed to measure one second using a different physical principle, and an atomic clock. In addition, there is an array of synchronized atomic clocks. The ship is traveling at .6 c relative to the array of clocks, and begins all of the experiments as it passes a clock. All of the physics experiments end at the same time, just as the spaceship passes the synchronized clock .75 light seconds away, which reads 1.25 s.
 

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