Understanding Time Dilation in Special Relativity

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Discussion Overview

The discussion revolves around the concept of time dilation in special relativity, specifically addressing the terminology and the perceived contradictions in describing time as "dilated" when it may seem to be "contracted" from different frames of reference. Participants explore the implications of these terms in relation to observers in different inertial frames.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question the terminology of "time dilation," suggesting that it implies a contradiction since it may seem that time is contracting from certain perspectives.
  • One participant clarifies that "dilation" refers to the lengthening of time intervals as observed from a moving frame, using the example of a strobe light flashing at different rates in different frames.
  • Another participant acknowledges the perspective difference, suggesting that while one observer sees time on the ship as dilated, the observer on Earth perceives it as contracted, highlighting the symmetry in the situation.
  • Further clarification is provided that the time experienced by observers in their rest frames is considered "proper time," and that all moving observers will see processes taking longer, reinforcing the concept of dilation.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of time dilation and its terminology, indicating that multiple competing perspectives remain without a consensus on the terminology's implications.

Contextual Notes

The discussion reflects varying interpretations of time dilation and its effects based on different inertial frames, with no resolution on the terminology used to describe these effects.

timpeac
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Hi,

Just out of idle curiosity - why do we talk of "time dilation" in terms of special relativity when in fact it contracts which is the opposite? Is there a reason or is it just accepted usage?
 
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timpeac said:
Hi,

Just out of idle curiosity - why do we talk of "time dilation" in terms of special relativity when in fact it contracts which is the opposite? Is there a reason or is it just accepted usage?

What do you mean it contracts? The specific word "dilation" refers to the lengthening of physical processes. i.e in my rest frame a strobe light flashes once per second, but if I put the same strobe light on a spaceship and shoot it off at relativistic velocities, I now see it flashing only once every two seconds. The period of flashing is dilated, not contracted.
 
Nabeshin said:
What do you mean it contracts? The specific word "dilation" refers to the lengthening of physical processes. i.e in my rest frame a strobe light flashes once per second, but if I put the same strobe light on a spaceship and shoot it off at relativistic velocities, I now see it flashing only once every two seconds. The period of flashing is dilated, not contracted.

Ah yes, I see. I think it's a case of you say tomahtoes I say tomaytoes -the way I was thinking of it is that the person left on Earth considers that for every one his seconds one on the ship his lasts 0.8 (or whatever) as long and so his has contracted. Yours is of course the same view but from the other perspective - and I suppose it is more valid like that since it is the ship that has undergone the acceleration and not him after all.
 
Last edited:
Ah, I see where your confusion was coming from now. Yeah, we call it dilation because we define the time of physical processes as the time occurring in their rest frames. So whenever we observe these processes in a moving frame, they always appear to take longer. Just for clarification, the guy on the rocket ship (or whatever) sees the clocks on Earth run .8s for every one second he experiences. In that respect, the situation is completely symmetric.
 

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