Special Relativity and Light -- How does speed of an object affect time?

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Discussion Overview

The discussion revolves around how the speed of an object affects the perception and measurement of time, particularly in the context of special relativity. Participants explore concepts related to time dilation, reference frames, and the nature of time itself, while also suggesting introductory resources for understanding these ideas.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions how speed affects time, suggesting that time slows down due to light "not catching up" with a moving object.
  • Another participant asserts that speed is relative and that the idea of "time depending on speed" is a misconception, emphasizing that each frame measures the other's time as running slow.
  • Some participants discuss the appropriateness of various introductory books on relativity, with differing opinions on their effectiveness for beginners.
  • A claim is made that all objects move through time at one second per second, regardless of speed, with perceived time being relative to the observer's frame of reference.
  • Time dilation is described mathematically, with a participant explaining how it can be measured using synchronized clocks in different states of motion.
  • One participant draws an analogy between time dilation and the measurement of distances in different reference frames, suggesting that nothing has "affected time" or "space" but rather that different intervals are being measured.
  • Another participant notes that in Galilean/Newtonian kinematics, elapsed proper times are equal, introducing a distinction between classical and relativistic concepts of time.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of time dilation and its implications, with no clear consensus reached. Some agree on the relative nature of time perception, while others challenge the interpretation of time dilation as an illusion.

Contextual Notes

Participants reference various introductory texts on relativity, noting that some may be outdated or not suitable for beginners. The discussion also highlights the complexity of time dilation and its mathematical representation, indicating that assumptions and definitions may vary among participants.

Who May Find This Useful

This discussion may be useful for individuals interested in understanding the concepts of time and speed in the context of special relativity, as well as those seeking recommendations for introductory literature on the subject.

  • #31
BvU said:
Right. :smile:

So ?

##\ ##

As the angular velocities of the minute hands of those watches are different, then it follows that those two watches have different ticking rates, because ticking rate of a clock is proportional to the angular velocity of a clock-hand of said clock.

So clocks with different velocities have different ticking rates.

Velocity is a relative thing. Ticking rate is a relative thing.
 
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  • #32
:nb)

Are you dangerously close to denying relativity altogether ? Good clocks have exactly the same ticking rates in their rest frames.

##\ ##
 
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  • #33
jartsa said:
As the angular velocities of the minute hands of those watches are different, then it follows that those two watches have different ticking rates, because ticking rate of a clock is proportional to the angular velocity of a clock-hand of said clock.
squirrel WHOA small.jpg
Uh ... you SERIOUSLY need to rethink that !
 
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  • #34
Mattergauge said:
And still it's correct. The fast moving hand is going somewhat slower in time. How can both time velocities keep up? If I find myself near a black hole, different parts of me move through time at different rates. My feet will move slower in time than my head. How will the flow of blood evolve? Will blood accumulate in some parts?
You don't need a black hole. As far as that makes sense, it applies when you're standing on Earth.
 
  • #35
jartsa said:
As the angular velocities of the minute hands of those watches are different
They are different 4-vectors in spacetime, but they each have the same relationship to the corresponding 4-vectors in spacetime that describe the 4-velocities of the clocks. So each clock's "ticking rate" in its rest frame is the same, as @BvU has said.

Mattergauge said:
And still it's correct. The fast moving hand is going somewhat slower in time.
No, it's not correct as he stated it. Each hand moves at the same speed relative to the clock it is attached to. See above.

phinds said:
You're changing the subject. We were talking about an ideal clock moving through space, not a physical clock in a gravity well.
Mattergauge said:
But the situation is comparable.
No, the situation is not comparable. The GR effect you refer to is different from the SR effect under discussion in this thread. If you want to discuss the GR effect, please start a new thread.
 
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  • #36
The OP question has been sufficiently addressed. Thread closed.
 
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