How does special relativity account for the time on a single moving clock?

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Discussion Overview

The discussion revolves around the relationship between clocks and time in the context of special relativity, exploring how time is measured and understood in different frames of reference. Participants engage with the implications of synchronization conventions and the philosophical aspects of time, while also referencing empirical evidence and historical context.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Historical

Main Points Raised

  • Some participants argue that clocks and time are fundamentally different, with time being a natural property observable through changes, while clocks are man-made devices that measure time.
  • Others propose that synchronization conventions, such as Einstein's, are arbitrary choices that do not reflect a fundamental property of time, suggesting alternatives like slow clock transport.
  • A participant emphasizes the importance of empirical evidence in understanding Einstein's theory, particularly the light postulate and its implications for measuring time.
  • There is a contention regarding the philosophical implications of time measurement, with some asserting that discussions about the nature of time belong in philosophical contexts rather than scientific ones.
  • Some participants express frustration with the philosophical debate, advocating for a focus on measurable behaviors of clocks and their relation to empirical science.
  • Historical references are made to Lorentz's explanations of the Michelson-Morley experiment, highlighting the evolution of thought leading to Einstein's theory.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement, particularly regarding the nature of time and the implications of synchronization conventions. While some acknowledge the arbitrary nature of these conventions, others defend the validity of Einstein's approach. The discussion remains unresolved with multiple competing views present.

Contextual Notes

Participants note that the debate over the nature of time and clocks involves assumptions about definitions and the philosophical implications of measurement, which may not have experimentally testable consequences.

  • #151
yuiop said:
The expression that all clocks tick at at a rate of one second per second relates to a comparison of one ideal clock to another ideal clock that are adjacent to each other and stationary with respect to each other.

HI yuiop, thanks for checking in. My latest thoughts on tick rate are in Post 140. What do you think of them?
JM
 
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  • #152
PhilDSP said:
Pauli's textbook on SR and Minkowski's EM (plus the basics of GR) is pretty decent IMO. Though it is oriented towards serious physics or engineering students. It's inexpensive and was written in the 1920's so it doesn't have newer, more abstract, more exotic developments in the field.

What are the titles and publisners ( or other source) for Pauli and Mink?
JM
 
  • #153
harrylin said:
Without following that discussion, I saw a later post by you from which it appears that it's still not clear to you. Maybe useful if someone else gives a try?

- A and B are different "stationary" points (xA, yA, zA) and (xB, yB, zB).

- the straight constant speed trajectory AB is one line of the polygon.

Thanks, harrylin. I follow your ideas. My need is for the math that connects the time t'' of moving rotated frame with the time t of the original stationary frame K. Assume the points A, (0,0,0 ) and B, ( 1,1,0) wrt K. I accept that the relation between the frames with their respective 'x' axes aligned with these points is the same as the relation between the original K and K' axes. But a clock moving at v along the line between A and B moves at only vcos45 wrt K, for example. So what is the math that connects t'' with t?
JM
 
  • #154
ghwellsjr said:
I have no idea what you are talking about here but I don't think it can be related to what Einstein said with regard to inertial coordinate systems in Special Relativity, which is what this thread is about.

Right on George!
 
  • #155
ghwellsjr said:
What would you call the clocks in the latticework described by Kip Thorne on page 3 of his upcoming http://www.pma.caltech.edu/Courses/ph136/yr2011/1102.2.K.pdf?
I would call them "clocks".
 
  • #156
JM said:
My answer is t' = [1/m + v2/c2 - uv/c2t.
Whats yours?
What is the question and what are m, u, and v?
 
  • #157
JM said:
Thanks, harrylin. I follow your ideas. My need is for the math that connects the time t'' of moving rotated frame with the time t of the original stationary frame K. Assume the points A, (0,0,0 ) and B, ( 1,1,0) wrt K. I accept that the relation between the frames with their respective 'x' axes aligned with these points is the same as the relation between the original K and K' axes. But a clock moving at v along the line between A and B moves at only vcos45 wrt K, for example. So what is the math that connects t'' with t?
JM
It looks as if my next remark didn't reach:
"
- the straight same constant speed trajectory BC is another line of the polygon. The Lorentz transformation relating "time" in a co-moving frame along AB is identical to that along BC: x is by definition the direction of motion. And obviously from point B the clock has to continue its counting from where it was the moment before - that's just common sense.
"
I'll try again. For the first leg, the X-axis of K and K' is by definition chosen along the line AB. It is you who draws the lines and defines the frames for the calculation. Thus you give A and B the same Y and Z coordinate (in this case you can keep them both 0), and v along x is simply v. That's how the Lorentz transformations are defined. And how the math between the polygon lines is connected I explained next. So, I'm afraid that you could not follow me. :rolleyes:
To elaborate: you choose for the calculation for BC new reference frames with X and X' oriented along BC.
 
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  • #158
DaleSpam said:
ghwellsjr said:
What would you call the clocks in the latticework described by Kip Thorne on page 3 of his upcoming http://www.pma.caltech.edu/Courses/ph136/yr2011/1102.2.K.pdf?
I would call them "clocks".
Then what would you do to JesseM's quote to make it satisfactory to you?
 
  • #159
DaleSpam said:
What is the question and what are m, u, and v?

m is the coefficient in the LT often referred to as gamma. v is the speed of the frame moving in the x direction of the stationary frame K. u is the speed of a single clock moving in the + x direction of K. The question is 'what is the time on the single moving clock'?
 
  • #160
harrylin said:
It looks as if my next remark didn't reach:

I think you didn't understand my question.
Section 4 of 1905 envisions a single clock moving along a polygon path wrt a stationary frame K. The clock starts at a point of K and returns to the same point of K. What you have described is the time of the clock wrt the polygon path. What you have not described is the time of the clock wrt the original frame K. This is the time that is required in order to make a valid comparison with the K time at the end of the path.
 
  • #161
JM said:
I think you didn't understand my question.
Section 4 of 1905 envisions a single clock moving along a polygon path wrt a stationary frame K. The clock starts at a point of K and returns to the same point of K. What you have described is the time of the clock wrt the polygon path. What you have not described is the time of the clock wrt the original frame K. This is the time that is required in order to make a valid comparison with the K time at the end of the path.

If the time on the clock at rest wrt the polygon is T and the speed of the second observer is v, then the clock for the observer moving wrt the polygon will show t=T \sqrt{1-(v/c)^2} when the observers are reunited so they can compare clocks.
Does this answer your question?
 
  • #162
JM said:
m is the coefficient in the LT often referred to as gamma. v is the speed of the frame moving in the x direction of the stationary frame K. u is the speed of a single clock moving in the + x direction of K. The question is 'what is the time on the single moving clock'?
For approximately the 100th time I refer you to the formula I posted back in post 36. The time displayed on the clock is:

\tau = \int \sqrt{1-v(t)^2/c^2} dt
So in frame K
\tau = t \sqrt{1-u^2/c^2}+C_1
And in the other frame
\tau = t \sqrt{1-\frac{(u+v)^2}{c^2(1+uv/c^2)^2}}+C_2
 

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