What Physically Causes Time to Progress and Vary in Different Places?

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Discussion Overview

The discussion revolves around the nature of time, its progression, and its variability in different contexts, particularly in relation to special relativity and concepts such as the Twin Paradox. Participants explore theoretical and conceptual questions about the physical basis of time, its relationship with velocity and entropy, and the implications of these ideas in physics.

Discussion Character

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

Main Points Raised

  • Some participants express confusion about the fundamental nature of time and its progression, noting that it appears to depend on an observer's velocity relative to the speed of light.
  • Others argue that the speed of light is a constant in any inertial frame, but the reasons behind this remain unclear.
  • One participant suggests that time may not progress at all, proposing that the perception of time's passage is an illusion linked to increasing entropy.
  • Another viewpoint posits that time could be viewed as a geometric dimension, similar to spatial dimensions, which may help explain its dependence on the observer's perspective.
  • Some participants challenge the idea that entropy is the cause of time, suggesting instead that it might be an effect of time.
  • There is interest in exploring geometric interpretations of time, akin to those used in general relativity, with references to alternative theories such as Self Creation Cosmology.
  • Several participants express skepticism about the notion of time's progression and its implications for measuring change in physical systems.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of time or its progression. There are multiple competing views, particularly regarding the relationship between time and entropy, as well as the interpretation of time in relation to geometry and physics.

Contextual Notes

The discussion highlights limitations in understanding the fundamental nature of time, including unresolved questions about its physical causes and the implications of various theoretical frameworks. Some arguments rely on assumptions that may not be universally accepted.

Who May Find This Useful

This discussion may be of interest to individuals exploring the philosophical and theoretical aspects of time in physics, particularly those curious about relativity, entropy, and geometric interpretations of physical concepts.

  • #31
Don't you think that it is possible, in principle, to arrange such initial conditions that entropy decreases with (the coordinate) time in a small region of the universe?
 
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  • #32
Don't you think that it is possible, in principle, to arrange such initial conditions that entropy decreases with (the coordinate) time in a small region of the universe?

If you take the belief that time is a result of entropy changes (B1) then yes. But the probability is too small. And in a really, really small bit of the universe, if things momentarily, for a very, very short moment of time, go the other way, does it make a difference?

I have a question too: Assuming the above belief B1 is true, if the universe started off (started off doesn't even make sense in this context, but bear with me) in a state of high entropy, then there would be no noticeable evolution of time. Am I correct?
 
  • #33
Entropy, anyone?

Well, any serious discussion of entropy on cosmological scales raises all kinds of issues, not least of which is that there are many things one might mean by "entropy". However, a good place to begin would be the very readable book by Lawrence Sklar, Space, Time, and Spacetime. See in particular the discussion of ergodic theory. Then see Poincare and Kac recurrence theorems, plus the relationship between measure-theoretic and topological entropy in Walters, Introduction to Ergodic Theory. Note that measure-theoretic entropy is related to a purely combinatorial notion, Boltzmann entropy, which can be interpreted in terms of group actions... and so on and on and on. There are many distinct but interesting notions of entropy, which tend to bear specific relationships to each other, and ferreting these out is a fascinating task for mathematicians.
 
  • #34
Demystifier said:
Don't you think that it is possible, in principle, to arrange such initial conditions that entropy decreases with (the coordinate) time in a small region of the universe?

Yes, you are the result.
 
  • #35
masudr said:
I have a question too: Assuming the above belief B1 is true, if the universe started off (started off doesn't even make sense in this context, but bear with me) in a state of high entropy, then there would be no noticeable evolution of time. Am I correct?
Yes you are.
 
  • #36
quantum123 said:
Yes, you are the result.
Thanks, you too. :smile:
 

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