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I was wondering how time propagates through the spacetime and how its pace is slowed down by effect of gravity? Without understanding the propagation of time , I found it impossible to understand the slowing down of time? It would be much better and highly appreciated if it can be explained with an example.


marked as duplicate by user108787, knzhou, Ruslan, user36790, heather Oct 3 '16 at 17:19

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  • $\begingroup$ This gives a short account of the development of relativity: space.com/17661-theory-general-relativity.html and this link, the best answer is at the bottom of a long page physics.stackexchange.com/q/82767 but your question How does time propagate? is more a philosophical than a physics based question. $\endgroup$ – user108787 Oct 3 '16 at 15:51
  • $\begingroup$ I'm voting to close this question as off-topic because the the concept of the propagation of time is more a philosophical question than a physics based one. $\endgroup$ – user108787 Oct 3 '16 at 16:04
  • $\begingroup$ One thing to remember is that, while we talk about "time slowing down," what we actually mean is "all empirical measurements we take are consistent with time slowing down according to these particular equations." The effects measured are so consistent that we tend to drop the layer of indirection, and just make ontological claims about time itself. $\endgroup$ – Cort Ammon Oct 3 '16 at 16:05

Personally i feel like using the word "time" here is a bit confusing. I prefer to think of it as the rate at which systems evolve. Now i'm sure some people will disagree but the concept of time being defined by this evolution, is more of a philosophical question if you ask me. An analogy i've found helpful is thinking that the universe "updates" itself at the speed of light. Whether that has any grounding in reality, i'm not really sure.

So to answer your question, the faster something moves, the slower it physically evolves. For example, an atomic clock uses the transition of energy levels of the caesium atom as it's point of reference because for a particular inertial frame, the interval is always the same. Relativity tells us that the faster that atom moves through space, the slower that transition becomes. With that in mind, gravity accelerates mass. Acceleration changes inertial frames and with it changes the rate at which a system evolves.

  • $\begingroup$ @CountTo10 no, the statement is quite fine: it's made from observer's frame, where indeed the object moving fast does evolve slower. $\endgroup$ – Ruslan Oct 3 '16 at 16:23
  • $\begingroup$ If take a glass of packed still and clean water and keep it for 1 crore years, how much would it evolve? $\endgroup$ – Anubhav Goel Oct 3 '16 at 16:35
  • $\begingroup$ I'm not sure what "crore" means but the water will evolve as much as it would evolve for a particular inertial frame (momentum if you will) $\endgroup$ – Yogi DMT Oct 3 '16 at 17:23
  • $\begingroup$ Crore means 10million. Will $H_2O$ evolve into aliens? $\endgroup$ – Anubhav Goel Oct 11 '16 at 3:22
  • $\begingroup$ It would evolve as much as water would over 10 million years. Idk if that's long enough for it to turn into aliens lol $\endgroup$ – Yogi DMT Oct 11 '16 at 12:43

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