Resultant time dilation from both gravity and motion

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Discussion Overview

The discussion revolves around the resultant time dilation experienced by a frame moving in relation to an observer at infinity while situated in a gravitational well. Participants explore the interplay between gravitational and motion-induced time dilation, examining various expressions and models, including those derived from the Schwarzschild metric. The scope includes theoretical considerations and mathematical reasoning related to general relativity and special relativity.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that the resultant time dilation can be expressed as a sum of motional and gravitational dilations, represented mathematically as t=τ(γ-1g-1).
  • Others argue against the summation approach, suggesting that the correct expression should be derived from the Schwarzschild metric, indicating that the relationship is more complex than a simple sum.
  • One participant mentions that for objects in circular orbits, the total time dilation is a product of gravitational and velocity-based time dilation, while noting that other cases may be more complicated.
  • Another participant discusses the use of Newtonian theory in non-relativistic situations, suggesting that the combined effects of time dilation can be treated as additive fractions based on energy ratios.
  • Several participants engage in clarifying and correcting expressions related to time dilation, particularly focusing on the differences between radial and circular motion, and the implications of using coordinate versus local velocities.
  • One participant asserts a specific equation for time dilation that applies to various motions, emphasizing the need for proper definitions of velocity in the context of local observers.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct expression for time dilation, with multiple competing views and models presented throughout the discussion. Disagreements persist regarding the validity of specific expressions and the interpretation of results derived from the Schwarzschild metric.

Contextual Notes

Limitations include potential misunderstandings of the Schwarzschild metric and the definitions of velocity used in different contexts. Some expressions may depend on specific assumptions about the motion and the gravitational field, which remain unresolved.

  • #121
kev said:
Let's start with this equation for the time dilation ratio:

\frac{{d}\tau}{{d}t}= \sqrt{1-r_s/r} \sqrt{1- \left (\frac{dr/dt}{c(1-r_s/r)} \right)^2 - \left (\frac{r d\theta/dt}{c \sqrt{1-r_s/r} } \right)^2 - \left(\frac{r\sin\theta d\phi/dt}{c\sqrt{1-r_s/r}} \right)^2 }

Much better, how did you manage to get the winning combination after all the false starts?
All you needed to do is to start from the correct Schwarzschild metric and to factor out 1-r_s/r
 
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  • #122
starthaus said:
You are making the same mistakes as JesseM, we are talking about the delay experienced by clocks on the Erath surface due to Earth rotation. What do you think I have been trying to explain to you starting with post 6?
No, we are not talking about clocks on Earth's surface. You were talking about that in response to Dmitry67's post, not the OP by espen180 (you claim Dmitry67's post was originally on this thread and that it was later split, but I'm not even sure you're correct about that--given that you seemed to think Dmitry67's post was always the first one, it's quite possible the two threads were always separate and that you simply got confused and posted on this thread thinking you were still looking at the other thread, I don't remember Dmitry67's post ever being on this thread). The whole debate between you vs. everyone else got started because you claimed there was something dreadfully wrong with kev's derivation, which was meant to deal with the question of time dilation experienced by clocks in arbitrary circular orbits. The set of all valid circular orbits in Schwarzschild spacetime would include orbits with many different orbital planes, just like Pluto and Earth have different orbital planes despite orbiting the same Sun--some of these orbits would be ones where d\theta is equal to 0 (orbits in the \theta = \pi/2 plane), but others would be ones in a different plane where d\theta is not equal to 0. Do you disagree?
 
  • #123
JesseM said:
No, we are not talking about clocks on Earth's surface. You were talking about that in response to Dmitry67's post, not the OP by espen180 (you claim Dmitry67's post was originally on this thread and that it was later split, but I'm not even sure you're correct about that--given that you seemed to think Dmitry67's post was always the first one, it's quite possible the two threads were always separate and that you simply got confused and posted on this thread thinking you were still looking at the other thread, I don't remember Dmitry67's post ever being on this thread). The whole debate between you vs. everyone else got started because you claimed there was something dreadfully wrong with kev's derivation,

Yes, look at the post above , kev finally got the right formula after a lot of false starts. Feel free to peruse all his false starts throughout this thread (posts 97, 112, etc). I am done.
 
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  • #124
starthaus said:
Yes, look at the post above , kev finally got the right formula after a lot of false starts. Feel free to peruse all his false starts throughout this thread. I am done.
I haven't been following the more recent posts between you and kev on this thread so I don't know if there were any "false starts" in his last few equations, but the original derivation I linked to was fine, and I pointed out in post 117 you could get the exactly the same formula from the equation you were using in post 6. If you want to use some minor error in a recent post by him as an excuse to avoid addressing all the flaws and confusions in your own arguments (in particular your own confused criticisms of my posts, not kev's), be my guest.
 
  • #125
starthaus said:
This is wrong. Since you are putting in results by hand again, try deriving it from the basics and you'll find out why.
How about you tell us why instead? Or is this thread destined to exceed 300 posts, too?

Many readers miss out on opportunities to learn due to their understandable unwillingness to sort through 300+ posts of confrontational nonsense that could be avoided by you doing everyone a huge favor by just specifying what you object to and explaining why.

Just try it for once. You might even enjoy being helpful.
 
  • #126
Al68 said:
How about you tell us why instead? Or is this thread destined to exceed 300 posts, too?

These are basic math errors, if you can't see them all by yourself, you should find a different hobby. This does not include your current one :trolling.
Enough said that kev understood his errors.
 
  • #127
starthaus said:
These are basic math errors
If kev made any "basic math errors" in his recent posts to you they are apparently minor ones which don't affect the final equation he derived for circular orbits, as I showed you in post 117 using your own equation to derive it. And of course you have made plenty of minor math errors yourself, like not including the factor of c in post #6.

But never mind, you found a trivial error in someone else's argument, therefore you win the thread! Hooray! (claps very slowly)
 
  • #128
starthaus said:
These are basic math errors, if you can't see them all by yourself, you should find a different hobby. This does not include your current one :trolling.
You keep accusing me of trolling, but you are the one who keeps destroying threads, making them completely worthless for most readers, with your shenanigans.

Back to the point, I'll take that as a NO, you either can't or won't explain (in any rational way) your claims.
 
  • #129
Al68 said:
You keep accusing me of trolling, but you are the one who keeps destroying threads, making them completely worthless for most readers, with your shenanigans.

Back to the point, I'll take that as a NO, you either can't or won't explain (in any rational way) your claims.
I help people that are sincere, I don't help trolls. You contributted noothing to this thread.
If you can't spot the errors, you have no business (other than trolling) in this thread. But, I'll give you a hint, the errors have to do with the wrong variables in the expression.Compare against the correct final expression.
 
  • #130
starthaus said:
If you can't spot the errors, you have no business (other than trolling) in this thread.
LOL. Yep, that's why you can't substantiate your claims: because if I can't "spot the errors" I have "no business in this thread".

Is that also why you're so rude and condescending?

Seriously, dude, it might feel good to say something constructive and useful in your posts.
 
  • #131
Al68 said:
LOL. Yep, that's why you can't substantiate your claims: because if I can't "spot the errors" I have "no business in this thread".

Finally. You understand.
Is that also why you're so rude and condescending?

Standard response to your trolling <shrug>
Seriously, dude, it might feel good to say something constructive and useful in your posts.
So, you are unable to see the wrong variables. ...
I did, I put up quite a few solutions but you can only see the stuff that makes you tick, err troll.
 
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  • #132
starthaus said:
Al68 said:
LOL. Yep, that's why you can't substantiate your claims: because if I can't "spot the errors" I have "no business in this thread".

Is that also why you're so rude and condescending?

Seriously, dude, it might feel good to say something constructive and useful in your posts.
I did, I put up quite a few solutions but you can only see the stuff that makes you tick, err troll.
LOL. I was responding to your last post which contained nothing useful or constructive.
 
  • #133
Al68 said:
LOL. I was responding to your last post which contained nothing useful or constructive.

Try reading the other posts, the ones that contain formulas. Can you read formulas?
 
  • #134
starthaus said:
Try reading the other posts, the ones that contain formulas. Can you read formulas?
I read them. They weren't the ones I was referring to. Was that not obvious? Can you read English?
 
  • #135
Since we are at the point in this thread where people are no longer discussing the topic, but rather who is a troll and who isn't, I take it that the topic is no longer interesting. So this thread is done.

Note that if you think someone is trolling, DO NOT FEED THE TROLL!. Please use the REPORT button and report the post/thread to the Mentors.

Zz.
 

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