# Gravity slows down time.

Discussion in 'Pseudoscience' started by chinglu, Aug 18, 2013.

1. ### chingluValued Senior Member

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1,637
Assume two observers are at the same place on the earth.

One climbs a very high pole and remains there for a very long time.

Eventually, the observer climbs down.

That high observer is older since time went faster for him/her.

The land based observer is younger.

So, the high observer says the time on his clock is 12:00 am and the land based observer claims time on his clock is 12:00pm.

That means the high observer claims the earth is in a different rotational position from the land based observer, which is a contradiction.

Can anyone resolve this?

3. ### AlexGLike nailing Jello to a treeValued Senior Member

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The high observer says his clock reads 12:00, but he observes the lower clock as reading slower. The rotational position of the earth will be based on the lower clock reading, since that's the frame of reference the earth occupied.

No contradiction, just a matter of the relativity of simultaneity.

Of course, since you deny relativity, it's not something you'll ever understand.

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7. ### MarkM125Registered Senior Member

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First, we need to define simultaneity. For a particular inertial frame, spacetime can be foliated into a series of hypersurfaces defined by constant time coordinate. Two events lying on the same "plane of simultaneity" are then deemed simultaneous. Of course, the time coordinate varies in between inertial frames, and so does the notion of simultaneous events.

This is the special relativistic description. In GR, the issue becomes more complicated. From MTW:

"In Newtonian theory or special relativity, one chooses hypersurfaces of constant time. But in dynamic regions of curved spacetime, no naturally preferred time coordinate exists. This situation forces one to make a totally arbitrary choice of hypersurfaces to use in visualizing the time-development of geometry, and to keep in mind how very arbitrary that choice was."

So, for two different observers in GR, we can't assign any notion of simultaneity - since we can't usually define a global frame of reference.

However, in local frames, GR reduces to SR, and so we obtain the usual description of simultaneity. Over short enough periods of time and intervals of space, or in weak fields, spacetime is roughly flat.

So, the answer to the original question - comparing the observations taken from two different points in curved spacetime yields no meaningful results. And thus there is no contradiction.

Note that this certainly does not mean we can't compare observations made at different points on Earth - its gravitational field is comparatively weak, and the effect of gravitational time dilation itself is not noticeable. However, the hypothetical posed is not even slightly local - and we can't compare those measurements.

8. ### Russ_WattersNot a Trump supporter...Valued Senior Member

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There is no contradiction: they see earth spinning at different rates.

9. ### AlphaNumericFully ionizedRegistered Senior Member

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There is, as yet, nothing to resolve as you have just failed to go into the details. This is what you always do, you do not know the equations and so instead you hear qualitative superficial explanations of various aspects of relativity, combine them together in a way you don't understand and declare it a contradiction.

If you claim there is a contradiction then please go through the explicit calculations involving a rotating system in general relativity which lead to a contradiction, such as 1=2. Your wordy description doesn't account for how distances and times are modified by the motion and position of the person in question. You're only showing that you have no experience dealing with multiple frames within a GR context. The modifications in the points of view due to gravitational and kinetic effects result in the two observers seeing things like the size of the Earth, its orbit around the Sun, the rate of rotation and the rate of orbit all slightly differently. At the end of it, when they meet up their clocks will disagree and yet it will be completely consistent with their own observations.

If you cannot provide the detailed calculations of your claim or at least show you are familiar with the details then I'm going to move this to pseudo-science. The thread as it currently stands, if it were authored by another member, is fine but we all know which way this is heading, you make assertions you cannot back up, your errors are explained to you and you refuse to listen because you don't understand. You obviously don't put much qualitative thought to anything before posting because if a contradiction in GR were that obvious it would have been seen long ago. Different observers with precise clocks moving up and down in the Earth's gravitational field is exactly what the GPS network does, as they have a small but non-zero eccentricity, meaning their orbital distance varies.

Given the fact GPS are a demonstrable reality and use GR calculations of the kind pertaining to your question the conclusion is that you're mistaken about GR. As such provide details or you're off to pseudo science.

10. ### AlphaNumericFully ionizedRegistered Senior Member

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Off to pseudo-science as I promised, all because it is yet another thread by chinglu where he makes an unjustified claim about a domain of science he doesn't understand.

Next time you get another infraction for trolling.

11. ### chingluValued Senior Member

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Let's see. in GR, closer to earth implies slower clocks.

Now, some claim ROS as the cause. ROS only comes into play in high orbits if it is in fact true.

This is verified by GPS.

Anyway, I asked if it could be resolved in what appeared to be a contradiction.

Maybe I am wrong.

Can you resolve it yes or no.

Keep in mind, all time clocks are supposed to sync with the earth's rotation and orbit.

If they become out of sync with these items, then they do not keep time correctly for some reason.

Anyway, it seems you have all the answers and I asked the question.

Does the high user climb down with a clock with more time on it than the low user yes or no.

Further does time dilation on the earth mean the two clocks conclude a different rotational position of the earth yes or no.

Last edited: Aug 24, 2013
12. ### chingluValued Senior Member

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Why do you conclude this specifically?

13. ### chingluValued Senior Member

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GR claims the high clock and low clock beat differently. GPS verifies this.

So, when the two are re-united, how is it not a contradiction to the earth's rotational position?

14. ### chingluValued Senior Member

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Assume I had clocks that would speed up in heat.

Then, the clocks are close but one is heated.

After some time period, I bring them together and the heated one shows a future time compared to the non-heated one.

Would I be so stupid as to claim the one holding the heated clock really experienced more time?

No, we would simply look at the sun's position at the same place and say the heated clock was wrong.

Likewise, if gravity or speed affects a clock and I bring it back to an earth clock, would one clock claim the earth is in a different position from the other clock?

Of course not, that would be completely stupid. We would claim one clock became out of sync with the earth's orbit and that would be a clock measuring error, not a user time change event.

So, SR wants the casual user to claim 2 observers in different motion experience different times.

Yet, bring them back to earth and that forces the sun to be in 2 different positions, which is a contradiction.

That is SR.

15. ### AlphaNumericFully ionizedRegistered Senior Member

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So in answer to my question of whether or not you can do the necessary relativity calculations your answer is no. Why not just admit that rather than beating around the bush? You claim a contradiction but you cannot do the calculations to demonstratd it. Both you and us have seen how you do NOT have good intuition for relativity, given all previous threads of yours like this have always ended with you being shown to be wrong. Now we have another example of you making claims about relativity based on your gut and devoid of mathematics.

You demonstrably have no sound understanding of relativity, neither quantitative or qualitative, yet you arr always so sure youre right THIS time. Until you're refuted again.

Go on, one more chance. Can you do the maths or not?

16. ### chingluValued Senior Member

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What is this all about AN. Sure I can do the math.

And, I am not refuted. Are you claiming that a clock with a distance from the earth up high beats the same as a clock on the earth?

17. ### AlphaNumericFully ionizedRegistered Senior Member

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If you could do the maths of the scenario you'd not be claiming there is a contradiction. And you would also not be dishonest anc misrepresentation me as saying the passage of time is unaffected. Yes, clocks in weaker gravitational fields, ie higher orbits, do tick faster. The mistake of yours, which you'd see if you could do the maths, is that such a fact does not lead to contradictions in physical models. If it were that trivial to break GR it would have been done long ago.

So the issue is still whether or not you know how to mathematically describe the scenario in your complaint. You have shown you cannot do it for special relativity for problems little more than homework exercises to anyone learning special relativity in university, I doubt you can handle general relativity.

So go on, show gr necessarily leads to a conflict. Show it algebraically and properly. Just assert it again, misrepresentating me, and I'll pit this down as another bit of ignorant trolling from someone too dishonest and stupid to learn relativity, yet constantly whines about it. Ball's in your court, provide the maths so a viable discussion can be had or don't and be dismissed as a hack.

18. ### chingluValued Senior Member

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Here is an IOP article that verifies time is slowed the closer you get to the earth. So, a higher observer beats faster than an earth based observer.

http://physicsworld.com/cws/article/news/2010/feb/17/gravitys-effect-on-time-confirmed

Now, bring the two together very slowly after some long period of time.

Then, the high observer says the earth's position is different from the ground observer, which is a contradiction.

19. ### ZenoRegistered Senior Member

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I've thought of the same thing as you are thinking of chinglu. If somebody is at the top of a tall building and somebody is at the bottom, wouldn't the person at the top eventually view more sunrises and sunsets than the person at the bottom because time is passing more quickly for them? If somebody at the top is dropping pennies at a rate of one per second to somebody at the bottom, then wouldn't there be a build up of pennies towards infinity in-between the person at the top and the person at the bottom?

20. ### AlphaNumericFully ionizedRegistered Senior Member

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Which no one has any issue with.

Why don't you show the relevant worldline calculations and indeed show a contradiction. Simply asserting it is no more a justification in your previous assertions about special relativity, all of which turned out to be invalid when actual calculations were done by people who can do them, ie not you.

Please do the actual GR calculations of the motion of 2 different observers and show the contradiction. I've banned you for 1 week due to trolling elsewhere so you have plenty of time to do the calculations if you can really do them. Which we all know you cannot.

21. ### Janus58Valued Senior Member

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You're confusing local time(measured by a co-located clock) with astronomical time(measured by watching the passage of the Sun). Your assuming that both observers measure 24 hrs between per rotation of the Earth as measured by their local clock. What happens instead is that the observer on top of the building sees the same number of sunrises and sunsets, he just measures a longer time between them with his clock.
Here you seem to be assuming that the person at the bottom measures the pennies as arriving at 1 per sec. He wouldn't, he would measure them arriving at interval of less than a sec apart. In other words, according the person at the top it would take 1 hour to drop 3600 pennies, but for the person at the bottom, those pennies all arrive less than 1 hr apart. Both count the same number of pennies dropped, they just disagree as to the rate at which they are dropped according to their own clock.

22. ### LakonValued Senior Member

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Bolded .. good clear, math free and understandable explanation. Thanks. Staying in that vein, can you say WHY time would pass faster for the guy at the top of the building (I have a good idea .. I think .. but I'd just like to hear it from you in similar terms).

23. ### ZenoRegistered Senior Member

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Then, how is this situation different than one where there is no time dilation and the clock at the top is just running at different rate than the clock at the bottom?

Again, how is this situation different than one where there is no time dilation and the clock at the top is just running at different rate than the clock at the bottom?