# CONCEPT OF RELATIVE MOTION- How Can We Say That Planets revolve around Sun?

Discussion in 'Physics & Math' started by ash64449, Sep 14, 2013.

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1. ### TachBannedBanned

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You are no position to tell me how GPs works since you have no clue.

False. You don't know what you are talking about

As usual , you don't know what you are talking about.

As usual, you have no clue what you are talking about.

3. ### AlphaNumericFully ionizedRegistered Senior Member

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Someone mentioning Lorentz transformations does not mean the effect is strictly due to special relativity. General relativity includes Lorentz transforms as a local symmetry through the use of vierbeins and the spin connection, which defines how to track Lorentzian effects when moving with objects along geodesics.

But you wouldn't know that because you don't actually know any relativity, you can only misinterpret the wordy descriptions other have written. That is the source of ALL of your claimed problems with relativity, it is not relativity which has the problem but it is your understanding of it (or lack there of).

5. ### chingluValued Senior Member

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I could not agree with you more.

Yet, if you took the time to read that chapter, you would have discovered he was writing about strictly the sagnac effect leaving out all others.

Now, are you claiming Ashby is wrong?

7. ### chingluValued Senior Member

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Does t = d/c hold true in both ECEF and ECI, yes or no.

Does SR claim t = d/c is true in all frames.

8. ### TachBannedBanned

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you are unable to formulate any coherent and/or correct question

Light speed is c in both ECEF and in ECI. You need to get that.

9. ### TachBannedBanned

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Nope, just that you are unable to understand what Ashby is writing. <shrug>

10. ### chingluValued Senior Member

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Relativity claims t = d/c is true in all frames.

Is this true or false in both ECEF and ECI.

11. ### TachBannedBanned

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Relativity claims no such thing, I already corrected you on this issue. It claims that the speed of light is the same in all frames, both inertial and accelerated. Your childish t=d/c is meaningless.

I am not your servant, so you know what you do with your orders.

12. ### OnlyMeValued Senior Member

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chinglu, (taking some licence) SR asserts that the laws of physics hold as true for all inertial frames of reference, as "The Principle of Relativity" and raises it to the level of a postulate.

The ECEF and ECI frames are not inertial relative to one another.

An ECI frame can be treated as an inertial frame within which the earth is centered, but the earth in that case which spins on its axis within that frame is not itself inertial... And both, the ECI frame and the earth, if viewed from some more distant point are moving (orbiting) the sun and are thus neither from that perspective inertial.

An ECEF frame sets the earth as an inertial object at its center and the coordinate system rotates around a fixed point at the Earth's center of mass, such that all points on the surface of the earth have fixed coordinates.

These are two different coordinate systems. Each could be considered as inertial from some frame of reference, but they are not both inertial from any one frame of reference... And they both exist within the context of general relativity, spacetime and gravity, where except within suficiently local limits, SR does not apply.

They are not equivalent.., and yet yes one can transform coordinates between the two. But think it through, an object at rest in one frame will be accelerating in the other and visa versa. Think about it. Besides objects are inertial or not, coordinate systems are abstract systems used to define and describe the relationships and motions of objects. They can be inertial only to the extent they are attached to an object that is inertial, or to the extent they describe an inertial relationship between two or more objects.

13. ### chingluValued Senior Member

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Well, that is not true that ECEF and ECI are not inertial frames. ECI is when the known GR effects are excluded.

And, Neil Ashby claimed the relativity of simultaneity with co-moving frames with the earth's rotation for ECEF.

But, in fact, you can make ECEF SR also.

1) Exclude the GR effects.
2) While the GPS satellite signal travels, time elapses about .6 seconds if I remember correctly.
3) Again, if I remember correctly, that means the GPS unit moves down .4 cm during that time based on the earth's rotation.
4) So, uniformly raise the unit .4 cm while the signal travels and you have a SR frame for ECEF.

However, under these condition, it is false that t = d/c for both ECI and ECEF as required by SR.

Why is that?

14. ### chingluValued Senior Member

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2.Any ray of light moves in the “stationary” system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body.

Hence, c = light path / time interval.

where time interval is to be taken in the sense of the definition in § 1.

http://www.fourmilab.ch/etexts/einstein/specrel/www/

Yes, I am afraid t=d/c is true for SR.

Now what?

15. ### TachBannedBanned

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why are you afraid?

You go to school and you learn. Instead of wasting your life trolling.

16. ### chingluValued Senior Member

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You claimed t=d/c is false for SR and I provided proof that Einstein made the claim t=d/c is true.

Are you suggesting Einstein is wrong?

17. ### TachBannedBanned

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No, I pointed out that your grasp is childish. Still is.

Nope, just that you are trolling , as usual .<shrug>

18. ### chingluValued Senior Member

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OK if you are now claiming t=d/c, then please explain when t=d/c is false in the ECEF frame.

19. ### TachBannedBanned

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What gives you the idea that it is "false" in ECEF? Hint: It isn't.

20. ### PeteIt's not rocket surgeryRegistered Senior Member

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Correct.

Correct

Not quite correct.

The speed of light in vaccum is c in any inertial reference frame, as OnlyMe points out.
The ECEF is not an inertial frame. No, you can't make it inertial. Yes, you can use SR to describe it if you know what you're doing, but SR won't say that light moves at c in that frame.
Yes, Dr Ashby is correct.

Are you saying that we should reach different conclusions depending on whether we work in the ECEF or the ECI?

21. ### wellwisherBannedBanned

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The reason we know the planets revolve around the sun is due to an energy balance, not due to relative motion. The earth used to be the center of the universe due to the assumption of relative motion, since all references are the same and thereby made relative to the earth. This was changed by energy conservation and an energy balance.

I am not sure why science has gone pre-science with this notion of relative motion? Now we need dark matter and dark energy to close the energy balance. The old earth center approach used a similar thing, but with gods appearing out of the dark matter and energy, with the ability to influence local matter using dark energy. For example. since dark energy causes the expansion against gravity, the gods could use dark energy to defy gravity. This just shows how much was recycled from the past when the center was relative and they used the earth.

22. ### chingluValued Senior Member

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ECEF is an inertial frame if you exclude GR effects, almost.

Then, while the signal travels, the GPS unit rotates down by .4 cm. So, raise the unit .4 cm uniformly during signal travel.

You would then have an inertial frame.

Ashby supports this conclusion by claiming sagnac is an application of the relativity of simultaneity using frames co-moving with the earth's rotation.

But, that also means t=d/c does not hold in the collection of co-moving frames or the one smoothed out by raising the unit .4 cm.

23. ### PeteIt's not rocket surgeryRegistered Senior Member

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The ECEF clocks are not synchronized in that inertial frame.

No, that's not correct. Using clocks that are synchronized in a given comoving frame gives a constant speed of light.