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

[brucep]

Hi OnlyMe,
I don't know the details of how actual UTC standard clocks are synchronized with each other in practice, so this post is purely theory-based.
There is a theoretical problem with synchronizing clocks in a rotating reference frame.

Imagine a set of clocks spread around the equator. Starting from a master clock, each clock is synchronized with its neighbor using Einstein synchronization or equivalent. When we get back to the last clock, it will be out of synch with the master clock (its neighbor) by about 200 nanoseconds.

So, if we are to have ECEF clocks meaningfully synchronized to high precision without a discontinuity at some longitude, then whenever two ECEF clocks at different longitudes are synchronized, the synchronization has to be artificially adjusted so that they are synchronized in the ECI frame.


Chinglu's argument is essentially that:
1 - We should be able to use two close-together ECEF clocks to make measurements in their momentary comoving inertial reference frame
2 - Doing so would result in different speeds for East to West light and West to East light (by about 900m/s)

If these two points were correct, then this would obviously mean a violation of SR.

The second point is correct, but the first point is not. The side-by-side ECEF clocks are not synchronized in the comoving inertial reference frame, but in the ECI.

No, kidding? You mean if he knew how to do the clock synchronization he wouldn't make stupid assertions about relativity theory?

 

[chinglu]

No, kidding? You mean if he knew how to do the clock synchronization he wouldn't make stupid assertions about relativity theory?

SR claims clock synchronization is valid in any frame.

Is clock synchronization valid in ECEF sans GR effects?

 

[chinglu]

Where does it say you can't?

It says that the clock sync method holds true in any frame.

Do you disagree?

 

[chinglu]

Hi OnlyMe,
I don't know the details of how actual UTC standard clocks are synchronized with each other in practice, so this post is purely theory-based.
There is a theoretical problem with synchronizing clocks in a rotating reference frame.

Imagine a set of clocks spread around the equator. Starting from a master clock, each clock is synchronized with its neighbor using Einstein synchronization or equivalent. When we get back to the last clock, it will be out of synch with the master clock (its neighbor) by about 200 nanoseconds.

So, if we are to have ECEF clocks meaningfully synchronized to high precision without a discontinuity at some longitude, then whenever two ECEF clocks at different longitudes are synchronized, the synchronization has to be artificially adjusted so that they are synchronized in the ECI frame.


Chinglu's argument is essentially that:
1 - We should be able to use two close-together ECEF clocks to make measurements in their momentary comoving inertial reference frame
2 - Doing so would result in different speeds for East to West light and West to East light (by about 900m/s)

If these two points were correct, then this would obviously mean a violation of SR.

The second point is correct, but the first point is not. The side-by-side ECEF clocks are not synchronized in the comoving inertial reference frame, but in the ECI.

"The second point is correct, but the first point is not. The side-by-side ECEF clocks are not synchronized in the comoving inertial reference frame, but in the ECI"

Please show me in SR where clocks in one frame are supposed to synchronize in another fame.

 

[Pete]

It says that the clock sync method holds true in any frame.

No, only in any inertial frame. You can't consistently use einstein synchronization in a rotating reference frame, as I explained in the previous post:

Imagine a set of clocks spread around the equator. Starting from a master clock, each clock is synchronized with its neighbor using Einstein synchronization or equivalent. When we get back to the last clock, it will be out of synch with the master clock (its neighbor) by about 200 nanoseconds.​

"The second point is correct, but the first point is not. The side-by-side ECEF clocks are not synchronized in the comoving inertial reference frame, but in the ECI"

Please show me in SR where clocks in one frame are supposed to synchronize in another fame.

Not sure what you're thinking. The question here isn't whether clocks are "suppose to" synchronize in another frame, but whether we can have clocks at rest in one frame which are synchronized in a different frame.
And yes, we certainly can. The choice of ECEF clock synchronization is a practical choice. SR doesn't force us to use einstein synchronization.

If you have two clocks side by side, what's stopping you from adjusting the time (and rate, if necessary) on one of them so that they are synchronized in another frame?


SR predicts the measurements that would be made with rulers and einstein synchronized clocks at rest in inertial reference frames. Do you agree?

So, when we define a reference frame in which the clocks are not einstein-synchronized (like the ECEF), you can't naively apply simple SR any more. You have to make specific adjustments, such as the Sagnac effect.

 

[eram]

Evolution denialists are mainly motivated by their religious beliefs.

But what about relativity and climate change denialists? I wonder why there are so many of them...

 

[RJBeery]

Evolution denialists are mainly motivated by their religious beliefs.

But what about relativity and climate change denialists? I wonder why there are so many of them...

I sympathize with relativity denialists because it's so unintuitive. Regarding climate change I'll let you in on a secret: it isn't actually about climate change for many people on either side. Rather it's about advancing or defending underlying political agendas. Debating the science itself us a sideshow.

 

[chinglu]

No, only in any inertial frame. You can't consistently use einstein synchronization in a rotating reference frame, as I explained in the previous post:

Imagine a set of clocks spread around the equator. Starting from a master clock, each clock is synchronized with its neighbor using Einstein synchronization or equivalent. When we get back to the last clock, it will be out of synch with the master clock (its neighbor) by about 200 nanoseconds.​

Not sure what you're thinking. The question here isn't whether clocks are "suppose to" synchronize in another frame, but whether we can have clocks at rest in one frame which are synchronized in a different frame.
And yes, we certainly can. The choice of ECEF clock synchronization is a practical choice. SR doesn't force us to use einstein synchronization.

If you have two clocks side by side, what's stopping you from adjusting the time (and rate, if necessary) on one of them so that they are synchronized in another frame?


SR predicts the measurements that would be made with rulers and einstein synchronized clocks at rest in inertial reference frames. Do you agree?

So, when we define a reference frame in which the clocks are not einstein-synchronized (like the ECEF), you can't naively apply simple SR any more. You have to make specific adjustments, such as the Sagnac effect.

None of this is SR.

SR claims clocks can sync in their own frame. You cannot Einstein sync in ECEF sans GR, That is the problem.

 

[arfa brane]

SR claims clocks can sync in their own frame. You cannot Einstein sync in ECEF sans GR, That is the problem.

Inaccurate. To synchronise clocks, there has to be at least two of them. Einstein synchronisation is only relevant in rest frames.
The problem is that you don't seem to understand this.

No surprises there.

 

[chinglu]

Inaccurate. To synchronise clocks, there has to be at least two of them. Einstein synchronisation is only relevant in rest frames.
The problem is that you don't seem to understand this.

No surprises there.

So, are you claiming that ECI is a rest frame and ECEF is not a rest frame?

Can you show me this can happen under SR with supporting documentation?

Thanks

 

[brucep]

None of this is SR.

SR claims clocks can sync in their own frame. You cannot Einstein sync in ECEF sans GR, That is the problem.

You're just making stupid assertions and claiming they have some scientific value. You don't want to understand corrections to your stupid world view so you should quit asking for them in this forum. Alphanumeric told you to put a cork in it. Hopefully he'll do it for you.

 

[brucep]

You're just making stupid assertions and claiming they have some scientific value. You don't want to understand corrections to your stupid world view so you should quit asking for them in this forum. Alphanumeric told you to put a cork in it. Hopefully he'll do it for you.

Deleted.

 

[chinglu]

You're just making stupid assertions and claiming they have some scientific value. You don't want to understand corrections to your stupid world view so you should quit asking for them in this forum. Alphanumeric told you to put a cork in it. Hopefully he'll do it for you.

I assume you can back up your claims by documentation.

Let's see it.

Prove both ECI and ECEF are both SR rest frames. Make sure you refer to the original SR document to support your assertions.

Have a nice day.

 

[OnlyMe]

I assume you can back up your claims by documentation.

Let's see it.

Prove both ECI and ECEF are both SR rest frames. Make sure you refer to the original SR document to support your assertions.

Have a nice day.

Neither, is a SR rest frame in general. They both are centered at the Earth's center of mass and the earth is in orbit around the sun. That means by virtue of their solar orbits they are both accelerating frames.

As mentioned in the Wiki article earlier referenced, and ECI frame could be considered an inertial frame when compared to an ECEF frame... But that is not the same as saying it is a rest frame.

All of our laboratory experiments, that is experiments based on lab coordinate systems are modified ECEF frames. The 0,0,0 coordinates of a lab frame here on earth are equal to some x,y,z coordinate in an ECEF frame. In the lab and for the purposes of experiments conducted in the lab that modified frame can be considered inertial.., even though it is rotating with the earth and orbiting the sun.

It does not matter which frame you chose once you attempt to use it to describe the orbits of satellites, as in the GPS system you mentioned earlier, they are neither one any longer inertial within the context of SR... And you can not exclude gravity and GR effects.

Chinglu, we live in a universe that is dominated by gravity. SR is valid only in a weak (GR) field limit, and where the distances and times involved are small enough that the GR affects are negligible... It was perhaps inaccurate to say, "SR is valid only", it would be more accurate to say, that in the grander scheme of things, the affects of GR dominates.

Any way there is no rest frame, and either one can be thought of as inertial depending on scale and application......,

 

[Pete]

None of this is SR.

Prove it.

SR claims clocks can sync in their own frame.

SR says that clocks at rest in rotating reference frame such as the ECEF can't consistently synch using Einstein synchronization.

You cannot Einstein sync in ECEF sans GR, That is the problem.

Not sure what you mean, or why you think it's relevant. The problem is that you claim that SR says that the speed of light should be the same in all directions in the ECEF, but you can't prove this claim (because it's wrong).

I assume you can back up your claims by documentation.

Let's see it.

Prove both ECI and ECEF are both SR rest frames. Make sure you refer to the original SR document to support your assertions.

Have a nice day.

Chinglu, your argument is unclear.
Can you explain exactly what you mean by "SR rest frame"?
Are you now arguing that the ECI or the ECEF or both are not SR rest frames?

Because before, it seemed that you were claiming that the ECEF is an SR rest frame, and that SR says that the speed of light in the ECEF should be the same in all directions.

 

[chinglu]

Neither, is a SR rest frame in general. They both are centered at the Earth's center of mass and the earth is in orbit around the sun. That means by virtue of their solar orbits they are both accelerating frames.

As mentioned in the Wiki article earlier referenced, and ECI frame could be considered an inertial frame when compared to an ECEF frame... But that is not the same as saying it is a rest frame.

All of our laboratory experiments, that is experiments based on lab coordinate systems are modified ECEF frames. The 0,0,0 coordinates of a lab frame here on earth are equal to some x,y,z coordinate in an ECEF frame. In the lab and for the purposes of experiments conducted in the lab that modified frame can be considered inertial.., even though it is rotating with the earth and orbiting the sun.

It does not matter which frame you chose once you attempt to use it to describe the orbits of satellites, as in the GPS system you mentioned earlier, they are neither one any longer inertial within the context of SR... And you can not exclude gravity and GR effects.

Chinglu, we live in a universe that is dominated by gravity. SR is valid only in a weak (GR) field limit, and where the distances and times involved are small enough that the GR affects are negligible... It was perhaps inaccurate to say, "SR is valid only", it would be more accurate to say, that in the grander scheme of things, the affects of GR dominates.

Any way there is no rest frame, and either one can be thought of as inertial depending on scale and application......,

I have been through the GR argument over and over in this thread.

GR effects in GPS can be accounted for and cancelled leaving only SR.

Read back a few pages to understand the posts.

 

[chinglu]

Prove it.


SR says that clocks at rest in rotating reference frame such as the ECEF can't consistently synch using Einstein synchronization.


Not sure what you mean, or why you think it's relevant. The problem is that you claim that SR says that the speed of light should be the same in all directions in the ECEF, but you can't prove this claim (because it's wrong).



Chinglu, your argument is unclear.
Can you explain exactly what you mean by "SR rest frame"?
Are you now arguing that the ECI or the ECEF or both are not SR rest frames?

Because before, it seemed that you were claiming that the ECEF is an SR rest frame, and that SR says that the speed of light in the ECEF should be the same in all directions.

1) The "proof it" part is the fact that your claim is already answered in this thread.

Ashby claimed there is a set of co-moving frames with ECEF during signal transport. He then said each of these frames is an implementations of the relativity of simultaneity of ECEF co-moving to ECI. I indicated that the GPS unit moves down .4 cm during signal transport. Hence, move the unit up uniformly with the earth's rotation during signal and sans GR, you have an SR frame.

So, Ashby has already claimed these frames are SR ROS. So, if one can smooth them out of the rotation, then they are SR frames.

And, under these conditions, ECI is the preferred frame. Further, you cannot Einstein sync in this virtual SR frame because the of the Sagnac effect.

Hence, this is not SR since you can Einstein sync in ECEF using the logic above.

2) And, if you eliminate GR effects as is done in the GPS article I posted by Ashby and you raise the unit .4 cm during signal transport, then SR does not say you cannot sync under this condition since it is an SR frame.

In short, GR effects can be eliminated or GPS does not work.

Next, you can move the unit such up that during signal transport, the earth rotates and the unit moves in an absolute straight line making it an SR frame.

Yet, this is not an SR frame because light does not measure c in this virtual coordinate system because of the Sagnac effect.

 

[OnlyMe]

GR effects in GPS can be accounted for and cancelled leaving only SR.

This is the problem chinglu. You can account for affects of GR, which allows you to isolate affects of SR.., but you are not in doing so canceling GR. If there were no gravity, your satellite would just fly off into space instead of orbiting the planet.

And you are still confusing the frame of the satellite with one or both.., an ECEF and/or ECI frame. All satellites move (ie. accelerate) relative to an ECI frame.., the frame remains fixed while the satellite orbits the earth. In all but equitorical geosynchronous orbits all satellites also accelerate relative to an ECEF frame. That means for all intents and purposes all satellites are accelerating relative to both frames. They are not inertial relative to either frame.

All of our clocks are synchronized, to an arbitrarily agreed upon location, in an ECEF frame, a location on the surface of the earth. A rotating frame not an inertial frame. That time standard is then used for the purposes of experiment in all frames we choose to explore.

You can account for both GR and SR in a wide variety of situations and comparrisons. That does not mean that you cancel either one.

 

[Pete]

1) The "proof it" part is the fact that your claim is already answered in this thread.

Rubbish.

Ashby claimed there is a set of co-moving frames with ECEF during signal transport. He then said each of these frames is an implementations of the relativity of simultaneity of ECEF co-moving to ECI. I indicated that the GPS unit moves down .4 cm during signal transport. Hence, move the unit up uniformly with the earth's rotation during signal and sans GR, you have an SR frame.

So, Ashby has already claimed these frames are SR ROS. So, if one can smooth them out of the rotation, then they are SR frames.

No, that's not enough. Unless the clocks are Einstein synchronized, it's not an SR frame.

Further, you cannot Einstein sync in this virtual SR frame because the of the Sagnac effect.

You can use Einstein synchronization in the instantaneously comoving reference frame, and doing so would give you an SR frame.
But when we choose not to use Einstein synchronization, and use ECI frame time instead, then the Sagnac effect appears.

Hence, this is not SR since you can Einstein sync in ECEF using the logic above.

You can't consistently use Einstein synchronization between all clocks on the Earth's surface.
You can use Einstein synchronization in a small part of the Earth, and if you did so you would not measure a Sagnac effect. for measurement made using those clocks.

2) And, if you eliminate GR effects as is done in the GPS article I posted by Ashby and you raise the unit .4 cm during signal transport, then SR does not say you cannot sync under this condition since it is an SR frame.

If you Einstein synch the clocks to eliminate the Sagnac effect, then it's an SR frame.

 

[brucep]

Since the correction is so small requiring both gravitational and relative motion tick corrections we use GR to find the combined correction for the satellites natural path. The satellites are following the natural path, freefall orbit, which is an inertial reference frame. Inertial reference frames are not just the domain of SR. chinglu needs to do his homework. The ECEF was the GPS operations group pragmatic choice for obvious reasons.