# Thread: Is time universal? NO (and its proof)

1. Originally Posted by Pete
'Fraid not.
Special relativity says that the Earth clock ticks faster than the satellite clock in all frames.

Careful! In special relativity, the satellite rest frame is not inertial, and a naive application of the time dilation formulas is not appropriate.
How many times do you need to be told that special relativity can hand acceleration frames? Furthermore, the time dilation is only dependent on the instantaneous velocity at any given time and is never dependent on the derivative of the velocity.

Originally Posted by Pete
Consider the following scenario, and an analysis using simultaneity:

Consider two clocks, A and B.
The rest frame of A is inertial.
B is moving in a circular path with A at the centre, with a constant speed of 0.5c relative to A.
Here in lies your problem. In the case of GPS, neither A nor B are inertial even if you assume A to be the gravitational potential of Earth. Remember that the Earth is orbiting the sun and the sun is orbiting in the Milky Way. If we were to believe what you say is true regarding simultaneity, then GPS would be impossible as you could never define a truely inertial frame. As it turns out, thankfully, accelerations can be handled in special relativity.

2. Originally Posted by MacM
A veloicty adjsument made using SRT predicts -5.8us/day an incorrect value as justified by actual emperical results.
MacM, given your rather limited understanding of relativity, I think it's very likely that you have simply calculated the correction wrong.

3. Mac,
Perhaps you should read what I actually write, instead of picking out a word or two and filling in the blanks based on your stupid stereotype of a "relativist".

I've asked you before, and I'll ask you again - Please do not assume that you know what I'm thinking. Just respond to the words I actually write.

OK?

4. Originally Posted by KitNyx
There are two things (well two main things) that I am confused about. Would anyone mind explaining them?

1) what is the "frame of the gravitational potential of the Earth"? I am in Earths "gravity field" yet my frame of reference can never be the same as yours (also in Earths gravity field). Do you mean Greenwich Standard Time?
Very good question. If I remember correctly, it is explained as approximately a frame in which something is stationary in both heliocentric and geocentric perspective since the Earth "local ether" would be imbedded in the Sun "local ether". It is approximate because there would also be the Galactic "local ether".

Originally Posted by KitNyx
2) reciprocity? What does relativity have anything to do with mutual give and take?
You have just heard of reciprocity at this late date? You may want to read a primer on special relativity here

5. Aer:

Again, I do not necessarily support any conclusions Hatch has made with his so-called "unconventional theories", so would you too classify me as one whom would give him an unfavorable review?
If you like.

Yes it does. It does not use either the frame of the satellites or the frame of someone on Earth. It uses the frame of the gravitational potential of the Earth.
You need to read up on GPS a little more. The system uses at least three separate reference frames at various stages of the calculations made.

Better yet, I'll make a clickable search just for you: Local Ether. The very first result is a very good location to start reading.
Thanks. I might take a look when I have time.

Wrong. If you chose any other frame, you would use a different synchronization. For instance, if we assume the surface of Earth is at rest, we would say the satelites time is dilated. If we assume the satellite is at rest, then the surface of the Earth's time is dilated and we would never be able to get synchronization.
I think we're agreed on this, then. You can only choose to synchronise clocks in one frame. The choice made for GPS is the ground frame. In the satellite frame, for example, clocks synchronised for the ground frame will not be synchronised. Agree?

MacM can't seem to cope with this simple point.

"Universal time" just means that time dilation occurs with motion relative to a preferred frame, in this case, Earth's gravitational potential.
Ok. If that's all you mean by that, I have no problem. It's just that cranks tend to use the term "universal time" in the sense of some kind of absolute reference frame.

Agreed. It is a medium in the context of "local ethers" which is the context I have intended.
Fair enough. So, I take it we are in agreement here.

6. Originally Posted by Aer
As it turns out, thankfully, accelerations can be handled in special relativity.
No shit, Sherlock. Do the maths, and you'll find that SR predicts that in all frames, the Earth surface clock runs faster than the satellite clock.

7. Originally Posted by James R
You need to read up on GPS a little more. The system uses at least three separate reference frames at various stages of the calculations made.
What are these frames? Are they related to the Earth, Sun, and 500-600 closest stars respectively? I believe that is how you define the so called "local ether" frame.

Originally Posted by James R
I think we're agreed on this, then. You can only choose to synchronise clocks in one frame. The choice made for GPS is the ground frame. In the satellite frame, for example, clocks synchronised for the ground frame will not be synchronised. Agree?
As far as I know, they are not synchronised in either frame (well, they are, but according to special relativity, they would not be). They are synchronised in the so-called "local ether" frame which is neither the ground frame or the satellite frame. Perhaps you could make an argument that it is ok for them to be synchronised in this frame and everything is ok with special relativity?

As a side note, Pete disagrees with this point. Can you point out where he is going wrong? He doesn't listen to me.

8. Pete,

I think Aer's right about the satellite frame. If the satellite was orbiting faster enough, then in its own frame the relative-velocity time dilation relative to the ground would make the satellite's clock tick faster than the ground clock. The relative-velocity effects would be greater than the gravitational red-shift effects.

If I am wrong, I'd appreciate a reference. I am suspicious of your claim that clocks on the satellite and earth always remain synchronised if you ignore gravitational effects.

9. Aer:

What are these frames? Are they related to the Earth, Sun, and 500-600 closest stars respectively? I believe that is how you define the so called "local ether" frame.
As I understand it, the GPS system uses the frame of the "fixed stars", as well as an "earth-centred inertial" (ECI) frame based on a non-rotating Earth, and the ground frame, which rotates relative to the ECI frame.

10. Originally Posted by Physics Monkey
MacM, given your rather limited understanding of relativity, I think it's very likely that you have simply calculated the correction wrong.
1 - Your assumption that I have a limited understanding is unwarranted and is nothing more than selfserving innuendo.

2 - Your assertions are not rebuttals. Show any mathematical errors please.

************************* Extract *******************

Proof: GPS satellites have a velocity (V1) of 3,874.5 m/s. A surface clock (at the equator) has an absolute velocity (V2) of 463.8 m/s and "0" m/s at the poles or Earth Center Frame.

The "Relative Velocity" between the orbiting clock and a clock at the equator is V3 = (V1 - V2) = (3,874.5m/s - 463.8m/s) = 3,410.7m/s.

Using Special Relativity in GPS one gets: 3,410.7/c = 1.1369E-5, squared = 1.2925E-10. Divided by 2 = 6.4627E-11.

Time loss would be 6.4627E-11 * 24 * 3,600 = 5.58378E-6 or - 5.58 micro-seconds per day.

HOWEVER: Using the absolute velocity of orbit of 3,874.5 m/s and NOT "Relative Velocity" per SRT one gets 1.2915E-5c, squared = 1.66797E-10. Divided by 2 = 8.33986E-11.

8.33986E-11 * 24 * 3,600 = 7.205E-6 or 7.2 micro-seconds per day due to orbit velocity.

For the earth surface clock I calculate V2 = 463.8 m/s = 1.546E-6c. Squared = 3.29E-12. Divided by 2 = 1.195058E-12 * 24 * 3,600 = 1.0325E-7 or -0.10325 Micro-seconds per day being only about 1% in the daily time loss may be disregarded. (Furthermore it happens that the GR affect of the earth's shape and the velocity of a clock on its surface are precisely offset such that all surface clocks run at a common tick rate at sea level.)

*************************************************

11. Well, without context it is hard to make heads or tails of this. I would assume you'd have to use all of the following frames:

define local ether (or arbitrary SR inertial frame):
so called "fixed stars" / sun
ECI

motion relative to local ether (or arbitrary SR inertial frame):
ground frame
satellite frame

12. Originally Posted by Pete
Mac,
Perhaps you should read what I actually write, instead of picking out a word or two and filling in the blanks based on your stupid stereotype of a "relativist".

I've asked you before, and I'll ask you again - Please do not assume that you know what I'm thinking. Just respond to the words I actually write.

OK?
I would be more inclined to heed your words if you were to have pointed out where you have been misquoted.

13. Originally Posted by James R
You need to read up on GPS a little more. The system uses at least three separate reference frames at various stages of the calculations made.
None of which are conventional SRT frames. All are preferred frames where reciprocity inherent in SRT are prohibited.

I think we're agreed on this, then. You can only choose to synchronise clocks in one frame.
Total BS. Take two clocks on the earth and two clocks in orbit. How would lyou synchronize them?

1 - You would employ the GPS and adjust one orbiting clock to slow down by a net 38us/day (-45us/day GR and +7.2us/day velocity).

2 - You would adjust one earth bound clock to run fast by 38us/day (+45us/day GR and -7.1us/day velocity).

Each set of clock would remain synchronized but be running at different rate. But that is not at issue. The point you seem to miss is how they are calibrated.

3 - You did not and cannot calibrate from the view of SRT where each is running slower than the other.

An SRT arguement:

a - Calibrate the orbiting clock to a net -38us/day.

b - Calibrate the surface clock to a net of -7.2us/day. (Since GR does not have reciprocity).

Oh shit that doesn't work.

MacM can't seem to cope with this simple point.
Well when the dust settles it seems MacM has a better grip on reality and GPS than yourself.

14. If I am wrong, I'd appreciate a reference. I am suspicious of your claim that clocks on the satellite and earth always remain synchronised if you ignore gravitational effects.
Hi James,
You can think of this as a disguised version of the twin paradox.

Consider another clock that is in the same frame as the Earth-surface clock, but in the path of the satellite clock.

This second Earth clock is synchronised with the Earth-surface clock.

The punchline?
The second Earth-clock is the stay-home twin.
The satellite clock is the travelling twin.

... am I right?

15. I think the problem is, you are simplifying "on Earth" as "at the center of the Earth".

16. Can you point out where he is going wrong? He doesn't listen to me.
Sure I listen. I just don't agree!

Yes, SR can handle the satellite clock frame.
No, you can't just blindly apply the time-dilation formula.

Care to do it properly?

17. It is properly done as I stated. It is your assumption that is not proper.

18. Originally Posted by Aer
I think the problem is, you are simplifying "on Earth" as "at the center of the Earth".
Correct! Which as far as SR is concerned means that I've assumed a non-rotating Earth, right?

So, take it from there. What conclusions do you draw?

19. Originally Posted by Pete
Correct! Which as far as SR is concerned means that I've assumed a non-rotating Earth, right?
No, if you chose the center of the Earth as your reference point, the Earth can still be rotating as that would not matter. The point is that the ground clock and satellite clocks are not synchronized with respect to each other. Are they synchronized in some other frame? Yes, there will always be a frame in which they are synchronized (I believe, or should say, I see no reason why such a frame cannot exist).

20. Originally Posted by James R
If the satellite was orbiting faster enough, then in its own frame the relative-velocity time dilation relative to the ground would make the satellite's clock tick faster than the ground clock. The relative-velocity effects would be greater than the gravitational red-shift effects.
What a joke. Based on nothing but regurgitated SRT reciprocity. Totally without any emperical or logical support.

The faster it goes the slower it goes relative to the earth and yo CANNOT justify having it both ways at the same time. PERIOD.

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