# What happens inre time if a clock is independent of the motion of its reference body?

1. Jan 13, 2009

### Bob K

Einstein wrote ...

Q: What would happen inre (in regards to) time if, for any reason, a clock were to be 'independent of the state of motion of [its] body of reference'?
A: _____ (?)

2. Jan 14, 2009

### schroder

Re: What happens inre time if a clock is independent of the motion of its reference b

It seems to me, you are asking; “What would happen if we found a clock which does not obey Relativity”. We haven’t, at least at the macroscopic level, and as far as I know in Quantum Mechanics as well. We can send synchronizing pulses to a clock to make it appear to be independent of its own motion, which is essentially what is done in the GPS system. But that process must be repeated over and over, several times a day, and it never provides 100% compensation, only an approximation. Even then, this only synchronizes the moving clock to a more stable source, or one that has been designated to be so. The reality is, there is no absolute time source. That is one of the most primary tenets of relativity.

3. Jan 14, 2009

### G Hathaway

Re: What happens inre time if a clock is independent of the motion of its reference b

We can use a clock to measure time locally. We can correct for relative motions of any similar clock, right? Is it not theoretically possible to "synchronize" relative to, say, our earth rather than our lab? And to synchronize relative to, say, our solar system? Or, say, our galaxy? Our local cluster? The observable universe?

And would we be remiss to call the time standard of the observable universe absolute time?

4. Jan 14, 2009

### schroder

Re: What happens inre time if a clock is independent of the motion of its reference b

No. The synchronizing pulses can only be sent at the speed of light, which is finite. You would need to compensate for the delay time of the synchronizing signal as well as the relative motion of all the clocks. Even in the present GPS, which operates near the earth’s surface, these delays are not fully compensated for, only approximated. If we tried to extend GPS, say, to include the moon, the delays would become too great to compensate for. You could calculate the delays, then use powerful computer processing power, which is already incorporated into the present GPS. But the processing power to compensate for delay and relative motion of a GPS of any size, at any distance would be enormous! It simply would not be possible to carry such processing power “on board” the moving clocks. So you centralize the processing power at a single location. Then what do you do about the delay in sending the computed correction? You see the problem? Absolute time is absolutely out of the question as long as the speed of light is the speed limit in the Universe.

5. Jan 14, 2009

### Bob K

Re: What happens inre time if a clock is independent of the motion of its reference b

INRE 1: [1] S: It seems to me, you are asking; “What would happen if we found a clock which does not obey Relativity”.

BK: Excellent paraphrase.

INRE 2: [2] S: We can send synchronizing pulses to a clock to make it appear to be independent of its own motion, which is essentially what is done in the GPS system.

BK: The physicist who supervised the development of the GPS system is a personal friend and in a private conversation he confirmed that the GPS timing system consists of a master clock (originally at Falcon AFB, Colorado) which sends radio signals to relay stations which relay the signals to slave clocks in the GPS satellites.

This timing system can be called the master clock<->slave clock timing system.

He confirmed that the slave clocks are not measuring the local time/LT of the satellites.

This has to be, and is proof, that the GPS satellite slave clocks are 'independent of the state of motion of [their bodies] of reference,' e.g., the GPS satellite slave clocks are 'independent of the state of motion of [the GPS satellites].'

Therefore, the GPS satellite slave clocks fufill Einstein's requirement that a clock be 'independent of the state of motion of the body of reference.'

INRE 3: [3] S: But that process must be repeated over and over, several times a day, and it never provides 100% compensation, only an approximation.

BK:

Q: What is wrong with a continuous repetition inre the radio signaling process of the GPS master clock<->slave clock timing system?
A: _____ (?)

Q: What is wrong with an approximation of absolute time/AT so long as the approximate time has practical applications, including the coordination/synchronization of events in different reference frames?
A: _____ (?)

The GPS nav system is accurate to within 3 feet at the Earth's surface at the equator. That accuracy is not 100% and yet it has successful practical applications for civilian navigiation and military navigation and targetting.

INRE 4: [4] S: Even then, this only synchronizes the moving clock to a more stable source, or one that has been designated to be so.

BK:

Q: What is wrong with synchronizing a moving clock to a more stable source?
A: _____ (?)

The Earth has been reasonably stable inre its rotation about its axis and inre its orbit about the Sun for 4-5 billion years, and as a consequence, atomic clocks have been stable and accurate to one second in a million years, and the GPS clocks, within their tolerances, have been stable since they have been deployed and the GPS satellite slave clocks have been 'independent of the state of motion of [their bodies] of reference' also since deployment.

INRE 5: [5] S: The reality is, there is no absolute time source.

BK: There is another type of clock that could be 'independent of the state of motion of the body of reference': the motion-sensing self-adjusting clock, MSSAC, which uses accelerometers/decelerometers to detect changes of its state of motion and use a computer to adjust its rate of ticking/RoT, time-interval/TI, timepoints, timeline, and timecount, to maintain a pre-set Rot, TI, timepoints, timeline, and timecount, and when deployed, at least in theory, it would be independent of any and all reference frames K', K'', etc., including its initial reference frame, K, and would therefore be closer to what you may require for a clock to disobey relativity.

Such MSSACs may exist in military inertial guidance systems.

INRE 6: [6] S: That [the reality that there is no absolute time source] is one of the most primary tenets of relativity.

BK: If stability is one of the criteria for an absolute time source/ATS, e.g., an absolute time clock/ATC, then any clock which is stable inre its RoT, TI, timepoints, timeline, and timecount would measure AT as well as LT so long as it was stable and its body of reference was also stable.

If, for any reason, clocks, e.g., master clock<->slave clocks or MSSACs, in different reference frames should have identical RoTs, TIs, timepoints, timelines, and timecounts, then they would generate the timepoints, timelines and timecounts necessary for the determination of absolute simultaneity/AS and the coordination/synchronization of events in those different reference frames.

Last edited: Jan 14, 2009
6. Jan 14, 2009

### matheinste

Re: What happens inre time if a clock is independent of the motion of its reference b

Hello all.

Perhaps someone can quickly answer this question which may be relevant to this thread.

What exactly does it mean, if anything,for two clocks moving inertially relative to each other to be in synchronism.

Matheinste.

7. Jan 14, 2009

### G Hathaway

Re: What happens inre time if a clock is independent of the motion of its reference b

When the twin of twin paradox fame returns to his twin, his clock has proceeded at a different rate from his life processes. That clock having been adjusted to compensate for the trip. It has been adjusted so when he returns to his twin, the clocks agree. And, of course, he knows just how old his twin is at all times. At least he thinks he does with his adjusted clock.

8. Jan 14, 2009

### matheinste

Re: What happens inre time if a clock is independent of the motion of its reference b

Quote:-

----It has been adjusted so when he returns to his twin, the clocks agree.----

Yes but how can synchronicity be defined for non colocated clocks moving inertially with respect to each other.

Matheinste.

9. Jan 14, 2009

### Naty1

Re: What happens inre time if a clock is independent of the motion of its reference b

What does this mean?

10. Jan 14, 2009

### Bob K

Re: What happens inre time if a clock is independent of the motion of its reference b

Both clocks are ticking at the same rate of ticking/RoT, have the same time-interval/TI, the same set of timepoints, the same timeline, and the same timecount, so that clocks which are in different reference frames/on different reference bodies and which are near to events in those different reference frames/on those different reference bodies and have cameras linked to them can provide time-stamps for photographs of the events and observers who collect the time-stamped photographs can determine that those events which have identical time-stamps were simultaneous with each other (simultaneity = two or more events occurring at the same timepoint).

Note that the photographing and time-stamping of the photographs can occur regardless of relativistic observers (observers whose rates of metabolism/RoM and rates of perception/RoPs change inversely with accelerations/decelerations) and regardless of the reference frames or reference bodies.

The simultaneity thereby established by the identical timestamped photographs would be absolute simultaneity/AS, which in relativity is not supposed to exist/to be a reality.

The Fitzgerald-Lorentz transformation equations assume specific initial conditions wherein two clocks, C1 and C2, are identical inre their RoTs, TIs, timepoints, timelines, and timecounts and are in the same initial reference frame, K, and one of the clocks, C2, is accelerated or decelerated from K into a different reference frame, K', and is therefore traveling at a different velocity from C1 and the K reference frame. Thus, whereas relativity requires symmetry inre observers O1 in K and O2 in K' being unable to know which observer/reference frame is traveling with a greater objective velocity, when it is known by both O1 and O2 that C2 has been accelerated or decelerated from K into K', and there is a difference velocity, v, between C1/K and C2/K', then the symmetry of relativity is broken.

The F-L transforms describe what should happen inre time, t', e.g., the RoT, TI, timepoints, timeline, and timecount of C2 when C2 has been accelerated or decelerated into K', so t in K ≠ t' in K', e.g., t ≠ t'.

Thus, if C2 has been accelerated, t' < t, and if C2 has been decelerated, then t' > t.

The Galileian transformation equations describe what happens inre the t' of C2 and therefore the RoT, TI, timepoints, timeline, and timecount of C2 when C2 has been adjusted to maintain the same/identical RoT, TI, timepoints, timeline, and timecount as C1 regardless of accelerations or decelerations of C2, e.g., t' of C2 = t of C1, e.g., t' = t, and the RoT TI, timepoints, timeline, and timecount of C2 = the RoT, TI, timepoints, timeline, and timecount of C1.

Thus, under such conditions, wherein C2's RoT, TI, timepoints, timeline, and timecount have been adjusted to compensate for accelerations/decelerations, C2 is 'independent of the state of motion of [its] body of reference' (Einstein's requirement for clocks to be capable of measuring/counting absolute time), and, therefore, C2 would be capable of measuring/counting absolute time/AT, and for sure C2 would not be measuring/counting the local time/LT of K'.

11. Jan 14, 2009

### matheinste

Re: What happens inre time if a clock is independent of the motion of its reference b

Hello Bob K

All very interesting but before learning how to do it i was looking for a defintion of what it MEANS for non colocated clocks moving inertially with respect to each other to be synchronized.

Matheinste.

12. Jan 14, 2009

### Bob K

Re: What happens inre time if a clock is independent of the motion of its reference b

If a description of what happens inre clocks' RoTs, TIs, timepoint, timelines, and timecounts being identical and thus AT can be measured/counted and t = t' and AS for events in different reference frames can be determined and thereby people can coordinate/synchronize events such as setting and keeping appointments when 'non colocated clocks moving inertially with respect to each other [are] synchronized' is not 'a definition of what it MEANS for non colocated clocks moving inertially with respect to each other to be synchronized,' then I need you to specificy what is 'a defintion of what it MEANS for non colocated clocks moving inertially with respect to each other to NOT be synchronized' so I can understand what you mean by 'a definition of what it MEANS.'

13. Jan 14, 2009

### Staff: Mentor

Re: What happens inre time if a clock is independent of the motion of its reference b

The satellite slave clocks are not independent of their state of motion in this sense, it is just that their state of motion is carefully controlled and accounted for. In any case, it is certainly not independent of the state of motion of the master clock.

However, you really should make some effort to understand the geometric approach mentioned by Fredrik.