# An absolute time clock!

by roineust
Tags: absolute, clock, time
P: 8,430
 Quote by roineust Hey ghwellsjr, I have sat in a classroom thorough all of SR course. I did it only twice (once in a real room and once watching on a video course portal), and made just a little amount of homework in the subject. I am not sure if this answers your question. I remember equations with a big L and a little l, the v and v' and other variables and part of equations. I didn't go through this extraordinary frustrating process lately again (most of all frustrating because this process did not explain time dilation to me). Thanks, Roi.
And do you understand what it means for a set of equations to be "Lorentz invariant"? Do you understand for example that if we know the correct equations to describe the laws of physics in one frame, the question of whether or not these laws are Lorentz-invariant is a purely mathematical issue, not an experimental one? (though of course it is an experimental problem to determine whether we have the equations precisely correct in that one frame). Likewise, do you understand that if the laws are Lorentz invariant this guarantees they will work the same in all the different inertial frames of relativity, and that any physical systems governed by these laws (including clocks) is guaranteed to obey time dilation as SR predicts? In this sense Lorentz-invariance "explains" time dilation, although of course physics cannot "explain" why the universe obeys one set of mathematical equations as opposed to some others, this is a question for philosophy or theology.
 P: 120 Hey DaleSpam, What you say in post 46 I absolutely agree with. On the other hand I gave it my best, and couldn't understand it (SR), although I understood each and every mathematical move. Telling me to go into an endless loop of starting again every time I get to the end and still time dilation looks like magic, doesn't make sense to me. Anyway, I will try to check out if a geometrical approach makes it seem a different path, in understanding time dilation. Thanks a lot, Roi.
 P: 120 JesseM, You might be right. I don't know. Roi.
Mentor
P: 15,571
 Quote by roineust On the other hand I gave it my best, and couldn't understand it (SR), although I understood each and every mathematical move. Telling me to go into an endless loop of starting again every time I get to the end and still time dilation looks like magic, doesn't make sense to me.
It is a difficult subject. It took me 7 years of sporadic study before I understood it.

 Quote by roineust Anyway, I will try to check out if a geometrical approach makes it seem a different path, in understanding time dilation.
I highly recommend it. There are two things which made it finally "click" for me:
1) Spacetime diagrams
2) Four-vectors

For 1) in particular I did a diagram where I used the Lorentz transform to draw the t'=0, t'=1, t'=2, x'=0, x'=1, and x'=2 for a primed frame moving at v=0.6. When you do that you can look at your diagram and visually see the invariance of c, relativity of simultaneity, length contraction, and time dilation and how they all fit together.
Merry Christmas everyone!
 P: 120 Can someone explain to me why diagram 2 depicts a contradiction with the laws of energy conservation (a 'perpetum mobilum’)? Is this exactly the same issue as with time dilation, or maybe it is simpler to explain? Because, for example, I know that in old ‘perpetum moblium’ machines, what happens is that they stop working because of friction, but what diagram 2 has to do with friction or with a ‘perpetum mobilum’ at all? Thanks, Roi.
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P: 4,163
 Quote by ghwellsjr Roi, I wasn't asking you to understand SR historically, I was asking if you studied how length contraction (and time dilation) was used by Lorentz (and others) to explain the null result of MMX prior to SR. At this stage, it is important to NOT try to understand SR. Forget about what happened after Einstein's 1905 paper came out. I just want you to answer that one question: do you understand how length contraction explains why MMX could not detect an ether wind?
 Quote by roineust Hey ghwellsjr, I have sat in a classroom thorough all of SR course. I did it only twice (once in a real room and once watching on a video course portal), and made just a little amount of homework in the subject. I am not sure if this answers your question. I remember equations with a big L and a little l, the v and v' and other variables and part of equations. I didn't go through this extraordinary frustrating process lately again (most of all frustrating because this process did not explain time dilation to me). Thanks, Roi.
Roi, chances are those classes did not teach how Lorentz explained the null result of MMX using Length Contraction and Time Dilation. It can be done purely graphically with very little math. Would you like me to walk you through this exercise?
 P: 120 Hey ghwellsjr, Yes, Please. Roi.
P: 8,430
 Quote by ghwellsjr Roi, chances are those classes did not teach how Lorentz explained the null result of MMX using Length Contraction and Time Dilation. It can be done purely graphically with very little math. Would you like me to walk you through this exercise?
There is actually no need to use time dilation in the explanation of the null result of MMX, since the measurement was just based on whether waves remained in phase and there was no testing of the total amount of time they took to travel up the interferometer arm and back.
P: 8,430
 Quote by roineust Can someone explain to me why diagram 2 depicts a contradiction with the laws of energy conservation (a 'perpetum mobilum’)?
No one said your idea contradicted energy conservation, Vanadium said it an absolute time clock is 'the SR equivalent of the Newtonian "A Perpetual Motion Machine!"', which just means that it is analogous in the sense that it is as basically impossible in an SR context as perpetual motion is in Newtonian physics (and perhaps also in the sense that both hold a persisting appeal to physics cranks).
P: 8,430
 Quote by roineust JesseM, You might be right. I don't know. Roi.
Which part of what I said are you not sure about? The only uncertain issue is whether the fundamental laws of physics will ultimately turn out to be Lorentz-invariant, but it's certainly true that the most accurate equations found so far are, and that it's a guaranteed theoretical truth that if all the fundamental laws of physics are Lorentz-invariant then all clocks governed by these laws will show time dilation and an "absolute time clock" must be impossible.
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P: 4,163
 Quote by ghwellsjr Roi, chances are those classes did not teach how Lorentz explained the null result of MMX using Length Contraction and Time Dilation. It can be done purely graphically with very little math. Would you like me to walk you through this exercise?
 Quote by roineust Hey ghwellsjr, Yes, Please. Roi.
OK, good. Now the first thing we must do is put ourselves in the mindset of most of the great scientists of that era. They believed in an absolute ether rest frame in which light propagated at the same constant speed in all directions. Imagine a very brief bright flash of light being set off in this stationary frame. It will create an ever-expanding spherical shell of light, centered on its point of origin with respect to the stationary ether. They believed that if the source of light were moving with respect to this stationary ether frame, the source would not remain in the center of this expanding spherical shell but would move off-center.

But the question is: how can we tell if the light source remains in the center of this expanding shell or moves off-center? By analogy, we could visualize what would happen if we were observing an expanding ring of waves on the surface of a pool after dropping a pebble in the water because we use light to observe the water, but how can we observe a lightwave once it has started moving away from us? Therein lies the problem: we cannot directly observe the propagation of light so we do the next best thing which is to set up an array of mirrors to reflect the light back to us.

Now the best way to "observe" an expanding spherical shell of light is to set up a whole bunch of mirrors, all an equal distance from the source and in all possible directions. Then when we set off the flash it will expand until it simultaneously hits all the mirrors which turn the expanding spherical shell of light into a contracting spherical shell of light which will eventually collapse on the source simultaneously from all directions.

For purposes of illustration, we will consider a two-dimensional subset of mirrors and an expanding ring of light, much like the expanding ring of waves on the surface of a circular pool of water as it simultaneously strikes the entire pool wall circumference, reverses direction and simultaneously collapses on the source in the center of the pool.

I realize this is pretty simple so far, but I want to make sure you grasp all the concepts before moving on so if there is anything that is ambiguous or confusing, please let me know before we continue.
 P: 5 What if, in the simplest form that the recorded time of emission of a pulse of light directed at one mirror at the far end of the train where this mirror has event time recording capabilities also, that is when the time of light arrival is recorded and imbeded in the return/reflected signal. Then the distance of light travel of the outbound and inbound trajectories can be calculated, or it appears so (let C=1 a unit SOL). If both trajectories are equal the attached frame has no motion, otherwise, the frame is moving. I do not intend to divert the direction of this very interesting thread and I only came upon it by accident, having just registered in early December. There has to be a simple correction to this simplistic intervention.
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P: 4,163
 Quote by Ymyk What if, in the simplest form that the recorded time of emission of a pulse of light directed at one mirror at the far end of the train where this mirror has event time recording capabilities also, that is when the time of light arrival is recorded and imbeded in the return/reflected signal. Then the distance of light travel of the outbound and inbound trajectories can be calculated, or it appears so (let C=1 a unit SOL). If both trajectories are equal the attached frame has no motion, otherwise, the frame is moving. I do not intend to divert the direction of this very interesting thread and I only came upon it by accident, having just registered in early December. There has to be a simple correction to this simplistic intervention.
The act of setting the time on the distant event time recording device will result in getting whatever answer you want when you "make" this measurement. If you follow Einstein's method for setting the time on your distant device, then you will determine that your frame has no motion--that's exactly what Special Relativity is all about.
 P: 120 ghwellsjr, So far so good, Please continue. Roi.
P: 5
 Quote by ghwellsjr The act of setting the time on the distant event time recording device will result in getting whatever answer you want when you "make" this measurement. If you follow Einstein's method for setting the time on your distant device, then you will determine that your frame has no motion--that's exactly what Special Relativity is all about.
Let A0 be the emission time from A at which time the B clock is Bu, unknown.
The pulse arrives at B at Bu + B1 where B1 is the TOF of the pulse from A to B and Bu + B1 is a recorded value.
The pulse returns to A at A2 at which time the B clock is Bu + A2 = x1 (recorded).
At A2 another pulse is emitted arriving at B at Bu + A2 + B1 = x2 (recorded)
Subtracting x2 - x1 = Bu + A2 + B1 - A2 - Bu = B1 the TOF of the pulse from A to B. and where this time is the used to synchronize both clocks, perfectly.

Now the outbound and inbound trajectories are B1 - A0 and A2 - B1 respectively with C = 1 the unit SOL. The difference in the distances are B1 - A0 - (A2 - B1) = 2B1 - A2 + A0 which is the distance of travel of the two transponders which remain a constant distance D apart.

D = Vab(A2 - A0) = 2B1 - A2 - A0

Hence Vab = [2B1 - (A2 + A0)]/(A2 - A0); or for A0 = 0 ,

Vab = 2B1/A2 -1

AE had never had the opportunity to consider transponders which are standard air traffic control devices used world wide and where the emission and receipt/reflection times are imbeded in the pulse signal.
 PF Patron P: 4,163 Ymyk, it is very difficult to understand your scenario. It appears that you are using some of your nomenclature to refer to absolute times (A0, Bu, A2?) and others for delta times (B1). But whatever you are doing, it is not legitimate. You cannot measure the one-way speed of light. You cannot tell how long it takes for light to go from A to B or B to A without some previously defined answer to the question. I'm sure that transponders are relying on a previously defined timing conventions and so cannot be used to measure the times of receipt/reflection as you are proposing. You should be able to figure out what is wrong with your idea if you understand Special Relativity. In fact, you wouldn't even attempt to find a way around the problem. You do realize that if what you are proposing is legitimate, that you have just dethroned Einstein and you will be able to take his seat. Is that what you really believe?
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 Quote by roineust ghwellsjr, So far so good, Please continue. Roi.
Good.

You're going to have to be patient with me. I'm working on some animations to illustrate the ideas I'm presenting so it will take me some time but I think in the long run this will be much more effective.
P: 5
 Quote by ghwellsjr Ymyk, it is very difficult to understand your scenario. It appears that you are using some of your nomenclature to refer to absolute times (A0, Bu, A2?) and others for delta times (B1). But whatever you are doing, it is not legitimate. You cannot measure the one-way speed of light. You cannot tell how long it takes for light to go from A to B or B to A without some previously defined answer to the question. I'm sure that transponders are relying on a previously defined timing conventions and so cannot be used to measure the times of receipt/reflection as you are proposing. You should be able to figure out what is wrong with your idea if you understand Special Relativity. In fact, you wouldn't even attempt to find a way around the problem. You do realize that if what you are proposing is legitimate, that you have just dethroned Einstein and you will be able to take his seat. Is that what you really believe?
ghwellsjr, My clumsy language perhaps garbled what is a simple arrangement. Two tranbsponder are separated by a constant distance. A transponder is a device that substitutes fro air traffic control radar. Insted of bouncing the outbound sihnal off of an aircraft, the signal is coded and the 'reflected signal' has the time of arrival and reflection imbeded in the return signal - aircraft ID, azimuth and elevation and calculated distance are included.

The transponders are identical in all respects. My argument is straightgforward. A0 is the time imbeded in the outbound pulse in the direction of the B transponder. At A0 the B clock is unknown, or Bu, a recordwed vcalue. When the pulse arrives at B the B clock registers Bu + B1 , where both Bu and B1 are unbknown but their total clock value is recorded when the pulse arrives. In other words the pulse simple tells the clock to give out the current clock time, he Bu + B1. When the pulse returns to A at A2, the B clock now reads Bu + A2, again recorded as x1. Immediately emitting a pulse from A where the clock now is A2, arrives at B at Bu + A2 + B1 = x2 subtracting thye two x's x2 - x1 = Bu + A2 + B1 - Bu - A2 = B1, which is the time of flight of the pulse from A to B. There is no measure of the SOL which is presumed to be constant at unit SOL C = 1.

The two clock are ticking at the same rate and even thoughn there was initially no information of what the clock time on B happened to be when the A clock reas A0.

There is also the presumption that the motion of the [pulse is independent of the motion of the source of the light - I already knew what the SOL was before the pulse motions began.

The repeat of the round tripm trajectory was intended for the purpose of determining what the instantaneous clock time difference of the two transponders happened to be.

The transponders work as I have indicatedbut I am sure that the system disrfegards any relativity effects for the reason thagt the velocities are soi slow.

Look at it as two clocks separated by a constant distance. On clock emits a pulse at A0 when the B clock time is inknown or Bu, a time recorded when triggered by the arriving pulse.

We don't even need to imbed the time of arrival in the reflected pulse. As long as the A transponder has the A0 and A2 times recorded and the B clock has the Bu + B1 time recorded. Calculating the trajectory distances is then trivial and can be accomplished at the observer's pleasure.

You made a great deal claiming that I couldn't measure the one way sol. I didn't try to measure the sol. I already knew the sol as approximately 3x 10^8 km/sec which IO copied out of AE's book "relativity". AE didn't know about transponders in 1905.

I didn't violate any relativity concept. In fact I claim that determining the velocity of the transponder is determined soley from the three time-of -day events A0, A2, and B1. Which is NOT a measurement of the velocity NOR detection of motion. The three event times are carefully recorded.

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