An absolute time clock!

ghwellsjr

Quote by ghwellsjr

Roi, have you studied the historical interpretation of MMX (prior to Einstein) and how Lorentz (and others) concluded that the experimental apparatus was length-contracted in the direction of motion and experienced time dilation? This conclusion was based on an absolute ether rest frame, so I think it is easier to grasp. From there, it is an easy step to SR.

Quote by roineust

Hey ghwellsjr,

Yes I have tried to understand SR this way as well.

What I don't understand regarding the phenomenon of length contraction, and grasping by it the idea of ether as the cause of this phenomenon, by the way of it becoming a preparatory concept, that when assimilated correctly by the student, brings him to a point where SR is understood, while at the very same time, somewhat mysteriously, he also understands why actually the ether itself, as an entity of having any real physical properties, is redundant, is this:

1. First of all when completing this lesson the student will feel a little bit 'cheated', because he will ask himself if bringing up length contraction and ether, was just in order to never bring up these entities again, without any explanation. And then it gets worse:

2. I saw this problem brought up by many SR students: How can you build an experiment showing length contraction? When the answer here is, that there is no such experiment, then, in the way of accepting the conclusion of time dilation that happens by no means of ether, at least in my mind as a student of SR, the way to get to that conclusion becomes barricaded again, even if the teacher will say, 'hold on a minute!' and go on to time dilation.

That is because the student will feel that he never got an answer to a concrete part of the course of events described by the teacher - e.g. an experimental proof of length contraction! not some mathematical complexity, that he can work out later by himself!

3. If a SR student such as me, gets 'stuck' with understanding SR at the point described above, and will understand that bringing a proof of length contraction is impossible, he may start thinking that it is all a result of science not having yet enough experiments that were built with advanced enough equipment to prove a type of ether, that actually has nothing to do with length contraction.

At this point the student will feel that he must invest much more in understanding the history of ether experiments than in the history resulting from SR conclusions. Here are some thoughts I came up with at this stage:

- An atomic clock does not work the same as the device in diagram 2 that I made. An atomic clock has only the 'upper' part of that device, e.g. only one electromagnetic signal going towards a counter, but it has no comparison between two electromagnetic signals within one device.

So if an ether of the type I am looking for exists, it will cause time dilation, but it will not cause the effect of dis-synchronization between the two signals. And such an effect will be considered a change of physical laws as a result of velocity differences - but it can not be found at present experimental structuring.

- The jets carrying these atomic clocks, where moving at a non-relativistic velocity, so maybe also jet speed is not enough to prove the existence of time dilation as a result of ether, maybe some sort of a very small device put in a powerful accelerator should be built.

-Any other experiment that proves time dilation by properties of accelerated particles, again works in the same way as the atomic clock - with no comparison of two synchronized signals compared before and while relative movement.

- At this point, I am usually told that C invariance is not inconsistent with time dilation, because it is somehow mathematically separate from light, although light moves inside that same time dilated frame - but I was never given, in my point of view, any good explanation to think there is no contradiction here.

And therefor my reasoning goes on and maybe this type of ether can resolve that contradiction by somehow having light not affected by ether, while matter is affected in a some non-friction way.

- Then the most dissident thought of such a student as myself will conclude - never mind the exact properties of such a type of ether, what is sure is that if you have a device that can tell you, without recording acceleration and without 'looking out of the window' of the 'jet', that you are at a different speed, then there must be some kind of ether - and this is something that not only Einstein rejected, but also Newton and Galilei - so maybe it is just a matter of advance enough experimental technology, in order to put all these three huge figures together, as correct but not enough precise, in their theories ability to describe and explain, what might be experimentally discovered in the future.

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?

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.

roineust

Vanadium 50,
I'v dealt with such expressions all my life. I am not lazy. so please stop.

How does this thread represent a contradiction with the laws of energy conservation?

Thanks,
Roi.

JesseM

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.

roineust

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.

roineust

JesseM,
You might be right. I don't know.

Roi.

DaleSpam

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!

roineust

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.

ghwellsjr

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?

roineust

Hey ghwellsjr,

Yes, Please.

Roi.

JesseM

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.

JesseM

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).

JesseM

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.

ghwellsjr

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.

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.

ghwellsjr

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.

roineust

ghwellsjr,
So far so good,
Please continue.

Roi.

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roineust	Vanadium 50, I'v dealt with such expressions all my life. I am not lazy. so please stop. How does this thread represent a contradiction with the laws of energy conservation? Thanks, Roi.