# An absolute time clock!

by roineust
Tags: absolute, clock, time
P: 5
 Quote by roineust Here is my question, starting from a suggested experiment that reminds a known example that Einstein gave about special relativity including a moving train, two mirrors inside the train and a light beam reflected between the mirrors (this suggested thought experiment described here only reminds the historically well known thought experiment –please note critical differences): 1. Lets question how to measure and compare measurements for an amount of time that it takes a light beam to travel from a bottom mirror to a top mirror in a train, once when the train is not moving (stationary at dock) and once when its moving at constant speed relative to dock (when measured only from within the train). As much as I understand this amount of time has got to be the same in both cases because the speed of light is constant at any direction and relative speed, while regarding the height of the train - there exists only horizontal length contraction, as seen from outside the train (in the same direction that the train is moving), so anyway there is no vertical length contraction from within the train. It seems that the time it takes light to travel from top to bottom mirror or from bottom to top mirror when looked at from inside the train is the same - doesn't matter if train is moving or not. I think it's important to repeat that point: we are measuring from within the train, and not what is seen from outside the train. Measuring once when the train is not moving and once when the train is moving. The measurement is made by dividing the height of the train by the speed of light (constant at any speed or direction).
If Einsteins posulate borrowed from De Witter is a parameter in the totality of motion described here, how could the reflecting light seem to move along with the moving frame? The reflection should have no effect of dragging the reflecting beam along with the motion of the frame. The model you use here necessarily adds a component of light in the direction of the frame motion resulting in the speed of light being dependent on the speed of the frame, as described by your model - the same flaw is ingrained in virtually every published MichelksonMorely experimental arrangement.
Mentor
P: 16,269
 Quote by Ymyk The reflection should have no effect of dragging the reflecting beam along with the motion of the frame. ... the same flaw is ingrained in virtually every published MichelksonMorely experimental arrangement.
I have never seen any publication showing a reflection dragging a beam. What are you talking about?
P: 5
 Quote by DaleSpam I have never seen any publication showing a reflection dragging a beam. What are you talking about?
For instance, in Michelson Morely schematics the down beam that reflects from the surface does not reflect up on the same trajectory as the down trajectory.

Similalry, your description of the up and down beam from inside the moving frame, the beam seems to be move along with the moving frame and would be appear to be the same if observing a frame "at rest".

If de Witter is correct as AE seemed to agree, once the beam is released it knows nothing of the motion of the devide from which the beam was emitted. - the motion of light is independent of the motion of the source of the light. If this is the case then as the beam seen from inside the moving frame would not strike a point directly in line with (or directly below) the point of emission - the frame would have moved away from the beam which would strike the mirror 'behind' a point directly below the emission point.

I agree my 'dragging' term was not clear. I vaguely remember some references (MM experiments if memory serves me) describing the trajectory as being dragged along by the moving frame, that is the mirror.
 PF Gold P: 4,425 Michelson suggested in his original paper that the ether was dragged along by the earth much like the atmospheric air is dragged along by the earth so that we don't experience a wind from the air and so he speculated that the experiment would need to be repeated at the top of a high mountain to minimize the supposed ether dragging. But this idea was discarded by other scientists in favor of Length Contraction (and Time Dilation) as the proper explanation. These ideas predated Einstein.
Mentor
P: 16,269
 Quote by Ymyk For instance, in Michelson Morely schematics the down beam that reflects from the surface does not reflect up on the same trajectory as the down trajectory.
The law of reflection in all frames is that the angle of incidence is equal to the angle of reflection (http://en.wikipedia.org/wiki/Reflect..._of_reflection). There is no dragging in any frame. The light simply follows the same rule in all frames.

Have you any example where the angle of incidence is different from the angle of reflection? I have never seen such an example.

 Quote by Ymyk the motion of light is independent of the motion of the source of the light.
No, the SPEED of light is independent of the motion of the source. You need to be much more careful with your analysis.
 P: 128 Hello Ymyk, Please look at diagram 2 - for me it seems much simpler, and try to explain to me again where is the flaw ingrained in it, that makes it another MichelksonMorely experimental arrangement. Thanks a lot, Roi.
 P: 128 DaleSpame, If your question is if I ever went through the mathematical didactic process or learning, how time dilation and the invariance of c are obtained from the Lorentz transform, the answer is yes. If you are implying that only when I know these mathematics by heart, I will also feel that I understand that phenomenon (of time dilation), now there I have a problem with such an implication. If so, then a person who truly understands a physical breakthrough, actually never tells himself in non-mathematical words why this is a breakthrough, but only is really able to understand it thinking of its math? This seems to me anyway, a philosophical debate that is not relevant to my question, that is fashioned in very simple terms in diagram2 - If you can please help me understand my misunderstanding that is included in diagram2, then maybe I will be able to understand time-dilation in spoken words. Thanks, Roi.
 Mentor P: 15,354 If you don't understand the math, you don't understand the theory. "What goes up must come down" is not a theory - for it to be theory it needs to describe where and when it comes down, how high it goes and how long it stays in the air. This is part of what distinguishes science from woolly speculation. If you don't understand the theory, you cannot make a breakthrough.
Mentor
P: 16,269
 Quote by roineust If your question is if I ever went through the mathematical didactic process or learning, how time dilation and the invariance of c are obtained from the Lorentz transform, the answer is yes.
OK, so then you must understand that both time dilation and the invariance of c are compatible concepts.

 Quote by roineust If you are implying that only when I know these mathematics by heart, I will also feel that I understand that phenomenon (of time dilation)
I certainly never implied that. The feeling of understanding is a personal thing and different people achieve it in different ways (some people even achieve the feeling without actually understanding).

I am completely uninterested in whether or not someone feels that they understand it. My only concern is whether or not they are able to correctly apply the theory to analyzing physics experiments. That does require the math.

 Quote by roineust that is fashioned in very simple terms in diagram2 - If you can please help me understand my misunderstanding that is included in diagram2, then maybe I will be able to understand time-dilation in spoken words.
Your diagram2 has no position information in it, so it cannot be analyzed rigorously, but recall my above replies. If the crystal is time dilated by a factor of 2 then so is the pile of wire. Everything time dilates at the same rate.
 P: 128 DaleSpam, Please refer me to an experiment that was already executed in the past and that attempted what is shown in diagram 2. What I mean is an experiment that tells us that the laws of physics are the same in any inertial frame, regardless of position or velocity. Many experiments that I heard of do not apply, either because: 1. The complete experimental action is not done from within the inertial frame itself with results recorded and sealed way before velocities are equaled. These experiments are a result of having the experiment not complete before and part of the action of both frames meet at the same velocity. Or: 2. These experiments are not attempted at relativistic speeds. Any particle decay or accelerating experiment will belong to no.1 Any atomic clock put on a jet and not in a special accelerator, without the arrangement described in diagram 2, will belong to no.1 and no.2. Please try to explain to me where I got it wrong. Thanks, Roi.
 P: 128 Vanadium, Can the difference between physics and mathematics be understood by mathematical terms? Thanks, Roi.
 Mentor P: 16,269 I don't know why you think that such a device would ever be built nor why you would think that the fact that it hasn't been built would indicate that relativity is somehow incompletely tested. The fact is that with the precision of modern-day atomic clocks, the speed of a jet liner is relativistic. Additionally, there are many other experiments which have been done to confirm that electromagnetism exhibits Lorentz symmetry. I provided a link earlier which goes over the overwhelming experimental evidence. Have you read it?
 P: 128 Hey DaleSpam, Exactly! I am being referred again and again (not just by you) to this huge list of past experiments, and it just blurs the issue. I am looking for just one or for a few specific experiments, that can be compared to diagram 2. Otherwise it is very hard to understand what exactly it is that bothers me and to either affirm or negate this possibility in a structured way. Roi.
PF Gold
P: 4,425
 Quote by roineust Please refer me to an experiment that was already executed in the past and that attempted what is shown in diagram 2. What I mean is an experiment that tells us that the laws of physics are the same in any inertial frame, regardless of position or velocity. Many experiments that I heard of do not apply, either because: 1. The complete experimental action is not done from within the inertial frame itself with results recorded and sealed way before velocities are equaled. These experiments are a result of having the experiment not complete before and part of the action of both frames meet at the same velocity. Or: 2. These experiments are not attempted at relativistic speeds.
Roi, is the essence of your experiment that light must start from one source, be split into two paths where one of the paths has a medium that slows light down while the other one doesn't and then you want to see if the relative arrivals of the light from the two paths when they come together is influenced in any way by the experiment being performed under different states of motion?

And is it your contention that such an experiment would show a difference and from that difference an absolute ether rest frame could be determined?
 P: 128 Hello ghwellsjr, Yes, But it is not a contention. It results from not being able to understand time dilation. Thanks, Roi.
Mentor
P: 16,269
 Quote by roineust Exactly! I am being referred again and again (not just by you) to this huge list of past experiments, and it just blurs the issue.
Have you read the page? The issue is not the absence of one strange experimental apparatus that you dreamed up, the issue is that the existing evidence is overwhelming.
 Mentor P: 21,897 ....in other words, any new theory would still have to be mathmatically equivalent to Relativity as applied to those other experiments.
 Mentor P: 16,269 Roineust, I don't think that you actually need some specific experiment to be performed. What you need is to better understand the theory. All classical (non quantum) EM phenomena are governed by Maxwell's equations which are invariant under the Lorentz transform. It doesn't matter if you are talking about some EM in a crystal or in a jumble of wire. They will both be dilated by the same amount.

 Related Discussions Special & General Relativity 16 General Physics 3 Special & General Relativity 4 Special & General Relativity 3 General Physics 23