Invariance of Light

Jim
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21 years 3 months ago #6290 by Jim

Replied by Jim on topic Reply from

Can we get back to the two objects in motion emmitting a beam of light and not get in the "deep dodo" to quote an another thinker of note.

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Jan
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21 years 3 months ago #6173 by Jan

Replied by Jan on topic Reply from Jan Vink

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
[TVF]: The emission and detection events are at two different places and times.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I meant the emission and detection in the same frame of reference. The measurement equipment on the probe and on Earth, both having a laser with detection unit, just imagine a lab on Earth and an "identical" lab on a space craft. But, like you said, should I also consider the emission and detection equipment as being at different places and "times"? Thus, for both labs, giving the laser its frame and the detector its frame, although they do not have a relative speed withing the lab. I absolutely agree with you, the labs themselves are at two different places and "times". Note that I strictly separate the Earth bound observer with the one in space, both are in an identical "boxed" environment with relative speeds, just as two "cubes" with relative speeds. In that sense it "feels" as if synchronisation is unnecessary. Only rates are important, since each cube has its own clock that starts as soon as the laser is fired and stops when the light reaches the detector. To sum up, _one_ clock on Earth and _one_ clock on the space craft.

Perhaps it is better to actually have a single wave front traversing identical cubes having relative speeds. Thus one laser puls first traveling through a lab on Earth and then through a high speed lab in space. The obervers do not look at the events in the other lab. It seems as if SR is ignoring an independent component, the wave front in this case, which simply existed before the labs came into being, and with this in mind, SR does actually render the speed of light observer dependent: Both cubes have to measure "c", but the wave front couldn't care less about the cubes in my view. What do you think about this?

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
[TVF]: It is not clear what you mean by this. A speed cannot be measured at an instant. It requires taking the ratio of a finite distance interval and a finite time interval.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Could the light speed be measured by considering radiation pressure?

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Because eleven independent experiments that tested the relativity of motion have been declared to have confirmed SR. But the historically accurate truth is that four of those experiments were declared at the time to falsify SR, and were only reconciled with it at a later date.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

So the effects of relativity have been measured, but why not argue that lifetime of muons or apparent mass increases and such are manifestations of energy injection and/or dissipation, and that physical processes have been altered from an energetic point of view? What is your view on this?

By the way, you said that you would publish an article discussing SR and LR here on Meta Research. Like many others, I look forward to read it. When will it appear?

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tvanflandern
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21 years 3 months ago #6057 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>[Jan]: Only rates are important, since each cube has its own clock that starts as soon as the laser is fired and stops when the light reaches the detector.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Very confusing. I now seem to read that you have both an emitter and a receiver in the Earth-bound lab. But then you need two clocks there, one at emitter and one at receiver. And the measured speed in the lab still depends on how the two lab clcoks are synchronized.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Could the light speed be measured by considering radiation pressure?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Radiation pressure is too weak, and would be a function of frequency, not speed. Frequency, of course, does change with observer motion.

But even when light is "slowed" by some medium (e.g., air, water, glass), theory indicates that the speed of light is still c between absorbtion/re-emission events by the medium, which are responsible for the propagation delays.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>So the effects of relativity have been measured, but why not argue that lifetime of muons or apparent mass increases and such are manifestations of energy injection and/or dissipation, and that physical processes have been altered from an energetic point of view? What is your view on this?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I don't understand the proposal. But in any case, in an SR context, SR's explanation is sufficient. As I understood this discussion, we weren't trying to re-invent SR, but to understand it as it is.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>By the way, you said that you would publish an article discussing SR and LR here on Meta Research. Like many others, I look forward to read it. When will it appear?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

If space permits, it will appear in the September 15 issue of the Meta Research Bulletin. By Board-of-Directors policy, MRB articles cannot appear on the web site for a minimum of two years. Most never appear there. The Bulletin remains our most valuable vehicle for disseminating information about the science we do, and an important source of income to support that research. -|Tom|-

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Jan
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21 years 3 months ago #6060 by Jan

Replied by Jan on topic Reply from Jan Vink

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
[TVF]: I now seem to read that you have both an emitter and a receiver in the Earth-bound lab. But then you need two clocks there, one at emitter and one at receiver. And the measured speed in the lab still depends on how the two lab clcoks are synchronized.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

It seems that I slowly start to realise that with SR we are quite possibly chasing our own tail, because each location needs a clock. Hence, synchronisation of all clocks is needed, even if, as you say, locations do not travel with relative speeds.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
[TVF]: Radiation pressure is too weak, and would be a function of frequency, not speed. Frequency, of course, does change with observer motion.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Photons seem to have momentum, so do these photons transmit there impuls to an object they come in contact with? If so, could the change of impuls of both objects guide us to their velocities?

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I don't understand the proposal. But in any case, in an SR context, SR's explanation is sufficient. As I understood this discussion, we weren't trying to re-invent SR, but to understand it as it is.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Of course, if SR is predicting the measurements, then that is all we need, but especially for newcomers, take me for example, SR is so nonintuitive. At the same time, shouldn't it be recognised that countless scenarios could exist that explain phenomena as predicted by SR? For example, numerous mechanisms can exist that deal with "interaction" rather than "geometry". Hence, any apparent change of physical attributes need not be caused by geometric aspects, but may well be the result of certain interactions between "objects" and/or "substances". Do these arguments look justifiable?

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tvanflandern
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21 years 3 months ago #6061 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>[Jan]: Photons seem to have momentum, so do these photons transmit there impulse to an object they come in contact with? If so, could the change of impulse of both objects guide us to their velocities?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

The momentum of a "photon", being a wave despite its inappropriate naming, is a function solely of its frequency. If there were a subtle dependence on speed also, we do not yet have the means to detect it.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>SR is so nonintuitive.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

It is indeed. That is why it has been debated so hot-and-heavy over the past century.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>At the same time, shouldn't it be recognised that countless scenarios could exist that explain phenomena as predicted by SR?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

This is where the mathematical relativists have done harm, pushing the viewpoint that one set of equations has one physical interpretation. My recent papers have been stressing the reverse.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Do these arguments look justifiable?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

They do to me. The experiments are all we have to set constraints on the physical interpretation of phenomena. -|Tom|-

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Larry Burford
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21 years 3 months ago #6174 by Larry Burford

Replied by Larry Burford on topic Reply from Larry Burford

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
[tvf]
But then you need two clocks there, one at emitter and one at receiver. And the measured speed in the lab still depends on how the two lab clcoks are synchronized.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
This particular experimental requirement is one that I've always had trouble believing. In various searches on the Internet over the past few years I've seen it mentioned dozens of times. But I've yet to find a justification for it, other than "it's needed to make SR match observations". (If anyone knows of a reference for such, I'd appreciate a note.)

If you want to measure the time it takes a light beam to travel 0.299 meters why is it not possible to use *one* clock and two photo detectors - one to start the clock and one to stop it? A two channel oscilloscope with the necessary time resolution sounds just right.

As a guess, I'd say that it's because the time slippage in SR's version of the Lorentz transforms is transfered from the two clocks to the two photo detectors? Because in SR it is not the clock that changes with position, but time itself. What matters (in SR) is where you detect the light beam, not how.

(Couldn't you just factor out 0.299 meters worth of time slippage from one of the clocks?)

---

The Lorentz transforms in LR, on the other hand, don't have the time slippage term.

I believe this means (using LR instead of SR to interpret your measurement) that two clocks *can* be synchronized and then separated, or that you could use one clock and two detectors, to measure the time it takes for light to move 0.299 meters?

And I believe it means that you won't get 1 nanosecond if the measuring rig is moving relative to the ECI frame (or to the appropriate local gravitational potential field if you are not on Earth)?

Regards,
LB

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