Mass of Photon: Consequences & Experiments - L.C. Tu et al (2004)

[Nereid]

Just another little comment ... what is 'a photon'? It's as much a theoretical construct as 'mass'. The3-decades-after-the-discovery-of-the-non-zero-'photon'-mass resolution may be that the concept of a 'photon' was off-base ... maybe it is, 'in fact', an illusion (a beautiful but complex superposition of 10^600 different types of 10^20 dimensional entities, interacting in a breath-takingly elegant fashion, describable by math that's today only vaguely known to a dozen or so folk engaged in what everyone else thinks of as just too arcane to even comment on).

Also, if the 'photon' has mass, then EM theory will need some revision. Also2, if SR needs some modification, then so will GR ... maybe leading to an entirely different view of the first microsecond of the Big Bang?

 

[Andrew Mason]

But again, as I have pointed out, and as jcsd is also trying to get across, is that it isn't AUTOMATIC that SR needs to be overhaul if we ever discover a non-zero photon mass.

Well, let me put it this way. Since
1.the SR postulates would have to be replaced,
2. the speed of light would be frame dependent and
3. the concept of a limiting speed (c) would have to be changed from the speed of light to the speed which light and everything else can approach but never reach,

our understanding of WHY there is a limiting speed at all and why relativistic effects occur (and which you see every day in your work at the Advanced Photon Source (synchrotron)) would be lost. The insight provided by SR would be lost.

However, once you get close to the Planck scale, anything can happen! Why? Because once you get close there, then our notion of how we define a LENGTH comes into play. Clearly, it is a valid question on how we actually measure the speed of anything! So the issue here isn't the fact that a photon has mass, and therefore, moves at slightly lower than c, but rather the uncertainty in our MEASUREMENT will cause an apparent shift in a photon's property. ...

It's just that, when "space" and "time" are not well-defined concepts, you will have a trouble with preserving your Lorentz symmetry.

I agree that effects observed on the Planck scale as you describe would not invalidate SR. But the existence of such effects would also not imply that all photons have rest mass.

AM

 

[ZapperZ]

I agree that effects observed on the Planck scale as you describe would not invalidate SR. But the existence of such effects would also not imply that all photons have rest mass.

AM

Correct. Only SOME photons will have "rest mass"! These are the ones we are "measuring" over the Planck scale. The rest of the photons that we are observing in the macroscopic universe are behaving the way we are familiar with.

In NONE of the papers postulating violation of the Lorentz invariance was there ever any mention of overhauling SR. In fact, none of them even claim that the discovery of such violation would require SR to be modified.[1,2] Again, I am not arguing for the validity of these idea. I am arguing the fact that even when variation to such properties of the photon/Lorentz transformation are proposed, SR is still valid! If such a scenario can exist and be thought of, then the claim that SR needs to be automatically overhaul is not correct.

Zz.

1. V.A. Kostelecky and S. Samuel, Phys. Rev. D v.63, p.111101 (2001).
2. V.A. Kostelecky and R. Potting, Phys. Rev. D v.41, p.3923 (1995).

 

[Andrew Mason]

In NONE of the papers postulating violation of the Lorentz invariance was there ever any mention of overhauling SR. In fact, none of them even claim that the discovery of such violation would require SR to be modified.[1,2] Again, I am not arguing for the validity of these idea. I am arguing the fact that even when variation to such properties of the photon/Lorentz transformation are proposed, SR is still valid! If such a scenario can exist and be thought of, then the claim that SR needs to be automatically overhaul is not correct.

Of course you could simply insert a correction term into SR. A tweaked SR would no doubt 'work'. While it would still be useful in predicting results, as a theory to explain nature, it would provide little insight.

... I am reminded of Lorentz' attempt to explain the Michelson Morely result by an arbitrary tweak to Newtonian mechanics (suggesting that motion physically shrinks distances in the direction of motion by \sqrt{1-v^2/c^2}^{-1}). But he could offer no fundamental explanation why this would be so. The importance of Einstein was that he explained the result.

AM

 

[ZapperZ]

Of course you could simply insert a correction term into SR. A tweaked SR would no doubt 'work'. While it would still be useful in predicting results, as a theory to explain nature, it would provide little insight.

... I am reminded of Lorentz' attempt to explain the Michelson Morely result by an arbitrary tweak to Newtonian mechanics (suggesting that motion physically shrinks distances in the direction of motion by \sqrt{1-v^2/c^2}^{-1}). But he could offer no fundamental explanation why this would be so. The importance of Einstein was that he explained the result.

AM

But we're NOT arguing about "insight". We're arguing your assertion that by simply having ANY non-zero mass (no matter how weak, or under what circumstances it appears), that automatically, SR cannot be salvaged and must be overhaul. I have repeated this many times that this is what I disagree.

What bothers me here is that it appears you haven't read the paper that I cited that started this thread. If you have, you would have immediately realized that there ARE formulations and adjustments made to both Maxwell equation and SR to allow for such mass. The Proca equations have been mentioned here in this thread, and in the paper in question:

The effects of a nonzero photon rest mass can be incorporated into electromagnetism straightforwardly through the Proca equations, which are the simplest relativistic generalization of Maxwell’s equations.

Furthermore:

γ Phase invariance (U(1) invariance) is lost in Proca theory, but the Lorentz gauge is automatically held, and this is indispensable to charge conservation, i.e. the Lorentz condition becomes a condition of consistency for the Proca field.

Again, I will repeat. The issue here isn't the validity of any of these things. The issue here is the claim that any such discovery on the photon mass will automatically imply an overhaul of SR, and that Lorentz symmetry cannot be salvage. If you have read this paper that started this thread, you would not have made such knee-jerk statement, because this clearly show a possibility that none of those overhauls are called for.

Zz.

 

[jcsd]

Of course you could simply insert a correction term into SR. A tweaked SR would no doubt 'work'. While it would still be useful in predicting results, as a theory to explain nature, it would provide little insight.

... I am reminded of Lorentz' attempt to explain the Michelson Morely result by an arbitrary tweak to Newtonian mechanics (suggesting that motion physically shrinks distances in the direction of motion by \sqrt{1-v^2/c^2}^{-1}). But he could offer no fundamental explanation why this would be so. The importance of Einstein was that he explained the result.

AM

Is simply restricting the set of possible postulates of SR really altering SR in any important way? I would sya not.

The explanatory power of physicasl theories lies entirely in predicting results (Lorentzian and special relativity were not strictly the same, or at least that's what I've lawas beeen led to believe).

 

[Rob Woodside]

If the postulate that all inertial frames see the same speed of light is abandoned you don't have special relativity anymore. And if the photon were to have a rest frame it could see its own speed as zero while others saw it as moving, so the postulate would have to go.

Reply:
Try replacing the second postulate with the demand of a maximum invariant speed and say nothing about light. This produces a purely mechanical special relativity that just happens to give the space-time arena required by electromagnetism- either Maxwell theory OR Proca theory.

Originally Einstein wanted to call S.R. the German equivalent of "Invariant Theory" for the invariance of light speed as required by Maxwell theory. There was not then and there is not now any physical reason to suspect that light has a rest frame. Clever theorists like Proca can play a "what if" game and people can rummage around inside error bars looking for proof. The situation is comparable to abandoning a global vector potential and looking for Dirac monopoles.

 

[Rob Woodside]

There is a big difference between an electron, or any massive object, and a photon. If Maxwell's equations are valid in all frames of reference, the speed of a photon is frame independent. There is no law of physics that requires the speed of an electron to be frame independent.

I did not give the photon a special role. Nature (and Einstein) did.

AM

Reply: Yes you did! You were claiming that if the photon had mass then BOTH postulates of Special Relativity were wrong. The great divide between massive and massless objects would not necessarily disappear if the photon had mass.

 

[Andrew Mason]

But we're NOT arguing about "insight".

Well I guess that is where we differ. I am. If a theory loses its ability to explain WHY things are the way they are, we need another theory.

You could say that Ptolemy's cycloids were a valid theory of the solar system because they 'worked'. But as a theory it offered no insight into why planets and the sun moved that way. Ptolemy needed an overhaul.

What bothers me here is that it appears you haven't read the paper that I cited that started this thread.

Your link gives me "access forbidden" so if you want me to read it, you'll have to give me a way of accessing it. Besides, you explained its essential point. The important point is the null result for the rest mass of the photon.

If you have read this paper that started this thread, you would not have made such knee-jerk statement, because this clearly show a possibility that none of those overhauls are called for.

I can assure you it is not a 'knee-jerk' reaction. It is based on about 35 years of thinking about and studying relativity. Now I may have not learned anything in those 35 years, but that is what my reaction is based on. I guess we will just have to disagree on the meaning of 'overhaul'.

I have looked at the very recent paper cited by jcsd, BTW, on the "Mass of the Photon" and find this passage illuminating:

"In the limit \omega \rightarrow \infty, the group velocity will approach the constant c, which is consistent with Einstein's assumption that there is a unique limiting velocity c for all phenomena. Therefore, a new postulate must be introduced in order to restore the features of special relativity theory for photons of nonzero mass. The postulate is as follows (Goldhaber and Nieto 1971b): given any two inertial frames, the first moving at velocity v with respect to the second, there exists a frequency \omega_0 depending on |v| and the desired accuracy \epsilon, such that any light wave of frequency greater than \omega_0 will have a speed between c and c - \epsilon in both frames.

A nonzero photon mass implies that the speed of light is not a unique constant but is a function of frequency. In fact, the assumption of the constancy of the speed of light is not necessary for the validity of special relativity, i.e. special relativity can instead be based on the existence of a unique limiting speed c to which speeds of all bodies tend when their energy becomes much larger than their mass (Kobzarev and Okun 1968, Goldhaber and Nieto 1971b). Then, the velocity that enters in the Lorentz transformation would simply be this limiting speed, not the speed of light."​

The authors say the validity of SR can maintained by changing the assumptions behind SR (BTW, Einstein did not assume the constancy of the speed of light as a unique limiting speed - he found that SR predicts that result). They offer no explanation as to what would cause the new limiting speed to exist. Would you not see the need for some new theory if that were to occur?

AM

 

[jcsd]

Andrew, Einstein did assume that the speed of light was constant, that is why it is called the second postulate, after all from a theoretical point of view a postulate is an assumption offered without explanation. And what explanation did Einstein offer for a finite constant speed of light in all inertial frames?

 

[ZapperZ]

Well I guess that is where we differ. I am. If a theory loses its ability to explain WHY things are the way they are, we need another theory.

First of all, I NEVER said that having an insight isn't necessary. I am not arguing about insight, or what it means. I am arguing your point that if A happens, then B MUST happen, without fail. The paper I cited (and I also gave a corrected link later on) clearly shows that if A happens, then it is possible that C could follow. Based on this, I argue that your

A -----> B

isn't valid, since there is a plausible alternative in C. I am not arguing if C has any "insight" or if C has any philosophical implication for the existence of the universe. All I care to point out is that its existence shows a flaw in your conclusion, that there IS another way to think of the possible consequences of A.

NOW do you get it?

Zz.

 

[Andrew Mason]

Andrew, Einstein did assume that the speed of light was constant, that is why it is called the second postulate, after all from a theoretical point of view a postulate is an assumption offered without explanation. And what explanation did Einstein offer for a finite constant speed of light in all inertial frames?

Einstein's second postulate was that the speed of light was independent of the speed of its source.See: http://www.fourmilab.ch/etexts/einstein/specrel/www/

"They suggest rather that, as has already been shown to the first order of small quantities, the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good. We will raise this conjecture (the purport of which will hereafter be called the 'Principle of Relativity') to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body."​

The conclusion that c is constant for all observers and consitutes a limiting speed readily flows from those postulates, however.

AM

 

[jcsd]

Einstein's second postulate was that the speed of light was independent of the speed of its source.See: http://www.fourmilab.ch/etexts/einstein/specrel/www/

"They suggest rather that, as has already been shown to the first order of small quantities, the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good. We will raise this conjecture (the purport of which will hereafter be called the 'Principle of Relativity') to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body."​

The conclusion that c is constant for all observers and consitutes a limiting speed readily flows from those postulates, however.

AM

That amounts to the statement that c is a constant in inertial frames and that is what it has always been understood to mean.

 

[Andrew Mason]

NOW do you get it?

Not really. I understand that one could tweak SR so that SR would still give observed results. I understand that you think that might be quite sufficient so that SR would not require a complete overhaul. I have stated my case why I disagree.

If I am driving my motorcylcle and my engine falls off, I need a major overhaul. You wouldn't say that no overhaul is needed because I can still push it and get to where I am going. I say the discovery of photon mass is like the engine falling out of SR. No amount of rubber bands are going to fix it.

To explain the ultraviolet catastrophe, Planck tried to 'tweak' classical physics by quantizing energy. But Planck never thought that was the complete answer, nor did anyone else. Planck started a revolution in physics. I am suggesting that something similar would happen if it were discovered that all photons had rest mass. I guess we will just have to wait and see. My bet is that it will not happen.

AM

 

[ZapperZ]

Not really. I understand that one could tweak SR so that SR would still give observed results. I understand that you think that might be quite sufficient so that SR would not require a complete overhaul. I have stated my case why I disagree.

I have also NEVER questioned if what you are proposing is wrong (or right, or not quite fully baked, etc). It ISN'T the point of my objection. Somehow, you are not getting this point clearly even when I have tried to illustrate the flaw in your logic.

You said that if A occurs, then ONLY B will be the consequence. I have shown you that C is also possible. Heck, C is the reason this thread exists! I really don't care if B is a valid argument. That's all it is, ONE of the POSSIBLE consequences. The fact that C also is there already negates your insistance that only B can occur. The issue isn't A, B, or C. The issue here is that C exists, and unless you can determine that it is logically incorrect, it cannot be dismissed to leave B as the ONLY possible consequence. For some odd reason, even without bothering to read the paper I cited, you dismiss ALL possible alternatives.

Zz.

 

[Andrew Mason]

The issue isn't A, B, or C. The issue here is that C exists, and unless you can determine that it is logically incorrect, it cannot be dismissed to leave B as the ONLY possible consequence. For some odd reason, even without bothering to read the paper I cited, you dismiss ALL possible alternatives.

Well I guess we are not communicating very well. Actually I have read the paper because I see that it is the same one that jcsd cited and which I quoted above.

I never said that C can't exist. I merely said that C (tweaking SR) would not prevent B from occurring (an overhaul of SR).

And in case I have confused anyone, the point I wanted to make is that the discovery of any rest mass of the photon would fundamentally change our understanding of the universe. It is not like discovering rest mass for the neutrino.

AM

 

[pervect]

of SR).

And in case I have confused anyone, the point I wanted to make is that the discovery of any rest mass of the photon would fundamentally change our understanding of the universe. It is not like discovering rest mass for the neutrino.

AM

Finding a rest mass for the photon would certainly be a big discovery, but if you are claiming that it would necessarily change our understanding of relativity, I have to disagree.

(The phrase "changing our understanding of the universe" is rather vague.)

 

[Andrew Mason]

Finding a rest mass for the photon would certainly be a big discovery, but if you are claiming that it would necessarily change our understanding of relativity, I have to disagree.

(The phrase "changing our understanding of the universe" is rather vague.)

Perhaps it is a little old-fashioned, and it is a generalization, but I look at physics as a means of understanding the physical reality we inhabit and observe, otherwise referred to as the universe.

But I guess I don't understand your question. Relativity is a theory. It is not physical reality. It is a theory that is consistent with all known facts (so far) and is successful in predicting results. So it provides a model that helps us to understand and explain physical reality.

If we should find that it is not consistent with a newly discovered fact, one wouldn't say: "I no longer understand relativity". One would say: "I no longer understand this particular physical reality because the theory of relativity, which I understand, is inconsistent with physical reality".

So I am NOT saying discovery of photon mass would change our understanding of relativity at all. Relativity would have to change. But since relativity is built on the premise that the speed of light is the same to all observers, the theory would have to change fundamentally.

AM

 

[jcsd]

Andrew what we are trying to tell you is that the idea that special relativity is dependent on electro magnetism is a misconception¹ and there are several derivations of the Lorentz transformations that do not use Einsetin's second postulate².

Clearly special relativity CAN handle a massive photon without any signifcant change, it is quite possible that the only change would be that we would no longer use derivaivations which assumed a massless photon like Einstein's original, few would agree that this would constitutes a major overhaul.


1. http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=AJPIAS000049000005000504000001&idtype=cvips&gifs=yes

2. http://arxiv.org/PS_cache/physics/pdf/0410/0410262.pdf

 

[ZapperZ]

Well I guess we are not communicating very well. Actually I have read the paper because I see that it is the same one that jcsd cited and which I quoted above.

I never said that C can't exist. I merely said that C (tweaking SR) would not prevent B from occurring (an overhaul of SR).

And I disagree for the very reason that C exists (which doesn't require B).

We have seen too many evidence that when new "violations" come into play, what in fact tends to happen is a re-evaluation of the "property" of certain quantities and a redefinition of what things mean. Case in point: what exactly in SR that cannot exceed the speed of light! We know that the phase velocity can be greater than c. So we say that the group velocity is the one that cannot exceed c. Well then, after the NEC experiment a few years ago with anomalous dispersion medium, the group velocity CAN be made to appear to be greater than c. We then reexamine what exactly is the limit imposed by SR and realize that it is actually the speed of a "signal" or "information" transfer. This is the part that is meant in SR that cannot be greater than the "speed of light".[1]

Again, the point here being that there ARE cases where we only have to readjusts the definitions and how we measure things, rather than throwing the baby out with the bathwater. These possible alternatives clearly proves that your "A must lead to B" scenario isn't correct.

Zz.

1. N Brunner et al. Phys. Rev. Lett. v.93, p.203902 (2004).

 

[Andrew Mason]

Andrew what we are trying to tell you is that the idea that special relativity is dependent on electro magnetism is a misconception¹ and there are several derivations of the Lorentz transformations that do not use Einsetin's second postulate².

Thank you for the cites. I would be particularly interested in reading the Srivastava article which, I gather, is no longer available for free. Is it worth $30 (US)?

Clearly special relativity CAN handle a massive photon without any signifcant change, it is quite possible that the only change would be that we would no longer use derivaivations which assumed a massless photon like Einstein's original, few would agree that this would constitutes a major overhaul.

While electro-magnetism provided Einstein with the insight that led to his development of the theory of relativity, his theory applies to all energy and matter. So it is not dependent on EM.

Einstein concluded that there is a relationship between time, space and the nature of energy and matter. It can be viewed in different ways. One way is to say that the speed of light is a universal constant (ie the same to all inertial observers), which was Einstein's starting point. Another way is to say that the ratio of energy to mass is a universal constant, which is what Einstein concluded. The latter statement is non-EM dependent. That could have been Einstein's postulate. And his second postulate (frame independence of c) could have been one of his conclusions.

AM

 

[jcsd]

Thank you for the cites. I would be particularly interested in reading the Srivastava article which, I gather, is no longer available for free. Is it worth $30 (US)?

I wouldn't pay that much money for an artilce, you could get a book for that much! Your library may have a susbcription and your local university library defintely will (I really don't know how these things work in the US though)

While electro-magnetism provided Einstein with the insight that led to his development of the theory of relativity, his theory applies to all energy and matter. So it is not dependent on EM.

Einstein concluded that there is a relationship between time, space and the nature of energy and matter. It can be viewed in different ways. One way is to say that the speed of light is a universal constant (ie the same to all inertial observers), which was Einstein's starting point. Another way is to say that the ratio of energy to mass is a universal constant, which is what Einstein concluded. The latter statement is non-EM dependent. That could have been Einstein's postulate. And his second postulate (frame independence of c) could have been one of his conclusions.

AM

It's the wya with any theory, you can make results into postulates and postulates into results.

 

[Andrew Mason]

Again, the point here being that there ARE cases where we only have to readjusts the definitions and how we measure things, rather than throwing the baby out with the bathwater. These possible alternatives clearly proves that your "A must lead to B" scenario isn't correct.

I don't recall having said that "A must lead to B" as in "Discovery of photon mass must lead to SR being overhauled". If I did I wish to retract that. The Theory of Relativity is a human creation and I cannot predict what humans will do in the future. I meant that "A will likely lead to B".

In my view, C (tweaking SR) would make SR no longer a theory of principle and would reduce it to a constructive theory that will not provide a sufficient understanding of our physical reality to satisfy all theoretical physicists. I predict that at least one of them, at some future time, would provide a fundamentally different theory that would successfully explain relativistic phenomena (if all photons are found to have rest mass, which I doubt will occur).

For the same reason, I predict that at least one theoretical physicist, at some future time, will provide a theory that will elevate the Standard Model from a constructive (I will avoid saying 'ad hoc') theory to a theory of principle.

AM

 

[ZapperZ]

In my view, C (tweaking SR) would make SR no longer a theory of principle and would reduce it to a constructive theory that will not provide a sufficient understanding of our physical reality to satisfy all theoretical physicists. I predict that at least one of them, at some future time, would provide a fundamentally different theory that would successfully explain relativistic phenomena (if all photons are found to have rest mass, which I doubt will occur).

For the same reason, I predict that at least one theoretical physicist, at some future time, will provide a theory that will elevate the Standard Model from a constructive (I will avoid saying 'ad hoc') theory to a theory of principle.

AM

Again, I disagree. We "tweaked" Maxwell Equations to make it covariant under a Lorentz transformation. I don't hear you downgrade it to a "constructive" theory.

Again, this tweaking process occurs all the time in physics. We tweaked Einstein's photoelectric effect equation to now include the properties of the material. We tweaked electron transport equation to include a more generalized idea of "transport" in exotic material, etc... etc. We add to our knowledge of things that start off being "simple". This process does not diminish the original concept. What Einstein postulated as something that doesn't change in all reference frame may in fact has a more generalized or redefined idea (refer to my description of group velocity versus signal velocity). In the history of science, that has often been the path that is taken in forming a more comprehensive idea. I do not see this as being a problem

Zz.

 

[Andrew Mason]

Again, I disagree. We "tweaked" Maxwell Equations to make it covariant under a Lorentz transformation. I don't hear you downgrade it to a "constructive" theory.

Well it is not a matter of downgrading it. Constructive theories play an essential part in the evolution of science. Constructive theories, such as Maxwell's equations, quantum theory, and the Standard Model are very important and useful. There are no 'pure' theories of principle and few useful theories which completely lack principle. There is a continuum from 'constructive' to 'principled' theories.

I would put Maxwell's equations about midway between a purely constructive theory and a pure theory of principle. Quantum theory and General Relativity required tweaking EM theory but since Maxwell's equations were essentially empirically derived no fundamental change in principle was required. EM theory did not predict the existence of, or rule out the existence of, the ether, of energy quanta or of gravitational effects. So nothing fundamental had to be changed to accommodate QM, SR and GR. (I may be overstating that a bit, but I think it is essentially true).

Theories of Gravitation provide good examples of this continuum. Before Newton, the theory was basically "all things naturally fall down" - a purely constructive theory with no illuminating principle to help us understand "why" or to allow us to generalize to all of nature. Planets moved the way they did because of metaphysical crystal spheres - which didn't explain much. Newton was able to provide greater insight into nature. His law of universal gravitation was based on rough measurement and astonishing intuition. Newton took a more principled approach (mathematical) than his predecessors but still it was largely a constructive theory.

Einstein took gravitation much farther and, using the principle of equivalence and the principles of relativity and the constancy of c, he developed a theory that explained the nature of gravity and described in detail how gravity and inertia defined and affected space and time.

The more 'principled' a theory is the more difficult it is to make it adapt when it is discovered that the underlying principles are wrong. That is essentially the point I was trying to make.

AM

 

[ZapperZ]

Well it is not a matter of downgrading it. Constructive theories play an essential part in the evolution of science. Constructive theories, such as Maxwell's equations, quantum theory, and the Standard Model are very important and useful. There are no 'pure' theories of principle and few useful theories which completely lack principle. There is a continuum from 'constructive' to 'principled' theories.

But I think you missed the entire point of my reply. We DO continually tweak many theories along the way. This is a common practice in physics. Either new things are found, or that certain things have to be redefined. And all of them are as important theoretically as any other. It doesn't diminish or make them less useful, even conceptually, after they have been tweaked.

I will not be surprised if SR would follow suit.

Zz.

 

[Andrew Mason]

But I think you missed the entire point of my reply. We DO continually tweak many theories along the way. This is a common practice in physics. Either new things are found, or that certain things have to be redefined. And all of them are as important theoretically as any other. It doesn't diminish or make them less useful, even conceptually, after they have been tweaked.

I will not be surprised if SR would follow suit.

I actually agree with everything you have said (after the first sentence), even your last statement. I would be surprised, however, if it turns out that photons are found to have rest mass (ie. all photons).

AM

 

[T.Roc]

Andrew,

Why do you think all photons would have the same rest mass? They don't all have the same energy, and through quantization, gives out its' info in steps (even though continuous). With mass quanta, it could be non zero and still not "trigger" our "measuring devices" (calculators included). So, all photons would not have to have non zero mass. It's really just a question of how many zeros are in front of the # representing the loss of energy as the wavelength increases. It must be replaced by mass.

TRoc

 

[Andrew Mason]

Andrew,

Why do you think all photons would have the same rest mass? They don't all have the same energy, and through quantization, gives out its' info in steps (even though continuous). With mass quanta, it could be non zero and still not "trigger" our "measuring devices" (calculators included). So, all photons would not have to have non zero mass. It's really just a question of how many zeros are in front of the # representing the loss of energy as the wavelength increases. It must be replaced by mass.

I never suggested that they would have the same rest mass (if they had rest mass). I just said they would all have to have some rest mass. Since there is no lower limit on energy for a photon a photon's rest mass would have no lower limit. But the point is, it would not be zero.

AM