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

[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