Reasoning for photon having no mass

[JulianM]

Other than relativity is there any theory, proof, experiment, etc. that tells us a photon has no mass?
i.e. Is the concept of zero mass solely derived from relativity

 

[Arman777]

Other than relativity is there any theory, proof, experiment, etc. that tells us a photon has no mass?
i.e. Is the concept of zero mass solely derived from relativity

What it will change about the reality ?

 

[Dale]

Other than relativity is there any theory, proof, experiment, etc. that tells us a photon has no mass?
i.e. Is the concept of zero mass solely derived from relativity

Certainly. There are many experiments which have measured 0 photon mass to within the experimental precision. See section 3.4 below

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

 

[DrStupid]

Is the concept of zero mass solely derived from relativity

How should it be derived instead?

 

[Vanadium 50]

DD Ryutov, Plasma Phys. Control. Fusion 49 (2007) B429–B438, "Using plasma physics to weigh the photon"

 

[JulianM]

What it will change about the reality ?

You are answering a question with a question?

 

[JulianM]

Certainly. There are many experiments which have measured 0 photon mass to within the experimental precision. See section 3.4 below

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

I don't see a section 3.4

 

[JulianM]

How should it be derived instead?

I have no idea, which is why I asked

 

[JulianM]

DD Ryutov, Plasma Phys. Control. Fusion 49 (2007) B429–B438, "Using plasma physics to weigh the photon"

I can't find any info in this ref, can you please point to some more specific part of the ref?

 

[anorlunda]

@JulianM ,

you marked this as a B level thread but most answers are too difficult to understand at B level. I recommend that you just accept what @Dale said that there are lots of experiments. To understand those experiments, you'll need more study first.

 

[Dale]

I don't see a section 3.4

Then look more carefully. It is there and it contains the experiments you asked for.

 

[Vanadium 50]

I can't find any info in this ref,

It's the whole paper!

 

[russ_watters]

Other than relativity is there any theory, proof, experiment, etc. that tells us a photon has no mass?
i.e. Is the concept of zero mass solely derived from relativity

There are some good responses, but I feel like there is another angle here, due to several questionable premises in the OP that can be addressed themsevles:

1. Relativity doesn't tell us the photon has no mass, it tells us things traveling at "the speed of light" must not have mass. This, when applied to other theories, tells us the photon should have no mass. The theory [family] describing the photon is Quantum Mechanics, not Relativity. More generally:

2. Realtivity isn't about specifically about light at all. It is essentially an historical coincidence that "C" is called "the speed of light" in Relativity, due to the fact that light was used as a tool for investigating it. Perhaps if things had gone differently at the time, "C" would be called "the speed of gravity". Or better yet, "the maximum speed of interactions/information transfer".

 

[JulianM]

It's the whole paper!

OK, let me clarify - there is nothing more than an abstract that I can find online and in order to get the whole paper it needs to be purchased. This was a high school level question so my guess is that the responses would be something better than "buy a paper on Using Plasma physics, etc."

When I read the abstract it essentially says that if the photon has mass it is very small and then recommends more work.

Some of the other responses have re-posted links they have used before without real explanation, and those (that are actually available, rather than needing a subscription or purchase, essentially seem to say the same thing.

So my interpretation of what I am being given is something like this

1. Zero mass is implied by Relativity
2. There are no other theories that would imply this (as determined from this thread)
3. Some experiments (which are too difficult for the ordinary person to understand, so just accept them) have shown that if the photon has mass then it is incredibly small, and smaller than we have been able to measure.

Did I get this right?

 

[Dale]

This was a high school level question so my guess is that the responses would be something better than "buy a paper on Using Plasma physics, etc."

Clicking a link and finding section 3.4 is entirely within the capability of a high-school level student! I cannot tell you how frustrating your response was. If a high school student cannot find it by looking at the hyperlinked table of contents, or by scrolling through the document itself, then for sure they should be able to find it by doing a text search for "3.4". I am sorry, but this is simply laziness.

3. Some experiments (which are too difficult for the ordinary person to understand, so just accept them) have shown that if the photon has mass then it is incredibly small, and smaller than we have been able to measure.

This is correct, where "ordinary person" is an "ordinary high school student". It is silly to expect that a high school student should be able to understand the experiments, however they can understand the fact that the experiments measured the mass and found it to be zero to within the experimental precision, and they can understand that the experimental precision has improved over time, and they can see what the current best precision is. At the high school level that is sufficient and is similar to the status of high-school level presentations of most modern scientific fields.

 

[Vanadium 50]

I see. So you didn't mean "I couldn't find it", you meant "I didn't look". This is very frustrating.

You asked if a measurement had been made. I pointed one out to you - what I believe is the best measurement out there at the moment. Then you said you couldn't find it - and we find out now that the reason you couldn't find it is that you didn't look. I'm not sure what else I can do here.

Dale's also right - there are several measurements on that page, and finding them requires nothing more than clicking and/or scrolling.

Equally frustrating is that your post #13 asks if zero photon mass is implied by relativity. This was already answered in Dale's post #12.

 

[JulianM]

I see. So you didn't mean "I couldn't find it", you meant "I didn't look". This is very frustrating.

You asked if a measurement had been made. I pointed one out to you - what I believe is the best measurement out there at the moment. Then you said you couldn't find it - and we find out now that the reason you couldn't find it is that you didn't look. I'm not sure what else I can do here.

Dale's also right - there are several measurements on that page, and finding them requires nothing more than clicking and/or scrolling.

Equally frustrating is that your post #13 asks if zero photon mass is implied by relativity. This was already answered in Dale's post #12.

OK, I give up - if you think it is frustrating to read my questions and what I conclude from your your postings then try reading it from my perspective.

I am gone, this forum is about as helpful as a poke in the eye.

 

[Dale]

OK, I give up

I believe this is the source of the problem. What precisely did you do to find section 3.4 before you gave up?

 

[Dale]

and we find out now that the reason you couldn't find it is that you didn't look

I googled 'DD Ryutov, Plasma Phys. Control. Fusion 49 (2007) B429–B438, "Using plasma physics to weigh the photon" ' and the first three links were full .pdf's, not just the abstract and no paywall.

 

[ZapperZ]

You can only lead a horse to water...

Zz.

 

[JulianM]

I googled 'DD Ryutov, Plasma Phys. Control. Fusion 49 (2007) B429–B438, "Using plasma physics to weigh the photon" ' and the first three links were full .pdf's, not just the abstract and no paywall.

Well I didn't, I only found a pay link, but if being the best web link poster on the forum floats your boat then have fun.

I am just going to assume that you are at least as lazy because instead of a simple response at the level asked you inflated your ego by a bunch of links.

If you can't respond appropriately then don't just humiliate andf demean.

 

[russ_watters]

I think we're done here. Julian, if you want to take a day to catch your breath and try to absorb what you've been given, please feel free to try again with specific questions referencing what has been provided to you.