Advanced and Delayed magnetic field's.

[Pirate88179]

I think that this will help:  http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html

Thanks Mark.  I see that they are making a very important distinction between "mass" and "rest mass", otherwise, their formulas are problematic.(according to them)   Also, I see that is very difficult to measure the mass of a photon at rest, probably impossible.

Sorry for the off-topic posts here but this is very interesting.

Thanks,

Bill

[MarkE]

Thanks Mark.  I see that they are making a very important distinction between "mass" and "rest mass", otherwise, their formulas are problematic.(according to them)   Also, I see that is very difficult to measure the mass of a photon at rest, probably impossible.

Sorry for the off-topic posts here but this is very interesting.

Thanks,

Bill

Rust never sleeps and photons never rest.

[dieter]

Tinman, thanks for the on-topic answer.


BR

[NoBull]

In college we learned that photons have "mass" as proved by some university experiments in the 70's.  (I do not recall which one)

The circularly polarized ones transfer measurable momentum on impact.

[tinman]

I think that this will help:  http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html

I dont think it helps at all.

Quote: In classical electromagnetic theory, light turns out to have energy E and momentum p, and these happen to be related by E = pc.  Quantum mechanics introduces the idea that light can be viewed as a collection of "particles": photons

Quote: Is there any experimental evidence that the photon has zero rest mass?
Answer quote: Alternative theories  of the photon include a term that behaves like a mass, and this gives rise to the very advanced idea of a "massive photon".

Quote: It is almost certainly impossible to do any experiment that would establish the photon rest mass to be exactly zero.

Quote: Likewise, the behavior of static magnetic fields would be modified.  An upper limit to the photon mass can be inferred through satellite measurements of planetary magnetic fields.  The Charge Composition Explorer spacecraft was used to derive an upper limit of 6 × 10−16 eV with high certainty.   This was slightly improved in 1998 by Roderic Lakes in a laboratory experiment that looked for anomalous forces on a Cavendish balance.  The new limit is 7 × 10−17 eV.  Studies of galactic magnetic fields suggest a much better limit of less than 3 × 10−27 eV, but there is some doubt about the validity of this method.

So we have theories and ideas based around the impossable to messure.
Next comes a change to the certain upper limit,and we have a new limit.
Then there was more studdies,and along came a much better limit,but this much better limit has some doubt about the validity of the test.

It is great to see that science and physics is soooo precise

So you see Mark,all your knowledge is based around only theories,ideas and the impossable to messure.