Originally posted by Eyesaw
Well, Maxwell's equations for EM radiation are wave equations,
so they need a medium since waves don't exist as far everyday
observations go, independent of a medium.
Why not? What substrate is implied by Maxwell's equations?
Everyone at the time believed in an ether so I think it’s a good assumption to say that the whole Electromagnetic model was based on an ether as substrate. I don’t think anyone before Einstein would have been crazy enough to think a wave can exist absence of a medium since waves are not the actual particle motion but the silhouette of their collective motion. A common illustration of wave motion is the people in a stadium who start standing up and down one by one- if you only have one person in the stadium, you can’t have wave motion.
To derive Maxwell's
equations without an ether then would require one to show
that the vacuum is completely empty, else one can always assume
a medium that is just too small to be observed.
"Too small"?
The light that we see from the sun travels 93 million miles to Earth! In what sense is this supposed medium "too small"?
I think you misunderstood the sentence. I’m saying there’s no way to reject the idea that some medium exists in which light is just the disturbance in the medium, like any normal wave, since one can always argue that the stuff consisting of the medium are too small to be detectable by current technology. For example, Dr. Tom Van Flandern proposes such a medium in the Meta Model which they called the Elysium. The medium you are speaking of here is total empty space of which there would exist no properties, which is entirely opposite to the ether medium Maxwell and all those who developed the Maxwell equations envisioned. So if you are going to derive Maxwell’s equations based on the ability of light as a wave that travels without a medium, you have to show that this is possible in the first place. But as mentioned before, you can’t rule out the possibility of a medium consisting of particles too tiny to be detected which could explain the wave motion so you this introduction of a radically new concept- that of a wave existing without a medium- becomes unnecessary.
Since this can never be done, it's more economical to assume light, if it is a wave, requires like every observable wave phenomenon,
a medium for propogation. So you need an ether to derive Maxwell's equations.
Why is it more economical to add an assumption?
You are not adding an assumption when considering an ether necessary for wave motion. Are you adding an assumption by saying that ocean waves need an ocean to exist? If so, you should take that up with Mother Nature. While you’re at it, you should file the complaint also that gravity is unnecessary since we already have attractive motion in Electromagnetism. If a wave model already exists that can explain EM radiation, the introduction of a new model for waves just to accommodate light becomes uneconomical, especially since it contradicts the mountains of evidence for normal wave behaviour in sound and other waves.
An alternative would be to consider light as particles, in which case you would have to explain why their velocity is not source dependent like other ballistic particles.
Tom:
We do consider light as particles, when the intensity of the radiation is sufficiently weak. But why do we have to explain why the velocity of those particles is not source dependent? That is like demanding an explanation of why the charge of an electron has the value that it does.
Well, because in every particle we know of when momentum is transferred, they gain velocity. Since SR rejected the ether and yet assumes source independency of light, both of which are “assumptions” which totally contradicted all evidence of wave and particle behavior prior to Einstein, the one proposing such radical ideas should provide some clear evidence such contradictions are necessary to explain the behavior of light. Or develop a mathematical model to demonstrate this special behavior. All Einstein seemed to have done in SR is point out that Maxwell’s equations predict a constant speed c for EM waves propagating in a uniformly dense ether. But since he got rid of the ether, he loses
his right to use Maxwell's equations for his theories.
