No light

[initiate]

Say there were no photons, and therfore no light, though electromagnetism is otherwise unaffected. Would a "light" barrier still hold?

 

I understand the question is extremely simplistic.

[pavelcherepan]

Say there were no photons, and therfore no light, though electromagnetism is otherwise unaffected. Would a "light" barrier still hold?

 

I understand the question is extremely simplistic.

 

If by 'light barrier' you mean the barrier of speed of light then the answer is yes. If all electromagnetism still stands (and hence the Special Relativity is valid) massive particles would still be limited by the speed of light and massless particles (of which in absence of photon only gluons will be left) will be required to always travel at the speed of light.

[initiate]

hmmm... yeah yeah i get it. Even if there were no propagation of light and that somehow removed the light barrier, then "superluminal" massive particles would still be able to send signals... though that opens up new questions.

 

Well anyway, now lets say that no signal can be detected in any way, superluminal or otherwise. Would just the lack of causality violations be enough to break the light barrier?

Edited April 3, 2015 by initiate

[pavelcherepan]

From SR you get that an infinite amount of energy is required to accelerate a massive body to the speed of light.

[ajb]

I like to think of the speed of light c, as a universal constant that allows us to mix space and time. In particular as dx has units of length and dt units of duration c dt has units of length. This 'mixing' is mathematically expressed using the Lorentz transformations. Anyway, the causal structure of space-time is written into these transformations and this explicitly depends on c. It 'just happens' that the speed at which photons propagate through space is c. More carefully the speed of light is written into Maxwell's equations, but I think to think of c and the propagation of speed of light as being separate although deeply related things.

 

 

hmmm... what else about electromagnetism is maintaining it from reaching superluminal speeds aside from causality paradoxes?

Well, to answer this properly you need to study a bit more about special relativity and Maxwell's equations. With no details, special relativity is written into Maxwell's equations and you can calculate that the speed of light in vacuum and for non-accelerating observers is always c.

Edited April 3, 2015 by ajb