As I understand, the speed of light in vacuum is bound by the speed of causality. So, light would go at infinite speed, if it could (it being massless means any acceleration should result in infinite speed), but instead it goes as fast as the universe allows, which is the speed of causality.
If you consider light in motion as a wave (as it is in EM models and I think also in current mainstream physics) then you can’t expect it to work like matter. The speed of light is the speed at which EM waves propagate. Causality is the same because many interactions are mediated by exchange of photons via EM waves.
The speed of light in aluminium is ~0.95c, the EM waves in an aluminium antenna aren’t going to interact outside the aluminium faster than 0.95c. I would bet the effective speed of causality would never be greater than the speed of light in whatever medium the light is in
As I understand, neutrons and gravitational waves are also bound by the speed of causality, because they have no mass. And I believe, unlike light, they are unaffected by electromagnetic forces that a material exerts, so they would presumably (always?) travel faster than light in that medium.
I will also say, that from what little I understand of this video: https://www.pbs.org/video/pbs-space-time-speed-light-not-about-light/
…it sounds like trying to determine the speed of causality by measuring it, is kind of backwards. You’re at best experimentally confirming what has to be a given under our laws of physics.
If the photons were travelling faster than the local speed of light, why would light be emitted? The Cherenkov radiation takes away the excess energy as the light is immediately slowed as it moves from whatever radioactive metal to water
Gravity waves are indeed different. I don’t know the maths of relativity, but I bet those equations also require specific wave speeds. They don’t care about matter aside from it’s gravity which can bend space-time and change the wave path
I think we’re pushing this beyond both our understanding
Measuring causality/c despite those being given by our maths refines our values for the various constants
Speed of light in a true vacuum.
Speed of light through any non-vacuum decreases.
The speed of causality remains the same.
is the speed of causality tied to speed of light in a vacuum, or independent of it?
As I understand, the speed of light in vacuum is bound by the speed of causality. So, light would go at infinite speed, if it could (it being massless means any acceleration should result in infinite speed), but instead it goes as fast as the universe allows, which is the speed of causality.
If you consider light in motion as a wave (as it is in EM models and I think also in current mainstream physics) then you can’t expect it to work like matter. The speed of light is the speed at which EM waves propagate. Causality is the same because many interactions are mediated by exchange of photons via EM waves.
The speed of light in aluminium is ~0.95c, the EM waves in an aluminium antenna aren’t going to interact outside the aluminium faster than 0.95c. I would bet the effective speed of causality would never be greater than the speed of light in whatever medium the light is in
I’m no expert. I probably know too little about the propagation speed of a wave to understand what you mean there.
But here is a scenario where something is faster than light in the given medium: https://en.wikipedia.org/wiki/Cherenkov_radiation
As I understand, neutrons and gravitational waves are also bound by the speed of causality, because they have no mass. And I believe, unlike light, they are unaffected by electromagnetic forces that a material exerts, so they would presumably (always?) travel faster than light in that medium.
I will also say, that from what little I understand of this video: https://www.pbs.org/video/pbs-space-time-speed-light-not-about-light/
…it sounds like trying to determine the speed of causality by measuring it, is kind of backwards. You’re at best experimentally confirming what has to be a given under our laws of physics.
If the photons were travelling faster than the local speed of light, why would light be emitted? The Cherenkov radiation takes away the excess energy as the light is immediately slowed as it moves from whatever radioactive metal to water
Gravity waves are indeed different. I don’t know the maths of relativity, but I bet those equations also require specific wave speeds. They don’t care about matter aside from it’s gravity which can bend space-time and change the wave path
I think we’re pushing this beyond both our understanding
Measuring causality/c despite those being given by our maths refines our values for the various constants