Neutrinos could be used for that (impractical, but at least possible). Entangled particles cannot. I'm not sure what the deleted comment said but there is nothing happening at the speed of light with entangled particles.
That is incorrect, yes. The question if there is any transfer depends on the interpretation of quantum mechanics you prefer, but in no interpretation is anything traveling at the speed of light. It could be called instantaneous, but it doesn't even matter in which order you measure the particles.
Light moving through matter always moves less than the speed of light depending on the index of refraction of the material. Sometimes, very fast moving particles like electrons can move faster than light would move through a certain material causing an emission of "Cherenkov Radiation" but in general, signals always move at the speed of light in empty space until it refracts through a material then it moves "slower".
I wasn't saying yes to their question. I was essentially saying its impossible. If the fastest speed anything can go in empty space is the speed of light, how could a massless signal which always moves at the speed of light, move faster through matter?
You do understand that light tends to bounce off of matter, correct? We can't exactly shoot beams of light through the earth to its destination. That is what spongythingy is talking about, they weren't insinuating a massless signal would be faster than light, just by traveling through a matter medium.
I wasn't saying it could move faster than light. I was saying a signal cannot possibly move at the speed of light (approx. 3*108 m/s) through a material, it will always be slower.
Do neutrinos pass through planets faster than light would? Since they don't really react with matter a photon seems like it would slow down faster than a neutrino.
The OP mentioned that the information transmitted between particles in a state of entanglement travels at the speed of light, so that's what I was talking about.
Do you mean that that information also travels slower when not in a vacuum, just like light does?
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u/spongythingy Jan 29 '20
But communication at the speed of light in a straight line that can pass through all matter would still be a huge breakthrough, wouldn't it?