Thread: Do photons ALWAYS travel at c through their current medium?

I read on a post that photons have 0 rest mass. This made me wonder if this meant (and this could be ludicrous) that any propulsion applied to them, no matter how small, would accelerate them to c meaning that all photons would either be at c or at rest (if even that is possible).

Also an entirely different question that I didn't think was worth creating another whole topic for; Is there such a thing as a unit of space so small that it could be said to be an "elementary" unit of space? I guess you could define this as nothing other than a boson could fit more than one of itself into it. I do wonder if the defining an elementary unit of space nullifys the question.

To give context of where the thought rose, I was reading the "boson" page on Wikipedia and it mentioned that multiple bosons could occupy the same "quantum state" and I didn't really understand the definition of quantum state.

Photons CANNOT be at rest. They only travel at C.

There is speculation that at the Planck length the distinction between space and time disappears into a sort of quantum foam. If string theory is correct and elementary particles such as bosons, have a 'size' near Planck length, then yes, maybe only a certain number can fit into this space, unless the strings can overlap.

A quantum state is not the same as space, rather it is defined by a set of quantum numbers.

Quantum numbers define the exact location of an electron in an atom.

Try fundamentals of physics by halliday resnik. And H.C. Verma physics .
You have to read about a state of matter called bose einstien condensate .

They have been able to slow photons in cesium gas(cold/liquid?) to a point where we can see it as storing them:

http://www.cosmosmagazine.com/node/985

". They're currently working towards delaying dozens of pulses for as long as several milliseconds, and as many as 10,000 pulses for up to a nanosecond."

But this is achieved through successive absorptions and emissions. While in existence the photon always travels at c.

Quantum numbers do not define an exact location in space, but a probability of finding a particle in a specified location.
You should try fundamental physics of Heisenberg and his uncertainty principle upon which all QM is based.