Are any materials faster than light?

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Offline thedoc

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Are any materials faster than light?
« on: 28/09/2015 19:50:01 »
Joey Kanyi asked the Naked Scientists:
   
Which material is faster than light?
What do you think?
« Last Edit: 28/09/2015 19:50:01 by _system »

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Offline chiralSPO

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Re: Are any materials faster than light?
« Reply #1 on: 28/09/2015 21:15:17 »
Nothing with mass can move faster than light does in a vacuum.

One can shoot particles with non-zero mass at really high speeds through a medium like water, where they can have speeds greater than the speed of light in that medium (https://en.wikipedia.org/wiki/Cherenkov_radiation)

Particles can also tunnel and "instantaneously" be in one place and then the other, but it didn't actually move from point A to point B, the distances over which this happens are almost always significantly shorter than the width of a human hair, and no information can be transmitted this way (as far as we know) so don't get your hopes up. (https://en.wikipedia.org/wiki/Quantum_tunnelling)

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Offline evan_au

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Re: Are any materials faster than light?
« Reply #2 on: 28/09/2015 22:09:55 »
There are some materials, where if you carefully prepare them, and inject light of just the right frequency, will slow down the propagation of light to a walking pace (and even stop it).

So, you could outrun light traveling through such a material!

But the speed of light as a speed limit only applies to light traveling in a vacuum.

(There are some theoretical particles called "Tachyons" which only move faster than the speed of light, but there is no solid evidence for them at this point in time.)

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Offline mathew_orman

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Re: Are any materials faster than light?
« Reply #3 on: 29/09/2015 08:54:37 »
Again, it is not possible to slow down a photon or electromagnetic wave...
Life of a photon ends when it intersect an atomic structure...
Experiments showing assumed slow down of a photon are noting else but an acousto-optic phenomena of moving light emission spot or source... 
Visible spectrum photon would be invisible if slowed down...
« Last Edit: 29/09/2015 08:56:30 by mathew_orman »

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Offline PmbPhy

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Re: Are any materials faster than light?
« Reply #4 on: 29/09/2015 10:42:58 »
Quote from: Aquarius
there is no such thing as a vacuum in space,
That's not quite correct. You're thinking that a vacuum is a region of space which has literally nothing in it. That's not what physicists mean when they speak of a vacuum. We think of regions of space which has no atoms in it. That's different than what you said.

Quote from: Aquarius
Photons are force carriers spinning pole over pole.
That's not what a photon is. It doesn't even make a hell of a lot of sense either.