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Forum: Processes Involving Optical Photons
Re: Question Faster Than Light Photons? (Joel Long)
Re: More Re: Faster Than Light Photons? (Joel Long)
Re: More Re: Faster Than Light Photons? (Joel Long)
Re: Feedback Re: Faster Than Light Photons? (Gumplinger Peter)
Re: Feedback Re: Faster Than Light Photons? (Joel Long)
Date: 16 Jul, 2012
From: Gumplinger Peter <Gumplinger Peter>

Hello Joel,

> 
> > > My understanding was that the group velocity *could* be greater than the
> > > speed of light,
> > That's news to me...
> 
> To quote: "A widespread misconception is that since, according to the
> theory of relativity, nothing can travel faster than the speed of light
> in vacuum, the refractive index cannot be lower than 1. This is
> erroneous since the refractive index measures the phase velocity of
> light, which does not carry energy or information, the two things
> limited in propagation speed. The phase velocity is the speed at which
> the crests of the wave move and can be faster than the speed of light in
> vacuum, and thereby give a refractive index below 1."
> 
> Maybe that's wrong - it's not my area of physics at all - but that's
> where I got that understanding from.

You are quoting that the phase velocity can by larger than the speed of light. Optical photons in G4 are particles, they carry energy and information and travel with group velocity.

> In any case, I might actually see some photons go through in reality.

For a dielectric_dielectric surface you may specify a transmittance which will replace the refraction probability.

Peter

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1 Idea: Re: Faster Than Light Photons?   (Erik Dietz-Laursonn - 14 Sep, 2012)
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