Empirically Confirmed Superluminal Velocities?

Perfectly Innocent · sentient bipedal physicist Joined: 19 May 2003 Posts: 6

There are plenty of scientific papers and news reports touting superluminal velocities and even negative transit times for pulses of light propagating through atomic caesium vapor.

http://www.neci.nec.com/homepages/lwan/paper/paper39.pdf
http://www.neci.nec.com/homepages/lwan/paper/paper49.pdf

I wonder if this is all nonsensical hoopla based on the antiquated wave theory of light or if there is a real, measurable faster-than-light particle view of quantum mechanical tunneling going on. If I understand Richard P. Feynman correctly, photons are always particles; the wave nature of light only reveals itself in terms of probabilities. All quantum mechanists know the rules of adding amplitudes but I would like to know if something new about quantum mechanical tunneling has been revealed. Are individual photons in these experiments moving at velocities faster than light?

Eugene Shubert

The sheer mention of this result together with Einstein's theory of special relativity and the principle of causality is a scam. Not a single photon is moving faster than light.

The alleged generation of superluminal velocities without violating causality is intentionally misleading physicists' hoopla and all the media hype is pure distortion. The fact that the dramatic 60 ns advance is only one fiftieth of the width of the pulse is a clear indication of this.

starrwriter

Eugene Shubert · Posted: Wed Nov 05, 2003 1:26 pm Post subject:

Hi starrwriter.

I recall reading several articles on the sensational science news that you've mentioned. I agree on this point: If my view of physics were based on all the popular accounts that I've read, then yes; "Spooky action at a distance" has been confirmed experimentally. It's certainly not what mainstream science believes. It all boils down to how to interpret quantum mechanics. In the Copenhagen interpretation of quantum theory, particles don't have definite properties (like position and momentum) until those properties are measured. Here's the way the experiment was explained to me by one of my physics professors in a class on quantum mechanics. (I'm modifying the analogy slightly but I assure you that the professor's explanation was equally simplistic).

Imagine you have a jar of red marbles and a jar of blue marbles. Suppose you're unable to distinguish which jar is which—because your room is totally dark—but you're able to take one marble from each jar and put each marble in a separate container and then close the containers. The selection process is totally random. Suppose you mail one of these packages to a distant location at less than the speed of light. Here's the experiment. You open your container, shine a light into it and discover you have a blue marble. That measurement determines instantaneously that the color property of the transported, distant marble is red.

The original illustration used different colored socks—presumably because socks are associated in pairs and some sort of particle coupling process is involved in the experiment. Needless to say, this one physics professor wasn't impressed by the fact that certain physical properties can be thought of as propagating instantaneously.