For all you physics lovers

I read (perhaps two years ago?) that a scientist had managed to slow a photon or group of photons down to about 35 miles per hour or something else drastically slow from the expected 186K per second. What in the hell did she do? Did it have something to do with a Bose-Einstien Condensate or is this something totally different?

I don’t know about the particular experiment to which you refered, but if I recall my physics correctly, there’s nothing particularly difficult about slowing light down. C in a vaccum is 186K and change, but light in a different medium has a slower speed (this causes the refraction effect when you put something into water. C in water is slower than C in air).

35 miles per hour seems pretty drastic, tho, and I’d also be interested in hearing how that was done…

Note that photons themselves don’t really slow down – when they hit some medium, the matter essentially absorbs and emits photons, which takes more time. While they are in between (until they hit something, so to speak) the photons still move at c.

Another interesting experiment (won a Nobel prize, I think) – electrons (probably other stuff too) can move ‘faster’ than light through some media.

Panama, are you sure about that? Granted, I’ve been away from physics for a while, but I’m sure I recall that the photons DO, in fact, slow down (depending on the medium, of course)… at least in media which are transparent (maybe translucent too)to light.

Or do I just have my head up my butt (wouldn’t be the first time; and the view’s not so great…)?

All anti-particles can be considered to be moving backward in time. Accelerating an electron itself would be impossible because it would become a black hole before it made it to c. Of course, in Feynman Diagrams reactions which do not violate standard theory can involve electrons moving backward in time (and they, too, are positrons).

Astro, you got it. I was wondering what sort of medium would be required to slow light down that much. Around that same time I recall reading about Bose Einstien Condensates which I think would be “thick” enough to slow light down. I do not believe that was how it was done, though…

Panama, the speed of light in any particular medium is constant. Interesting that you feel its caused by absorb/emit function. Don’t know one way or the other

Now I’m all curious about this… I know I have some Bose Einstein condensate around here somewhere. I just had some last week… what did I do with it?


It was a number of months ago, I vaguely remember it. The research group vaporised something… I want to say Sodium and then froze it when it was in the gas state or something odd like that (about a fraction of a degree above 0 K) then found that light moved slower than freeway speedlimits

Check this site for a quick explanation.

I’ll post another more in depth link soon.

Here’s a better article.

The faster than light concept you are talking about is called “Quantum Tunneling”. I’ll post a link to that too.

Have fun!

Tunnel diode article.

Teleportation technique article.

Laser emits matter waves article.

I KNEW it had something to do with a Condensate.

First off, there is no “C in a medium”. C is C, no matter what, and is an absolute constant. The speed of light in vacuum is C, and the speed of light in a material is less than C.

That said: Nothing can go faster than C. However, things (in principle anything, but realistically someting lightweight like an electron) can go faster than the speed of light in a given medium. There’s a shockwave produced called Cherenkov radiation, which is analogous to a sonic boom.