Speed of light exceeded?

I’m sure this has been discussed already, but my search of the archives is still promising to forward me when results are available. It’s been 24 hours, so I’m starting to disbelieve its promise.

This article
claims that the speed of light has been exceeded under laboratory conditions.

Dr. Chu, the physicist they quote, is very dismissive of these results, saying they just confirm what is already known. I don’t understand several of the claims he makes, or that the article implies he makes.

  1. This is a natural result of wave propagation. The waves may propagate more quickly than the speed of light, causing it to seem like the light exits the chanmber before it enters. Somehow this doesn’t violate Einstein’s principle of causality.

  2. This is only possible for photons because they have no mass. I thought photons had a small, finite mass. If they have no mass, why do they fall into black holes?

  3. There is no way information could be transmitted this way. The article almost implies that information would have mass, as opposed to photons. Why couldn’t information be transmitted by light pulses?

Basically, how is it possible that this light has exceeded the speed of light in a vacuum, and why do the results not surprise Dr. Chu?

You’re right, this has been discussed before a few times. Here’s a GD thread which was kind-of hijacked by this subject. Go to the end of the thread and work backwards if you’re in a hurry!


Be sure to check out Tracer’s “barber’s pole” analogy in a post a little before mine.