Fast, Slow and Backwards Light

[Dan]

Hello, I was just doing a bit of research on general relativity when I came across this about backwards travelling light.

 

http://www.rochester.edu/news/show.php?id=2544

 

Is this legitimate because all other sites I have looked on all refer to this one page. Is it possible? And I also wasn’t aware they made light go slower and faster, is that true as well? What are the implications of it?

 

Here are some of the other sites I looked at:

 

http://www.physorg.com/news66582110.html

http://www.livescience.com/technology/060518_light_backward.html

[Klaynos]

I think it's real, but no information is travelling faster than c so relativity is not violated.

[swansont]

Anomalous dispersion, i.e. pulse-reshaping. It's really neat but has been discussed several times. You can use the search function to find the existing threads.

[Meir Achuz]

It's smoke and mirrors. The animation on the webpage is a computer animation, not an experiment. In the experiment a short pulse is distorted by anomalous dispersion so that the maximum of the pulse drifts a bit backward, while the pulse moves forward. If they define speed as the movement of the peak, they call it backward.