lene hau

anonymous asked:

I just saw a small post on tumblr about a woman, Lene Hau, who managed to stop light completely in 2001, how is that possible? how do you stop light? I tried reading about her, but it was all too complicated to understand

Yes, that’s mad science if I’ve heard of it. Very very cool.

I don’t know the technical details of how you do this but I know the gist:

Light moves through a vacuum at a constant speed of about 300,000 km/h.

When light goes through a different medium however it slows down. It slows down a lot in really dense mediums (technically in mediums with high a “high index of refraction” actually but density works for this).

Now, when something cools down it contracts (gets more dense). When it heats up, it expands (less dense). Lene Hau used lasers to cool down sodium molecules to such a ridiculous degree that it became a phase of matter called a Bose-Einstein condensate where the sodium molecules basically became more cold than anywhere else in the universe (told you this was… cool).

When light is passed through a BEC it slows incredibly. Somehow Lene was able to halt it completely within the sodium.