## Saturday, March 08, 2008

### Hawking radiation "heard"

The physics arXiv blog (don't get too confused by the officially sounding name!) has pointed out a pretty entertaining condensed matter "experiment":
Carusotto et al. (preprint)
The Italian team has constructed an acoustic counterpart of a gravitational black hole out of a flowing one-dimensional Bose-Einstein condensate. The velocity creates a sonic barrier, a version of the event horizon.

And this "acoustic black hole" indeed does emit Hawking radiation composed of phonons, as demonstrated by long-range patterns in the density-density correlation function of the gas i.e. by everything strange about the picture above away from the yellow diagonal line.

I haven't told you one more disappointing thing. Even the acoustic "experiment" has so far only been done numerically. Some skillful experimenters will hopefully do better. ;-)

1. I just read this yesterday:

http://www.physorg.com/news124041342.html

They can't observe the analogue of Hawking radiation yet, but at least they say they can form an optical black hole.

2. This is not directly related to this post.

I was curious to see if one could approach real analysis from a more physical standpoint. I am not aware of similar work.

I would welcome any comments

http://www.newcomensengine.com/2008/03/interesting-creature_09.html

3. Hi Lubos,
where are you right now?
I find this on Wiki:"Luboš Motl... He currently has no known academic affiliation, though in July, 2007 he announced his plans to return to the Czech Republic after leaving academia.[1] His blog[2] lists his current location as Pilsen, Czech Republic."

4. This comment has been removed by the author.