## Thursday, March 09, 2006

### Sonofusion - star in a jar

Thermonuclear fusion is perhaps the most realistic energy source for the future. It will only become usable once experiments such as ITER succeed.

However, there are geniuses who can do the same thing in tabletop experiments. Some time ago, people would talk about the "cold fusion" all the time.

The scientists at Purdue University led by the physicist Rusi P. Taleyarkhan claim to be able to start the fusion in even more modest conditions. A popular explanation of the sonofusion is that you need two (...) things:
• Pilsner Urquell, a bottle of beer
• Some helium added to improve the flavor
• Britney Spears, a CD

You play the CD and immerse the speakers into a glass of beer. Britney, producing sound (henceforth "sonofusion") will implode the bubbles in the beer - which is why sonofusion is also called "bubble fusion". She will also generate flashes which is why sonofusion is supposed to occur during sonoluminiscence. (Sonoluminiscence is real!) Once the bubbles implode, the nuclei are so close to each other that a thermonuclear fusion starts. After a few more bottles of beer, you see that you have just made the most important breakthrough for the energy industry ever. To prove your point, you can detect by-products of thermonuclear fusion in the glass.

The scientists use acetone instead of beer, un-melodic supersound instead of Britney Spears, and neutrons and tritium instead of helium, but it is just a matter of choice. Their method is not cold fusion because by listening to Britney Spears, the beer heats up to millions of degrees, they say. ;-)

Their results were celebrated at Purdue University as early as in 2002. And the "research" apparently continues and after their 2002 findings that should normally discredit them, they were given about 1 million of dollars to replicate their "findings". The Purdue University physicist insists that his work is correct. Some of his reactionary colleagues are, however, giving this genius a hard time. See Los Angeles Times and news.google.com.

The authors admit that the number of events is not enough to build a power plant. However, there is some controversy whether the number of fusion events is what the authors say or whether it is lower by a few dozens of orders of magnitude, as implied by physics.

The mechanism behind sonoluminiscence remains a bit controversial. Claiming that a thermonuclear fusion occurs during sonoluminiscence is among the more conservative explanations. The physicist Claudia Eberlein argued that the correct explanation is that the imploding bubbles create sonic black holes and the flashes are the counterpart of Hawking radiation as the sonic black hole evaporates. You should not think that this is an example of a very, very low energy quantum gravity because the sonic black holes have no connection with the scales of gravity. It is not a supercollider in a glass of beer. But let me admit that as an undergrad, I was excited by this proposal, at least for a few minutes, but I apparently forgot the details of that encounter.

Let's wish sonofusion researchers a very good luck, they will need it. ;-) Meanwhile, I will continue to assume that experiments with the bubbles don't create QCD-scale energies.