Could the future of energy be found in a "star in a jar?"
In Sonofusion (2004), we introduced research from Purdue showing that sound waves pulsing through bubbles in a liquid could pop them with enough energy to produce (for a brief, tiny instant) a nuclear fusion event; in Son of Sonofusion (2005), we pointed to research by the University of Illinois at Urbana-Champaign confirming key elements of the research, including the extremely high temperatures within the bubbles; in Return of Sonofusion (2005), we presented more confirmation, and a lengthy discussion of just how this process appears to work. Now Sonofusion is back, with an answer for a key criticism of the work.
The primary piece of evidence that fusion is happening is the measurement of bursts of neutrons coinciding with the flashes from bursting bubbles. But the process, as we noted in the first sonofusion post, requires an external neutron source to prime the reaction; critics have pointed out that there's no way to be absolutely sure that the measured neutrons aren't just from the external source. Now researchers from Purdue, Rensselaer Polytechnic Institute and the Russian Academy of Sciences have produced a sonofusion reaction without any external neutron source -- and found neutron emissions from the jar:
To verify the presence of fusion, the researchers used three independent neutron detectors and one gamma ray detector. All four detectors produced the same results: a statistically significant increase in the amount of nuclear emissions due to sonofusion when compared to background levels.
As a cross-check, the experiments were repeated with the detectors at twice the original distance from the device, where the amount of neutrons decreased by a factor of about four. These results are in keeping with what would be predicted by the “inverse square law,” which provides further evidence that fusion neutrons were in fact produced inside the device, according to the researchers.
Before you go looking invest in sonofusion companies, bear in mind that the amount of energy produced by the sonofusion process is far, far less than the energy needed to make it happen. "Break-even" -- the point where a fusion reaction can sustain itself by producing more energy than it consumes -- is well off in the future, if it's possible at all. It may well be that the primary direct value of the sonofusion research is as an "inexpensive and portable source of neutrons for sensing and imaging applications." That said, there's as yet no reason to believe that a break-even version of sonofusion is impossible, and we may at some point a few decades from now be able to produce usable amounts of power from what seems on the surface to be a bizarre and surprising physical process.
But the greater value of the sonofusion research is as a confirmation that the world still holds surprises. In the first sonofusion post, I wrote something that remains true today:
...what this discovery does do right now is provide us with a friendly reminder that we can't assume that all the tools we'll have for fighting global problems have already been invented. New discoveries, new technological or social innovations add to our response capabilities. While we certainly shouldn't assume that a deus ex machina is going to save us all, neither should we despair that our current abilities are insufficient for the task at hand.
I'm not arguing that technology will save us all; I'm arguing that human innovation, ingenuity and insight -- the fruits of our global civilization -- are the best tools for giving us a shot at saving ourselves.
Sure imaging devices may be improved by this thing, but we are also sure that the greatest challenge facing human kind is the peak oil + global warming + ecological destruction tripple whammy.
I like walking distance www.ecocitybuilders.org, public transport, Solar Chimney's and flying wind turbines myself! ;-)
But I pretty much agree that it is exciting that there are still new discoveries to be made. Who knows what clever combination of existing technologies is around the corner, let alone bold new discoveries.
This changes the paradigm that nuclear physicists work under and forces a rethink in engineering of nuclear energy systems. This alone is the most important change to occur in several decades for the theoretical and applied physics community.
The cobwebs will be shaken loose and the next generation of physicist will have a wide open intellectual field to explore. I agree with Jamais...technology is a tool, not a route for salvation.
Assuming sonofusion is a reality but is not a viable source of energy, what could the neutron source be used for?
Well, if it had a high enough and cheap enough output, it might help us to cheaply transmute danagerous radioactive elements to more stable isotopes. That might help us with some forms of nuclear waste.
These days I see about the great potential of Helium-3 fusion, and the surprising possibilities of sonofusion. Could sonofusion create the higher heat necessary to fuse Helium-3?