March 3, 2004
Experts Say New Desktop Fusion Claims Seem More Credible
By KENNETH CHANG
Sourcecientists are again claiming they have made a Sun in a jar, offering perhaps a revolutionary energy source, and this time even some skeptics find the evidence intriguing enough to call for a closer look.
Using ultrasonic vibrations to shake a jar of liquid solvent the size of a large drink cup, the scientists say, they squeezed tiny gas bubbles in the liquid so quickly and violently that temperatures reached millions of degrees and some of the hydrogen atoms in the solvent molecules fused, producing a flash of light and energy.
"It can do some interesting science stuff as is," said Dr. Richard T. Lahey, a professor of engineering at Rensselaer Polytechnic Institute and an author of a paper describing the findings that will appear in the journal Physical Review E.
"Our interests are to see if we can't scale it up to something more exciting," he said.
The experiment could conceivably shrink the science of fusion — slamming hydrogen atoms together, producing heat and light — from giant, expensive reactors to the tabletop.
When this team of researchers made the same claim in an article in the journal Science two years ago, many scientists reacted with skepticism, even ridicule. But new experiments, using better detectors, offer more convincing data that the phenomenon is real.
"We've addressed all the issues and now they all speak for themselves with far greater intensity than they did before," said Dr. Rusi P. Taleyarkhan, the scientist who conducted the experiments at Oak Ridge National Laboratory in Tennessee and is a professor of nuclear engineering at Purdue University.
Skepticism remains, but Dr. Lawrence A. Crum, a professor of electrical engineering at the University of Washington who was highly critical of the Science paper, said the new work was "much better" and deserved attention to determine whether the effect could be reproduced.
"It's getting to the point where you can't ignore it," Dr. Crum said.
For decades, physicists have dreamed of harnessing the ferocious alchemy of the Sun as a clean, limitless energy source. Most experiments have been conducted in giant, expensive reactors using magnetic fields to confine the ultrahot gases.
In contrast, the new experiment, which cost less than $1 million, uses the power of sound to create energy comparable to the inside of stars.
To many scientists, however, the phenomenon, nicknamed sonofusion, bears uncomfortable similarities to "cold fusion," which has now been discredited.
Sonofusion has already achieved more scientific respectability than cold fusion ever did, with two articles published in major journals.
And unlike cold fusion, sonofusion is based on known science. Scientists have long observed a phenomenon known as sonoluminescence, in which a burst of ultrasound causes a bubble in a liquid to collapse and emit a flash of light; some have speculated that the gases trapped in the collapsing bubbles could be heated to temperatures hot enough for fusion to occur.
Still, controversy enveloped the Science paper two years ago. The new research by Dr. Taleyarkhan and Dr. Lahey provides a much clearer picture of neutrons that are ejected when fusion occurs.
Many scientists like Dr. Glenn Young, head of the physics division at Oak Ridge, said the experiment was solid, but still incomplete.
"Neutrons are slippery little rascals," he said. "They can fool you. They can bounce and show up around corners you don't expect."
Copyright 2004 The New York Times Company