A report in the journal 'Science' opens up the possibility that scientists may have created nuclear fusion on a minute scale in an acoustic cavitation experiment.
Russian and US scientists may have created nuclear fusion on a minute scale in an acoustic cavitation experiment that, if confirmed, would open the way for enormous advances in nuclear physics. Reporting on their experiment in the journal Science, Rusi Taleyarkhan of the Russian academy of Sciences, Richard Lahey of the Rensselaer Polytechnic Institute in New York and colleagues at said that they had started by creating a form of acetone by substituting deuterium for its hydrogen atoms. The ‘heavy’ acetone was then chilled to 0°C and pulsed with sound waves. Tiny bubbles no bigger than 0.1 mm appeared and then imploded, emitting flashes of light and, reportedly, high energy neutrons, the signature of an energetic nuclear reaction. However, attempts to duplicate these results (Shapira and Saltmarsh, Oak Ridge National Laboratory, Tennessee) by looking for the telltale neutron signature of the deuterium fusion reaction have yielded mixed results. While they found indications of neutron emission, subsequent experiments with a different detector system showed no neutron production at the characteristic 2.5 MeV energy level.
The phenomenon of acoustic cavitation has been known and studied for over a century. The bubbles, which grow in the presence of sound waves, collapse to produce locally high pressures and temperatures. These pressures and temperatures can be sufficiently high to result in light emissions, called sonoluminescence, long considered a pointer to creating nuclear reaction conditions.
The team used 14 MeV neutrons shot into the liquid by a pulsed neutron generator. These special conditions are believed to result in a significant increase in the final pressure of the collapsing bubbles, suggesting the possibility of producing densities and temperatures necessary for nuclear reactions. Results suggested the presence of small but statistically significant amounts of tritium above background level, which could result from the nuclear fusion of two deuterium nuclei. Tritium was not observed during cavitation of normal acetone.
But according even to Taleyarkhan and Lahey, a cautionary view is appropriate. Interpretation of tritium and neutron measurements is notoriously difficult, and the difference in neutron measurements has not been explained; but there is justification for further experimentation and grounds for a legitimate scientific debate.