CLAIMS that bubbles popping in a simple benchtop experiment can produce nuclear fusion may be overinflated. In March, researchers led by Rusi Taleyarkhan at Oak Ridge National Laboratory in Tennessee said they could make hydrogen nuclei fuse to produce tritium and energy by making tiny bubbles in acetone collapse, reaching temperatures of millions of degrees Celsius.
Now Ken Suslick at the University of Illinois at Urbana-Champaign and his colleagues say they鈥檙e worried about tritium found in and around the experimental apparatus. 鈥淚t appears to us that their lab was contaminated by low levels of tritium,鈥� says Suslick. But Richard Lahey of Rensselaer Polytechnic Institute in New York state counters that levels measured in the experiment were much higher than this background.