Physicists angry at apparent inertia in misconduct investigation.
Nine months after serious allegations were levelled against high-profile 'bubble fusion' research at Purdue University in West Lafayette, Indiana, the institution is being criticized by researchers within and outside its walls for its apparent failure to respond.
Lefteri Tsoukalas, head of the nuclear-engineering school where the work was carried out, resigned his position in October, expressing disappointment over the slow pace and secrecy of the university's response. Last week, he made his concerns public. In an open letter from his lawyer to Purdue's provost Sally Mason, Tsoukalas called for the university to release an interim report on its progress. “Purdue is a great public university, not a private club,” he told Nature.
In response, Purdue spokesman Joe Bennett confirmed for the first time that there is an ongoing inquiry at the university. “We are not going to have any comment while this is under way,” he said.
The allegations relate to the work of Rusi Taleyarkhan, a professor of nuclear engineering at Purdue. Since 2002, Taleyarkhan has published three major papers claiming to have achieved nuclear fusion by using sound waves to collapse bubbles in deuterated liquids, raising the prospect of a virtually unlimited energy source1,2,3. Tsoukalas' letter comes days after the announcement that a Texas physicist, working with Taleyarkhan in his lab, has achieved similar results (see 'Bubbling up').
In March, Nature reported concerns over the validity and reliability of Taleyarkhan's work4, based on statements made by members of Purdue's nuclear-engineering school, as well as an analysis by physicist Brian Naranjo at the University of California, Los Angeles. Naranjo's study5 showed that the spectrum of neutrons produced by Taleyarkhan's experiments fits not fusion, but the radioactive decay of californium, a standard lab material.
I'm not horrified they didn't respond, but it is in keeping with their other foot-dragging.
Purdue quickly announced that a university panel would review Taleyarkhan's work and make the findings public. In June, it said the review was complete but that its findings and any future steps would remain confidential. Since then, Purdue has released no information (until Bennett's comment this week) about whether or not it is investigating Taleyarkhan. Tsoukalas says he decided to write to Purdue because he had received no adequate response to his concerns since he first expressed them in March. Purdue's policies suggest a timeline of three months for investigating misconduct allegations.
Other researchers in the field are also far from impressed by the apparent lack of progress. Ken Suslick, for example, a professor of chemistry at the University of Illinois at Urbana-Champaign, sent a confidential note in June to Purdue's associate vice-president for research, Peter Dunn, stating that he believed Taleyarkhan's research claims are fraudulent. Suslick detailed a number of reasons for his view, including Naranjo's analysis; the fact that other teams were unable to repeat the work; and an experimental demonstration he attended at which he believed data were being “cherry-picked” by Taleyarkhan. Suslick has received no reply from Purdue.
“They have to be careful what they say in case the accusations are false, so I'm not horrified they didn't respond,” Suslick says. “But it is in keeping with their other foot-dragging. At some point they have to say that they have had an investigation and that they either exonerated him or didn't.”
Internally, misconduct allegations have been made that centre on the claim that Taleyarkhan wrote up work with his postdoc Yiban Xu claiming to have achieved bubble fusion, then left his own name off the resulting paper (he is listed in the acknowledgments)6. Taleyarkhan cited this study in a later paper3 as independent confirmation of his work.
Taleyarkhan has indicated that he is unable to respond to requests for comment about the various allegations because this might violate university's confidentiality procedures. But Taleyarkhan's co-author, Richard Lahey of Rensselaer Polytechnic Institute in Troy, New York, has defended him. “As far as I have been told, [the data] were taken by the authors of this paper,” Lahey says.
Concerns have been raised, however, over the fact that data published in Xu's paper are apparently identical to separate data reported by Taleyarkhan. Xu included a figure showing microphone measurements taken during a fusion experiment at Purdue. It includes data that look identical to those reported by Taleyarkhan from a prior experiment carried out at Oak Ridge National Laboratory in Tennessee7, where he previously worked, as well as those presented by him in a slideshow for DARPA, the Pentagon's research agency, in 2005. The results from Oak Ridge and Purdue were reported to have been produced under different experimental conditions, and the papers have no common authors. Xu has defended the measurements as his own, but declined to say who wrote the paper.
Nature showed the data to three scientists from different groups in the field. All concluded that the measurements must have been taken from the same experiment, because different acoustic cells tend to have characteristic outputs. Lahey disagrees. “If the test sections were of the same design (which they were), the response during cavitation events will be essentially the same,” he says.
For Tsoukalas, the lack of word from Purdue is damaging the reputations of all concerned. In the letter to Mason, Tsoukalas's lawyer, Philip Michael, writes: “Significant time has now elapsed since the Purdue Administration made any public statement on the progress of its investigation, inquiry or examination of the allegations of misconduct which Professor Tsoukalas and other researchers have made... we believe that it is appropriate to ask for an interim report.”
Taleyarkhan, R. P. et al. Science 295, 1868–1873 (2002).
Taleyarkhan, R. P. et al. Phys. Rev. E 69, 036109 (2004).
Taleyarkhan, R. P. et al. Phys. Rev. Lett. 96, 034301 (2006).
Reich, E. S. Nature doi:10.1038/news060306-1 (2006).
Naranjo, B. Phys. Rev. Lett. 97, 149403 (2006).
Xu, Y. & Butt, A. Nucl. Eng. Des. 235, 1317–1324 (2005).
Taleyarkhan, R. P., Lahey, R. T. & Nigmatulin, R. I. Multiphase Sci. Technol. 17, 191–224 (2005).
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Concerns grow over secrecy of bubble-fusion inquiry
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Reich, E. Purdue attacked over fusion inquiry. Nature 444, 664 (2006). https://doi.org/10.1038/444664a
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