Nuclear fusion is normally understood to occur at temperatures in the tens of millions of degrees. This is called "
thermonuclear fusion". Since the 1920s, there has been speculation that nuclear fusion might be possible at much lower temperatures by
catalytically fusing hydrogen absorbed in a metal catalyst. In 1989, a claim by Stanley Pons and Martin Fleischmann (then one of the world's leading
electrochemists) that such cold fusion had been observed caused a brief
media sensation before the majority of scientists criticized their claim as incorrect after many found they could not replicate the excess heat. Since the initial announcement, cold fusion research has continued by a small community of researchers who believe that such reactions happen and hope to gain wider recognition for their experimental evidence.
Early research The ability of
palladium to absorb hydrogen was recognized as early as the nineteenth century by
Thomas Graham. In the late 1920s, two Austrian-born scientists,
Friedrich Paneth and
Kurt Peters, originally reported the transformation of hydrogen into helium by nuclear catalysis when hydrogen was absorbed by finely divided palladium at room temperature. However, the authors later retracted that report, saying that the helium they measured was due to background from the air. In 1927, Swedish scientist John Tandberg reported that he had fused hydrogen into helium in an
electrolytic cell with palladium electrodes. On the basis of his work, he applied for a Swedish patent for "a method to produce helium and useful reaction energy". Due to Paneth and Peters's retraction and his inability to explain the physical process, his patent application was denied. After
deuterium was discovered in 1932, Tandberg continued his experiments with
heavy water. The final experiments made by Tandberg with heavy water were similar to the original experiment by Fleischmann and Pons. Fleischmann and Pons were not aware of Tandberg's work.
Fleischmann–Pons experiment The most famous cold fusion claims were made by Stanley Pons and Martin Fleischmann in 1989. After a brief period of interest by the wider scientific community, their reports were called into question by nuclear physicists. Pons and Fleischmann never retracted their claims, but moved their research program from the US to France after the controversy erupted.
Events preceding announcement Martin Fleischmann of the
University of Southampton and
Stanley Pons of the
University of Utah hypothesized that the high compression ratio and mobility of
deuterium that could be achieved within palladium metal using electrolysis might result in nuclear fusion. To investigate, they conducted electrolysis experiments using a palladium cathode and heavy water within a
calorimeter, an insulated vessel designed to measure
process heat. Current was applied continuously for many weeks, with the
heavy water being renewed at intervals. Some deuterium was thought to be accumulating within the cathode, but most was allowed to bubble out of the cell, joining oxygen produced at the
anode. For most of the time, the power input to the cell was equal to the calculated power leaving the cell within measurement accuracy, and the cell temperature was stable at around 30 °C. But then, at some point (in some of the experiments), the temperature rose suddenly to about 50 °C without changes in the input power. These high temperature phases would last for two days or more and would repeat several times in any given experiment once they had occurred. The calculated power leaving the cell was significantly higher than the input power during these high temperature phases. Eventually the high temperature phases would no longer occur within a particular cell. In 1988, Fleischmann and Pons applied to the
United States Department of Energy for funding towards a larger series of experiments. Up to this point they had been funding their experiments using a small device built with $100,000
out-of-pocket. The grant proposal was turned over for
peer review, and one of the reviewers was
Steven Jones of
Brigham Young University. Jones had worked for some time on
muon-catalyzed fusion, a known method of inducing nuclear fusion without high temperatures, and had written an article on the topic entitled "Cold nuclear fusion" that had been published in
Scientific American in July 1987. Fleischmann and Pons and co-workers met with Jones and co-workers on occasion in
Utah to share research and techniques. During this time, Fleischmann and Pons described their experiments as generating considerable "excess energy", in the sense that it could not be explained by
chemical reactions alone. They felt that such a discovery could bear significant commercial value and would be entitled to
patent protection. Jones, however, was measuring neutron flux, which was not of commercial interest. To avoid future problems, the teams appeared to agree to publish their results simultaneously, though their accounts of their 6 March meeting differ.
Announcement In mid-March 1989, both research teams were ready to publish their findings, and Fleischmann and Jones had agreed to meet at an airport on 24 March to send their papers to
Nature via
FedEx. Fleischmann and Pons, however, pressured by the University of Utah, which wanted to establish priority on the discovery, (they claimed in the press release that it would be published in
Nature Many scientists were also reminded of the
Mössbauer effect, a process involving
nuclear transitions in a solid. Its discovery 30 years earlier had also been unexpected, though it was quickly replicated and explained within the existing physics framework. The announcement of a new purported clean source of energy came at a crucial time: adults still remembered the
1973 oil crisis and the problems caused by oil dependence, anthropogenic
global warming was starting to become notorious, the
anti-nuclear movement was labeling nuclear power plants as dangerous and getting them closed, people had in mind the consequences of
strip mining,
acid rain, the
greenhouse effect and the
Exxon Valdez oil spill, which happened the day after the announcement. In the press conference,
Chase N. Peterson, Fleischmann and Pons, backed by the solidity of their scientific credentials, repeatedly assured the journalists that cold fusion would solve environmental problems, and would provide a limitless inexhaustible source of clean energy, using only seawater as fuel. They said the results had been confirmed dozens of times and they had no doubts about them. In the accompanying press release Fleischmann was quoted saying: "What we have done is to open the door of a new research area, our indications are that the discovery will be relatively easy to make into a usable technology for generating heat and power, but continued work is needed, first, to further understand the science and secondly, to determine its value to energy economics."
Response and fallout Although the experimental protocol had not been published, physicists in several countries attempted, and failed, to replicate the excess heat phenomenon. The first paper submitted to
Nature reproducing excess heat, although it passed peer review, was rejected because most similar experiments were negative and there were no theories that could explain a positive result; while
CERN physicist Douglas R. O. Morrison said that "essentially all" attempts in Western Europe had failed. Even those reporting success had difficulty reproducing Fleischmann and Pons' results. On 10 April 1989, a group at
Texas A&M University published results of excess heat and later that day a group at the
Georgia Institute of Technology announced neutron production—the strongest replication announced up to that point due to the detection of neutrons and the reputation of the lab. became the only scientific support for cold fusion in 26 April US Congress hearings. and his research was derided by scientists who saw it later. For the next six weeks, competing claims, counterclaims, and suggested explanations kept what was referred to as "cold fusion" or "fusion confusion" in the news. In April 1989, Fleischmann and Pons published a "preliminary note" in the
Journal of Electroanalytical Chemistry. This paper notably showed a gamma peak without its corresponding
Compton edge, which indicated they had made a mistake in claiming evidence of fusion byproducts. Fleischmann and Pons replied to this critique, but the only thing left clear was that no gamma ray had been registered and that Fleischmann refused to recognize any mistakes in the data. A much longer paper published a year later went into details of calorimetry but did not include any nuclear measurements. Nevertheless, Fleischmann and Pons and a number of other researchers who found positive results remained convinced of their findings. The University of Utah asked Congress to provide $25 million to pursue the research, and Pons was scheduled to meet with representatives of President Bush in early May. On 30 April 1989, cold fusion was declared dead by
The New York Times. The
Times called it a circus the same day, and the
Boston Herald attacked cold fusion the following day. On 1 May 1989, the
American Physical Society held a session on cold fusion in Baltimore, including many reports of experiments that failed to produce evidence of cold fusion. At the end of the session, eight of the nine leading speakers stated that they considered the initial Fleischmann and Pons claim dead, with the ninth,
Johann Rafelski, abstaining.
Steven E. Koonin of
Caltech called the Utah report a result of "
the incompetence and delusion of Pons and Fleischmann," which was met with a standing ovation.
Douglas R. O. Morrison, a physicist representing
CERN, was the first to call the episode an example of
pathological science. On 4 May, due to all this new criticism, the meetings with various representatives from Washington were cancelled. From 8 May, only the A&M tritium results kept cold fusion afloat. In July and November 1989,
Nature published papers critical of cold fusion claims. Negative results were also published in several other
scientific journals including
Science,
Physical Review Letters, and
Physical Review C (nuclear physics). However, no further DOE nor NSF funding resulted from the panel's recommendation. By this point, academic consensus had moved decidedly toward labeling cold fusion as a kind of "pathological science". University faculty were then "stunned" when a lawyer representing Pons and Fleischmann demanded the Salamon paper be retracted under threat of a lawsuit. The lawyer later apologized; Fleischmann defended the threat as a legitimate reaction to alleged bias displayed by cold-fusion critics. In early May 1990, one of the two A&M researchers,
Kevin Wolf, acknowledged the possibility of spiking, but said that the most likely explanation was tritium contamination in the palladium electrodes or simply contamination due to sloppy work. In June 1990 an article in
Science by science writer
Gary Taubes destroyed the public credibility of the A&M tritium results when it accused its group leader
John Bockris and one of his graduate students of spiking the cells with tritium. In October 1990 Wolf finally said that the results were explained by tritium contamination in the rods. An A&M cold fusion review panel found that the tritium evidence was not convincing and that, while they couldn't rule out spiking, contamination and measurements problems were more likely explanations, it found no excess heat, and its reports of tritium production were met with indifference. On 1 January 1991, Pons left the University of Utah and went to Europe. In 1992, Pons and Fleischmann resumed research with
Toyota's IMRA lab in France. Fleischmann left for England in 1995, and the contract with Pons was not renewed in 1998 after spending $40 million with no tangible results. The IMRA laboratory stopped cold fusion research in 1998 after spending £12 million. Pons has made no public declarations since, and only Fleischmann continued giving talks and publishing papers. Mostly in the 1990s, several books were published that were critical of cold fusion research methods and the conduct of cold fusion researchers. Over the years, several books have appeared that defended them. Around 1998, the University of Utah had already dropped its research after spending over $1 million, and in the summer of 1997, Japan cut off research and closed its own lab after spending $20 million. == Later research ==