Cold fusion is a hypothesized type of

nuclear reaction In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformatio ...

that would occur at, or near,

room temperature Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...

. It would contrast starkly with the "hot" fusion that is known to take place naturally within

stars A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

and artificially in

hydrogen bombs A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lowe ...

and prototype fusion reactors under immense pressure and at temperatures of millions of degrees, and be distinguished from muon-catalyzed fusion. There is currently no accepted theoretical model that would allow cold fusion to occur. In 1989, two electrochemists, Martin Fleischmann and Stanley Pons, reported that their apparatus had produced anomalous heat ("excess heat") of a magnitude they asserted would defy explanation except in terms of nuclear processes. They further reported measuring small amounts of nuclear reaction byproducts, including

neutrons The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beha ...

and

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus ...

. ("It is inconceivable that this

mount of heat Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

could be due to anything but nuclear processes... We realise that the results reported here raise more questions than they provide answers...") The small tabletop experiment involved electrolysis of heavy water on the surface of a

palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself nam ...

(Pd) electrode. The reported results received wide media attention and raised hopes of a cheap and abundant source of energy. Many scientists tried to replicate the experiment with the few details available. Hopes faded with the large number of negative replications, the withdrawal of many reported positive replications, the discovery of flaws and sources of experimental error in the original experiment, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts. By late 1989, most scientists considered cold fusion claims dead,, , , and cold fusion subsequently gained a reputation as pathological science. In 1989 the

United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United Stat ...

(DOE) concluded that the reported results of excess heat did not present convincing evidence of a useful source of energy and decided against allocating funding specifically for cold fusion. A second DOE review in 2004, which looked at new research, reached similar conclusions and did not result in DOE funding of cold fusion. Presently, since articles about cold fusion are rarely published in

peer-reviewed Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work ( peers). It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer revie ...

mainstream

scientific journal In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Content Articles in scientific journals are mostly written by active scientists such ...

s, they do not attract the level of scrutiny expected for mainstream

scientific publications : ''For a broader class of literature, see Academic publishing.'' Scientific literature comprises scholarly publications that report original empirical and theoretical work in the natural and social sciences. Within an academic field, sc ...

. Nevertheless, some interest in cold fusion has continued through the decades—for example, a Google-funded failed replication attempt was published in a 2019 issue of ''Nature''. A small community of researchers continues to investigate it,, , , , , "Advocates insist that there is just too much evidence of unusual effects in the thousands of experiments since Pons and Fleischmann to be ignored", , , . calculates between 100 and 200 researchers, with damage to their careers. often under the alternative designations ''low-energy nuclear reactions'' (''LENR'') or ''condensed matter nuclear science'' (''CMNS'').

History

Nuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifest ...

is normally understood to occur at temperatures in the tens of millions of degrees. This is called "

thermonuclear fusion Thermonuclear fusion is the process of atomic nuclei combining or “fusing” using high temperatures to drive them close enough together for this to become possible. There are two forms of thermonuclear fusion: ''uncontrolled'', in which the re ...

". 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 Media circus is a colloquial metaphor, or idiom, describing a news event for which the level of media coverage—measured by such factors as the number of reporters at the scene and the amount of material broadcast or published—is perceived t ...

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 Friedrich Adolf Paneth (31 August 1887 – 17 September 1958) was an Austrian-born British chemist. Fleeing the Nazis, he escaped to Britain. He became a naturalized British citizen in 1939. After the war, Paneth returned to Germany to b ...

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 An electrolytic cell is an electrochemical cell that utilizes an external source of electrical energy to force a chemical reaction that would not otherwise occur. The external energy source is a voltage applied between the cell′s two elect ...

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 Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...

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. The term "cold fusion" was used as early as 1956 in an article in ''The New York Times'' about Luis Alvarez's work on muon-catalyzed fusion.

Paul Palmer Paul Palmer may refer to: * Paul Palmer (American football) (born 1964), American football player * Paul Palmer (cricketer) (born 1992), Jamaican cricketer * Paul Palmer (minister) (died 1747), American religious leader * Paul Palmer (physicist) (1 ...

and then Steven Jones of

Brigham Young University Brigham Young University (BYU, sometimes referred to colloquially as The Y) is a private research university in Provo, Utah. It was founded in 1875 by religious leader Brigham Young and is sponsored by the Church of Jesus Christ of Latter-day ...

used the term "cold fusion" in 1986 in an investigation of "geo-fusion", the possible existence of fusion involving hydrogen isotopes in a

planetary core A planetary core consists of the innermost layers of a planet. Cores may be entirely solid or entirely liquid, or a mixture of solid and liquid layers as is the case in the Earth. In the Solar System, core sizes range from about 20% (the Moon ...

. In his original paper on this subject with Clinton Van Siclen, submitted in 1985, Jones had coined the term "piezonuclear fusion".

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 USA to France after the controversy erupted.

Events preceding announcement

Martin Fleischmann of the

University of Southampton , mottoeng = The Heights Yield to Endeavour , type = Public research university , established = 1862 – Hartley Institution1902 – Hartley University College1913 – Southampton University Coll ...

and Stanley Pons of the

University of Utah The University of Utah (U of U, UofU, or simply The U) is a public research university in Salt Lake City, Utah. It is the flagship institution of the Utah System of Higher Education. The university was established in 1850 as the University of D ...

hypothesized that the high compression ratio and mobility of

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

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 Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work ( peers). It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer revie ...

, and one of the reviewers was Steven Jones of

. 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 ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it i ...

'' in July 1987. Fleischmann and Pons and co-workers met with Jones and co-workers on occasion in

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

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 reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...

s 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 Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans ar ...

'' via FedEx. Fleischmann and Pons, however, pressured by the University of Utah, which wanted to establish priority on the discovery, broke their apparent agreement, disclosing their work at a press conference on 23 March (they claimed in the press release that it would be published in ''Nature'' but instead submitted their paper to the ''Journal of Electroanalytical Chemistry''). Jones, upset, faxed in his paper to ''

'' after the press conference. Fleischmann and Pons' announcement drew wide media attention. But the 1986 discovery of

high-temperature superconductivity High-temperature superconductors (abbreviated high-c or HTS) are defined as materials that behave as superconductors at temperatures above , the boiling point of liquid nitrogen. The adjective "high temperature" is only in respect to previo ...

had made the scientific community more open to revelations of unexpected scientific results that could have huge economic repercussions and that could be replicated reliably even if they had not been predicted by established theories. 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 In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate variability and change, Climate change in a broader sense also includes ...

was starting to become notorious, the

anti-nuclear movement The anti-nuclear movement is a social movement that opposes various nuclear technologies. Some direct action groups, environmental movements, and professional organisations have identified themselves with the movement at the local, nationa ...

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 The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...

and the

Exxon Valdez oil spill The ''Exxon Valdez'' oil spill occurred in Prince William Sound, Alaska, on March 24, 1989. '' Exxon Valdez'', an oil supertanker owned by Exxon Shipping Company bound for Long Beach, California struck Prince William Sound's Bligh Reef, west ...

, which happened the day after the announcement. In the press conference,

Chase N. Peterson Chase Nebeker Peterson (December 27, 1929 – September 14, 2014) was an American physician who became dean of admissions at his alma mater, Harvard University, and dean of the health sciences at the University of Utah, before being selected presi ...

, 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; this paper was later accepted for publication by the journal ''Fusion Technology''. Nathan Lewis, professor of chemistry at the

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

, led one of the most ambitious validation efforts, trying many variations on the experiment without success, 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 Texas A&M University (Texas A&M, A&M, or TAMU) is a public, land-grant, research university in College Station, Texas. It was founded in 1876 and became the flagship institution of the Texas A&M University System in 1948. As of late 2021, T ...

published results of excess heat and later that day a group at the

Georgia Institute of Technology The Georgia Institute of Technology, commonly referred to as Georgia Tech or, in the state of Georgia, as Tech or The Institute, is a public research university and institute of technology in Atlanta, Georgia. Established in 1885, it is part of ...

announced neutron production—the strongest replication announced up to that point due to the detection of neutrons and the reputation of the lab. On 12 April Pons was acclaimed at an ACS meeting. But Georgia Tech retracted their announcement on 13 April, explaining that their neutron detectors gave false positives when exposed to heat. Another attempt at independent replication, headed by

Robert Huggins Robert Alan Huggins is Professor Emeritus at the Department of Materials Science and Engineering at the Stanford University School of Engineering, School of Engineering at Stanford University and Honorary Professor at the University of Kiel and the ...

at Stanford University, which also reported early success with a light water control, became the only scientific support for cold fusion in 26 April US Congress hearings. But when he finally presented his results he reported an excess heat of only one degree Celsius, a result that could be explained by chemical differences between heavy and light water in the presence of lithium. He had not tried to measure any radiation 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 Johann Rafelski (born 19 May 1950) is a German-American theoretical physicist. He is professor of Physics at The University of Arizona in Tucson, guest scientist at CERN (Geneva), and has been LMU-Excellent Guest Professor at the Ludwig Maximil ...

, abstaining.

Steven E. Koonin Steven Elliot Koonin (born December 12, 1951) is an American theoretical physicist and former director of the Center for Urban Science and Progress at New York University. He is also a professor in the Department of Civil and Urban Engineering at ...

Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

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 Douglas may refer to: People * Douglas (given name) * Douglas (surname) Animals *Douglas (parrot), macaw that starred as the parrot ''Rosalinda'' in Pippi Longstocking * Douglas the camel, a camel in the Confederate Army in the American Civil ...

, 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

s including ''

Science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earli ...

'', ''

Physical Review Letters ''Physical Review Letters'' (''PRL''), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. As also confirmed by various measurement standards, which include the '' Jou ...

'', and '' Physical Review C'' (nuclear physics). In August 1989, in spite of this trend, the state of

invested $4.5 million to create the National Cold Fusion Institute. The

organized a special panel to review cold fusion theory and research. The panel issued its report in November 1989, concluding that results as of that date did not present convincing evidence that useful sources of energy would result from the phenomena attributed to cold fusion. The panel noted the large number of failures to replicate excess heat and the greater inconsistency of reports of nuclear reaction byproducts expected by established

conjecture In mathematics, a conjecture is a conclusion or a proposition that is proffered on a tentative basis without proof. Some conjectures, such as the Riemann hypothesis (still a conjecture) or Fermat's Last Theorem (a conjecture until proven in 1 ...

. Nuclear fusion of the type postulated would be inconsistent with current understanding and, if verified, would require established conjecture, perhaps even theory itself, to be extended in an unexpected way. The panel was against special funding for cold fusion research, but supported modest funding of "focused experiments within the general funding system". Cold fusion supporters continued to argue that the evidence for excess heat was strong, and in September 1990 the National Cold Fusion Institute listed 92 groups of researchers from 10 countries that had reported corroborating evidence of excess heat, but they refused to provide any evidence of their own arguing that it could endanger their patents. However, no further DOE nor NSF funding resulted from the panel's recommendation. By this point, however, academic consensus had moved decidedly toward labeling cold fusion as a kind of "pathological science". In March 1990, Michael H. Salamon, a physicist from the

, and nine co-authors reported negative results. 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 Kevin () is the anglicized form of the Irish masculine given name (; mga, Caoimhghín ; sga, Cóemgein ; Latinized as ). It is composed of "dear; noble"; Old Irish and ("birth"; Old Irish ). The variant '' Kevan'' is anglicized from , a ...

, 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, and Bockris never got support from his faculty to resume his research. On 30 June 1991, the National Cold Fusion Institute closed after it ran out of funds; 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 Motor Corporation is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 m ...

'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

A 1991 review by a cold fusion proponent had calculated "about 600 scientists" were still conducting research. citing After 1991, cold fusion research only continued in relative obscurity, conducted by groups that had increasing difficulty securing public funding and keeping programs open. These small but committed groups of cold fusion researchers have continued to conduct experiments using Fleischmann and Pons electrolysis setups in spite of the rejection by the mainstream community. ''The Boston Globe'' estimated in 2004 that there were only 100 to 200 researchers working in the field, most suffering damage to their reputation and career. Since the main controversy over Pons and Fleischmann had ended, cold fusion research has been funded by private and small governmental scientific investment funds in the United States, Italy, Japan, and India. For example, it was reported in ''Nature'', in May, 2019, that

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

had spent approximately $10 million on cold fusion research. A group of scientists at well-known research labs (e.g, MIT, Lawrence Berkeley National Lab, and others) worked for several years to establish experimental protocols and measurement techniques in an effort to re-evaluate cold fusion to a high standard of scientific rigor. Their reported conclusion: no cold fusion. In 2021, following ''Nature's'' 2019 publication of anomalous findings that might only be explained by some localized fusion, scientists at the Naval Surface Warfare Center, Indian Head Division announced that they had assembled a group of scientists from the Navy, Army and

National Institute of Standards and Technology The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into Outline of p ...

to undertake a new, coordinated study. With few exceptions, researchers have had difficulty publishing in mainstream journals. The remaining researchers often term their field Low Energy Nuclear Reactions (LENR), Chemically Assisted Nuclear Reactions (CANR), Lattice Assisted Nuclear Reactions (LANR), Condensed Matter Nuclear Science (CMNS) or Lattice Enabled Nuclear Reactions; one of the reasons being to avoid the negative connotations associated with "cold fusion". The new names avoid making bold implications, like implying that fusion is actually occurring. The researchers who continue their investigations acknowledge that the flaws in the original announcement are the main cause of the subject's marginalization, and they complain of a chronic lack of funding and no possibilities of getting their work published in the highest impact journals. University researchers are often unwilling to investigate cold fusion because they would be ridiculed by their colleagues and their professional careers would be at risk. In 1994, David Goodstein, a professor of physics at

, advocated increased attention from mainstream researchers and described cold fusion as:

United States

United States Navy researchers at the

Space and Naval Warfare Systems Center Naval Information Warfare Center Pacific (NIWC Pacific), formerly Space and Naval Warfare Systems Center Pacific (SPAWAR Systems Center Pacific or SSC Pacific) provides the US Navy with research, development, delivery and support of integrated co ...

(SPAWAR) in San Diego have been studying cold fusion since 1989. In 2002 they released a two-volume report, "Thermal and nuclear aspects of the Pd/D₂O system," with a plea for funding. This and other published papers prompted a 2004 Department of Energy (DOE) review.

2004 DOE panel

In August 2003, the U.S. Secretary of Energy, Spencer Abraham, ordered the DOE to organize a second review of the field. This was thanks to an April 2003 letter sent by MIT's

Peter L. Hagelstein Peter L. Hagelstein is an associate professor of electrical engineering at the Massachusetts Institute of Technology (MIT), affiliated with the Research Laboratory of Electronics (RLE). Hagelstein received a B.S. and M.S. in 1976 and Ph.D. in elec ...

, and the publication of many new papers, including the Italian ENEA and other researchers in the 2003 International Cold Fusion Conference, and a two-volume book by U.S.

SPAWAR The Naval Information Warfare Systems Command (NAVWARSYSCOM), based in San Diego, is one of six SYSCOM Echelon II organizations within the United States Navy and is the Navy's technical authority and acquisition command for C4ISTAR, C4ISR (Command ...

in 2002. Cold fusion researchers were asked to present a review document of all the evidence since the 1989 review. The report was released in 2004. The reviewers were "split approximately evenly" on whether the experiments had produced energy in the form of heat, but "most reviewers, even those who accepted the evidence for excess power production, 'stated that the effects are not repeatable, the magnitude of the effect has not increased in over a decade of work, and that many of the reported experiments were not well documented.'" In summary, reviewers found that cold fusion evidence was still not convincing 15 years later, and they didn't recommend a federal research program. They only recommended that agencies consider funding individual well-thought studies in specific areas where research "could be helpful in resolving some of the controversies in the field". They summarized its conclusions thus: Cold fusion researchers placed a "rosier spin" on the report, noting that they were finally being treated like normal scientists, and that the report had increased interest in the field and caused "a huge upswing in interest in funding cold fusion research." However, in a 2009 BBC article on an American Chemical Society's meeting on cold fusion, particle physicist

Frank Close Francis Edwin Close, (born 24 July 1945) is a particle physicist who is Emeritus Professor of Physics at the University of Oxford and a Fellow of Exeter College, Oxford. Education Close was a pupil at King's School, Peterborough (then a g ...

was quoted stating that the problems that plagued the original cold fusion announcement were still happening: results from studies are still not being independently verified and inexplicable phenomena encountered are being labelled as "cold fusion" even if they are not, in order to attract the attention of journalists. In February 2012, millionaire

Sidney Kimmel Sidney J. Kimmel (born January 16, 1928) is an American businessman, philanthropist, and film producer. He is ranked number 2141 in the ''Forbes'' list of the richest people alive in 2021.Robert Duncan on the US news show ''

60 Minutes ''60 Minutes'' is an American television news magazine broadcast on the CBS television network. Debuting in 1968, the program was created by Don Hewitt and Bill Leonard, who chose to set it apart from other news programs by using a unique st ...

'', made a grant of $5.5 million to the

University of Missouri The University of Missouri (Mizzou, MU, or Missouri) is a public land-grant research university in Columbia, Missouri. It is Missouri's largest university and the flagship of the four-campus University of Missouri System. MU was founded ...

to establish the Sidney Kimmel Institute for Nuclear Renaissance (SKINR). The grant was intended to support research into the interactions of hydrogen with palladium, nickel or platinum under extreme conditions.Janese Silvey
"Billionaire helps fund MU energy research"
, Columbia Daily Tribune, 10 February 2012University of Missouri-Columbi
"$5.5 million gift aids search for alternative energy. Gift given by Sidney Kimmel Foundation, created by founder of the Jones Group"
, 10 February 2012, (press release)

/ref>"Sidney Kimmel Foundation awards $5.5 million to MU scientists"
Allison Pohle, Missourian, 10 February 2012 In March 2013 Graham K. Hubler, a nuclear physicist who worked for the Naval Research Laboratory for 40 years, was named director. One of the SKINR projects is to replicate a 1991 experiment in which a professor associated with the project, Mark Prelas, says bursts of millions of neutrons a second were recorded, which was stopped because "his research account had been frozen". He claims that the new experiment has already seen "neutron emissions at similar levels to the 1991 observation". In May 2016, the

United States House Committee on Armed Services The U.S. House Committee on Armed Services, commonly known as the House Armed Services Committee or HASC, is a standing committee of the United States House of Representatives. It is responsible for funding and oversight of the Department of D ...

, in its report on the 2017 National Defense Authorization Act, directed the Secretary of Defense to "provide a briefing on the military utility of recent U.S. industrial base LENR advancements to the House Committee on Armed Services by September 22, 2016."

Italy

Since the Fleischmann and Pons announcement, the Italian national agency for new technologies, energy and sustainable economic development ( ENEA) has funded Franco Scaramuzzi's research into whether excess heat can be measured from metals loaded with deuterium gas. Such research is distributed across ENEA departments, CNR laboratories, INFN, universities and industrial laboratories in Italy, where the group continues to try to achieve reliable reproducibility (i.e. getting the phenomenon to happen in every cell, and inside a certain frame of time). In 2006–2007, the ENEA started a research program which claimed to have found excess power of up to 500 percent, and in 2009, ENEA hosted the 15th cold fusion conference.

Japan

Between 1992 and 1997, Japan's

Ministry of International Trade and Industry The was a ministry of the Government of Japan from 1949 to 2001. The MITI was one of the most powerful government agencies in Japan and, at the height of its influence, effectively ran much of Japanese industrial policy, funding research and d ...

sponsored a "New Hydrogen Energy (NHE)" program of US$20 million to research cold fusion. Announcing the end of the program in 1997, the director and one-time proponent of cold fusion research Hideo Ikegami stated "We couldn't achieve what was first claimed in terms of cold fusion. (...) We can't find any reason to propose more money for the coming year or for the future.", In 1999 the Japan C-F Research Society was established to promote the independent research into cold fusion that continued in Japan. The society holds annual meetings.Japan CF research society meeting Dec 2011
Perhaps the most famous Japanese cold fusion researcher was Yoshiaki Arata, from Osaka University, who claimed in a demonstration to produce excess heat when deuterium gas was introduced into a cell containing a mixture of palladium and zirconium oxide, a claim supported by fellow Japanese researcher Akira Kitamura of Kobe University and

Michael McKubre Michael Charles Harold McKubre is an electrochemist involved with cold fusion energy research. McKubre was the director of the Energy Research Center at SRI International in 1998. He is a native of New Zealand. Education McKubre completed two de ...

at SRI.

India

In the 1990s, India stopped its research in cold fusion at the

Bhabha Atomic Research Centre The Bhabha Atomic Research Centre (BARC) is India's premier nuclear research facility, headquartered in Trombay, Mumbai, Maharashtra, India. It was founded by Homi Jehangir Bhabha as the Atomic Energy Establishment, Trombay (AEET) in January ...

because of the lack of consensus among mainstream scientists and the US denunciation of the research. Yet, in 2008, the National Institute of Advanced Studies recommended that the Indian government revive this research. Projects were commenced at

Chennai Chennai (, ), formerly known as Madras ( the official name until 1996), is the capital city of Tamil Nadu, the southernmost Indian state. The largest city of the state in area and population, Chennai is located on the Coromandel Coast of ...

Indian Institute of Technology The Indian Institutes of Technology (IITs) are central government owned Institute of technology, public technical institutes located across India. They are under the ownership of the Ministry of Human Resource Development, Ministry of Educat ...

, the Bhabha Atomic Research Centre and the

Indira Gandhi Centre for Atomic Research Indira Gandhi Centre for Atomic Research (IGCAR) is one of India's premier nuclear research centres. It is the second largest establishment of the Department of Atomic Energy (DAE), next to Bhabha Atomic Research Centre (BARC), located at Kal ...

. However, there is still skepticism among scientists and, for all practical purposes, research has stalled since the 1990s. A special section in the Indian multidisciplinary journal '' Current Science'' published 33 cold fusion papers in 2015 by major cold fusion researchers including several Indian researchers.

Reported results

A cold fusion experiment usually includes: * a metal, such as

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

, in bulk, thin films or powder; and *

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

, or both, in the form of water, gas or plasma. Electrolysis cells can be either open cell or closed cell. In open cell systems, the electrolysis products, which are gaseous, are allowed to leave the cell. In closed cell experiments, the products are captured, for example by catalytically recombining the products in a separate part of the experimental system. These experiments generally strive for a steady state condition, with the electrolyte being replaced periodically. There are also "heat-after-death" experiments, where the evolution of heat is monitored after the electric current is turned off. The most basic setup of a cold fusion cell consists of two electrodes submerged in a solution containing palladium and heavy water. The electrodes are then connected to a power source to transmit electricity from one electrode to the other through the solution. Even when anomalous heat is reported, it can take weeks for it to begin to appear—this is known as the "loading time," the time required to saturate the palladium electrode with hydrogen (see "Loading ratio" section). The Fleischmann and Pons early findings regarding helium, neutron radiation and tritium were never replicated satisfactorily, and its levels were too low for the claimed heat production and inconsistent with each other. Neutron radiation has been reported in cold fusion experiments at very low levels using different kinds of detectors, but levels were too low, close to background, and found too infrequently to provide useful information about possible nuclear processes.

Excess heat and energy production

An excess heat observation is based on an energy balance. Various sources of energy input and output are continuously measured. Under normal conditions, the energy input can be matched to the energy output to within experimental error. In experiments such as those run by Fleischmann and Pons, an electrolysis cell operating steadily at one temperature transitions to operating at a higher temperature with no increase in applied current. If the higher temperatures were real, and not an experimental artifact, the energy balance would show an unaccounted term. In the Fleischmann and Pons experiments, the rate of inferred excess heat generation was in the range of 10–20% of total input, though this could not be reliably replicated by most researchers. Researcher Nathan Lewis discovered that the excess heat in Fleischmann and Pons's original paper was not measured, but estimated from measurements that didn't have any excess heat. Unable to produce excess heat or neutrons, and with positive experiments being plagued by errors and giving disparate results, most researchers declared that heat production was not a real effect and ceased working on the experiments. In 1993, after their original report, Fleischmann reported "heat-after-death" experiments—where excess heat was measured after the electric current supplied to the electrolytic cell was turned off. This type of report has also become part of subsequent cold fusion claims.

Helium, heavy elements, and neutrons

Known instances of nuclear reactions, aside from producing energy, also produce

nucleon In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number (nucleon number). Until the 1960s, nucleons w ...

s and particles on readily observable ballistic trajectories. In support of their claim that nuclear reactions took place in their electrolytic cells, Fleischmann and Pons reported a

neutron flux The neutron flux, φ, is a scalar quantity used in nuclear physics and nuclear reactor physics. It is the total length travelled by all free neutrons per unit time and volume. Equivalently, it can be defined as the number of neutrons travellin ...

of 4,000 neutrons per second, as well as detection of tritium. The classical branching ratio for previously known fusion reactions that produce tritium would predict, with 1

watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...

of power, the production of 10¹² neutrons per second, levels that would have been fatal to the researchers. In 2009, Mosier-Boss et al. reported what they called the first scientific report of highly energetic neutrons, using

CR-39 Poly(allyl diglycol carbonate) (PADC) is a plastic commonly used in the manufacture of eyeglass lenses alongside the material PMMA ( polymethyl methacrylate). The monomer is allyl diglycol carbonate (ADC). The term CR-39 technically refers to t ...

plastic radiation detectors,, but the claims cannot be validated without a

quantitative analysis Quantitative analysis may refer to: * Quantitative research, application of mathematics and statistics in economics and marketing * Quantitative analysis (chemistry), the determination of the absolute or relative abundance of one or more substanc ...

of neutrons. Several medium and heavy elements like calcium, titanium, chromium, manganese, iron, cobalt, copper and zinc have been reported as detected by several researchers, like

Tadahiko Mizuno is a Japanese nuclear-chemist known for his work on cold fusion. He was a former assistant professor teaching the Atomic Power Environmental Materials program at Hokkaido University. He was also a member of Energy Environmental Institute of Eng ...

or George Miley. The report presented to the United States Department of Energy (DOE) in 2004 indicated that deuterium-loaded foils could be used to detect fusion reaction products and, although the reviewers found the evidence presented to them as inconclusive, they indicated that those experiments did not use state-of-the-art techniques. In response to doubts about the lack of nuclear products, cold fusion researchers have tried to capture and measure nuclear products correlated with excess heat. Considerable attention has been given to measuring ⁴He production. However, the reported levels are very near to background, so contamination by trace amounts of helium normally present in the air cannot be ruled out. In the report presented to the DOE in 2004, the reviewers' opinion was divided on the evidence for ⁴He, with the most negative reviews concluding that although the amounts detected were above background levels, they were very close to them and therefore could be caused by contamination from air. One of the main criticisms of cold fusion was that deuteron-deuteron fusion into helium was expected to result in the production of

gamma rays A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically sh ...

—which were not observed and were not observed in subsequent cold fusion experiments. Cold fusion researchers have since claimed to find X-rays, helium, neutrons and

nuclear transmutation Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed. A transmutation ...

s. Some researchers also claim to have found them using only light water and nickel cathodes. The 2004 DOE panel expressed concerns about the poor quality of the theoretical framework cold fusion proponents presented to account for the lack of gamma rays.

Proposed mechanisms

Researchers in the field do not agree on a theory for cold fusion. One proposal considers that hydrogen and its

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

can be absorbed in certain solids, including palladium hydride, at high densities. This creates a high partial pressure, reducing the average separation of hydrogen isotopes. However, the reduction in separation is not enough to create the fusion rates claimed in the original experiment, by a factor of ten. It was also proposed that a higher density of hydrogen inside the palladium and a lower potential barrier could raise the possibility of fusion at lower temperatures than expected from a simple application of

Coulomb's law Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that quantifies the amount of force between two stationary, electrically charged particles. The electric force between charged bodies at rest is conventio ...

. Electron screening of the positive hydrogen nuclei by the negative electrons in the palladium lattice was suggested to the 2004 DOE commission, but the panel found the theoretical explanations not convincing and inconsistent with current physics theories.

Criticism

Criticism of cold fusion claims generally take one of two forms: either pointing out the theoretical implausibility that fusion reactions have occurred in electrolysis setups or criticizing the excess heat measurements as being spurious, erroneous, or due to poor methodology or controls. There are a couple of reasons why known fusion reactions are an unlikely explanation for the excess heat and associated cold fusion claims.

Repulsion forces

Because nuclei are all positively charged, they strongly repel one another. Normally, in the absence of a catalyst such as a

muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of , but with a much greater mass. It is classified as a lepton. As wi ...

, very high kinetic energies are required to overcome this charged repulsion. Extrapolating from known fusion rates, the rate for uncatalyzed fusion at room-temperature energy would be 50 orders of magnitude lower than needed to account for the reported excess heat. In muon-catalyzed fusion there are more fusions because the presence of the muon causes deuterium nuclei to be 207 times closer than in ordinary deuterium gas. But deuterium nuclei inside a palladium lattice are further apart than in deuterium gas, and there should be fewer fusion reactions, not more., , , quoting

Howard Kent Birnbaum Howard Kent Birnbaum (18 October 1932 Brooklyn, New York – 23 January 2005 Urbana, Illinois) was an American metallurgist who was well known due to his works on the interaction of point, linear and planar defects in plastic deformation of materia ...

in the special cold fusion session of the 1989 spring meeting of the Materials Research Society, , citing Paneth and Peters in the 1920s already knew that palladium can absorb up to 900 times its own volume of hydrogen gas, storing it at several thousands of times the

atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibar ...

. This led them to believe that they could increase the nuclear fusion rate by simply loading palladium rods with hydrogen gas. Tandberg then tried the same experiment but used electrolysis to make palladium absorb more deuterium and force the deuterium further together inside the rods, thus anticipating the main elements of Fleischmann and Pons' experiment. They all hoped that pairs of hydrogen nuclei would fuse together to form helium, which at the time was needed in Germany to fill

zeppelin A Zeppelin is a type of rigid airship named after the German inventor Count Ferdinand von Zeppelin () who pioneered rigid airship development at the beginning of the 20th century. Zeppelin's notions were first formulated in 1874Eckener 1938, ...

s, but no evidence of helium or of increased fusion rate was ever found. This was also the belief of geologist Palmer, who convinced Steven Jones that the helium-3 occurring naturally in Earth perhaps came from fusion involving hydrogen isotopes inside catalysts like nickel and palladium. This led their team in 1986 to independently make the same experimental setup as Fleischmann and Pons (a palladium cathode submerged in heavy water, absorbing deuterium via electrolysis). Fleischmann and Pons had much the same belief, but they calculated the pressure to be of 10²⁷ atmospheres, when cold fusion experiments achieve a loading ratio of only one to one, which has only between 10,000 and 20,000 atmospheres. John R. Huizenga says they had misinterpreted the

Nernst equation In electrochemistry, the Nernst equation is a chemical thermodynamical relationship that permits the calculation of the reduction potential of a reaction ( half-cell or full cell reaction) from the standard electrode potential, absolute tempera ...

, leading them to believe that there was enough pressure to bring deuterons so close to each other that there would be spontaneous fusions.

Lack of expected reaction products

Conventional deuteron fusion is a two-step process, in which an unstable high-energy intermediary is formed: : D + D → ⁴He ^* + 24 MeV Experiments have observed only three decay pathways for this excited-state nucleus, with the branching ratio showing the probability that any given intermediate follows a particular pathway. The products formed via these decay pathways are: :⁴He^* → n + ³He + 3.3 MeV (

ratio In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...

=50%) :⁴He^* → p + ³H + 4.0 MeV (ratio=50%) : ⁴He^* → ⁴He + γ + 24 MeV (ratio=10⁻⁶) Only about one in one million of the intermediaries decay along the third pathway, making its products comparatively rare when compared to the other paths. This result is consistent with the predictions of the

Bohr model In atomic physics, the Bohr model or Rutherford–Bohr model, presented by Niels Bohr and Ernest Rutherford in 1913, is a system consisting of a small, dense nucleus surrounded by orbiting electrons—similar to the structure of the Solar Sy ...

. If one watt (6.242 × 10¹² MeV/s) of nuclear power were produced from ~2.2575 × 10¹¹ deuteron fusion individual reactions each second consistent with known branching ratios, the resulting neutron and tritium (³H) production would be easily measured. Some researchers reported detecting ⁴He but without the expected neutron or tritium production; such a result would require branching ratios strongly favouring the third pathway, with the actual rates of the first two pathways lower by at least five orders of magnitude than observations from other experiments, directly contradicting both theoretically predicted and observed branching probabilities. Those reports of ⁴He production did not include detection of

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic wav ...

s, which would require the third pathway to have been changed somehow so that gamma rays are no longer emitted. The known rate of the decay process together with the inter-atomic spacing in a

metallic crystal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

makes heat transfer of the 24 MeV excess energy into the host metal lattice prior to the intermediary's decay inexplicable in terms of conventional understandings of

momentum In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass ...

and energy transfer, and even then there would be measurable levels of radiation. Also, experiments indicate that the ratios of deuterium fusion remain constant at different energies., In general, pressure and chemical environment cause only small changes to fusion ratios. An early explanation invoked the Oppenheimer–Phillips process at low energies, but its magnitude was too small to explain the altered ratios.

Setup of experiments

Cold fusion setups utilize an input power source (to ostensibly provide

activation energy In chemistry and physics, activation energy is the minimum amount of energy that must be provided for compounds to result in a chemical reaction. The activation energy (''E''a) of a reaction is measured in joules per mole (J/mol), kilojoules p ...

), a

platinum group The platinum-group metals (abbreviated as the PGMs; alternatively, the platinoids, platinides, platidises, platinum group, platinum metals, platinum family or platinum-group elements (PGEs)) are six noble, precious metallic elements clustered to ...

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials ...

, a deuterium or hydrogen source, a

calorimeter A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimete ...

, and, at times, detectors to look for byproducts such as helium or neutrons. Critics have variously taken issue with each of these aspects and have asserted that there has not yet been a consistent reproduction of claimed cold fusion results in either energy output or byproducts. Some cold fusion researchers who claim that they can consistently measure an excess heat effect have argued that the apparent lack of reproducibility might be attributable to a lack of quality control in the electrode metal or the amount of hydrogen or deuterium loaded in the system. Critics have further taken issue with what they describe as mistakes or errors of interpretation that cold fusion researchers have made in calorimetry analyses and energy budgets.

Reproducibility

In 1989, after Fleischmann and Pons had made their claims, many research groups tried to reproduce the Fleischmann-Pons experiment, without success. A few other research groups, however, reported successful reproductions of cold fusion during this time. In July 1989, an Indian group from the

( P. K. Iyengar and M. Srinivasan) and in October 1989, John Bockris' group from

reported on the creation of tritium. In December 1990, professor

Richard Oriani Richard A. Oriani (July 19, 1920 – August 11, 2015) was an El Salvador-born American chemical engineer and metallurgist who was instrumental in the study of the effects of hydrogen in metal. He also made significant contributions to the field of ...

of the

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

reported excess heat. Groups that did report successes found that some of their cells were producing the effect, while other cells that were built exactly the same and used the same materials were not producing the effect. Researchers that continued to work on the topic have claimed that over the years many successful replications have been made, but still have problems getting reliable replications.

Reproducibility Reproducibility, also known as replicability and repeatability, is a major principle underpinning the scientific method. For the findings of a study to be reproducible means that results obtained by an experiment or an observational study or in a ...

is one of the main principles of the scientific method, and its lack led most physicists to believe that the few positive reports could be attributed to experimental error. The DOE 2004 report said among its conclusions and recommendations:

=Loading ratio

Cold fusion researchers ( McKubre since 1994, ENEA in 2011) have speculated that a cell that is loaded with a deuterium/palladium ratio lower than 100% (or 1:1) will not produce excess heat. Since most of the negative replications from 1989 to 1990 did not report their ratios, this has been proposed as an explanation for failed reproducibility. This loading ratio is hard to obtain, and some batches of palladium never reach it because the pressure causes cracks in the palladium, allowing the deuterium to escape. Fleischmann and Pons never disclosed the deuterium/palladium ratio achieved in their cells; there are no longer any batches of the palladium used by Fleischmann and Pons (because the supplier now uses a different manufacturing process), and researchers still have problems finding batches of palladium that achieve heat production reliably.

Misinterpretation of data

Some research groups initially reported that they had replicated the Fleischmann and Pons results but later retracted their reports and offered an alternative explanation for their original positive results. A group at

Georgia Tech The Georgia Institute of Technology, commonly referred to as Georgia Tech or, in the state of Georgia, as Tech or The Institute, is a public research university and institute of technology in Atlanta, Georgia. Established in 1885, it is part o ...

found problems with their neutron detector, and Texas A&M discovered bad wiring in their thermometers. These retractions, combined with negative results from some famous laboratories, led most scientists to conclude, as early as 1989, that no positive result should be attributed to cold fusion.

Calorimetry errors

The calculation of excess heat in electrochemical cells involves certain assumptions. Errors in these assumptions have been offered as non-nuclear explanations for excess heat. One assumption made by Fleischmann and Pons is that the efficiency of electrolysis is nearly 100%, meaning nearly all the electricity applied to the cell resulted in electrolysis of water, with negligible

resistive heating Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor produces heat. Joule's first law (also just Joule's law), also known in countries of former US ...

and substantially all the electrolysis product leaving the cell unchanged. This assumption gives the amount of energy expended converting liquid D₂O into gaseous D₂ and O₂. The efficiency of electrolysis is less than one if hydrogen and oxygen recombine to a significant extent within the calorimeter. Several researchers have described potential mechanisms by which this process could occur and thereby account for excess heat in electrolysis experiments. Another assumption is that heat loss from the calorimeter maintains the same relationship with measured temperature as found when calibrating the calorimeter. This assumption ceases to be accurate if the temperature distribution within the cell becomes significantly altered from the condition under which calibration measurements were made. This can happen, for example, if fluid circulation within the cell becomes significantly altered. Recombination of hydrogen and oxygen within the calorimeter would also alter the heat distribution and invalidate the calibration.

Publications

The

ISI ISI or Isi may refer to: Organizations * Intercollegiate Studies Institute, a classical conservative organization focusing on college students * Ice Skating Institute, a trade association for ice rinks * Indian Standards Institute, former name of ...

identified cold fusion as the scientific topic with the largest number of published papers in 1989, of all scientific disciplines. The

Nobel Laureate The Nobel Prizes ( sv, Nobelpriset, no, Nobelprisen) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make ...

Julian Schwinger Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was a Nobel Prize winning American theoretical physicist. He is best known for his work on quantum electrodynamics (QED), in particular for developing a relativistically invariant ...

declared himself a supporter of cold fusion in the fall of 1989, after much of the response to the initial reports had turned negative. He tried to publish his theoretical paper "Cold Fusion: A Hypothesis" in ''

'', but the peer reviewers rejected it so harshly that he felt deeply insulted, and he resigned from the American Physical Society (publisher of ''PRL'') in protest. The number of papers sharply declined after 1990 because of two simultaneous phenomena: first, scientists abandoned the field; second, journal editors declined to review new papers. Consequently, cold fusion fell off the ISI charts. Researchers who got negative results turned their backs on the field; those who continued to publish were simply ignored. A 1993 paper in ''Physics Letters A'' was the last paper published by Fleischmann, and "one of the last reports

y Fleischmann Y, or y, is the twenty-fifth and penultimate letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. According to some authorities, it is the sixth (or seventh ...

to be formally challenged on technical grounds by a cold fusion skeptic." The ''Journal of Fusion Technology'' (FT) established a permanent feature in 1990 for cold fusion papers, publishing over a dozen papers per year and giving a mainstream outlet for cold fusion researchers. When editor-in-chief

George H. Miley George H. Miley (born 1933) is a professor emeritus of physics from the University of Illinois at Urbana–Champaign. Miley is a Guggenheim Fellow and Fellow of the American Nuclear Society, the American Physical Society and the Institute of Electr ...

retired in 2001, the journal stopped accepting new cold fusion papers. This has been cited as an example of the importance of sympathetic influential individuals to the publication of cold fusion papers in certain journals. The decline of publications in cold fusion has been described as a "failed information epidemic". The sudden surge of supporters until roughly 50% of scientists support the theory, followed by a decline until there is only a very small number of supporters, has been described as a characteristic of pathological science. The lack of a shared set of unifying concepts and techniques has prevented the creation of a dense network of collaboration in the field; researchers perform efforts in their own and in disparate directions, making the transition to "normal" science more difficult. Cold fusion reports continued to be published in a few journals like '' Journal of Electroanalytical Chemistry'' and '' Il Nuovo Cimento''. Some papers also appeared in ''

Journal of Physical Chemistry ''The Journal of Physical Chemistry A'' is a scientific journal which reports research on the chemistry of molecules A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on conte ...

'', ''

Physics Letters A ''Physics Letters'' was a scientific journal published from 1962 to 1966, when it split in two series now published by Elsevier Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its ...

'', '' International Journal of Hydrogen Energy'', and a number of Japanese and Russian journals of physics, chemistry, and engineering. Since 2005, ''

Naturwissenschaften ''The Science of Nature'', formerly ''Naturwissenschaften'', is a monthly peer-reviewed scientific journal published by Springer Science+Business Media covering all aspects of the natural sciences relating to questions of biological significance. ...

'' has published cold fusion papers; in 2009, the journal named a cold fusion researcher to its editorial board. In 2015 the Indian multidisciplinary journal '' Current Science'' published a special section devoted entirely to cold fusion related papers. In the 1990s, the groups that continued to research cold fusion and their supporters established (non-peer-reviewed) periodicals such as ''Fusion Facts'', ''Cold Fusion Magazine'', ''

Infinite Energy Magazine ''Infinite Energy'' is a bi-monthly magazine published in New Hampshire that details theories and experiments concerning alternative energy, new science and new physics. The magazine was founded by the late Eugene Mallove, and is owned by the non-p ...

'' and ''New Energy Times'' to cover developments in cold fusion and other fringe claims in energy production that were ignored in other venues. The internet has also become a major means of communication and self-publication for CF researchers.

Conferences

Cold fusion researchers were for many years unable to get papers accepted at scientific meetings, prompting the creation of their own conferences. The International Conference on Cold Fusion (ICCF) was first held in 1990 and has met every 12 to 18 months since. Attendees at some of the early conferences were described as offering no criticism to papers and presentations for fear of giving ammunition to external critics, thus allowing the proliferation of

crackpots ''Crackpots'' is an Atari 2600 game designed by Dan Kitchen and published by Activision in 1983. It was Kitchen's first game for Activision. In ''Crackpots'', the player controls Potsy, a gardener. Potsy's Brooklyn building is being overrun by bu ...

and hampering the conduct of serious science.The first three conferences are commented in detail in , specially 240, 275–277 Critics and skeptics stopped attending these conferences, with the notable exception of Douglas Morrison, who died in 2001. With the founding in 2004 of the International Society for Condensed Matter Nuclear Science (ISCMNS), the conference was renamed the International Conference on Condensed Matter Nuclear Science ''anomalous effects in deuterated metals,'' which was the new, preferred, politically palatable nom de science for cold fusion ack in October 1989"—for reasons that are detailed in the subsequent research section above—but reverted to the old name in 2008. Cold fusion research is often referenced by proponents as "low-energy nuclear reactions", or LENR, but according to sociologist

Bart Simon Bart is a masculine given name, usually a diminutive of Bartholomew, sometimes of Barton, Bartolomeo, etc. Bart is a Dutch and Ashkenazi Jewish surname, and derives from the name ''Bartholomäus'', a German form of the biblical name ''Bartholo ...

the "cold fusion" label continues to serve a social function in creating a

collective identity Collective identity is the shared sense of belonging to a group. In sociology In 1989, Alberto Melucci published ''Nomads of the Present'', which introduces his model of collective identity based on studies of the social movements of the 1980 ...

for the field. Since 2006, the American Physical Society (APS) has included cold fusion sessions at their semiannual meetings, clarifying that this does not imply a softening of skepticism., (" bsolutely not Anyone can deliver a paper. We defend the openness of science" – Bob Park of APS, when asked if hosting the meeting showed a softening of scepticism) Since 2007, the

American Chemical Society The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all ...

(ACS) meetings also include "invited symposium(s)" on cold fusion. An ACS program chair, Gopal Coimbatore, said that without a proper forum the matter would never be discussed and, "with the world facing an energy crisis, it is worth exploring all possibilities." On 22–25 March 2009, the American Chemical Society meeting included a four-day symposium in conjunction with the 20th anniversary of the announcement of cold fusion. Researchers working at the U.S. Navy's

(SPAWAR) reported detection of energetic

using a heavy water electrolysis setup and a

detector, a result previously published in ''

''. The authors claim that these neutrons are indicative of nuclear reactions. Without quantitative analysis of the number, energy, and timing of the neutrons and exclusion of other potential sources, this interpretation is unlikely to find acceptance by the wider scientific community.

Patents

Although details have not surfaced, it appears that the University of Utah forced the 23 March 1989 Fleischmann and Pons announcement to establish priority over the discovery and its patents before the joint publication with Jones. The

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private Land-grant university, land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern t ...

(MIT) announced on 12 April 1989 that it had applied for its own patents based on theoretical work of one of its researchers,

, who had been sending papers to journals from 5 to 12 April. On 2 December 1993 the University of Utah licensed all its cold fusion patents to ENECO, a new company created to profit from cold fusion discoveries, and in March 1998 it said that it would no longer defend its patents. The U.S. Patent and Trademark Office (USPTO) now rejects patents claiming cold fusion. Esther Kepplinger, the deputy commissioner of patents in 2004, said that this was done using the same argument as with

perpetual motion machine Perpetual motion is the motion of bodies that continues forever in an unperturbed system. A perpetual motion machine is a hypothetical machine that can do work infinitely without an external energy source. This kind of machine is impossible, a ...

s: that they do not work. Patent applications are required to show that the invention is "useful", and this

utility As a topic of economics, utility is used to model worth or value. Its usage has evolved significantly over time. The term was introduced initially as a measure of pleasure or happiness as part of the theory of utilitarianism by moral philosoph ...

is dependent on the invention's ability to function. In general USPTO rejections on the sole grounds of the invention's being "inoperative" are rare, since such rejections need to demonstrate "proof of total incapacity", and cases where those rejections are upheld in a Federal Court are even rarer: nevertheless, in 2000, a rejection of a cold fusion patent was appealed in a Federal Court and it was upheld, in part on the grounds that the inventor was unable to establish the utility of the invention. A U.S. patent might still be granted when given a different name to disassociate it from cold fusion, though this strategy has had little success in the US: the same claims that need to be patented can identify it with cold fusion, and most of these patents cannot avoid mentioning Fleischmann and Pons' research due to legal constraints, thus alerting the patent reviewer that it is a cold-fusion-related patent. David Voss said in 1999 that some patents that closely resemble cold fusion processes, and that use materials used in cold fusion, have been granted by the USPTO. The inventor of three such patents had his applications initially rejected when they were reviewed by experts in nuclear science; but then he rewrote the patents to focus more on the electrochemical parts so they would be reviewed instead by experts in electrochemistry, who approved them. When asked about the resemblance to cold fusion, the patent holder said that it used nuclear processes involving "new nuclear physics" unrelated to cold fusion. Melvin Miles was granted in 2004 a patent for a cold fusion device, and in 2007 he described his efforts to remove all instances of "cold fusion" from the patent description to avoid having it rejected outright. At least one patent related to cold fusion has been granted by the

European Patent Office The European Patent Office (EPO) is one of the two organs of the European Patent Organisation (EPOrg), the other being the Administrative Council. The EPO acts as executive body for the organisation

. A patent only legally prevents others from using or benefiting from one's invention. However, the general public perceives a patent as a stamp of approval, and a holder of three cold fusion patents said the patents were very valuable and had helped in getting investments.

Cultural references

A 1990

Michael Winner Robert Michael Winner (30 October 1935 – 21 January 2013) was a British filmmaker, writer, and media personality. He is known for directing numerous action, thriller, and black comedy films in the 1960s, 1970s and 1980s, including several co ...

film '' Bullseye!'', starring

Michael Caine Sir Michael Caine (born Maurice Joseph Micklewhite; 14 March 1933) is an English actor. Known for his distinctive Cockney accent, he has appeared in more than 160 films in a career spanning seven decades, and is considered a British film ico ...

and

Roger Moore Sir Roger George Moore (14 October 192723 May 2017) was an English actor. He was the third actor to portray fictional British secret agent James Bond in the Eon Productions film series, playing the character in seven feature films between 1 ...

, referenced the Fleischmann and Pons experiment. The film – a comedy – concerned conmen trying to steal scientists' purported findings. However, the film had a poor reception, described as "appallingly unfunny". In ''Undead Science'', sociologist Bart Simon gives some examples of cold fusion in popular culture, saying that some scientists use cold fusion as a synonym for outrageous claims made with no supporting proof, and courses of ethics in science give it as an example of pathological science. It has appeared as a joke in ''

Murphy Brown ''Murphy Brown'' is an American television sitcom created by Diane English that premiered on November 14, 1988, on CBS. The series stars Candice Bergen as the eponymous Murphy Brown, a famous investigative journalist and news anchor for ''FYI'', ...

'' and ''

The Simpsons ''The Simpsons'' is an American animated sitcom created by Matt Groening for the Fox Broadcasting Company. The series is a satirical depiction of American life, epitomized by the Simpson family, which consists of Homer Simpson, Homer, Marge ...

''. It was adopted as a software product name

Adobe ColdFusion Adobe ColdFusion is a commercial rapid web-application development computing platform created by J. J. Allaire in 1995. (The programming language used with that platform is also commonly called ColdFusion, though is more accurately known as ...

and a brand of protein bars (Cold Fusion Foods). It has also appeared in advertising as a synonym for impossible science, for example a 1995 advertisement for

Pepsi Max Pepsi Max (also known as Pepsi Black in some countries) is a low-calorie, sugar-free cola, marketed by PepsiCo as an alternative to Pepsi and Diet Pepsi. Pepsi Max is still available primarily in Asian and European markets. While Pepsi Max w ...

. The plot of '' The Saint'', a 1997 action-adventure film, parallels the story of Fleischmann and Pons, although with a different ending. The film might have affected the public perception of cold fusion, pushing it further into the science fiction realm. In the ''

Legends of Tomorrow ''DC's Legends of Tomorrow'', or simply ''Legends of Tomorrow'', is an American Time travel in fiction, time travel superhero fiction, superhero television series developed by Greg Berlanti, Marc Guggenheim, Andrew Kreisberg, and Phil Klem ...

'' episode "No Country for Old Dads", Ray Palmer theorizes that cold fusion could repair the shattered Fire Totem, if it wasn't only theoretical. In Series 8 Episode 7 of

New Tricks ''New Tricks'' is a British television police procedural comedy drama, created by Nigel McCrery and Roy Mitchell, produced primarily by Wall to Wall (until its final year, when it was handled by Headstrong Pictures), and broadcast on BBC ...

, The Gentleman Vanishes, cold fusion is a topic of the investigation the UCOS team does in that episode.

Explanatory notes

References

Citations

Citations with quotations or other additional text

General bibliography

* * * * * * * *
MIT Open Access Articles
* * * * * * * * * * * * * * * * * * * * * * (manuscript). * * * * * * * * * * * * * * * * * * In the foreword by the president of ENEA the belief is expressed that the cold fusion phenomenon is proved. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

External links

*
International Society for Condensed Matter Nuclear Science
(iscmns.org), organizes the ICCF conferences and publishes the ''Journal of Condensed Matter Nuclear Science''. See

of published papers and proceedings.
Low Energy Nuclear Reactions (LENR) Phenomena and Potential Applications

Naval Surface Warfare Center * A Naval Surface Warfare Center (NSWC) is part of the Naval Sea Systems Command (NAVSEA) operated by the United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the ...

report NSWCDD-PN-15-0040 by Louis F. DeChiaro, PhD, 23 September 2015 {{DEFAULTSORT:Cold Fusion 1989 in science Discovery and invention controversies Electrolysis Fringe physics Nuclear fusion Nuclear physics Palladium Pathological science