What ever happened to cold fusion, that marvelous process for reproducing the energy source of the sun and the hydrogen bomb - in a test tube at room temperature?
Most scientists have written off the work of Martin Fleischmann and Stanley Pons, who five years ago claimed discovery of this potentially unlimited source of energy."Cold fusion?" Nobel Laureate Glenn Seaborg mused during a recent luncheon conversation. "No, I don't think there's anything there, and there never was. It's not real fusion, and it's way below levels where it could be a practical source of energy."
Seaborg is an authority on nuclear chemistry who advised President George Bush and other government officials after Pons and Fleischmann made their claims in March 1989.
Cold fusion has been dismissed as everything from an honest mistake to an outright scientific fraud. To most of the American scientific establishment, cold fusion is a delusion. It is the discovery that never was.
The Department of Energy funds no major research on the topic. The U.S. Patent Office regards cold fusion as bogus and won't issue patents related to it. Some scientific journals won't publish cold-fusion studies.
Yet surprisingly, cold-fusion research continues in the United States and other countries, with results positive enough to make some scientists wonder whether Pons and Fleischmann were right.
"The cold-fusion effect is one of the most intriguing scientific puzzles of this century," Edmund Storms concluded in a new report published by the Massachusetts Institute of Technology.
The analysis, which appeared in the June edition of MIT's Technology Review, is one of the most comprehensive overviews of cold-fusion research in years. Storms is a chemist who began cold-fusion research at the Los Alamos National Laboratory in New Mexico in 1989.
Storms suggests that scientists and laymen still dismiss cold fusion as bogus because of negative studies widely publicized in 1989 and 1990. His report notes:
"But enough reputable researchers have now published findings, produced from a broad enough range of experimental approaches, that it has become difficult to doubt that something is going on outside the explanations offered by conventional physics.
"What is happening might be fusion; it might not be. But to dismiss the claims as the result of experimental error or fraud is no longer appropriate. Regardless of admitted conflict with accepted theory, these results strongly support the conclusion that a new class of phenomena, which I call chemically assisted nuclear reactions, has been discovered.
"Given the enormous scientific and economic importance of this work if it turns out to be valid, it is prudent to examine the data with an open mind."
It was cold fusion's enormous economic potential - turning seawater into nuclear fuel for producing electricity - that so galvanized the world's imagination in 1989.
Achieving controlled nuclear fusion had been the Holy Grail of phys-ics for 40 years.
Fusion, the power behind the sun and the hydrogen bomb, releases energy when the nucleus of two light atoms come together to form a heavier nucleus. Atoms are the invisible units that make up everything in the universe. They consist of a central nucleus sur-rounded by a cloud of electrons.
Nuclear fission, the process used in the atomic bomb and nuclear power plants, releases energy when the nucleus of a heavy atom splits apart.
Scientists in 1989 were convinced that fusion could occur only under extremely hot conditions, such as the interior of stars or in hydrogen bombs. In a hydrogen bomb, a small atomic explosion provides the energy to ignite fusion reactions.
Extreme conditions seemed necessary for fusion because nuclei of atoms are positively charged. They repel each other, just like the repulsion apparent in everyday life when like poles of two magnets are brought close together. Atoms must be given enormous amounts of energy to overcome these natural repulsive forces.
In one approach to harnessing fusion, for instance, physicists try to fuse atoms of deuterium inside huge machines surrounded by magnets as big as houses.
Deuterium is "heavy hydrogen," an altered form of "isotope" of hydrogen, the lightest and simplest of all chemical elements.
Hydrogen consists of one electron vibrating around a nucleus containing one subatomic particle called a proton. Deuterium's nucleus has one proton and one neutron. Another hydrogen isotope, tritium, has one proton and two neutrons.
Deuterium is largely responsible for nuclear fusion's allure as an energy source. Deuterium can be extracted from seawater, and its use as fusion fuel would mean an almost-inexhaustible source of energy.
By 1989, thousands of physicists had spent billions of dollars in an unsuccessful pursuit of hot fusion.
Then, two upstart chemists, Pons and Fleischmann, announced achieving fusion at room temperature with a simple laboratory device that cost only $100.
Pons and Fleischmann's original apparatus, still the model for cold-fusion experiments, consisted of two electrodes immersed in a container of "heavy" water. Heavy water contains deuterium instead of hydrogen. One electrode consisted of a strip of the metal palladium. The other was a coil of platinum wire.
When an electric current is applied to the electrodes, it causes the heavy water to decompose into deuterium and oxygen. Atoms of deuterium are drawn into the palladium electrode. Pons and Fleisch-mann contended that the deuterium atoms pack together so tightly inside palladium's structure that they fuse, releasing energy as heat. Their apparatus produced more energy in the form of heat than went into it in the form of electricity.
Fleischmann, from the University of Southampton in England, was working with Pons at the University of Utah. Both were respected electrochemists, and other scientists scrambled to repeat and verify the experiments.
Excitement rose when a few reported achieving cold fusion, making Pons and Fleischmann media stars and immediate candidates for the Nobel Prize.
Then came a steady stream of negative findings. More than 100 laboratories repeated the experiments but detected no excess heat or other evidence for fusion. The whole notion of nuclear fusion at room temperature faded into the shadows of science.
But a handful of scientists persisted.
Pons and Fleischmann, for instance, are quietly continuing cold-fusion research at the European branch of Japan's Institute of Minoru Research Advancement in the French Riviera town of Sophia Antipolis. Their work is funded by a Japanese company, Technova, an affiliate of Toyota.
They continue to announce positive results. At an international conference on cold fusion last December, for instance, Fleischmann described cold-fusion experiments that produce about four times as much energy as they consume. In 1989, Pons and Fleischmann could produce only thousandths of a watt of excess power. Now they get more than 150 watts and soon expect to reach 500 watts.
Japan is solidifying its position as the leader in the field with the organization of a major national research program. The Ministry of Trade and Industry plans a $30 million, five-year research effort involving universities and big electric utilities and electronics and metallurgy companies. Many of the participants already have their own cold-fusion research programs.
Like many other scientists, the Japanese group is shying away from using the tainted term "cold fusion." They call the effort the "New Hydrogen Energy Project."
America's major cold-fusion program is being conducted at SRI International, a contract research firm in Menlo Park, Calif. The experiments are funded by the Electric Power Research Institute, the research and development arm of the electric utility industry.
Some cold-fusion research also continues in American university, government and industrial labs.
Research in America and other countries is doing more than verifying the production of excess energy, according to Storms. He cited dozens of published studies that have reported excess energy production. In some, the energy is thousands of times greater than what could result from any known chemical - non-nuclear - reaction.
Earlier in the cold-fusion controversy, skeptics argued that the excess heat resulted from unusual chemical reactions. When chemicals react, they produce new products. Yet scientists have been unable to detect any such new product in cold-fusion cells.
The more recent work also is helping to explain why so many early cold-fusion experiments failed and why replicating the experiments is so difficult.
Researchers at SRI, for instance, have shown that specially prepared palladium, with few microscopic cracks, is essential. Cracks apparently allow deuterium drawn into the electrode to escape rapidly, before accumulation of the large concentrations necessary for fusion.
Studies also show that cold-fusion cells must be operated for several days before they "turn on" and start producing excess heat. A specific amount of electrical current is necessary. Many earlier researchers apparently found no cold-fusion effect because they quit too soon or applied too little current.
"Experiments that use crack-free palladium and follow the proper procedures now routinely result in excess heat, nuclear products, or both," Storms added.
Conventional deuterium fusion leaves other footprints, the "nuclear products" mentioned by Storms. These include tritium, a radioactive isotope of hydrogen; helium; subatomic particles called neutrons; and gamma radiation.
Many experiments have provided additional support for the occurrence of cold fusion by yielding tritium and helium, which can be produced only by nuclear reactions, Storms noted.
But these findings also raise questions about exactly what kind of reactions are occurring. Tritium, for instance, is produced in smaller amounts than would be expected from conventional nuclear fusion. Gamma radiation and neutrons do not appear consistently, and occur at low levels.
Storms says it's tempting to compare cold fusion to other scientific puzzles, such as lasers and superconductivity, that remained laboratory curiosities for decades. Superconductivity is the tendency of certain materials to lose resistance to the flow of electric current when cooled to low temperatures.
But lasers and superconductors could be studied easily in any laboratory. There also were well-accepted theories that explained the basis for these phenomena and helped in developing practical applications.
Despite all the advances over the past five years, cold fusion, in contrast, remains difficult to replicate and lacks a theoretical foundation.