At a press conference in Salt Lake City held on March 23, 1989, electrochemists Martin Fleischmann of the University of Southampton, Britain, and Stanley Pons of the University of Utah made the blockbuster claim that they had achieved nuclear fusion at room temperature in a laboratory in Utah. If true, the discovery would carry with it the potential to revolutionize energy science and could conceivably change the socio-economic fabric of the entire world.
This announcement was the result of a series of experiments in which Fleischmann and Pons had attempted to enable fusion by forcing deuterium ions into a palladium cathode using electrolysis. During their electrolysis process, an electric current was passed through “heavy water” – water that contains the hydrogen isotope deuterium – and split the water into its constituents of oxygen and deuterium.
Fleischmann and Pons’ big breakthrough occurred while the duo were carrying out some exploratory tests. In the midst of these tests, a 1 cubic centimeter block of palladium disappeared in an explosion that occurred overnight. The explosion, nuclear or otherwise, also destroyed part of the building where the experiments were taking place. Fleischmann and Pons were motivated by this event, destructive though it was, to further pursue what appeared to be cold fusion. From then on, they kept a careful account of the power output and input of their experiments.
After a few weeks of subjecting the heavy water to first .05 amps, then .1 amps, and finally .2 amps of electricity, Fleischmann and Pons recorded an excess heat output of about 25 percent. Heat output is an indicator of nuclear fusion, but the duo could not find evidence of neutron production, another indicator of fusion. However, learning that Steven E. Jones of Brigham Young University, who had worked on muon-catalyzed fusion, had observed weak evidence of neutron production from cold fusion experiments, Fleischmann and Pons were encouraged to believe that their own experiments were probably producing neutrons as well.
Their morale boosted by this bit of news, and feeling some measure of pressure from the University of Utah to spread the word of what they may have uncovered, the scientists published their findings and then participated in the March 23 press conference.
The scientific community immediately began to scrutinize their published data, keen on either confirming or debunking the phenomenon of cold fusion. But the reviewers met with mixed results: no one could reproduce the required results of excess heat and neutrons, perhaps because many were still uninformed as to the exact details of Fleischmann and Pons’ experiments. Meanwhile, the media speculated that this new form of energy could be the answer to global concerns over diminishing fuel supplies, sparking international furor about cold fusion and producing varying accounts of the original experiments.
A month after the press conference that sparked it all, Linus Pauling wrote a letter to the editor of Nature, the esteemed interdisciplinary scientific journal, titled “Explanations of Cold Fusion” which discussed Fleischmann and Pons’ potential breakthrough. In it, Pauling noted that palladium is saturated with hydrogen at the composition PdH0.6. This given, Pauling suggested that the introduction of additional hydrogen atoms brought about by the Fleischmann-Pons experiments caused extra deuterons to be forced into the palladium cathode and form the unstable higher deuteride PdD2. The instability resulted from the free energy of the EMF (Electromotive Force) used during electrolysis, and also because palladium is saturated with hydrogen at the composition PdH0.6.
According to Pauling, it was the decomposition of this unstable deuteride that caused the increased heat observed by the scientists. In other words, what Fleischmann and Pons observed was not an occurrence of cold fusion.
Pauling further opined that the unstable higher deuteride PdD2 “may begin to decompose either slowly, resulting in the increased liberation of heat, or explosively, as was observed when a 1-cm cube of the deuterated palladium disappeared,” overnight in Fleischmann and Pons’ laboratory. Pauling believed that “because of the difference in amplitude of the zero-point vibrations of the nuclei with different masses, palladium dihydride would be less stable than palladium dideuteride.” Reasoning that the decomposition of the unstable compound was causing energy output to exceed input, Pauling provided the world with a rational explanation for why cold fusion was not occurring.
Pauling’s letter was published in the May 1989 issue of Nature, but it did not mark the end of his interest in the subject of cold fusion. In our next post, we’ll talk more about how this interest developed during the peak of the cold fusion craze.