Storm in a test tube

Here’s the last of the La Recherche pieces on 'controversies': a short profile of Martin Fleischmann and cold fusion.

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It would be unfair to Martin Fleischmann, who died last year aged 85, if he were remembered solely for his work on ‘cold fusion’ – the alleged discovery with his coworker Stanley Pons in 1989 that nuclear fusion of heavy hydrogen (deuterium), and the consequent release of energy, could be achieved with benchtop chemistry. Before making that controversial claim, Fleischmann enjoyed international repute for his work in electrochemistry. But to many scientists, cold fusion – now rejected by all but a handful of ‘true believers’ – cast doubt on his judgement and even his integrity.

Fleischmann was born in 1927 to a family with Jewish heritage in Czechoslovakia, and came to England as a young boy to escape the Nazis. He conducted his most celebrated work at the University of Southampton, where in 1974 he discovered a technique for monitoring chemical processes at surfaces. This and his later work on ultra-small electrodes made him a respected figure in electrochemistry.

After officially retiring, he conducted his work with Pons at the University of Utah in the late 1980s. They claimed that the electrolysis of lithium deuteroxide using palladium electrodes generated more energy than it consumed, presumably because of fusion of deuterium atoms packed densely into the ‘hydrogen sponge’ of the palladium metal. Their announcement of the results in a press conference – before publication of a paper, accompanied by very scanty evidence, and scooping a similar claim by a team at the nearby Brigham Young University – ensured that cold fusion was controversial from the outset. At the April 1989 meeting of the American Chemical Society, Fleischmann and Pons were welcomed like rock stars for apparently having achieved what physicists had been trying to do for decades: to liberate energy by nuclear fusion.

Things quickly fell apart. Genuine fusion should be accompanied by other telltale signatures, such as the formation of helium and the emission of neutrons with a particular energy. The claim also depended on control experiments using ordinary hydrogen in place of deuterium. Pons and Fleischmann were evasive when asked whether they had done these checks, or what the results were, and the only paper they published on the subject offered no clarification. Several other groups soon reported ‘excess heat’ and other putative fusion signatures, but the claims were never repeatable, and several exhaustive studies failed to find convincing evidence for fusion. The affair ended badly, amidst law suits, recriminations and accusations of fraud.

Fleischmann always maintained that cold fusion was real, albeit perhaps not quite the phenomenon he’d originally thought. The pattern of marginal and irreproducible effects and ad hoc, shifting explanations fits Irving Langmuir’s template of “pathological science”. But even now, some cling to the alluring dream that cold fusion could be an energy source.