Cold fusion experiment fails, but Google will keep trying

Almost exactly 30 years ago, chemists Martin Fleischmann and Stanley Pons of the University of Utah in the United States gained instant worldwide fame by announcing that they had detected evidence of cold fusion.

The fusion of atomic nuclei occurs routinely in astrophysical environments, as in the stars, being considered the definitive and inexhaustible option of clean energy because, unlike the nuclear fission, that occurs in the reactors of the present atomic plants, it virtually does not produce radiation.

The joy lasted little because no other laboratory was able to reproduce the results claimed by Fleischmann and Pons. The issue continued to be investigated marginally, including a rare scientific event on cold fusion conducted in 2010.

Then in 2015, Google announced that it had assembled a group of about 30 scientists, from various universities and laboratories, and would do whatever was necessary for the team to develop a series of rigorous experiments that stipulated strictly the conditions under which cold fusion could eventually be carried out. And if the team could detect the phenomenon, a reference experiment would be developed that the broader academic community could examine, verify, and replicate.

The justification was that the lack of evidence of cold fusion is not the same as proof that it can not be realized. In addition, the need for cheaper, cleaner energy sources is more urgent than ever, and if cold fusion were possible, it could be a disruptive technology that could change the world.

Reassessment of cold fusion

The team has now published its results: They have been unable to find evidence of cold fusion - yet.

The "still" is important - the team believes that it is worthwhile to continue trying because the "initial trial [on the Fleischmann and Pons experiment] may have been premature", in addition to presenting arguments that the effort made so far has already feather.

"We have embarked on a multi-institutional program to re-evaluate cold fusion with a high standard of scientific rigor." Here we describe our efforts, which are yet to produce any evidence of such an effect. provide new insights into highly hydrated metals and low-energy nuclear reactions, and we affirm that there is still a lot of interesting science to be done in this unexplored parameter space, "the team wrote in its report, published in the journal Nature.

Counting calories: a drawing of one of the calorimeters used in these latest cold fusion experiments. (Courtesy: C Berlinguette et al/Nature)

Cold fusion experiments

The team reports that it failed to reach the experimental parameters that appear to be the most suitable for achieving cold fusion - in fact, it seems extremely difficult to obtain these material conditions with the experimental settings idealized so far, although the team did not rule out this possibility.

Three experimental sets that had been proposed to generate cold fusion were explored, two involving palladium and hydrogen, and one involving metallic powders and hydrogen.

The first involved loading the palladium with amounts of deuterium supposedly necessary to trigger fusion. But the team was unable to create stable samples with the desired high palladium concentrations.

The second attempted to replicate a 1990s experiment in which physicists claimed to have generated anomalous levels of tritium - a heavy hydrogen isotope created only by nuclear reactions - bombarding palladium with pulses of deuterium hot ions. Nuclear signatures showed no evidence of tritium production.

One last line involved heating metallic powders in a hydrogen-rich environment, a process that some current proponents of cold fusion claim to produce excessive and unexplained heat, theorizing that this heat would be the result of the fusion of elements. But in 420 tests, the team did not detect any excess heat.

However, even following all the rigor proposed, the team claims that the negative results are not enough to discard the lines of experimentation using palladium. According to them, it is worth trying to improve the techniques for enriching palladium to obtain stable samples. In the other case, the hypothetical effects in the tritium experiment may be too small to be measured with the current equipment.

Scientific gains 

As for the scientific gains of the project to which the team refers in its report, there are calorimeters that operate in a robust and consistent way under extreme conditions that have had to be developed and that are now available for other experiments in several other fields.

The highly hydrated metals that the team obtained, in turn, could be useful in other works in the area of ​​energy, including batteries of flow and in the own hot fusion nuclear, that is being investigated in several enterprises around the world, like ITER and Wendelstein 7X, and even more ambitious and shorter-term proposals such as SPARC and HB11.

Moreover, in broader terms, the scientific community gains back an area where research can be done again without the risk that its authors will be ridiculed at congresses. "The project can help responsible research in this general area become less taboo, even though the chances of achieving cold fusion still seem extremely remote," Nature wrote in its editorial.

By the way, just over a month ago, a team claimed to have obtained signals of nuclear fusion on a tabletop device using a totally different apparatus, known as "Z-clamp." 

Revisiting the Cold Case of Cold Fusion Curtis P. Berlinguette, Yet-Ming Chiang, Jeremy N. Munday, Thomas Schenkel, David K. Fork, Ross Koningstein, Matthew D. Trevithick Nature DOI: 10.1038 / s41586-019-1256- 6


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