Cold Fusion: Comments on the State of Scientific Proof

SPECIAL SECTION: LOW ENERGY NUCLEAR REACTIONS

Cold fusion: comments on the state of scientific proof

Michael C. H. McKubre* SRI International, Menlo Park, CA, USA

examples of error given at any level of scientific sophisti- Early criticisms were made of the scientific claims made by Martin Fleischmann and Stanley Pons in cation. If pressed the authority of experts in the fields of 1989 on their observation of heat effects in electro- nuclear or particle physics are invoked, or early publica- chemically driven palladium–deuterium experiments tions of null results by ‘influential laboratories’ – that were consistent with nuclear but not chemical or Caltech, MIT, Bell Labs, Harwell. Almost to a man these stored energy sources. These criticisms were prema- experts have long ago retired or deceased, and the authors ture and adverse. In the light of 25 years further study of these early publications of ‘influential laboratories’ of the palladium–deuterium system, what is the state have long since left the field and not returned. The issue of proof of Fleischmann and Pons’ claims? of ‘long ago’ is important as it establishes a time window in which information was gathered sufficient for some to Keywords: Cold fusion, Fleischmann, Pons, scientific draw a permanent conclusion – some time between 23 proof. March 1989 and ‘long ago’. Absurdly for a matter of this seeming importance, ‘long ago’ usually dates to the Spring Meeting of the American Physical Society (APS) Introduction on 1 May 1989. So the whole matter was reported and then comprehensively dismissed within 40 days (and, THE question under discussion is whether the phenome- presumably, 40 nights). From what we now know is this non known as cold fusion has been proven to be existent sensible? Has pertinent new information and understand- or non-existent. This is an important question, for if real, ing developed over 25 years of further study been exam- the possibility exists that cold fusion might become a ined with the wisdom of hindsight? What is the status of meaningful primary energy source with few of the disad- these early null results? vantages associated with the power sources that we have Several questions lie on the table of increasing scientific available to us today. One expects science to be able to interest and technical importance. Do nuclear processes rationally investigate and determine answers to questions ever occur at all in metallic lattices? If yes, do these such as this. Having studied this phenomenon almost full occur by means differently than two-body interactions in time for the past 25 years, I will state my preliminary con- free space? Before Martin Fleischmann and Stanley Pons’ clusion up front and then proceed with a more nuanced dis- fateful press conference on 23 March 1989, most who had cussion. Whatever it is and by whatever underlying thought about it would have argued that nuclear processes mechanism it proceeds, the accumulated evidence strongly can be caused or observed to occur on or beneath the sur- supports the conclusion that nuclear effects take place in face of solids, but take no advantage from it. The size and condensed matter states by pathways, at rates and with timescales of atom–atom and inter-nuclear interactions products different from those of the simple, isolated, pair- are so vastly different that the chemical and physical state wise nuclear reactions that we are so familiar with in free in which a nuclear process occurs was generally consid- space (i.e. two-body interactions). The implications of this ered to have no influence over the nuclear reaction statement are profound and we will proceed with caution on mechanism, rate or product distribution. The only case the basis of validation of the envisaged new science. considered computationally for the involvement of mate- rials in the nuclear process1 was the tunnelling interaction Discussion of two like charged particles, which is strongly distance- dependent. The thinking was that the palladium lattice Occasionally, with decreasing regularity, one hears used by Fleischmann and Pons in their experiments might statements to the effect that ‘Cold fusion has been proven (somehow) confine deuterons sufficiently closely to to not exist or to have been based on errors’. Almost ‘meaningfully’ (see note 1) increase the tunnelling cross- always the words ‘long ago’ are appended. Never are section. This popular line of reasoning ignored following three crucial details. (1) At maximum loading of deuterium (D) into palla- *e-mail: [email protected] dium (Pd), the centre-to-centre distance between adjacent

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deuterons in PdD is greater than that in D2O. The rate of or generations. Very few people ever attempt this exer- spontaneous fusion by pairwise interaction of deuterons cise – those that do are called experts – those who do not in heavy water is not known, but it is very low. In PdD it look to these experts for answers. What is sought is not would be less. fact, but patterns and consistencies of behaviours. In his (2) Deuterons in PdD carry only a very small fractional most recent book7, Ed Storms reviews over 900 publica- positive charge. Their electrons are mostly localized so tions sorting through these patterns in the attempt to that their state is much more atomic than ionic. Calcula- create systematic order for those of us with less time, tions based on D+ are irrelevant (see note 2)1–4. talent or devotion. By any standards Storms is an expert (3) If tunnelling interaction took place just between on the subject of cold fusion – one could argue that he is two deuterons, the products would be exactly those of hot the preeminent expert on this topic. But where does one fusion – a nearly 50 : 50 ratio of tritium and neutrons. go to get a countervailing ‘expert’ opinion? I would argue Both these species would be very easily observed at the that there is no such place or person and has not been for heat generation levels claimed by Fleischmann and Pons5. more than two decades, and that this is a problem. Indi- So the reaction that most people spent most time con- viduals selected to evaluate the accumulated evidence or sidering could not happen, did not happen, and if it did some subset of evidence with an open mind invariably would not require palladium or electrochemistry. Given come to the conclusion that the case for cold fusion is not the power and energy densities of the heat effect claimed disproven (the experience of Rob Duncan and 60 min by Fleischmann and Pons5, only one of two possibilities comes to mind8). To hear a counter argument one must existed. Either they were wrong in their excess heat deter- approach experts in related fields and ask their opinion minations or nuclear reactions occurred in metallic lat- about matters that they have not studied. Of course, all tices by mechanisms and with product distributions one can expect is an intuitive, emotive or self-serving different from similar reactions in free space. Is there response. such a thing as condensed matter nuclear science How does one proceed as a thoughtful intelligent per- (CMNS)? son simply wanting ‘to know the truth (see note 4)’, but What is the state of proof? The case for cold fusion not having years to devote to experimental studies or certainly has not been disproved. This would be a literature review? I would suggest beginning with Storms’ challenging thing to do. To proceed case-by-case and books7,9 as resources to identify sub-topic areas of per- demonstrate that every instance where anomalous sonal interest and pointers to primary sources for further nuclear-products or nuclear-level excess heat were ob- study. Obviously, I have neither the time, patience nor served resulted from an identified experimental error or space to emulate Storms’ efforts here. I restrict attention misunderstanding would be exceedingly arduous under- to the conclusions arrived at ‘long ago’ in the deluge of taking and nothing like this has been attempted or ever information achieved hurriedly in the biblical 40 days and will be. The effort of finding a mistake in all of the thou- 40 nights leading up to the 1 May 1989 APS meeting. sands of published reports would be far too great an un- The conclusion and ‘voted consensus’, that Fleischmann dertaking even to begin, thus proving a negative is and Pons had made fundamental errors and elementary difficult if not impossible. A preliminary flurry of objec- mistakes, was itself premature and in error. This leaves tions, some valid and some not, was directed at early cold wide open the possibility that our free-space view of fusion results (not all of which were sound). Most of nuclear physics requires extension in potentially interest- these criticisms were founded on the complaint that cold ing directions. fusion does not behave like hot fusion. The counter Several authors have shown that what is now known as argument was made compellingly by Julian Schwinger the Fleischmann–Pons Heat Effect (FPHE) is not ob- with the statement that ‘the circumstances of cold fusion served with Pd wire cathodes until the D/Pd atomic ratio are not those of hot fusion’6. The fact that the reaction reached 0.85 or higher. This effect of the D/Pd loading occurs in lattice-constrained space in intimate (and possi- ratio on excess power production was reported simulta- bly coherent) association with unknown and uncountable neously and independently by McKubre et al.10 and Kuni- numbers of other nuclei (and electrons) makes a differ- matsu et al.11 at a conference in Japan in 1992 three and a ence in the reaction expectation and outcome. But this is half years after the ‘APS consensus’. For bulk pure palla- not a theoretical matter – one cannot ‘theoretically deny’ dium wire cathodes such as those used by Fleischmann a new experimental observation unless a fundamental law and most early replicators, the problem is compounded by is clearly violated (see note 3). In the scientific method the multi-threshold nature of the FPHE. Not only does experiment always takes precedence. How far along the initiation of the effect require D/Pd loadings rarely trail of experimental demonstration are we? achieved before 1989, these loadings must be maintained I would argue that the condition of certainty is for hundreds of hours in the presence of threshold current approached asymptotically – we achieve the comfortable densities of 100 mA cm–2 or larger, well beyond the condition of ‘knowing’ by painstaking repetition and current density of maximum loading. Of equal impor- accumulation of knowledge over periods of years, decades tance, surface damage and poor interface conditioning

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Figure 1. Histogram illustrating the number of early experiments at SRI International (formerly the Stanford Research Institute and ENEA (the Italian National Energy and Environment Agency) showing measurable excess power as a function of maximum cathode loading. Also illustrated are points for the Caltech13 and MIT14 and null experimental results.

and control, reduce the flux of deuterium through the in- and ENEA (Frascati) experiments producing positive ex- terface. The magnitude (but not direction) of this flux is cess power results as a function of maximum loading now known to be proportional to the magnitude of the achieved (see note 5). Even lower loading results were excess heat effect as expressed in the following empirical estimated by Fleming et al.15 at Bell Labs in another equation12 report of no excess heat. The authors15 state ‘the degree of deuterium incorporation was comparable to that for the 2 PX = M(x – x°) (i – i°)|iD| at t > t°, (1) open cells for the same time duration. The amount incor- porated in longer electrolysis experiments was typically where PX is the excess thermal power, x the atomic load- PdDx (0.45 < x < 0.75).’ ing ratio D/Pd, x° ~ 0.875, i the electrochemical current density for the cathode, iD the absorption deuteron flux through the surface expressed as current density (2– Conclusions 20 mA cm–2) and t° > 50 times the deuterium diffusional time constant in the cathode. From what we know today, and Figure 1 clearly illumi- The failure to meet one or more of the (now) known nates, none of the cells in any of these early cited null threshold conditions provides an easy explanation for studies would be expected to produce any excess heat. important early failures to reproduce what is now called Not only for the reasons of a loading deficiency (as stated the Fleischmann–Pons heat effect. As noted above, large explicitly); the durations of the experiments were wholly significance was attached to early null heat results insufficient. The Caltech work13 was completed and con- reported by a small number of groups at prestigious insti- clusions made public within 40 days of the Fleischmann tutions. In light of the above discussion, it is useful to ex- and Pons public announcement. None of the Caltech amine whether these experiments, as well as other early experiments was operated for the 300 h (12.5 days) that experiments, were operated in a relevant regime. The was the minimum initiation time observed at SRI for bulk most cited early result reporting no anomalous effects Pd cathodes and the entire set of Caltech experiments was was that of Lewis et al.13 from Caltech, in which they complete well within the 1000 h (42 days) established as stated that ‘D/Pd stoichiometries of 0.77, 0.79 and 0.80 the minimum time of observation at SRI (see note 6). In obtained from these measurements were taken to be rep- addition, the current density stimuli used in these early resentative of the D/Pd stoichiometry for the charged null experiments were too small to reliably produce the cathodes used in this work.’ Also widely cited is the early effect and the deuterium flux was not measured. None of null result of Albagli et al.14 from MIT, who discuss the criteria of eq. (1) was shown to be met, at least three ‘average loading ratios were found to be 0.75 ± 0.05 and demonstrably were not. In hindsight it is evident that the 0.78 ± 0.05 for the D and H loaded cathodes, respec- authors13–15 were victims of ‘unknown unknowns’, and tively’. perhaps ‘undue haste’ – but this is understandable in the The Caltech and MIT reports of no excess heat effects frantic circumstances of 1989. What is important is that are shown in Figure 1, illustrating a number of early SRI these experiments be recognized for what they are, not

CURRENT SCIENCE, VOL. 108, NO. 4, 25 FEBRUARY 2015 497 SPECIAL SECTION: LOW ENERGY NUCLEAR REACTIONS what they are not. They are important members of the 3. Czerski, K., Heide, P. and Huke, A., Electron screening constraints experimental database that teaches us under what condi- for cold fusion. In Proceedings of ICCF11 Science, Marseille, France, 2004; Screening potential for nuclear reactions in con- tions one encounters FPHE. They are not any part of densed matter. In Proceedings of ICCF14, Washington DC, 2008. a proof of nonexistence of the phenomenon and cannot be 4. Kasagi, J., Screening potential for nuclear reactions in condensed used to support such a conclusion; absence of evidence is matter. In Proceedings of ICCF14, Washington DC, 2008. not evidence of absence. 5. Fleischmann, M., Pons, S. and Hawkins, M., Electrochemically induced nuclear fusion of deuterium. J. Electroanal. Chem., 1989, 261, 301–308 (1989); errata, 263, 187. Notes 6. Schwinger, J., Nuclear energy in an atomic lattice. Prog. Theor. Phys., 1991, 85, 711. 7. Storms, E., The Explanation of Low Energy Nuclear Reaction, 1. Here ‘meaningfully’ means some 50 orders of magnitude. 2. Initial attempts at calculation1 also ignored electron screening Infinite Energy Press, New Hampshire, 2014. 2–4 8. http://www.cbsnews.com/news/cold-fusion-is-hot-again/ effects, but even when applied correctly , the calculated rates 9. Storms, E., The Science of Low Energy Nuclear Reaction, World were too low to account for the claims of Fleischmann and Pons, and objection 3 would still apply. Scientific, New Jersey, 2007. 10. McKubre, M. C. H., Crouch-Baker, S., Riley, A. M., Smedley, S. 3. Such as the first law of thermodynamics or the equivalence of mass I. and Tanzella, F. L., Excess power observations in electrochemi- and energy – neither of which is violated obviously by the FPHE. 4. Or, perhaps more rationally and motivationally, ‘to know where the cal studies of the D/Pd system; the influence of loading. In Fron- tier of Cold Fusion (ed. Ikegami, H.), Universal Academy Press, truth might lead’? Tokyo, 1993, pp. 5–19. 5. Fleischmann and Pons were well aware of the significance of loading and the need to measure it, and they did so by means of the 11. Kunimatsu, K., Hasegawa, N., Kubota, A., Imai, N., Ishikawa, M., Akita, H. and Tsuchida, Y., Deuterium loading ratio and excess cathode overvoltage. Since it is now clear that the FPHE occurs at heat generation during electrolysis of heavy water by a palladium or near the cathode surface, this measurement is possibly more relevant than the average loading inferred from bulk resistivity cathode in a closed cell using a partially immersed fuel cell anode. In Frontiers of Cold Fusion (ed. Ikegami, H.), Universal Academy measurements, but requires experienced interpretation. Press, Tokyo, 1993, pp. 31–45. 6. Unknown to the SRI group, Fleischmann and Pons established a minimum observation time of 3 months before an experiment 12. McKubre, M. C. H., Crouch-Baker, S., Hauser, A. K., Smedley, S. I., Tanzella, F. L., Williams, M. S. and Wing, S. S., Concerning would be regarded as ‘failed’. Having worked on observing the ef- reproducibility of excess power production. In Proceedings of fect for more than 3 years before 1989, this clearly shows that they were aware of a long initiation time. ICCF5, Monto Carlo, Monaco, 1995, pp. 17–33. 13. Lewis, N. S. et al., Searches for low-temperature nuclear fusion of deuterium in palladium. Nature, 1989, 340, 525–530. 14. Albagli, D. et al., Measurements and analysis of neutron and 1. Koonin, S. E. and Nauenberg, M., Calculated fusion rates in iso- gamma-ray emission rates, other fusion products, and power in topic hydrogen molecules. Nature, 1989, 339, 690. electrochemical cells having Pd cathodes. J. Fusion Energy, 1990, 2. Assenbaum, H. J., Langanke, K. and Rolfs, C., Effects of electron 9, 133–147. screening on low-energy fusion cross sections. Z. Phys. A: At. 15. Fleming, J. W., Law, H. H., Sapjeta, J., Gallagher, P. K. and Nucl., 1987, 327, 461. Marhon, W. F., J. Fusion Energy, 1990, 9, 517.

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