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Cold fusion: A case study for scientific behavior
Most people—including scientists and politicians—now recognize
that a serious energy crisis looms in our future. Human populations use an enormous amount of energy, and as the population
grows and standards of living increase, we will require even more.
Unfortunately, the energy sources currently available to us all have
major drawbacks in the long term. Oil is efficient, but contributes
to climate change and will run out eventually. Coal is plentiful but
polluting. Solar energy is appealing but only as dependable as a
sunny day—and it’s currently expensive to boot! A clean, reliable
energy source that won’t run out any time soon would solve our
energy problems and revolutionize the world. You might think such
an energy source is a pipe dream, but in fact, it has already been
discovered—in seawater! Seawater contains an element called deuterium—hydrogen with an extra neutron
(Fig. 1). When two deuterium atoms
are pushed close enough together, they
will fuse into a single atom, releasing a
lot of energy in the process. Unfortu- Figure 2. University of Utah chemists
Figure 1. A hydrogen atom
nately, figuring out exactly how to get Stanley Pons (left) and Martin Fleischmann.
has only a single proton
deuterium atoms close enough togethin its nucleus, whereas
deuterium, a rarer isotope of
er—in a way that doesn’t take even more energy than their union generates—has
hydrogen, has a proton and
been a challenge.
a neutron.
The process by which two atoms join together, or fuse, into a single heavier atom
is called fusion. Fusion is the energy source of stars, like our sun—where it takes place at about 27,000,000°
F. In 1989, chemists Stanley Pons and Martin Fleischmann (Fig. 2) made headlines with claims that they had
produced fusion at room temperature—“cold” fusion compared to the high temperatures the process was
thought to require. It was the kind of discovery that scientists dream of: a simple experiment with results that
could reshape our understanding of physics and change lives the world over. However, this “discovery” was
missing one key ingredient: good scientific behavior.
This case study highlights these aspects of the nature of science:
scrutiny of this community, science corrects itself.
perform the tests that would prove their ideas wrong and/or allow others to do so.
even if that means giving up a favorite hypothesis.
The ingenious idea
The chemists claiming to have solved the world’s energy problems with cold fusion, Stanley Pons and Martin
Pons and Fleischmann photo courtesy of the University of Utah
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
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Fleischmann, made a somewhat unlikely pair. Pons was a quiet and modest man from a small town in North
Carolina. Fleischmann was an outgoing European who exuded confidence and was almost old enough to be
England, where Fleischmann was a professor. Pons admired Fleischmann’s intelligence and ingenuity, and
Fleischmann soon became his mentor and friend. The two remained close over the years, as Pons moved from
a graduate student position into a professorship at the University of Utah. Shortly after Pons took up his post
as professor, the two began to collaborate on research projects.
The idea behind their cold fusion experiment was sparked by another one of Fleischmann’s studies. In the late 1960s, Fleischmann had been using palladium, a rare
metal, as a key ingredient to separate hydrogen from deuterium. In those experiments, he saw firsthand how palladium can absorb unusually large amounts of
hydrogen—about 900 times its own volume. That’s a bit like using a single kitchen
sponge to mop up 30 gallons of spilled milk! This amazing absorption power is due
to a chemical reaction on the surface of the palladium that draws hydrogen inside Figure 3.
the metal. Because hydrogen and deuterium are so similar (differing by just one neutron), the same reaction occurs with deuterium—it can also be sucked up by palladium in surprisingly large amounts (Fig. 3). Fleischmann
reasoned that since the deuterium absorbed by palladium undergoes a dramatic reduction in volume (by a factor
of about 900), the deuterium atoms must be squished together inside the palladium. He began to wonder if a
similar process could be used to force deuterium atoms close enough to fuse and release energy …
Idea into action
Fleischmann filed away his ideas about fusion until the
fall of 1983, when he and Pons started talking about
the possibility of using chemical processes (reactions
among atoms and molecules) to trigger a nuclear process (changes within the nuclei of atoms). They decided
to set up a full-blown experiment to test Fleischmann’s
idea. Working in Pons’ laboratory, the two put together what they called a “fusion cell” (Fig. 4). This cell
consisted of two pieces of metal, one palladium and
the other platinum, submerged in a container of heavy
water (water in which the hydrogen of each H2O mol- Figure 4. Pons and Fleischmann’s fusion cell.
ecule is replaced by deuterium). They knew that if they
zapped the cell with electricity it would trigger a chemical process called electrolysis, in which the heavy water
molecules would split, producing deuterium gas and oxygen. The deuterium could then be absorbed into the
palladium via a chemical reaction. Pons and Fleischmann hypothesized that, once inside the palladium, the deuterium atoms would be forced so close together that they would fuse and release large amounts of energy as heat.
Pons and Fleischmann measured the temperature of the cell continuously throughout its operation. After
some analysis of the data, they found that the cell was producing about 100 times more heat than could be
accounted for by chemistry alone (Fig. 5)! They interpreted this excess heat as evidence for fusion. Excited
by the possibility that they had found an inexpensive way to harness fusion for energy production, Pons and
Fleischmann were eager to test their idea further. However, more experiments required more money …
Teammate or rival?
With promising preliminary results to back their cold fusion hypothesis, Pons and Fleischmann applied for a
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
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Figure 5.
government grant to get funds for further experiments. As part of the grant process, Pons and Fleischmann’s
proposal had to go through peer review. One of the reviewers was Steven Jones (Fig. 6), a nuclear physicist at
Brigham Young University, just 50 miles away. As it happened, Jones and a group of collaborators were working on a similar experiment but were studying a different line of evidence. While
Pons and Fleishmann were concentrating on detecting the heat that would be produced by fusion, Jones’ group was looking for another sign of fusion—neutrons.
Nuclear theory—the theory of how protons and neutrons interact—explains how
fusion works and generates many expectations about what we should observe
when fusion actually happens. According to nuclear theory, deuterium atoms fuse
and release energy in a two-step process:
1) The two deuterium atoms unite to form a single atom of helium-4 (helium
with two protons and two neutrons).
2) This helium-4 atom has a lot of energy—so much energy that it is unstable.
The unstable atom quickly discharges some of this energy in one of three
ways: releasing a neutron, proton, or gamma ray (a type of electromagnetic
radiation) (Fig. 7).
Figure 6. Retired Professor
Steven E. Jones, Brigham
Young University.
The fusion process—the formation of helium-4 and the subsequent energy release—is expected to generate
a great deal of heat. Furthermore, nuclear theory tells us how much of each fusion product we should expect to observe: for a given amount of deuterium undergoing fusion, we should see the production of about
equal numbers of protons and neutrons and a much smaller number of gamma rays. The heat, neutrons, and
Figure 7.
Steven Jones photo courtesy of Steven Jones
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
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Figure 8.
helium-4 could all have been detected by equipment available at the time. That made at least three lines of
in the appropriate amounts would have been strong evidence in favor of cold fusion.
Using a brand new, state-of-the-art neutron detector, Jones’ team (Fig. 9) had found evidence of a small
conceptual agreement that cold fusion is possible, the details of Jones’ results did not mesh with Pons and
Figure 9. Professor Steven Jones and fellow BYU physicists
with their neutron detection equipment. From left are Jones,
J. Bart Czirr, Gary L. Jensen, Daniel L. Decker, and E. Paul
Palmer.
Fleischmann’s findings. The amount of fusion Jones thought he was detecting was so minute that it had no
practical application—whereas Pons and Fleischmann’s results indicated that fusion cells could be used as an
energy source, one day fueling entire power plants.
Jones’ team photo courtesy of Steven Jones
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
Since they were seeking different lines of evidence for the same phenomenon, Jones asked the funding agency,
a collaboration. Scientifically speaking, collaborating was a good idea. Scientists are expected to understand
the current research and theory in their fields in order to ensure that their work is up-to-date and takes recent
advances into account. Though Pons and Fleischmann had extensive training in chemistry, neither of them
had studied nuclear physics, which was Jones’ area of expertise. Additional physics knowledge would have
been especially helpful in this case because the hypothesis about fusion occurring in palladium was so unconventional. It went against the grain of well-supported physical theories—which suggested that the deuterium
atoms inside palladium wouldn’t get close enough to one another to fuse. Both groups had relevant knowledge
that the other lacked. By collaborating, they would broaden their understandings of the problem, techniques,
and evidence—and would be better able to judge whether or not fusion was occurring.
Unfortunately, the benefits of collaboration were not enough to persuade Pons and Fleischmann to work with
Jones’ group. Pons and Fleischmann were convinced that Jones had used details gathered from their grant application to get his experiment running. They refused to collaborate—and in so doing, missed an opportunity
to expand the expertise of their team (Fig. 10).
Figure 10.
Anomalous neutrons
Worried that Jones would scoop them, Pons rushed
to perform neutron experiments of his own, but his
search for neutrons did not start off well. He was initially unable to detect any sign of neutrons being released from his cold fusion cell, although the large
number of neutrons produced by fusion should have
been relatively easy to detect. Pons then tried a second
technique for neutron detection. This time he found
neutrons—but a hundred million times fewer than
the number he had expected to detect! However, this
was still many times more neutrons than the number
that Jones had found (Fig. 11). Nothing seemed to be
matching up—Pons’ neutron results didn’t agree with
his heat measurements, with Jones’ neutron results, or
with established nuclear theory, which suggested no
fusion should be occurring at all!
Figure 11.
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
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with established theory (Fig. 12)—and such anomalous results sometimes lead to major scientific advances.
Nuclear theory itself came about in this way, when Ernst Rutherford and his colleagues discovered that their
experimental findings didn’t fit with established views of the atom. Could the surprising cold fusion results
indicate that nuclear theory also needed to be reconsidered? Perhaps, but Pons, Fleischmann, and Jones would
Figure 12.
need strong evidence to support this conclusion. Such theoretical revolutions are the exceptions, not the rule.
Fifty years’ worth of scientific labor and all the evidence supporting nuclear theory was telling them that they’d
made a mistake; fusion couldn’t be occurring.
As scientists, the correct course of action was clear. Scientific conduct involves balancing skepticism and openmindedness. The cold fusion scientists were expected to keep both the new results and the old theory in
mind, while doing their best to gather more evidence. With such surprising results, they had an even greater
responsibility to complete thorough and careful testing to support their results and eliminate the possibility of
experimental error.
Though Jones, Pons, and Fleischmann knew their scientific responsibilities, there was new pressure to publish
quickly since the two groups would be competing. In science, it’s not uncommon for two or more groups to
investigate the same problem at the same time, and so science has a rule for assigning credit. The first group
to publish gets the credit for a new discovery. Thus, if either Jones or the Pons/Fleischmann team spent too
much time doing additional tests before publishing, they ran the risk of missing out on the scientific credit.
Additionally, Pons and Fleischmann’s results suggested the possibility of lucrative applications for power generation—and so they were also concerned about patent rights. The standards for scientific conduct (and the
Only two months after Pons and Fleischmann had
learned that they had competition, Jones informed
them that he was prepared to publish. Jones generously proposed that both groups submit their papers
to the same journal at the same time so that the credit
could be shared. The proposed date of submission
was just 18 days away, but Pons and Fleischmann had
been hoping for another 18 months to complete their
on their time to gather data, Pons and Fleischmann
felt they had no choice and agreed to the joint paper
submission. They returned to the lab (Fig. 13), determined to collect as much evidence as possible in the
remaining days.
Figure 13. Pons (left) and Fleischmann in their lab.
Pons and Fleischmann photo by Paul Barker, courtesy of Deseret News
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
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The rush to publish
Though they’d just agreed to a joint submission in 18 days and despite the fact that they’d originally wanted 18
months to complete their experiments, Pons and Fleischmann jumped ahead of Jones and submitted a journal
article on their own just five days later. This action broke with standards for scientific behavior on two levels (Fig.
14). First, they failed to uphold the ethical standards set by the scientific community by breaking the intent (if not
the letter) of their agreement with Jones. Second, they didn’t sufficiently expose their ideas to testing. In their rush
to publish, they failed to perform some simple and obvious experiments, the results of which would have provided key evidence about whether or not their cold fusion hypothesis was correct. For example, they could have:
Figure 14.
known as a control. If the experiment generated excess heat—even when it lacked the key ingredient,
deuterium—it would be strong evidence against the idea that fusion was the cause of the heat.
palladium could absorb. If another metal with less absorption capacity could produce similar results, then
this would also be strong evidence against fusion. This is another example of a control.
gasses were allowed to escape the fusion cell and then the amount of heat carried away by these gasses was
estimated. If they had used a different technique in which no gasses escaped, they would have obtained
more accurate results.
not easy, and Pons had no previous experience in this area. On top of that, the equipment Pons used was
not very sensitive. More sensitive equipment and more experience operating it would have added credibility to their claims.
Pons and Fleischmann submitted their paper to the Journal of Electroanalytical
Chemistry (Fig. 15), whose editor felt that the weight of Pons and Fleischmann’s
potential discovery merited special treatment. The editor put the article through
an abbreviated form of peer review—the system science has in place to make sure
journal articles meet good scientific standards. Peer review can catch a variety of
shortcomings in articles before they get published. For instance, peer reviewers
normally notice when the evidence is insufficient to support the authors’ claims
(as was the case for Pons and Fleischmann’s) and suggest that additional evidence
Figure 15.
© 2012 The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California • www.understandingscience.org
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logic—they had incorrectly calculated the magnitudes of the forces acting on deuterium while inside palladium. The correct calculation revealed forces much, much smaller—too small to push deuterium atoms close
enough together to fuse. However, this and other shortcomings in Pons and Fleischmann’s article slipped
through the rushed review. The reviewers had just one week to scrutinize the paper (when several weeks are
usually allowed) and didn’t get to review the changes the authors made in the second draft.1 This short review
period bypassed some of the checks set up in the process of science, and would eventually contribute to unnecessary confusion, as well as wasted time, energy and money.
It’s not entirely clear why Pons and Fleischmann chose to publish so much earlier than they had initially intended, but the impact on their study is apparent. Many scientists later criticized their lack of thoroughness as
well as the quality of their work. Pons and Fleischmann had not performed the experiments or the analysis very
carefully, and a month after the paper appeared, they had to publish a list of corrections two pages long that
included important modifications to their data. However, before the scientific community got their chance to
evaluate Pons and Fleischmann’s ideas about cold fusion, the two brought their claims to the public at large.
Publication by press conference
Instead of waiting for the scientific community to have its say on Pons and Fleischmann’s radical claims—or
even for the paper to be published—the University of Utah held a press conference (Fig. 16) to announce
the success of cold fusion to the world. Very little concrete information was given, but the two scientists and
university officials repeatedly emphasized the amount of energy that Pons and Fleischmann thought their fusion cells could produce in the future if the cells were made bigger and better. This gave the public a highly
optimistic view of cold fusion and aroused much excitement about the possibilities, all before the scientific
community had even had a chance to determine if cold fusion was real.
Figure 16. Pons (left) and Fleischmann at the March 23, 1989, University of Utah press
conference. These clips are taken from a video of the press conference, viewable on YouTube.
Roadblock to replication
While publicizing exciting discoveries is normal, early publicity, combined with curtailed peer review, caused
some problems in this case. The scientific community was in an uproar after the press conference. Pons and
Fleischmann had made extraordinary claims, but because the paper was not yet ava …
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