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What if there existed a cheap, never-ending supply of energy that produced no nuclear or environmental waste? Sound too good to be true? If the theories behind cold fusion were made feasible, it may not be just a dream. But fusion reactions at room temperature have been plagued by experimental problems, lack of reproducibility, and flat out lies. Therefore, the field and its proponents have been looked upon with skepticism, or even as quacks. Yet, the scientific community has demonstrated repeatedly its keen interest in this pie-in-the-sky phenomenon.

Nuclear Reactions

Nuclear fusion is the process by which several separate nuclei 'fuse' together to form one heavier nucleus - the byproduct of this reaction being either the release or absorption of energy. The factor that dictates whether energy is absorbed or released is the binding energy of the molecule's nucleus (i.e., the energy required to split the molecule apart). Hence, the higher the binding energy, the more stable the molecule and the more difficult it is to disrupt it through fusion or fission. Nickel and iron have the highest binding energy of the elements, and are the most stable; this is also the reason iron and nickel are quite common in planetary cores, since they are produced profusely in supernovas. Fusion produces energy by combining very light elements into more tightly-bound elements, such as hydrogen into helium, while fission produces energy by splitting very heavy elements, such as uranium and plutonium, into tightly-bound elements.

Currently, nuclear energy in power plants is produced through fission reactions. Fission creates a lot of radioactive waste, and is limited by the required amounts of materials like uranium. Nuclear fusion is an attractive idea because it has the potential to be a cheap, nearly limitless source of energy which results in less radioactive waste and radiation.

Hot Fusion

Most conventional fusion reactions fall under the category of "hot fusion," as high temperatures and pressures are required to fuse two nuclei together without special preparation. Although the negatively charged electron cloud surrounding a positively charged nucleus in an atom will result in a net neutral charge, the nuclei of different atoms will repel each other. As a result, high temperatures and pressures are required to overcome this repulsion in conventional fusion reactions. This type of reaction powers stars and hydrogen bombs.

Muonic Cold Fusion

The sheer amount of energy hot fusion generates is staggering, but this process is largely prohibitive due to the temperatures involved. Therefore, finding ways of generating the same reaction without high temperatures (i.e., 'cold') has been a pursuit since the 1940s. In the 1950s, L.W. Alvarez was the first to observe fusion experimentally using a particle called a muon.1 The muon is part of the same family of particles as the electron but 207 times heavier, and can only be created in a specialized nuclear accelerator. After creation, the muon only lasts about 2.2 microseconds before decaying into an electron. When a muon is fired at hydrogen, the muon knocks the electron off the hydrogen atom, but since the muon is so heavy it orbits very close to the nucleus and cancels some of the positive charge of the nucleus. This muonic hydrogen atom can then combine with another hydrogen atom, forming a molecule where the two atoms are bound closely enough by the muon to counteract the repulsion of the nuclei and fuse them. Muons are not consumed in the reaction, and can act as catalysts in many fusion reactions. They have been observed to catalyze up to 150 reactions before they decay - not bad for 2.2 microseconds! Currently, the main drawback to this approach is the creation of muons and the reactions are so energy-intensive; more energy is consumed than generated due to the quick decay of muons. Research to overcome this obstacle continues.2

Electrolytic Cold Fusion

Another 'cold' method of fusing hydrogen atoms is to force the atoms inside a metal using an electric current. In 1866, Thomas Graham discovered the metal palladium can absorb hydrogen;3 it can be 'loaded' with hydrogen by using it as an electrode in an electrolytic cell. In a normal electrolytic cell, water is split into hydrogen and oxygen gases which bubble out. If a palladium electrode is used, the hydrogen atoms migrate to the palladium and are absorbed into it. The theory goes thus: as more hydrogen atoms are forced into the palladium, some will fuse together to form helium. In 1926, two German chemists (Paneth and Peters) claimed to have discovered fusion in palladium loaded with hydrogen,4 but later retracted their claim, saying the helium they recorded was just background in the air.

The Fated Fleischmann and Pons Experiment

In 1989, two scientists at the University of Utah, Martin Fleischmann and Stanley Pons, famously claimed during a press release to have produced nuclear fusion at room temperature, producing excess heat but no radiation.5 The experiment became the most famous, most promising (initially), and most damning for the field. Their results were previously thought to be impossible, and scientists around the world immediately tried to replicate their findings. Their cell used specially prepared palladium and heavy water, and after 100 hours it suddenly melted down due to excess heat. The claim generated much controversy and press due to their claim no radiation was produced, which they said was because the fusion reaction taking place was one where two deuterium atoms fused together to produce regular helium and gamma rays, instead of the expected 3-helium and a neutron. For a few months, the entire world was a-buzz. Similar experiments using lithium deuteroxide and heavy water did produce excess heat and no radiation. A special session on cold fusion at the April 1989 American Chemical Society national meeting attracted an audience of around 7000 (mostly) enthusiastic chemists. Almost immediately, though, strong skepticism set in, as several of the highly publicized confirmations were retracted, with explanations of the experimental problems responsible. A special session at the American Physical Society meeting at the beginning of May featured a number of negative presentations; one in particular (by Nate Lewis) reported his research group's inability to detect any excess heat, possible experimental reasons why one might (erroneously) detect excess heat, and a deconstruction of the assumptions used by Pons and Fleischmann that, he argued, led to deducing excess heat evolved from unconvincing data. Later in May 1989, a publication appeared demonstrating that the claimed gamma-ray signature was artifactual. After a (very) brief celebrity, Fleischmann and Pons were widely attacked and discredited, and by late 1990 both Pons and Fleischmann had left Utah.6

The DOE's 2004 Report

Popular journals such as Scientific American and Nature have often rebuked the subject and most other journals reject papers on the subject without reviewing them. In January 2006, the Washington Post, Time magazine, the Guardian, and other major newspapers and magazines attacked cold fusion, claiming it was a "scientific misdeed" debunked in 1989 - referring to a 1989 Department of Energy panel which found no convincing evidence for cold fusion, and recommended against research centers and special funding. After this report, the scientific community declared cold fusion "basically dead."

This did not mean cold fusion research came to a screeching halt. Experiments continued sporadically around the world, including at the Naval Research Lab in Washington D.C., and the Space and Naval Warfare Systems Command in San Diego.7,8 Recently, the U.S. Department of Energy reviewed the accumulated experimental data for cold fusion, at the request of cold fusion proponents who argued enough progress had taken place to deserve a reassessment. Eighteen nuclear physicists, electrochemists, and materials scientists reviewed submitted research. However, instead of condemning it or vindicating it, the DOE's December 2004 verdict remained the same as the past 15 years: inconclusive.9 The panel was evenly split over whether the evidence for excess power seemed legitimate. Two-thirds of the panel thought the evidence nuclear reactions took place were unconvincing, one person was convinced, and the rest were "somewhat convinced."10

The panel cited many problems with current experiments, including misinterpretation of the data, poor methodology, and less than state-of-the-art equipment. However, even some of the skeptical reviewers believed the experiments to look for the products of standard fusion reactions were feasible. In the end it was suggested funding agencies should consider peer-reviewing studies on cold fusion. They concluded future research could investigate the properties of deuterium-loaded metals and look for fusion products with higher quality equipment and methodology. What this means for cold fusion research is unclear, as the scientific community's opinion as a whole has not yet changed. It may still be many years away from receiving much in the way of acceptance, or funding.

Conclusion

The story of cold fusion highlights the damage that can be done to an entire field very early on if less than reputable claims are first announced to the media. Many current cold fusion proponents lament Fleischmann and Pons did not wait for publication and rigorous review of their experiment in a peer-reviewed journal, which would have saved the entire world, and the field, a lot of headache. If experiments cannot be reliably replicated, the labs that have expended time, energy, and money will not soon forget the deception. This results in skepticism and often wholesale rejection, even if the theories behind the fakery may be sound.

In this case, the actions of two over-eager scientists may have set the field back 15 years, and it may be many more before the scientific community is ready to forgive, forget, and support cold fusion research again. On the other hand, if cold fusion really is impossible, this quick rejection may have saved the scientific community and the government from pursuing a quixotic quest. Is this a case of the high payoff of success discouraging scientists from letting go, even in the face of negative evidence? Or, is a rigid scientific community simply unwilling to support unconventional research? The DOE did not want to wager a guess, and neither do I.11

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