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Add some scientific background
'''Cold fusion''' is a popular name for an effect resulting in apparent excess heat, that some scientists have claimed could be produced from a nuclear reaction, mechanism unknown, near room temperature.
'''Cold fusion''' is a hypothesized form of [[nuclear fusion]] that takes place at much lower temperatures than are traditionally though required.
= Theory =
== Nuclear Fusion ==
In a nuclear fusion reaction [[nuclei]] of light [[elements]] join together (fuse) to produce heavier nuclei with a higher [[atomic number]]. The mass of these heavier nuclei is slightly less than the sum of the masses of the original nuclei and the missing mass is released as energy, in accordance with the famous equation [[E=mc²]].
For man-made fusion, the nuclei involved are usually two [[deuterium]] (heavy hydrogen) nuclei, each consisting of one [[proton]] and one [[neutron]] and combining to produce a [[helium]] nucleus or [[alpha particle]] (two protons and two neutrons). [[Tritium]] is sometimes also used, but the distinction is not relevant to this article.
However, since deuterium nuclei have a positive charge, they repel one another and thus the chief problem in achieving fusion is to get the nuclei close enough together to fuse.
== High Temperature Fusion ==
The approach that has generally been taken is to heat the gaseous deuterium to such a high temperature that it becomes a [[plasma]] and that the nuclei have sufficient [[kinetic energy]] so that some of them can overcome their repulsion and collide. Once this is achieved then the reaction becomes self-sustaining, with sufficient energy released to maintain the high temperature and provide a surplus of useful energy.
However, the main problem of this approach is the containment of the high energy plasma. This may be achievable using precisely shaped [[magnetic field|magnetic fields]], but to date the longest period of stable fusion under this mechanism has been around half a second <ref>http://www.edouardstenger.com/2009/02/03/the-end-of-nuclear-waste/</ref>.
== Low Temperature Fusion ==
There is, however, no fundamental law that says that this high temperature approach is the only way to get the deuterium nuclei close enough to react. Other approaches have been posited. For example, if the [[electrons]] of deuterium [[atoms]] could be persuaded to orbit much closer to the nucleus then the atom would have an overall neutral charge until it was in much closer proximity to another atom (i.e. until the nuclei were within the orbit of the electrons).
Quantum Theory tells us that this would be impossible with electrons, but it seems theoretically possible that deuterium atoms could be produced where the nucleus is orbited by a [[muon]] instead of an electron. Since a muon is 207 times heavier than an electron it would orbit 207 time closer. Thus there would be a much lower amount of energy needed to get the nuclei to collide, and thus a much lower temperature. <ref>http://www.rikenresearch.riken.jp/eng/frontline/5976</ref>
However, this Muon-catalyzed fusion has never been practically achieved, and neither have various other attempts to coax the nuclei closer together.
= Practice =
== Fleischmann Pons ==
In 1989, electrochemists Martin Fleischmann and Stanley Pons of the University of Utah claimed to have produced such an effect loading a [[palladium]] cathode through electrolysis in heavy water, and some speculated that this might possibly become a source of cheap energy in the future.
In 1989, electrochemists Martin Fleischmann and Stanley Pons of the University of Utah claimed to have produced such an effect loading a [[palladium]] cathode through electrolysis in heavy water, and some speculated that this might possibly become a source of cheap energy in the future.