Cold Fusion

Cold fusion is a hypothetical type of nuclear reaction that would occur at, or near, room temperature, compared with temperatures in the millions of degrees that is required for "hot" fusion. It was proposed to explain reports of anomalously high energy generation under certain specific laboratory conditions. It has been rejected by the mainstream scientific community because the original experimental results could not be replicated consistently and reliably, and because there is no accepted theoretical model of cold fusion.

Cold fusion gained attention after reports in 1989 by Stanley Pons and Martin Fleischmann, then one of the world's leading electrochemists, that their apparatus had produced anomalous heat ("excess heat"), of a magnitude they asserted would defy explanation except in terms of nuclear processes. They further reported measuring small amounts of nuclear reaction byproducts, including neutrons and tritium. The small tabletop experiment involved electrolysis of heavy water on the surface of a palladium (Pd) electrode.

The reported results received wide media attention, and raised hopes of a cheap and abundant source of energy. Many scientists tried to replicate the experiment with the few details available. Hopes fell with the large number of negative replications, the withdrawal of many positive replications, the discovery of flaws and sources of experimental error in the original experiment, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts.

By late 1989, most scientists considered cold fusion claims dead, and cold fusion subsequently gained a reputation as pathological science. In 1989, a review panel organized by the US Department of Energy (DOE) found that the evidence for the discovery of a new nuclear process was not persuasive enough to start a special program, but was "sympathetic toward modest support" for experiments "within the present funding system." A second DOE review, convened in 2004 to look at new research, reached conclusions similar to the first.

Some researchers continue to investigate cold fusion, now often preferring the designation low-energy nuclear reactions (LENR). Some have reported that, "under certain extreme conditions", they observe excess heat effects by interaction of hydrogen or deuterium with palladium, nickel or platinum. Since cold fusion articles are rarely published in refereed scientific journals, the results do not receive as much scrutiny as more mainstream topics.