What is “cold fusion”?

Unlike with “hot fusion”, where energy is to be derived by heating atomic nuclei to very high temperatures allowing fusion, here with “cold fusion” the process is being attempted at room temperature.

Since media reports in 1989 caused great excitement about two US electrochemists at the University of Utah, Martin Fleischmann and Stanley Pons, who claimed that they had  succeeded in doing this, the subject of “cold fusion” has been a long runner. After the initial hype, however, scientific interest has cooled down. But in films, novels, and internet forums the subject keeps cropping up. And also the one or other research group still treats diverse versions of cold fusion. However, reports of success hitherto have never been verified by independent third parties.

Where a cold-fusion method has been demonstrated to work, such as fusion catalysed by myons or pyroelectrically induced fusion, it has always been the case that more energy is needed to induce reactions than is finally released by fusion: Fusion does indeed succeed but there is no energy gain.