"Wouldn't it be nice," most reasonable people would agree, "if there were a way to obtain energy from fusion of some innocuous nuclei like deuterium without the enormous temperatures of nuclear explosions or the various `hot' controlled fusion reactors on the drawing boards." There certainly is a way to get deuterium nuclei close enough together to fuse without high temperatures - in fact I recently participated in an experiment that achieved D-D fusion at a temperature of 2.5 K: this involves forming a molecule of two deuterons and one negative muon - an unstable elementary particle which is more or less like an electron except that its mass is 207 times bigger. The heavy muon pulls the deuterons so close together that they fuse. This works. Unfortunately it doesn't work well enough to generate more energy than it took to make the muon in the first place! The closest anyone has come to "breakeven" using muons is more than a factor of ten too low in efficiency. Too bad. It is frustrating to come so close and then fail.
Perhaps because of this frustration, a few years ago some people deluded themselves into believing that they had coaxed deuterons into fusing by regular electrochemical means in a palladium metal matrix. Unfortunately this was bogus. Even more unfortunately, the fantasy remained so seductive that a lot of otherwise respectable scientists were willing to compromise their integrity (probably unconsciously - I hope) and generate supporting evidence from flawed experiments or muddy reasoning. Consequently, many gullible people still believe in "cold fusion." Who can blame them? If you can't trust the experts, who can you trust? Maybe the popularity of the X-Files and other signs of people losing their grip on reality can all be traced back to the betrayal of public trust in the "cold fusion" debacle. Oh well. I did what I could.