The whole "cold fusion" thing
Low Energy Nuclear Reactions (LENR) - whose investigators hate the term "cold fusion" - is either a field rife with errors or the dawning of a new era for humanity. (I suppose it could end up being of real but minor utility, but that's no fun to speculate on.)
Some very capable people in the US Navy, NASA Glenn Research Center, and other organizations are poking into this quite seriously, reporting excess heat, elemental transmutation, and other effects from room-temperature apparatus that shouldn't be producing any kind of nuclear effect. The emerging thinking is that this is not fusion at all, but some manifestation of electroweak interactions - that is, previously unsuspected effects of the "weak force" that causes radioactive decay, not the "strong force" involved in nuclear fission and fusion. I was in a meeting a while back where politely dueling physicists differed over whether any of the positive results (there have been negative findings, too) are valid or even possible. If the results are valid, the possibilities are almost endless - clean, unlimited energy, with all that goes with it. If they are wrong, it's probably the largest scale example in history of the "N-rays" problem - that is, that even highly qualified scientists are not immune to subconscious bias that leads to finding what they want to find.
The whole business is immensely complicated, not least by the economic stakes and the claims of two companies to be selling working LENR power devices - devices shown off in carefully controlled demonstrations, the way "zero point energy" companies do it, with skeptics allowed to observe but not to poke around in the demos to see if they might be rigged.
New Documentary looks interesting
COMMENT: Unqualified as I am to analyze the claims of the physicists and nuclear chemists, I still feel comfortable in offering the opinion that the devices for sale will never be independently proven to work. As for whether the effect (and there are many types of effects reported from different types of experiments, so I am generalizing here) is real, I have to come down on the side of the skeptics so far. But I wouldn't close the door, not when there are some well-qualified people on both sides. Fingers crossed.