cold fusion 
noun [mass noun]
Nuclear fusion supposedly occurring at or close to room temperature.What is the difference between nuclear fusion and cold fusion?...
- Indeed, in many areas of physics, such as cold fusion and high-temperature superconductivity, the scientific disputes have been extremely hostile and personal.
- There is probably just as much as chance that the next big surprise will be a thrilling one - the arrival of nuclear cold fusion to solve the energy dilemma, say - as a disaster.