On the topic of cold fusion, it's being rebranded as Low Energy Nuclear Reactions and is seeing a resurgence in research. We know catalyzed fusion is possible (

On the topic of cold fusion, it's being rebranded as Low Energy Nuclear Reactions and is seeing a resurgence in research. We know catalyzed fusion is possible (see Muon catalyzed fusion) and quantum phenomenon in complex crystalline structures is very poorly understood at best - as highlighted by superconductivity. We know nuclear processes can be influenced by solid state structure in rare cases, and don't know the limits of this. I'm not going to claim it's viable as an energy source, but it's exciting when we encounter physics we don't fully understand. Check out https://www.youtube.com/watch?v=ZbzcYQVrTxQ https://www.youtube.com/watch?v=ZbzcYQVrTxQ for a great summary of this controversial field.