There’s a way of interpreting the second law of thermodynamics that makes free energy machines impossible. Of course, we all get to decide for ourselves whether we’re in a position personally to know that this won’t fall by the wayside some day.
I think this is analogous to somebody selling a machine into which you insert two dollar bills, then insert two more dollar bills, and then five dollar bills drop out the bottom. The seller then fills a blackboard with confusing math, at the bottom of which appears “2 + 2 = 5”. You might not find it possible to debunk, and it would obviously be a great investment if it works, so, what’s your choice?
I had a similar experience, actually. I’m a physicist working in industry, and a proposal came to me for a system that supposedly could rearrange molecules to change various properties of substances in some way involving quantum mechanics. They said they could change the angles between the different atoms, and were vague about the possibilities, claiming nearly anything was possible. They sent me papers they’d written, about things like “time-reversed hertzian waves”, and I couldn’t understand everything in the papers, so I tracked down the professors at a nearby university who taught the grad level courses in quantum mechanics, and they couldn’t understand everything in the papers either. Finally I asked if they could make water more dense than normal, and they said they could, and I agreed that we would proceed further with them if they could send me a sample of extra-dense water I could verify with my own analysis.
So then they wanted to know how I was going to analyze the density, and I said, well, I was going to weigh a measured volume, of course, and how would you folks do it? They said they would use a microscope to measure the angle between the hydrogen atoms connected to the oxygen atom in the water molecules. So I wanted to know what kind of microscope, and they said it was a Bausch & Lomb. “An OPTICAL microscope? THAT’S what you’re basing this on?”
I hung up on them. But, it took hours of conversation and correspondence and checking up on things over a couple of months, and several of us technical folks at my company, to get to this point. Maybe I’m an idiot about quantum mechanics, and the professors who teach quantum mechanics at the local university too. I prefer to think that some elements of quantum mechanics are spooky enough that there is room for smart people to fail to see to the bottom of some things right off the bat.