Yesterday I made the mistake of entering the search term "perpetual motion" at youtube.com. Then I lost an hour of my life looking at videos claiming to make perpetual motion engines out of natural magnets. These videos fascinate me because I presume they are all fake. It seems to me that if any of these devices worked I wouldn't have to hunt around on youtube to find them. I'd already have one in the garage charging my electric car. So what is up with these videos?
One theory is that all of the inventors started out seriously trying to build perpetual motion machines, realized at some point they couldn't do it, and decided to salvage something out of the effort by making fake videos and getting some attention.
Another theory is that the so-called inventors never intended to do anything but create fake videos. But it sure seems like a lot of work for that. That option seems unlikely to me.
Lastly, we must entertain the possibility that the laws of physics have some sort of loophole, inventors sometimes find it, and the big corporations send around hit men every time it happens. That's why you never see the invention beyond youtube.com or some local news show. But that seems unlikely too. So it remains a mystery.
As I was googling around on this topic, I discovered that there is an element called gadolinium that is attracted to magnets up to about room temperature, then it abruptly loses its attraction . It seems to me you could build a generator using that principle. All you need is an external source of heat, and not much of it, to power the thing. A natural magnet could attract the gadolinium, which creates some mechanical energy, and some portion of that energy could be used to introduce heat from the outside that makes the gadolinium non-magnetic and puts the device back to its original position. Some of that energy from the return trip would turn off the outside heat source and the process repeats forever. It would only operate at about room temperature, but that's still pretty nifty. The inside of my house, for example, is always at about room temperature, so there is no shortage of that environment.
Yeah, I know, someone probably already invented it.