With the right material at the right temperature and a magnetic track, physics really does allow perpetual motion without energy loss.
The idea of levitating off the ground has been a staple of science fiction dreams and human imagination since time immemorial. While we don’t quite have the hoverboards that Back to the Future envisioned just yet, we do have the very real phenomenon of quantum levitation, which is almost as good. Under the right circumstances, a specially-made material can be cooled down to low temperatures and placed over a properly-configured magnet, and it will levitate there indefinitely. If you configure and construct a magnetic track, it will hover above or below it, and if you give it a nudge in the absence of air resistance, it will remain in motion perpetually.
But wait a minute: isn’t perpetual motion supposed to be an impossibility in physics?
It’s true that you can’t violate the law of conservation of energy, but you very much can make the resistive forces in any physical system as small as possible. In the case of superconductivity, a special set of quantum effects really does enable the resistance to drop all the way to zero, enabling all sorts of strange phenomena, including the one you see below…
