Perpetual motion devices are either a gag, a scam, or as in the case of this particular toy that [Big Clive] bought on AliExpress, a rather fascinating demonstration of a contact-free inductive sensor ...

A perpetual motion machine is (as the name implies) a machine that moves perpetually; it never stops. Ever. So if you created one today and set it going, it would keep on going until the Big Freeze.

Are these machines possible without violating the laws of physics? No. A wheel that spins forever; a bird that never quenches its thirst; a clock that never stops ticking, an endless source of free ...