The answer is to do with;

1) Gravity
2) Wave Harmonics
3) Whirlpools
4) Electronic induction

and maybe gyroscopes or Nazi scientists or something.

An interesting read on this type of stuff is “Hunt for Zero Point” by Nick Cook for the nazi anti-gravity, and “The Scientist, the Madman, the Thief and their Lightbulb” by Keith Tutt on perpetual motion machines and numerous claims by people to have built them.