Free Energy device successfully invented?

'53. Cool. & 54's

So you could just reverse the force of gravity, you could invent hovercraft that don't require propulsion to generate lift.

. . . but how to reverse the force of gravity without causing everything in the universe to explode?

Thanks for the summary above. I note that you have not mentioned 'entropy' which I understand is a key issue opposed to continuity of motion.
As I understand it, the word 'free' is problematic since it takes no account of monetry costs involved in development and maintenance. I am thinking of examples like wind farms here. Obviously all energy attributable to the sun as source, or geothermally sourced, is theoretically 'free', so 'free energy' seems to be no big deal in itself.

I built some solar headlights for my car.

I used sunlight to see in front of me during the day.