Very useful rules, I see… impossible to bypass :-)

Funghi

Sorry, but you are wrong, battery means exactly chemical battery

Gravity electrical storage is not a battery

https://en.wikipedia.org/wiki/Electric_battery?wprov=sfla1

Yep

And the picture from 1991 is in black and white?

GTFO

Edit: seems I was wrong in my assumptions

Well math might be, physics for sure isn’t

not yet

The same can be said for banknotes, they are quite useless as paper, they are mostly valuable because people see them as valuable and perceptions can change