There is no such
"thing" as energy. "Energy" is a mathematical invention.
I agree that I can't go to the store and buy a box of energy but there is
something about that bolder on the ledge that can crush my car and there is
something about that bolder falling toward my car at such and such velocity
that can crush my car and there is something about that gasoline in my fuel
tank that can cause my car to be pushed into a tree and once again be
crushed. My insurance company thinks energy is real.
I ask this question in no way being sarcastic but wanting to know what you
and perhaps others think. Do you consider momentum to be real or do you
think it is a mathematical invention as well?