baywax said:
First of all, is "potential energy" similar, the same or unrelated to "free energy"?
There are actually two types of free energy, Gibbs and Helmholtz. They are two types of thermodynamic potentials. In that way, you could consider free energy a type of potential energy. I don't claim to be an expert though.
baywax said:
If energy does not do work is it really there?
Yes. I could throw a piece of coal into my train's engine. I could get work from the heat produced by the chemical reaction of burning the coal. The train would move. If I didn't burn the coal, it would still contain energy. The coal's energy is not dependent on me getting work from it.
Or do you mean in some kind of philosophical sense of the word
real? And I suppose it might also depend on what you mean by
work...
baywax said:
When someone uses "x" amount of energy to tell me to look out for a falling rock... it would seem that "x" would be the amount of energy I would use to move out of the way... as in Newton's "every action" axiom.
Dodging a falling rock will almost certainly use more energy than warning some one about the rock. It would need to be a really passionate warning to compare to quickly moving your entire body out of the way of a deadly peril with adrenalin pumping through you veins, heavy breathing, and all that.
Pythagorean said:
Could information, for instance, be responsible for dark matter? Is it that real? Should it contribute to the total energy of the universe?
I would say that if dark matter exists, it contains information. If information really is energy, it should be considered as part of the total energy of the universe. But is it energy?
I'm going to go and rub my three good brain cells together and see if I can apply some numbers to any of this.