Thread: What is energy
View Single Post
Drakkith
#31
May13-11, 08:01 PM
Mentor
Drakkith's Avatar
P: 11,896
Quote Quote by JJBladester View Post
Drakkith, I appreciate your explanations, but the words "It simly happens" just don't sit well with me. Perhaps that is becuase I need to continue my study of physics.

Thanks to you and all for the replies to my question.
I'm not sure why it doesn't sit well. Why does an electron attract a proton? Because negative charges attract each other. Well why is that? Because that's how it works. But why? Because it's how the universe works. See where I'm going? It doesn't matter how far we go down or how much we explain, someone can always ask why. At a certain point you simply have to accept the fact that that's just how it works.

Quote Quote by SpectraCat View Post
That definition would seem to indicate that energy is exclusively a transient quantity in physics, like work or heat. I don't think that is the case. For example, in statistical thermodynamics, the internal energy, total energy and enthalpy of a system are all state functions, meaning that they are path independent parameters of the system, like mass or temperature. So it seems that thermodynamically, that book has a non-zero energy even when it is sitting on the table. Even from a macroscopic classical physics definition of energy being "the ability to do work", that book has gravitational potential energy (due to the force on it), thus it has the ability to do work.
Don't confuse the different types of energy. The thermal energy contained in a book on a table is most definately not zero. The book has zero gravitational potential energy UNTIL it is either pushed off the table or the table is removed or whatever.

Quote Quote by pergradus View Post
The problem is the assumption that these ideas we use like "energy", "force" and "field" describe real physical things.

Personally I just believe that they are convenient, but abstract concepts from which we can build up a set of equations that work. I really don't think anyone understands the actual physical mechanism by which two charges attract or on mass attracts another, but people have come up with ideas that for all purposes seem to be consistent with observation - however that doesn't make them real.

These "ideas" ARE what we observe and measure. The equations we used are 100% based upon observation of how the universe works. There is absolutely nothing abstract about them. The only thing abstract here is the idea that Energy is "something".