What is Energy?

[bdkeenan00]

I have been corrected before in this forum so I'm not going try to explain anything due mostly to the fact that all I really know about physics is from the internet, but I just wanted to bring up the second law of thermodynamics. Even though energy may be just "book keeping" it is known that this quantity called energy tends to be go froming being concentrated to being spread out(as in the total disorder of a closed system increases over time) and this tells use that time has a physical existence and is not just made up by humans. So if I know what I'm talking about it would seem that this energy is related to the direction of time(macroscopically) and tends to spread out. I'm sure that someone else here could better explain what I'm saying or they could correct me if I'm wrong. or not

 

[pmb]

Originally posted by bdkeenan00
I have been corrected before in this forum so I'm not going try to explain anything due mostly to the fact that all I really know about physics is from the internet, but I just wanted to bring up the second law of thermodynamics. Even though energy may be just "book keeping" it is known that this quantity called energy tends to be go froming being concentrated to being spread out(as in the total disorder of a closed system increases over time) and this tells use that time has a physical existence and is not just made up by humans. So if I know what I'm talking about it would seem that this energy is related to the direction of time(macroscopically) and tends to spread out. I'm sure that someone else here could better explain what I'm saying or they could correct me if I'm wrong. or not

Its not energy that is doing that. The energy of the Earth going around the Sun is not being "spread out" at all. The notion you're really thinking of is entropy.

Pmb

 

[bdkeenan00]

Thank you for your reply. When I said the entropy increases I meant the entropy of the entire universe. So when you said that our solar system has a low entropy doesn't that mean that somewhere else there is even more disorder to cancel out those places where there is high order? If am wrong please correct me for my knowledge of Physics is limited. Thank you very much

 

[FZ+]

Umm... I don't really understand the question, but I'll harzard an response anyways.

If we have a local decrease in entropy (like say, in a fridge), then by the 1st law of thermodynamics, you must have an increase in entropy somewhere else. (like in the air at the back of the fridge) Furthermore, by the second law of thermodynamics, that increase in entropy must be larger that the first decrease in entropy.

But that applies to change in entropy.
Saying the solar system has low entropy means that by some scale, the solar system has less than "normal". In the abscence of some comparision, I am assume that something like "low relative to the average entropy of the universe" is meant. In this case, it's kinda obvious - if something exists that is less than the mean, then somewhere there must be stuff that are higher.

 

[bdkeenan00]

Thank you "FZ+" that is exactly what I wanted to hear. Sorry that my question was vague.