Drakkith said:
I think I see what you are saying Mark. Consider my examples to mean that all this happens for NO reason. IE the rock is moved back up to it's starting position and the heat it created still exists, while the CO2 splits and combines back into gasoline yet there isn't enough energy to do so to all the molecules.
Well, the heat energy that the rock lost during the collision was regained and became kinetic energy, which gave it the ability to move upward, until gravity converted all of the kinetic energy back into potential energy. So, we could think of it like this:
total energy of system when rock is on ground = momentum the Earth received from the collision + heat energy
total energy while rock is moving upward = kinetic energy + potential energy
total energy while rock is at maximum height = potential energy
We could then separate the total system into two parts - the rock, and the environment. The rock has no energy on the ground, it's in a high entropy form (heat) in the surrounding area. While at the top, it's in a low entropy form (potential energy), and it's all in the rock. Since, due to the second law, low entropy systems evolve into high entropy ones (usually), we will see the rock falling more often then just randomly moving upward.
So, the point I'm trying to convey is this - if the reaction occurred one way, we know the total of all resultant forms of energy is equal to the total of all the forms of energy prior to the reaction. For the rock, we know that all of the above expressions are true. So, there was enough energy to get the rock to fall down. Therefore, there must be enough energy in the environment to get it back up, since all of the energy (kinetic) that it had when hitting the ground had to transferred int something else, no more, no less.
So, with the chemical reaction, we know that the energy needed for the reaction to occur one way must be the same amount needed for it occur the other way (if you record a chemical reaction on film, does playing it in reverse reveal any violation of the conservation of energy?). So, we know that the energy needed for it to occur is somewhere in the environment, either in the form of the resulting chemicals, heat, or whatever else you like. The key is just getting it back into the chemicals, so that they can do it in reverse. This is where the second law gets in your way, since the result of the reaction is a much higher entropy configuration, so getting it do anything is much more difficult.
Well, it wouldn't be for no reason. Since heat is just the non-mechanical transfer of energy due to a difference in temperature, we can imagine our rock regaining energy from the heat by having all of the excited air molecules (remember, temperature is just a measure of the average motion of the constituent particles) all simultaneously slamming into the rock, exciting the motion of its atoms, causing it to gain temperature, which may give it enough kinetic energy to rise up.
Once again, we see where the second law gets in the way - the chance of all of those particle simultaneously slamming into the rock is very, very small, so it won't happen very often.
) doesn't have a final nanosecond
