So, isentropic processes are pretty cool. It's where the entropy in state 1 is equal to the entropy in state 2, or no change in it, basically. Unfortunately, no such process exists. It's only an idealization by engineers to simplify problems where entropy change is negligable. And trust me, dealing with entropy is a serious pain. I can upload pictures of homework pages long for a single problem solving for it :(
Entropy, and thus, disorder, always increases in the universe whenever energy is being used. What exactly does that mean? Here's a simple example. Say you have a jar of various sized rocks with different densities (mass/volume) in no particular order throughout. If you shake the jar either with your hands or a machine, the rocks will arrange themselves so the highest density larger rocks are on the bottom and the smaller rocks are at the top. That seems to be more ordered, doesn't it? So how can entropy increase?
The answer is that even if you have a process which provides ideal work (also an idealization and impossible) or 100% efficiency for the energy into the system, it still will take more energy to get the rocks back into their original positions. So, entropy has increased even though the rocks appear to be more ordered! This, and of course the fact the process you use (your body or a machine) to shake the rocks also increases the entropy.
Of course, eventually the universe will be filled with so much entropy the energy required to get useful work done will be impossible. Interestingly, proton half-life has been measured to be about 10^40 years. I wonder if the protons will decay before the entropy wins!? Everything in the universe has a death date, it seems. Supermassive black holes will be the last thing to go at 10^80 years. Luckily for those black holes that's a ridiculously long time. Maybe vamps will still be around, they are immune to suffocation and freezing, right?
Comments appreciated and thanks for reading!
Have some future posts lined up, got a request to do something on time travel and I will be doing a piece about this awesome idea I had for a moon base on Europa, and future civilizations view of the universe!