There is no known mechanism that I can think of to reduce the overall entropy in our observable universe. You can have a local decrease, like laser-cooling something into a Bose-Einstein condensate, but especially on a cosmological scale, there's no way to significantly delay the system from progressing from low to high entropy, and it's actually believed to be impossible to reverse the flow of universal entropy. Globally, things progress from low to high disorganization. And that's basically the foundation of statistical thermodynamics. I think what mk is invoking is the "Big Crunch" Theory. That particular fate of the universe isn't yet ruled out, but current projections involving measured universal expansion rates see an acceleration of spacetime on a cosmological scale (a la dark energy), which suggests that we could be headed towards a "Big Rip", but we don't have enough data to really know yet. And yes, in the event of a "Big Crunch" scenario, the entropy of the universe would be minimized, just as it was at the moment of the Big Bang. It is more than likely that no one alive today will know what the ultimate fate of the universe will be.
For reference my question was lifted from The Last Question by Isaac Asimov. Couple of questions. As the rate of expansion increases the size of the observable universe decreases. There appears to be an assumption that this rage will indefinitely increase, thereby causing the size to become smaller than that which applies to forces, is my understanding correct? At the end of the big rip is the destruction of atoms. Is that a spontaneous conversion of atoms to dark energy, or something else?
This is a better response than I could've given. But let's talk about the Big Rip, because it's way more interesting than the Big Freeze. And for fart jokes. As soon as something vanishes optically from our visible horizon in space-time, we will be free of its gravitational influence. We do know that there is more universe beyond via dark flow observations. So yeah, we'll start to see things "going dark", but we don't even know the exact size of the observable universe. It's believed to be 46-47 billion light-years away, and a billion light-years of margin is a lot. And yes, the universe is only 13.8 billion years old, some people have trouble reconciling an apparent discrepancy there. What I'm really hazy on is whether or not the sizes of "fundamental" particles scales with universal expansion. Regardless, yeah, unless the physical constants change with time in lock-step with expansion (and they might, we don't know yet), there will eventually be effects on atomic and molecular structures, and then it all goes to hell pretty quickly after that, I imagine. I'm not well-versed enough in quantum mechanics to venture a guess as to how the strong, weak, and Coulomb forces will react, and in what order. Protons, neutrons and electrons are first separated from each other far enough to not interact. They might eventually have their mass converted to energy, as the diameters of quarks and electrons become the length at which information can no longer be communicated? This is actually a weird rabbit hole of not-so-well-established ideas, so I'm purely speculating. Tom Cruise and I are already working on MI:6 (which is Mi6 British-themed, of course) about using the LHC to create a local safe-zone surrounding our solar system when all baryonic matter goes radioactive simultaneously as a result of universal expansion. Yeah, the Big Rip is ripe for Hollywood exploit.There appears to be an assumption that this rage will indefinitely increase, thereby causing the size to become smaller than that which applies to forces, is my understanding correct?
At the end of the big rip is the destruction of atoms. Is that a spontaneous conversion of atoms to dark energy, or something else?