I appreciate your optimism. I tend to be optimistic about the future myself. But there is no law of the universe that everything will work out ok. Only if we make the right decisions as a species and we don't get unlucky.
I'm quite apprehensive that the great filter lies ahead - that technology accelerates too rapidly compared to our wisdom and we end up nearly destroying ourselves. We're getting the ability to program life itself and to likely to democratize the ability to harness the forces inside the atom. Neither of which we're ready for as a species.
Maximum entropy merely implies that the temperature everywhere is the same (any other situation would necessarily have a lower entropy). You could in theory have maximum entropy at 1000K. Our universe has a ton of empty space, and not all that much energy, so the temperature at which it equilibriates is very low. It's also expanding, so the hypothetical equilibrium temperature is decreasing all the time.
It's also worth noting that the entropy can be very large, even if the temperature is absolute zero. (You just need a system with a lot of different ground-states that all have the same energy.)
> I appreciate your optimism. I tend to be optimistic about the future myself. But there is no law of the universe that everything will work out ok.
Isn't there some QM law that says that with infinitesimal probability anything can materialize at any point in space? Meaning that after everything has collapsed, you can (will!) still re-materialize somewhere in space. An infinite number of times!
I kind of wonder, in a half-assed amateurish way, if the underlying reality of our universe isn't just an extremely rare random fluctuation in a fluid-like medium at thermodynamic equilibrium.
There are multiple explanations for why the sky isnt lit up with radio and laser signals from advanced civilisation. The great filter is one explanation, that there are existential crises or threats that wipe out most civilisations or cause them to collapse to subsistence level. Nuclear war, biological weapons, ecological collapse, paper clip maximising AI, etc.
I once ran a Traveller RPG exploration campaign where one of the systems they visited looked really odd on sensors. Just fuzzy clouds and clumps and ring formations of diffuse metallic debris. It turned out it was all paper clips.
For context, the examples you mentioned are cases of the great filter lying ahead of us. The more optimistic hope is that the great filter is behind us - things like abiogenesis or multicellular life being extremely unlikely to happen. "Great filter" is just the name for "a barrier that stops life from becoming a spacefaring civilization".
This explanation is also the reason why finding basic life (say, bacteria) in the Solar System would be a cause for worry - if life evolved independently twice in the same star system, it would imply abiogenesis isn't that unlikely - thus strongly suggesting the great filter is still ahead of us.
Could the great filter be something like developing language? That's something that seems quite rare (only one species on Earth has it). If so, then discovering bacteria in the Solar System wouldn't be such a cause for worry.
> Could the great filter be something like developing language?
Perhaps it's a combination of factors?
Dolphins are social animals that appear to be capable of complex communications among themselves, but don't have hands to manipulate their environment the way we can.
Another interesting one I've heard is getting into space, period. It's possible that there are other technological civilizations out there, but all stuck under a few hundred km of ice or on a 2-earth-mass monster where it's impractical to reach orbit.
Earth may only be special in being in a sweet spot between Mars (too small to hold an atmosphere or protect from cosmic radiation, hence no life) and Gliese 832c (with its low-orbit velocity of something like 15km/s, hence much less practical to put stuff in space).
You can also get shielding with a thick enough atmosphere, or being under a solid ice/rock crust. But both of those also make it much harder to reach space.
I'm quite apprehensive that the great filter lies ahead - that technology accelerates too rapidly compared to our wisdom and we end up nearly destroying ourselves. We're getting the ability to program life itself and to likely to democratize the ability to harness the forces inside the atom. Neither of which we're ready for as a species.