From: Richard Howard <rich@richardehoward.com>

A cold, slow universe is an interesting concept.

I note that no one has mentioned "The Last Question" by Isaac Asimov (1956) where he explored the idea of long times and dying universes. http://www.multivax.com/last_question.html

Perhaps because few people find its main premise, that a sufficiently powerful computer would somehow get the ability to create things, plausible. It could simulate things, but it would need a substrate to run on. Unless you accept Tegmark's idea, that every self-consistent system automatically exists. Tegmark says that if software could exist that would contain conscious sapient beings and a world for them to interact with, then nobody needs to run it, or even write it, unless they want to see what the beings do. The beings would perceive and act the same regardless. Just as pi definitely has a specific googolplexth decimal digit whether anyone ever calculates it or not. But then Multivax was redundant; its program would have run anyway, as would all other possible programs. As for a cold, slow, vast, inconceivably ancient, run down, and worn out universe, Stephen Baxter has played with that concept in several of his novels. In one of them, the big reveal at the end was that the viewpoint characters weren't in our distant future, but in our past, and that the setting was less than a trillionth of a nanosecond after the Big Bang. One person's hot and fast is another's cold and slow. As someone who prefers much warmer temperatures than most people, I can sympathize.

I wonder when quantum zero point energy will be large enough relative to the remaining energy in the cold universe to make organized life impossible. We may not have infinite time to do the calculations.

We should be okay for at least the next googol (10^100) years or so. Most of the known energy reserves of the universe are gravitational, i.e. we can power our civilization by dropping things into other things. As I implied in my mention of Tipler's scenario, if things can get arbitrarily dense and close to each other, you can get unlimited energy. Thanks to event horizons, there are limits, but you can come pretty close to total conversion of mass into energy. That does require that we have continued access to stuff. If everything beyond our solar system eventually retreats beyond the Hubble horizon, the future looks a lot more bleak. If we have our galaxy to play with, along with Andromeda (which is projected to collide and merge with our galaxy fairly soon (i.e. about 4 billion years from next Tuesday)), we should do pretty well for a while.

I was thinking of neutronium in the Robert Forward sense--on the surface of a neutron star.

Yes, the Cheela lived on the surface. And reasonable rates of cooling would require access to the surface in any case. (As does the plot of that novel, which involves them noticing and communicating with humans.) But then we're not talking about neutronium (material consisting almost entirely of neutrons), but about degenerate matter, or even ordinary matter. Neutronium requires lots of pressure from overlaying material. Whether degenerate matter can be solid at such temperatures, I don't think anyone knows. The pressure of the atmosphere may suffice to increase its melting point, and it's anyone's guess what an extremely strong magnetic field would do.

Gravitational energy is comparable to the nuclear binding forces--I don't see why it would be unpredictable or threaten to blow up the computer.

When a nucleon decays or otherwise changes, is random, as is the direction and fate of its decay products. If you think otherwise, please explain how, in principle, it would be possible to generate a coherent beam of neutrinos.

After all, all of our matter is held together by quantum forces (everything scaled down) and our computers don't often blow up. Aside from being a bit toasty, reactions should be well behaved.

Could you design a computer that would operate in the center of the sun? Could life evolve inside the sun?