[ExI] Meat v. Machine
anders at aleph.se
Thu Dec 30 16:33:21 UTC 2010
John Clark wrote:
> Right now virtually all photons of electromagnetic energy created in
> the universe are radiated uselessly away into infinite space, that's
> not very good evidence of a cosmic civilization deeply concerned with
> the conservation of resources. If they were thinking really long term
> they'd convert much of the mass in the universe into brains and the
> remaining mass into the smallest red dwarf stars that can still
> produce fusion, with Dyson spheres constructed around them to power
> the computers.
This was my previous position too, and it furnished a pretty good
argument that there were either no aliens about, or they had
"transcended our plane of existence". However, in a discussion with
Milan Circovic I realized that letting stars shine only lose you ~1% of
their mass-energy. If you are really advanced and long-term, you will
burn the matter in black holes achieving ~50% efficiency in a very cold
future where every Joule is worth many more bits. So if stopping stars
takes a significant effort (which seems likely, you have to star lift
them and then redistribute sizeable chunks of matter), then it might not
be worth it.
I guess I should do a proper economic analysis of this. But it seems
that if you have a huge time horizon then the current waste might not
matter much, unless it least to a lot of lost gas.
The reason to wait is the Brillouin inequality: you get 1/kTln(2) bits
of information out of a Joule of energy, so if you wait until the
universe is twice as cold you get twice as much computation. Eventually
(if current cosmological models are right) the temperature will reach a
steady level of ~10^-19 K due to de Sitter horizon radiation and there
is no point in waiting any more. But that means matter gets 10^19 times
more valuable if you wait!
It seems likely that Jupiter brains will have a pretty good theory of
the universe after a mere million years or so. It is not clear to me
that there is any reason to think that they will get a huge physics
surprise if they spend another billion years on the problem. Instead
they might decide to spend their calculations on whatever they consider
valuable and not just instrumentally useful.
Future of Humanity Institute
Philosophy Faculty of Oxford University
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