ASTROENGINEERING: When Stars go Dark, was Re: Why just simulation?

From: Robert J. Bradbury (
Date: Fri Mar 16 2001 - 11:52:35 MST

On Fri, 16 Mar 2001, Robin Hanson wrote:

> This scenario requires at least this element of simulation: there
> must be a big "screen" around Earth or the solar system which
> shows what a universe would look like if it were not full of
> posthumans disassembling stars, etc. on a vast scale. Doing that
> well seems even harder than just running a simulation.

Well, Robin, *most* of the baryonic matter in the universe *is*
unaccounted for. We don't have sufficiently good statistics
yet to know for sure that some stars are not in fact going dark.
The missions over the next decade should begin to give us enough
long term studies of enough stars (up to a billion or so) that
we can put constraints on the scenario that you suggest (and
Eric briefly investigated many years ago).

There are classes of stars called Long-period variable stars
where astronomers have not studied them for sufficiently
to know that their period is. Scientists have however published
reports (unfortunately as posters, not as more complete studies)
that more stars are growing dimer than are growing brighter
(though you have to be careful because this could simply be
an aspect of how their brightness varies).

Here is an economics question for you -- how do you value
"present" thought against "future" thought? I.e. If you
start disassembling the planets and find your energy resources
growing as you make the KT-I to KT-II transition you can use
that energy to power your computronium or use it to harvest
more energy that you dedicate to getting more material so
you can construct "better" computronium. As Dyson pointed
out you need the full solar output for ~800 years to
disassemble Jupiter -- but if you dedicate all the available power
to say the "sub-optimal" computronium of your MBrain, then Jupiter
will never get disassembled.

How do you make the tradeoff between a "lot" of cycles now and
somewhat more cycles later (if you sacrifice the cycles now)?

Can you imagine a scenario in which the universe looks the way
it does now because the posthumans simply got wrapped up in
their simulations and forgot to harvest the remnants that we
now see?


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