[FoRK] This read like a post here...

Paul Jimenez pj at place.org
Thu Jul 29 14:17:01 PDT 2010

...or is he a lurker here and I'm just a doofus?

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Text below included without permission for those too lazy to follow links:


      By Charlie Stross

In my last blog entry, I asked "What is the minimum number of people you 
need in order to maintain (not necessarily to extend) our current level 
of technological civilization?"

It occurs to me that besides the obvious ramifications we've been 
chewing over (read the comment thread if you dare --- it should only 
take a couple of hours), if you turn this question on its head it looks 
like a component of a set of answers to the Fermi Paradox 

Loosely stated, the Fermi Paradox is this: there are roughly 7 x 10^22 
stars in the observable universe. We know that planets aren't rare and 
that stars of our own sun's class aren't rare, so earthlike worlds are 
presumably not rare. Going by the principle of mediocrity, our own 
existence shouldn't be particularly unusual. So /where is everybody 
else/? There are plenty of stars old enough that, if intelligent 
space-going life has a non-zero probability of emerging, our galaxy 
should long since have been overrun. And if not, why do we detect no 
signs of extraterrestrial intelligence?

In general, there are two classes of solution to the Fermi paradox; ones 
that assume that we /are/ unique special snowflakes in an empty cosmos, 
and those that postulate that intelligent species are common, but some 
kind of mechanism stops them from colonizing interstellar space.

If we look at the second problem set, and broaden the focus ... well, 
intelligent species emerge as components of a biosphere bound to a 
particular planetary habitat. We humans are land-dwellers on Earth in 
the later high-oxygen period; conditions on earth even one billion years 
ago would have been rapidly fatal for an unprotected human, and even 
today, survival on 90% of our planet's surface area is contingent on the 
availability of cultural artefacts like boats (80% is water) or clothing 
(for protection in hostile climates). So the real question isn't, "can 
intelligent life colonize other star systems?" so much as "can 
intelligent life propagate itself, /and its supporting biosphere and 
technosphere/ to run in alien environments? Which is a very different 
question. Call it the Ark Problem; if your name is Noah and you're going 
on a one-way trip to another world, how big an Ark do you need (and how 
many specimens per speciality, be they biological or technological)?

(Last time I asked the minimal-biosphere question here, while ploughing 
a space colony furrow, one of the first answers was "oh, you just need 
humans and blue-green algae". That, plus soy beans and tilapia and five 
dollars /won't/ buy you a latte in Starbucks --- especially once your 
colonists begin dying of obscure micronutrient deficiency diseases.)

But enough with the ark problem and defining the minimum population of a 
stable self-maintaining technosphere; there are other fun concepts that 
might bear on the Fermi Paradox. Chief among these is the Simulation 
argument <http://www.simulation-argument.com/>. (In fact, I gather Steve 
Baxter has written a paper about it, but it doesn't seem to be on the web.)

Loosely stated, the simulation argument runs thuswise 
<http://en.wikipedia.org/wiki/Simulation_argument> (/pace/ wikipedia): 
it is taken as axiomatic that consciousness is an emergent property of 
physics (i.e. there's no ghost in the machine), and that we can simulate 
physical systems. Thus, it is possible in principle to construct a 
software simulation of a world inhabited by intelligent beings who will 
perceive that world as real. It then follows that /either/ no 
civilization will ever reach a technological level capable of 
constructing such simulations, /or/ that every civilization capable of 
doing so will choose /not/ to do so for some reason, /or/ ... we're 
probably living in a simulation (because any civilization capable of 
running a civ-sim is liable to do so many, many times; so the number of 
sim-civilizations will vastly outnumber the number of authentic ones, 
and by the principle of mediocrity we are not exceptional).

(NB: you can find a more formal treatment of the simulation argument in 
Nick Bostrom's original paper 
<http://www.simulation-argument.com/simulation.html>, although the idea 
goes back some way before then, to Hans Moravec and earlier less 
rigorous speculators.)

It's that danged principle of mediocrity 
<http://en.wikipedia.org/wiki/Principle_of_mediocrity> that's causing 
all these problems. It shows up in the Fermi Paradox, it turns up in the 
Simulation Argument, it turns up like a bent penny in all sorts of 
places --- it's a big problem for the standard model of spacetime, once 
you start digging into the Boltzman Brains 
<http://arxiv.org/abs/0802.0233> paradox (for a quick intro, look here 
or here <http://en.wikipedia.org/wiki/Boltzmann_brain>). Indeed, it 
seems to me to be a corollary of the weak anthropic principle 

... And I've run out of brain cells with which to continue this line of 
thought, but a dangling question remains: how relevant is the simulation 
argument to the Fermi paradox, either (naively) as a solution, or as a 
mode of temporal reasoning for examining the possibility of our being 
alone in the cosmos?

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