[ExI] fermi paradox- weighted summary

[Eugen Leitl]

On Thu, Dec 06, 2007 at 04:24:32PM +0000, BillK wrote:

> But these technologies only exist in speculation. They *may* be

If we go back 40 kYrs all technologies existed in speculation.
Postulating our current level is somehow special is arbitrary.

> possible in the future, if society decides to spend resources in those

I can easily go to visit America. Not so long ago it took whole national 
powers to launch such an expedition. Space launches are being funded
by single individuals now.

> directions and no insurmountable problems (technical or sociological)
> occur. If you are relying on unknown technology, then you can
> speculate all you like, but that doesn't make it a likely possibility.

Heavier than air flight is not a likely possibility. I can easily draw
you a plan to launch an interstellar probe at >0.1 c, using known
technologies. It will be expensive, but only because we're pathetically
primitive primates. Wait a bit, and things will get better.

> Well we can't see them, so we might as well assume they probably don't exist.

I agree! I also argue that anthropic principle prevents you from observing
them, but for the special case where them is us.

> You need the equivalent to stop at the other end.

Multiple answers to that. It's a bootstrap issue. You could
launch the first probe with is heavy enough for braking. You
could use a sacrifical sail, which outsources the complexity
and the power. 

> And you are assuming that a civilization will want to build these

I'm assuming individuals and small groups will. Probabilistically,
the probability is almost unity.

> useless devices in the first place.
> (Useless, because at vast expense the civilisation gets no benefit).

Few ten grams of energy is not a vast expense, even now.
 
> Self-heal? Against continual near-lightspeed cosmic radiation and
> dust? I think not.

I noticed.

> I thought you were all in favour of robot space exploration anyway,
> because of these and other problems.

What makes you think I'm talking about suited monkeys? These won't
go anywhere. "Robots" are just a figure of speech.
 
> You well know that humans have finished with darwinian evolution

"humans have finished with darwinian evolution". Where do you take
these howlers? http://www.physorg.com/news116169889.html

> already and we're not particularly advanced yet. Our first world

Most of current progress occured within a couple centuries, on
which scale evolution doesn't happen. Even if primates don't
evolve, autonomous artifacts will.

> peoples have already stopped breeding and are dying out and extending
> the life span of remaining members. They may, for a short period, be

Fitness function shape changes, yet it still remains a selective force.

> replaced by faster breeding nations, but they in turn will follow the
> same path. Advanced intelligence (or advanced civilisation) means very
> low reproductive rates.

Anything with a low reproductive rate self-selects into invisibility
on short temporal nevermind spatial scales. You'll only see the other
kind.

> (Sure, it's only evidence of one intelligent species as an example,
> but that's one more than you have as evidence for the alternative).

Evolution is not only limited to intelligent species. Evolution
happens at self-replication of any kind, since limited-resource and
limited-fidelity come in for free.
 
> There are speculations about grey goo eating everything, nano-robots
> expanding at lightspeed eating the universe, etc.  But we don't see
> any of that, so why give much credence to such ideas?

You've been on this mailing list for years. I presume you've read
the traffic. In case you haven't, there are the archives. Go out
and reread it. You might also reread mainstream literature starting
with 1900s, or before. 
 
> It's far more likely that advanced civilisations don't breed much,
> don't expand, and keep themselves to themselves. For many reasons,
> including Seth's latest article.

I'm sorry, but the article is crap, and we've done much, much better
on this list even few years ago. Things were better even a scant decade
ago. I don't know when they peaked, since I wasn't there at the time.

No, I definitely do not like the current state of affairs. I do not
see why I should write posts like that, we're not in kindergarden,
after all.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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