[ExI] fermi paradox- weighted summary

[BillK]

On Dec 6, 2007 2:57 PM, Eugen Leitl wrote:
> On Thu, Dec 06, 2007 at 02:36:15PM +0000, BillK wrote:
>
> Self-replicating technology, phased array radiators with lightminute
> aperture and gray sail probes are not exactly off-the wall.
>
> Why would any culture be limited to presently available technology?
>

But these technologies only exist in speculation. They *may* be
possible in the future, if society decides to spend resources in those
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.


>
> Any self-rep systems will become visible over astronomical
> distances, given a mere few megayears.

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

>
> Huge? Energy density less than a fusion weapon. And of course
> you leave the drive at home.
>

You need the equivalent to stop at the other end.
And you are assuming that a civilization will want to build these
useless devices in the first place.
(Useless, because at vast expense the civilisation gets no benefit).

> Why would you need radiation shielding at mere 0.9 c? Why would
> you not rather self-heal all the time?
>

Self-heal? Against continual near-lightspeed cosmic radiation and
dust? I think not.
I thought you were all in favour of robot space exploration anyway,
because of these and other problems.


>
> If you think darwinian systems are insane, welcome to the loony bin.
>

You well know that humans have finished with darwinian evolution
already and we're not particularly advanced yet. Our first world
peoples have already stopped breeding and are dying out and extending
the life span of remaining members. They may, for a short period, be
replaced by faster breeding nations, but they in turn will follow the
same path. Advanced intelligence (or advanced civilisation) means very
low reproductive rates.
(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).

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?

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.

BillK