[ExI] Fermi question, was is a FTL drive a dream . . .

[Eugen Leitl]

On Wed, Dec 21, 2011 at 12:30:43PM +0100, Anders Sandberg wrote:
> On 2011-12-21 10:44, Eugen Leitl wrote:
>> On Wed, Dec 21, 2011 at 09:57:36AM +0100, Anders Sandberg wrote:
>>> Which assumptions in the scenario make no sense?
>>
>> Basically almost every assumption is ad hoc. It's something an
>> economist would write, who is accustomed to deal with a narrow scope of
>> interactions among members of a single local species.
>>
>> You think the http://hanson.gmu.edu/filluniv.pdf paper is good, yes?
>
> It is a start. So you don't think the assumption that the propensity for  
> colonizing is partially "inherited" from the parent civilization would  
> be true?

I wouldn't call them civilizations, but ecosystems. But of course,
the pioneer front self-selects for expansibility over comparatively
short distances and times, in the classical darwinian way. 

We already see it in action: it has been a while since we've even
left LEO, we never went into translunar space while our probes
are currently entering insterstellar space. As soon as ISRU starts
approaching closure of unity it will vastly favor abiological 
self-replication even within our solar system. Anything capable
of crossing interstellar voids will see much higher fitness
pressures. A few hops there are going to make some pretty lean
and mean critters.

>> Do you disagree that the anthropic principle prevents observation
>> of relativistically expanding preexpansive observer-extinguishing
>> fronts very effectively?
>
> Not really. It prevents us from being inside the front, and might  

Not unless you're the nucleus. The species succession will tend
to create radiating waves, at least for a while. When you have reached
steady state then any wave propagation will be necessarily local
and short-lived, as diversity will be very high and what allows
invasion in one compartment is perfectly benign in another.
Pioneers see strongly convergent due to their niche selection,
so they're pretty much indistinguishable regardless of point of
origin, while the steady state is sufficiently diverse to make
the whole notion of "alienness" moot. Aliens'R'us. Or will be.

> (depending on our views on SIA/SSA) bias our probabilities towards  
> universes where there are a lot of observers (i.e. no fronts) or where  
> we are first. It is a bit like my anthropic shadow paper: the fact that  
> we cannot have giant meteor impacts in our recent past doesn't make them  
> less likely or invisible in the present.

The probability that we'd observe a front while we would recognize
it for what it is is probably just 2-3 centuries in our case. Unless
we collapse, we'll start expanding in about a century. I think the 
expansion will be close to relativistic (at least 0.1 c) right from
the first hop. Everything else would be too slow, and overtaken 
while still in transit. The first threshold is at the interstellar
distance. If you have a fusion metabolism, then slow outwards 
diffusion across Oort would work, with the last hop to the next 
star's Oort being quite small. If not, you fire up the big guns
and go right for the jugular (inner system of the next star with
sufficient flux). Arguably deep space like Oort is a different
niche, rather like the deep sea. Less metals, more fissibles,
need to make own power and maybe use QC in cold circuits for
information processing. The inner systems are awash in metals
and abundant energy.