[extropy-chat] fermi's paradox: m/d approach

[Robert J. Bradbury]

On Thu, 1 Jan 2004, Spike wrote:

[snipping a lot of spikes intro material]

> The M/D approach to Fermi's Paradox suggests that the reason the cosmic
> abyss is silent is that we are not worth the mass to talk to us.

I'm assuming M=mass and D=distance (correct if otherwise).

Well, I'm not sure you can discard Energy so easily -- due to E=MC^2.
It takes minimal amounts of mass to harvest all that energy (less than
the mass of Mercury if I recall).  And with all that energy you can
dismantle the Gas Giants (though it takes hundreds of years).
>From the GG you get another couple of dozen Earth masses of
metals most likely.  So it seems probable that even if you want
to optimize the computronium there is a period when it makes
sense to take the star dark to harvest all the metals in the
solar system.  After that it gets a little more interesting
as one is going to think about where and when nearby encounters
with Brown Dwarfs may occur and/or whether you should attempt
to bring them back whole, dismantle them using their own
H and send back a matter stream, etc.

Now getting back into the communication aspect -- I started a paper
on how much information an advanced civilization probably has at
its disposal -- I stopped after I got to 2^50+ bits (even though
I thought I could push it quite a bit further).  There isn't any
way you can push even a small fraction of that across interstellar
distances.  The only way you can share that much information is
when you get two civilizations *very* close to each other because
you have to set up highly parallel communication channels.  One
would like multi-meter diameter fiber bundles made out of 50 nm
fibers (we have 50 nm fibers *now* no telling how much smaller
we might go).  That is a *lot* of fiber capacity, particularly
if you use WDM on each cable to get thousands of carriers.

Now, I'm somewhat doubtful that you can get 2 JBrains much less
2 MBrains close enough to string the cable but one never knows
what their capabilities might be.  If not, then in a pinch
you resort to lots of lasers to send CCD arrays to receive.
Remember Spike -- an advanced civilization can have 100 billion
telescopes of lunar diameter using on ~1% of the available mass.
So there will be times when close encounters and very high
bandwidth communications opportunities may justify turning a
fairly large amount of material into transmitters and receivers.
When you are done with your phone call you just turn the mass
back into computronium.

Robert