From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sun Aug 03 2003 - 08:55:57 MDT
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(I don't believe I've made the following point to the list
before but my sent-mail logs are a bit confused on the point.
Please excuse if redundant.)
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Interestingly, Milan Circovic, Amara and I have been having
an offline discussion about the "temperature" of the galaxy.
Marvin Minsky suggested to Dyson ~30+ years ago at one of
the U.S.-USSR SETI conferences that advanced civilizations
would seek to approach the coolest temperature possible --
ideally the background temperature of the universe (~3 deg. K) [1].
This is because thermodynamically it is the most efficient.
As I've discussed in papers and on the list -- as Matrioshka
Brains "grow" the outer layers become cooler and cooler. But
as Milan and Amara have pointed out to me, one *cannot* get
to 3 deg. K. within a galaxy. The background temperatures
from stellar radiation and other radiation sources probably
keeps one above ~100 deg. K. (I still have to read some
of the documentation they have provided to get a more exact
"galactic" temperature limit but you get the idea.)
The implication of this is that advanced civilizations --
if they want to produce the most advanced computational
architectures -- have to *leave* the galaxy to seek the lowest
temperature (inter-galactic) environment.
So one answer for the Fermi Paradox is the fact that we
(or any other "developing" civilization) simply live in
a "bad" neighborhood. Advanced civilizations would gather
up sufficient materials and exit from galaxies entirely.
This makes sense from the additional perspective of avoiding
galactic hazard functions (esp. Gamma Ray Bursters,
wandering black holes, etc.).
Robert
1. "MINSKY: Since radiation at any temperature above 3 deg. K is
wasteful and a squandering of natural resources, the higher the
civilization, the lower the infrared radiation. We should look
for extended sources of 4 deg. K radiation. There should be
very few natural such sources." -- "Communication with Extraterrestrial
Intelligence", C. Sagen (ed.) MIT Press 1973.
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