From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Fri Apr 25 2003 - 13:58:15 MDT
On Fri, 25 Apr 2003, Greg Jordan wrote:
> Or, it could be that life is more common in the universe than dangerous
> life, which could explain a biosphere being ignored for millions of
> years.
Our biosphere is pretty uninteresting to species that can construct
anything constructable. Is an intelligent species developing around
a star that happens to have a hot-giant in close orbit around their
sun (if such species can develop in such a solar system) going to
focus its attention on communicating with us or focus their attention
on dismantling the gas giant?
> Dangerous civilizations in our vicinity may be reactive rather
> than proactive or predatory, waiting until threats appear or become
> obvious to deal with them.
There aren't any "threats" to a distributed replicated intelligence
(like a Matrioshka Brain) except perhaps a black hole. The only
weapon they would care about would be intertial weapons -- someone
throwing a *lot* of matter at them. But it requires one *huge*
amount of matter to deal with something that masses 10^25 to 10^27 kg
and is distributed over a volume of space from 30 AU to 3 light years
in diameter.
Just like Angel -- you can't kill it.
> Ah, worse than to be hated is to be ignored...
They have better things to do. I just read Egan's "The Plank Dive"
last night. Didn't understand much of the black hole stuff but
thought the transmission of a human "entity" in an exabyte of
information was great.
Previously I had thought this would be impossible. An exabyte
is 10^18 bytes which is a zettabit (10^21 bits). To even begin
thinking about this one has to learn how to modulate a carrier
of X-rays (10^18 Hz) to Gamma-rays (10^20 Hz) to carry a zettabit.
That did not look like an easy task to do in a short period
of time (SciFi authors get to ignore some of these more complicated
details with a little hand-waving).
But, if one used digital encoding of femtosecond (10^-15 sec) laser
pulses (~10fs is about the best we can do now) *and* used an array
of such lasers to send the pulses accurately synchronized with
each other (because the setup takes much longer than the pulse),
then it does appear that you could transmit an zettabit in less
than a month -- using current technology it could take anywhere
from 6-12 months.
So if ETI are communicating they are likely doing it at high pulse
rates (which almost all detectors we now use are unlikely to
detect for say OSETI). In addition it seems possible, if not probable,
that the frequencies may be high (UV to gamma) where we aren't
currently listening. Finally, they aren't going to be sending
these data streams at us -- all we will see is the spread of
the lasers if we happen to be along the line of sight between
them and someone they are sending the data to.
Robert
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