From: Spudboy100@aol.com <Spudboy100@aol.com>
>Why would you conclude, Darin, that ETI,s would use low-power signals and
>avoid making their presence known? Why should they care, and why need they
be
>mindful of us, if they exist?
It doesn't follow from their being mindful of us, anymore then the
undetectability of our radio signals to an 18th century scientist would. It
follows from simple efficiency.
If I'm sending over interstellar distances, I would want to use the least
amount of power possible over the least amount of time. Now, given that I,
as an "average" SI, have the ability to build pretty much whatever I want
(:)), I would use a tiny fraction of the vast amounts of computing power
available to me to allow me to use extreme amounts of data compression.
Remember, a digital PCS cell phone data signal would be completely
indistinguishable from thermal noise to any radio scientist, right up to
around the 1930s. And that's less then a 50 year gap in technology. And it
was only the findings in the mathematics of information theory that would
allow them to even consider a noisy signal as compressed information.
If I know how to do interstellar communication using only a
fraction-of-a-volt tight-beam phased-frequency signal that transmits data at
something like 100 Mbits per second, why on EARTH would I want to use a 5
million volt 3-bits-per-second spoken-audio-or-equivalent-thereof signal
visible across 90 degrees of sky?
Unless of course, I WANTED to speak to 18th century radio scientists :)
It's not that they're mindful of us. It's the exact opposite. They can't be
bothered to dumb themselves down to the point where we could detect them.
Another good example is found right here in our own solar system. The
communications from the Voyager spacecraft: the closest thing to
interstellar data communication we have practical experience with.
Voyager transmits a data signal with a signal strength of well less then a
volt, from well beyond the orbit of Pluto. The only reason we can detect it
is because we know to a VERY high precision exactly where in the sky it is,
and because we have several radio telescopes doing radio interferometry on
that point in the sky, and even then it can take weeks of computer time to
dig the signal out of the background noise.
Everybody on Earth is in direct line of sight of Voyager's transmissions
here. But even the Seti observations probably couldn't pick Voyager out of
the sky if they didn't know it was there.
Now you may argue that we operate within Voyager's power constraints because
we have to, and that an SI could very well choose to be more extravagant. I
would have to disagree. I find it highly unlikely that the design of an SI's
communications systems would be done by conscious subsystems at all.
Automated Engineering, at least the primitive beginnings we've made of it,
is nothing if not efficient.
Now, far be it from me to claim to know the mind of an SI, or even of a
significantly >H subsystem of an SI, but I can make a rough guess of it's
capabilities, and I know this: if they wanted to be extravagant in their use
of signal strength, we would see it. Forget alien television signals, we'd
be seeing stellar-sized fusion pumped MASERs, and pulse modulated
supernovae. Barring FTL communications, there's no better way to get a
message out to a galaxy then a couple trillion tons of smart dust
surrounding a supernova flickering out a Morse signal :)).
In conclusion, I take SI capabilities seriously, and I don't see any when I
look up into the night sky. That's why I think they'd use low powered
signals.
Darin Sunley
rsunley@escape.ca
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:50:18 MDT