From: Jim Deardorff <deardorj@proaxis.com>
Date: Sat, 30 Jan 1999 21:54:18 -0800 (PST)
Fwd Date: Sun, 31 Jan 1999 17:04:47 -0500
Subject: Re: Deficiency In SETI's Drake's Equation

>From: David Rudiak <DRudiak@aol.com>
>Date: Fri, 29 Jan 1999 23:22:01 EST
>To: updates@globalserve.net
>Subject: Re: Deficiency In SETI's Drake's Equation

>I received a mailer from Frank Drake and the SETI Institute last
>November soliciting funds, in which Drake writes:

>"Advances in science and technology are putting SETI on the fast
>track as never before. A team of world-renowned astronomers,
>engineers, and technologists -- specially commissioned by SETI
>Institute -- has proposed bold and exciting new SETI ventures
>that will provide humanity with its best opportunity to make
>contact.

>"We urgently need to build a new generation of telescopes and
>signal processors. We must harness the potential of optical
>infrared technology. These may be what it takes to detect a
>faint radio or a flashing infrared beacon sent our way from
>another civilization."
>
>So apparently SETI is considering expanding the search into the
>infrared and perhaps other domains. Freeman Dyson, e.g., has
>pointed out for many years that the best signature of an
>advanced civilization might be in the infrared rather than radio
>spectrum. I think many readers are familiar with the "Dyson
>sphere" concept, in which an advanced alien civilization
>forsakes interstellar travel. Instead the most efficient way to
>expand a specie's lebensraum might be to break up their solar
>system and use it to construct an enormous, self- contained
>spherical shell around their home star, thus capturing 100% of
>the star's solar energy. If the shell were at present earth
>orbit, e.g., the living space would be approximately 10^17 sq.
>miles compared to the paltry 2.5 ^ 10^8 sq. miles we currently
>have on earth's surface. In other words, building the sphere
>would give you the living space equivalent to colonizing 250
>million other worlds.  This would be the ultimate public works
>project.

>Dyson's point here is that all we would likely see of this
>sphere is the infrared heat signature. Any radio wave
>communications (if they still were used) would probably be
>largely confined to the inside of the sphere.

Hi David,

Dyson's Dyson-sphere sure is the height of impracticality, isn't
it? If the advanced civilization he had in mind could convert
all of the mass of a planet the size of Mars into material out
of which to make the spherical shell, and if it were placed at a
distance about equal to the Earth's orbit from the sun, the
shell would only be 0.024 in. thick! (barring an arithmetical
mistake). There'd be comets and meteors piercing it frequently,
and no good way to let the solar wind escape, etc. To make it
sturdy enough to withstand most of such stuff, say by extending
it to 10 feet thick, would then require the mass of 5000 more
Mars-sized planets converted into the shell's structural
material. To gather all that would in itself require the
capability of easy interstellar travel, unless they could
convert Jupiter-type planets' gases into building materials.
Somehow I think the environmentalists of the future would not
want any of that, and would prefer retaining the capability of
sleeping out under the stars with the feel of the cold night air
in their face.

>>(Ntot could be extended further, of course, by considering any
>>ETI who possess inter-galactic travel capabilities.)

>Not to mention any ETI who possess INTRA-galactic travel
>capabilities.

Thanks for correcting me on that. I had meant intra, of course.

>In fact this is probably the single biggest
>shortcoming in the thinking of most SETIists, their assumption
>that interstellar travel is essentially impossible. Well, that's
>simply not true. Even barring some breakthrough propulsion FTL
>propulsion scheme, sub-light travel is definitely theoretically
>possible.

As each new breakthrough in (our) science occurs, however, it
allows them to make tiny extrapolations that go a little farther
towards the feasibility of interstellar travel than before. The
"teleportation of a photon" is perhaps the latest example. But
what they seem incapable of doing is extrapolating our rate of
scientific discovery hundreds of thousands of years into the
future to admit that what we could do then would indeed seem
like magic to us now. Their extrapolations just come to a halt
after a few decades.

>...
>But SETI assumes that aliens remain forever confined to their
>home star system. Thus they generally restrict their searches to
>the most earthlike star systems, one's that would most likely
>evolve native life, rather than be colonized from beyond.

>However, even one ancient, advanced, relentlessly colonizing and
>expanding alien species (think Borg) could explore and colonize
>every nook and crook of the galaxy in only a few million years.
>At that point, throw out the Drake equation, because they could
>be everywhere.

Yes, that argument came out in 1979, and was used by the
we-are-alone advocates as evidence that no other intelligent
life more advanced than us exists in the galaxy, since we have
not been colonized or wiped out by such Borgs. Then Sagan and
other SETI types had to argue (in 1981 & 1983) that the
colonizing alien race would need to stop at each suitable
star/planetary system and pause 100,000 years there before
moving on to explore/colonize the next one further out. (Would
they be able to remember after all that time that colonization
was what their overriding aim was?) That gross assumption slowed
the whole colonization process down so much that the dispersal
of stellar systems, as they rotated around the galactic center,
would render such colonization ineffective. We could then escape
detection by falling through the cracks, which was SETI's
desired conclusion.

Both schools of thought neglected the effect of continuing
scientific advancement, and both neglected the likelihood that
for each alien race intent on wiping out all others, there would
likely be many others who would value the diversity of life.

>Jim, you just don't understand. No matter how intelligent or how
>great the headstart in science & technology, alien civilizations
>will always be limited to chemical rocket speeds.  You have
>Frank Drake's expert opinion on that. Therefore, they could
>never show up here.

OK, if Drake says so. ;)  It's interesting to hear, though, that
you sounded Drake out a few months ago. I'm sure you didn't
expect his response to be any different than what it was.

Jim Deardorff