Yesterday’s
post discussed the highly advanced Saturnian gas creatures and their battle
with interstellar foes in Donald Wandrei’s Something
From Above (1930). Both species
wanted to control the supply of Seggglyn, an invisible metal with anti-gravity
powers. In a later story,Wandrei’s Raiders of the Universes, (1932), the
evil Xlarbtians threaten to unleash the power of their ‘Dark Planet’—an enormous
spherical warship—to destroy Earth unless they receive all the radium on the
planet.
Both
stories exemplify the cosmicist view of earth as a puny, inconsequential world
at the mercy of vast extraterrestrial empires.
Space aliens seem especially interested in natural resources and real
estate. They are always running out of
these items.
Just
how many space aliens are out there?
Should we be concerned? Fortunately,
there is a mathematic formula to calculate their probable numbers. It is
called the Drake Equation, after Frank Drake, who presented it at the very
first SETI* meeting, back in 1961. For
future reference, here is a modified and simplified version of the equation:
N = R x P x E x
L x I x C x T
N stands for the number of alien
civilizations in our galaxy that may have developed communication via radio
waves, (as opposed to telepathy,
which is more typical in pulp science fiction).
R is the average rate at
which stars form in our galaxy. P is the number of those stars that
have planets orbiting them. (As of this
writing, 1056 “exoplanets” have been discovered so far, circling 802 stars, and
of these planetary systems, 175 have multiple planets.)
The
number of planets that are likely to support life is represented by E. These
would lie in the habitable orbital zone of a star—defined as at a sufficient distance
from the star to allow liquid water to exist on the planet. To date, some scientists have identified at
least nine exoplanets that meet this criterion, and possibly 30 planetary
moons.
L is the number of planets that
could actually evolve a form of life. I is the proportion of these planets that
could develop intelligent life. The number of inhabited planets capable of
inventing technology that can be detected from space is represented by C.
Finally, and perhaps most critically, T stands for the amount of time that an extraterrestrial
civilization has been producing detectable radio signals.
The
Drake Equation yields a ‘guestimate’ of the number of different alien civilizations
in our galaxy. It was intended to spur
discussion and support for the SETI project, not provide a hard figure. Obviously many of the variables themselves are
completely unknown and involve considerable speculation. In 1961, scientists estimated were that the Milky
Way contained between 1000 to 100,000,000 extraterrestrial civilizations. This was thought to be a conservative estimate.
The
recent identification of over a thousand exo-planets circling other stars and the
tantalizing findings of the Mars rover missions lends some credence to SETI’s
grand project. While we wait for that
telltale radio signal from beyond, it may fall to us to discover life that we
can bring with us to other planets,
in particular, Mars.
Robert
Zubrin, among others, (see his excellent book The Case for Mars) advocates terra-forming the planet, first by
creating a green house effect in the atmosphere, and then by introducing hardy microorganisms
from Earth. This would facilitate human
colonization over a period of a few decades. Given that the gas creatures of
Saturn and the evil Xlarbtians already have a head start on us, we should hurry to get this done.
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