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The Fermi Paradox

From: UFO UpDates - Toronto <ufoupdates.nul>
Date: Fri, 27 Jul 2007 10:15:00 -0400
Archived: Fri, 27 Jul 2007 10:15:00 -0400
Subject: The Fermi Paradox

Source: Steve Colgan's Worlds Of Possibility Blog - UK


Wednesday, 25 July 2007

The Fermi Paradox


You can't read any serious book on xenoscience without coming
across the Fermi Paradox and the Drake Equation. They may sound
like Robert Ludlum thrillers but they're actually a brace of
thought experiments that, in different ways, pose questions
about the likelihood of life in the universe. In this post, I'll
explain the Fermi Paradox. Drake can wait until later.

While having lunch with some colleagues back in 1950, physicist
Enrico Fermi posed this question (although maybe not in these
exact words): "Given the extreme age of the universe and the
vast numbers of stars, it seems almost inevitable that the
universe should be brimming with life. And, by the law of
averages, in an almost infinite universe of life, there must be
extraterrestrial civilisations that are technologically on a par
with, or in advance of, our own. They've had more than enough
time to litter the galaxy with their presence. So where is

=46rom that conversation we got the Fermi paradox, which continues
to taunt us nearly 60 years later. It is the apparent
contradiction between high estimates of the probability of the
existence of extraterrestrial civilizations and the lack of
evidence for, or contact with, such civilizations. To put some
numbers to this, there is estimated to be 250 billion
(250,000,000,000,000) stars in our own galaxy, the Milky Way,
and 70 sextillion (70,000,000,000,000,000,000,000) stars in the
visible universe (source: Dr Simon Driver, Australian National
University). Oh, and in case all of those zeros are hard to
relate to, one sextillion seconds equates to around 300 billion
years =85 and to put that into perspective, the Earth is only 4-5
billion years old and the universe itself is only 13-odd billion
years old. That's a lot of stars.


So, if only a tiny number of stars had planets around them, and
intelligent life only occurred on a tiny, tiny proportion of
those planets (or other environments), there should still be a
huge number of civilizations in our galaxy alone. So you can see
why Fermi's Paradox bugs the hell out of the astrobiologists.
They're aiming their radio telescopes and satellites at stars
likely to have 'Earth-like' planets and hoping to hear a
transmission from our alien brethren. But ET ain't on the phone.
A number of possibilities for this silence have been put
forward, all of which have generated thousands of academic
papers, books and studies. I've tried to group them here under
four easy to grasp categories:

Firstly, there is the faintly uncomfortable idea that we are the
first life form in the universe to achieve a sufficiently
advanced technology that allows us to attempt contact with other
worlds. This is sometimes called the Rare Earth Hypothesis; the
idea that we are a cosmic rarity.

Secondly, it could be that there are advanced civilisations out
there but their technology does not resemble ours in any way;
therefore they may not recognise our signals as signals and we
don't recognise theirs. I personally favour this idea as I am of
the xenoscientific view rather than the astrobiological view.

Thirdly, it may be that intelligent aliens have anticipated the
sorts of activities we're currently involved in (radio signals,
unmanned probes etc.) and choose to ignore it or hide themselves
from detection (I call this the Peek-a-boo Principle). The more
pessimistic philosophers among us, however, came up with the far
more sexy-sounding Doomsday Argument; that technological
civilizations usually or invariably destroy themselves before or
shortly after developing radio or space flight technology.

Lastly, there is the simple and unfortunate fact that the
universe is very, very large and, therefore, civilisations may
just be too far away from each other to communicate. We've been
chucking signals out into space for just a hundred-odd years and
there's only so far they can have travelled even at the speed of
light (186,000 miles per second). Who knows =85 far out in the
depths of deepest space our signals and theirs may be crossing
even now, but we won't hear them for another hundred years.

(For a more detailed look at the many theories I've tried to
simplify, check out the links at the bottom of this post.)

It's extraordinary that one fairly innocuous lunchtime comment
could generate so much thought. But as astronomer and science
writer Seth Shostak says:

'The Fermi Paradox is a remarkably strong argument. You can
quibble about the speed of alien spacecraft, and whether they
can move at 1% of the speed of light or 10% of the speed of
light. It doesn't matter. You can argue about how long it would
take for a new star colony to spawn colonies of its own. It
still doesn't matter. Any halfway reasonable assumption about
how fast colonization could take place still ends up with time
scales that are profoundly shorter than the age of the Galaxy.
It's like having a heated discussion about whether Spanish ships
of the 16th century could heave along at two knots or twenty.
Either way they could speedily colonize the Americas.'

I just hope that if aliens are looking for us, they're not using
the plaque devised by Frank Drake (of the Drake Equation) and
Carl Sagan and attached to the Pioneer 10 and 11 probes (see
illustration at top of post). The plaque depicts a solar system
with a sun and nine planets. As you know, we've added several
bodies to our solar system since then ...

Perhaps they are looking for us and they've got lost?

If you'd like to know more, check these links:


[Thanks to Stuart Miller of http://uforeview.net/ for the lead]

Listen to 'Strange Days... Indeed' - The PodCast



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