“Evolutionary selection,
acting on a cosmic scale," says Adrian Kent of the University of Cambridge
and Canada's Perimeter Institute. "tends to extinguish species which
conspicuously advertise themselves and their habitats.” The Fermi paradox 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.
As Enrico Fermi asked if the
Universe is conducive to intelligent life, “Where is everybody?”
The answer proposed by Kent
is that extraterrestial life sufficiently advanced to be capable of
interstellar travel or communication must be rare, since otherwise we would
have seen evidence of it by now. This in turn is sometimes taken as indirect
evidence for the improbability of life evolving at all in our universe.
“Intelligent species might
reasonably worry about the possible dangers of self-advertisement and hence
incline towards discretion” -- the “Undetectability Conjecture,” put forth by
Beatriz Gato-Rivera, a theoretical physicist at the Instituto de Fisica
Fundamental (previously Instituto de Matematicas y Fisica Fundamental) of the
CSIC (Spanish Scientific Research Council) in Madrid. According to Gato-Rivera,
we may find ourselves in a universe in which there exist intelligent
technological civilizations but they have chosen to be undetectable,
camouflaging themselves mainly for security reasons (because advanced
civilizations could also be aggressive).
“It often seems, Kent
concludes, "to be implicitly assumed, and sometimes is explicitly argued,
that colonising or otherwise exploiting the resources of other planets and
other solar systems will solve our problems when the Earth’s resources can no
longer sustain our consumption.
It might perhaps be worth
contemplating more seriously the possibility that there may be limits to the
territory we can safely colonise and to the resources we can safely exploit,
and to consider whether and how it might be possible to evolve towards a way of
living that can be sustained (almost) indefinitely on the resources of (say) our
solar system alone.”
In another take on the
"Fermi Paradox," Stephen Hawking asks In his famous lecture on Life
in the Universe: "What are the chances that we will encounter some alien
form of life, as we explore the galaxy?"
If the argument about the
time scale for the appearance of life on Earth is correct, Hawking says
"there ought to be many other stars, whose planets have life on them. Some
of these stellar systems could have formed 5 billion years before the Earth. So
why is the galaxy not crawling with self-designing mechanical or biological
life forms?"
Why hasn't the Earth been
visited, and even colonized? Hawking asks. "I discount suggestions that
UFO's contain beings from outer space. I think any visits by aliens, would be
much more obvious, and probably also, much more unpleasant."
Hawking continues:
"What is the explanation of why we have not been visited? One possibility
is that the argument, about the appearance of life on Earth, is wrong. Maybe
the probability of life spontaneously appearing is so low, that Earth is the
only planet in the galaxy, or in the observable universe, in which it happened.
Another possibility is that there was a reasonable probability of forming self
reproducing systems, like cells, but that most of these forms of life did not
evolve intelligence."
We are used to thinking of
intelligent life, as an inevitable consequence of evolution, Hawking
emphasized, but it is more likely that evolution is a `random process, with
intelligence as only one of a large number of possible outcomes.
Intelligence, Hawking
believes contrary to our human-centric existence, may not have just any
long-term survival value. In comparison to the other microbial world, will live
on, even if all other life on Earth is wiped out by our actions.
Hawking's main insight is
that intelligence was an unlikely development for life on Earth, from the
chronology of evolution: "It took a very long time, two and a half billion
years, to go from single cells to multi-cell beings, which are a necessary
precursor to intelligence. This is a good fraction of the total time available,
before the Sun blows up. So it would be consistent with the hypothesis, that
the probability for life to develop intelligence, is low. In this case, we
might expect to find many other life forms in the galaxy, but we are unlikely
to find intelligent life."
Another possibility is that
there is a reasonable probability for life to form, and to evolve to
intelligent beings, but at some point in their technological development
"the system becomes unstable, and the intelligent life destroys itself.
This would be a very pessimistic conclusion. I very much hope it isn't
true."
Hawkling prefers another
possibility: that there are other forms of intelligent life out there, but that
we have been overlooked. If we should pick up signals from alien civilizations,
Hawking warns, “we should have to be wary of answering them back, until we have
evolved" a bit further.
Meeting a more advanced
civilization, at our present stage, Hawking says, "might be a bit like the
original inhabitants of America meeting Columbus. I don't think they were
better off for it."
Via DailyMail