From: UFO UpDates - Toronto <post.nul>
Date: Fri, 06 Feb 2009 06:01:02 -0500
Archived: Fri, 06 Feb 2009 06:01:02 -0500
Subject: Number Of Alien Worlds Quantified




Source: BBC News - London, England, UK

http://news.bbc.co.uk/2/hi/science/nature/7870562.stm

Thursday, 5 February 2009


Number Of Alien Worlds Quantified

Intelligent civilisations are out there and there could be
thousands of them, according to an Edinburgh scientist.

The discovery of more than 330 planets outside our solar system
in recent years has helped refine the number of life forms that
are likely to exist.

The current research estimates that there are at least 361
intelligent civilisations in our Galaxy and possibly as many as
38,000.

The work is reported in the International Journal of
Astrobiology.

Even with the higher of the two estimates, however, it is not
very likely that contact could be established with alien worlds.

While researchers often come up with overall estimates of the
likelihood of intelligent life in the universe, it is a process
fraught with guesswork; recent guesses put the number anywhere
between a million and less than one.

"It's a process of quantifying our ignorance," said Duncan
Forgan, the University of Edinburgh researcher who carried out
the work.

In his new approach, Mr Forgan simulated a galaxy much like our
own, allowing it to develop solar systems based on what is now
known from the existence of so-called exoplanets in our galactic
neighbourhood.

These simulated alien worlds were then subjected to a number of
different scenarios.

The first assumed that it is difficult for life to be formed but
easy for it to evolve, and suggested there were 361 intelligent
civilisations in the galaxy.

A second scenario assumed life was easily formed but struggled
to develop intelligence. Under these conditions, 31,513 other
forms of life were estimated to exist.

The final scenario examined the possibility that life could be
passed from one planet to another during asteroid collisions - a
popular theory for how life arose here on Earth.

That approach gave a result of some 37,964 intelligent
civilisations in existence.

Form and function

While far-flung planets may reduce uncertainty in how many
Earth-like planets there are, some variables in the estimate
will remain guesses.

For example, the time from a planet's formation to the first
sparks of life, or from there to the first intelligent
civilisations, are large variables in the overall estimate.

For those, Mr Forgan says, we will have to continue to assume
Earth is an average case.

"It is important to realise that the picture we've built up is
still incomplete," said Mr Forgan.

"Even if alien life forms do exist, we may not necessarily be
able to make contact with them, and we have no idea what form
they would take.

"Life on other planets may be as varied as life on Earth and we
cannot predict what intelligent life on other planets would look
like or how they might behave."