Re: OT: UFO study finds no sign of aliens


Krustov wrote:
<quote>

Doesnt probabilty say that given the sheer number of planets in the
universe its unlikely that only one planet will have a evolution process
where 'not as we know it' life will form .



That's the Drake Eqation

N = N* fp ne fl fi fc fL

You get different answers depending on what values you put in.
The real problem isn't the number of other life forms or
even civiliations there may be in the Milky Way or Universe
but the fact that everything is so far away. Space and the
distances involved are a lot bigger than people think.

The Milky Way is reckoned to be 100,000 light years across.
So that if all the civilisations in the MW happened to be as
far away as possibe, the Earth would be recieving messsages
originally sent 100,000 years ago. The idea of being able
to enter into dialogue with other civilisations is therfore
highly improbable. Never mind travelling to their planets.

If the Earth was reduced to the size of a pea located in
Trafalgar Square, the nearest star would be in Australia.
Otherwise its 4.3 light years away. Which doesn't really
sound so bad by comparison.

There's an ongoing project searching for extra terresetial
life called SETI.


Anyway, you can work it out for yourself.

<quote>

N* represents the number of stars in the Milky Way Galaxy
Question: How many stars are in the Milky Way Galaxy?
Answer: Current estimates are 100 billion.

fp is the fraction of stars that have planets around them
Question: What percentage of stars have planetary systems?
Answer: Current estimates range from 20% to 50%.

ne is the number of planets per star that are capable of
sustaining life
Question: For each star that does have a planetary system,
how many planets are capable of sustaining life?
Answer: Current estimates range from 1 to 5.

fl is the fraction of planets in ne where life evolves
Question: On what percentage of the planets that are capable
of sustaining life does life actually evolve?
Answer: Current estimates range from 100% (where life can
evolve it will) down to close to 0%.

fi is the fraction of fl where intelligent life evolves
Question: On the planets where life does evolve, what percentage
evolves intelligent life?
Answer: Estimates range from 100% (intelligence is such a survival
advantage that it will certainly evolve) down to near 0%.

fc is the fraction of fi that communicate
Question: What percentage of intelligent races have the means
and the desire to communicate?
Answer: 10% to 20%

fL is fraction of the planet's life during which the communicating
civilizations live
Question: For each civilization that does communicate, for what
fraction of the planet's life does the civilization survive?
Answer: This is the toughest of the questions. If we take Earth as
an example, the expected lifetime of our Sun and the Earth is
roughly 10 billion years. So far we've been communicating with
radio waves for less than 100 years. How long will our civilization
survive? Will we destroy ourselves in a few years like some predict
or will we overcome our problems and survive for millennia? If
we were destroyed tomorrow the answer to this question would be
1/100,000,000th. If we survive for 10,000 years the answer will
be 1/1,000,000th.

When all of these variables are multiplied together when come up with:
N, the number of communicating civilizations in the galaxy

</quote>

http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html
http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179073



michael adams


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