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Old May 26th 11, 05:43 AM posted to sci.astro,talk.philosophy.misc,alt.atheism,alt.talk.creationism,alt.alien.research
Carl Sagan's billions
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Default Are we alone in our galaxy? Are we alone in our universe? Not a 'chance'?

'Statistically impossible' is incorrect.
'Statistically highly unlikely' is better phrasing.

The probability that we are alone in our universe is lower than
1/200 billion. The probability that we are alone in our galaxy is
lower than 1/billion. Of course these numbers are wild guesses.


With 200 billion galaxies, each with over 100 billion stars, there
are roughly 20,000 billion billion stars in our visible universe.
That is 20,000 - 000,000,000 - 000,000,000 stars.

Of course, it could be 2,000 or even 200,000 billion billion stars.
These numbers are rough extrapolations only as billions of stars
and billions of galaxies are not visible.

Let's assume there are 20,000 billion billion stars.
Also assume each galaxy has at least one planet with intelligent life
on it (at our level or better) (this is a very very conservative
guess) then there are 200, 000,000,000 civilizations in the visible
universe.

How many of these would be 1 million or 10 million or 100 million
years ahead of us, assuming the universe is approximately 15 billion
years old and 100 million years is only 0.66% of this total time
span?

100 million years is only 0.66% of the total time span!

So it is easy to contemplate that there can be millions of those
civilizations 1% or 1 or 10 million years or more ahead of us. Of
course, out of the 200 billion civilizations 99% or more may have
been destroyed or have become extinct.

So if we assume that only 1% avoided destruction, that still
leaves 2 billion civilizations that survived, colonized other
galaxies and/or are still traveling through space for millions
of years.

Assuming some are in galaxies over 1 billion light years away from
our Milky Way galaxy, then if they traveled e.g. in cryogenic
state for over 500 million years at the speed of light, they still
would not have reached us. This assumes that speed of light is the
upper limit.

Traveling in cryogenic state would also not age the travelers.
In addition, these travelers would basically be immortal,
being able to grow organs, limbs, etc., whenever needed. In addition,
they could return to their home galaxy after millions of years (if
they wanted) and still find the beings/friends they left behind as
those would not have aged either. Mind boggling.

In a nutshell, the numbers are so huge, even if you multiply a very
low probability factor times a very large number you will get a
sizable number. And I think that that probability factor is not that
small but much higher than one advanced planet per galaxy of
100 billion stars.

That means we are not alone in our own galaxy with its 200-500
billion stars. If I assume one 'more-advanced' civilization per 10
million stars, there would be 20,000 - 50,000 of such
'more-advanced' civilizations in our own galaxy.

Of course, all these numbers are wild guesses/speculations but
it's an illustration of the fact that when we talk about our galaxy
and our visible universe the numbers are 'astronomically' huge.

As the numbers are so huge = Carl Sagan's billions and billions,
or better billions TIMES billions, I believe that most galaxies
have many millions of habitable planets with life.

Many people don't understand very large numbers and
are not trained in statistics, and would immediately reject such
ideas. They cannot understand what billions TIMES billions
really represents. Even with low probabilities and massive
destruction of civilizations, the remaining numbers most
likely are still huge.

If you asked me to guess how many 'more-advanced' civilizations
there are in our own Milky Way, I would say many more than 20,000.

If you asked me why 'they' have not contacted us, I would say I don't
know, maybe we are not advanced enough - yet.

I find it a very exciting and intriguing idea that we most likely
have tens of thousands of advanced civilizations right in our
own galaxy.

I also realize the vastness of the universe and even the vastness
of our own galaxy. Our own galaxy's rough diameter is estimated
at over 100,000 light years! That means it takes light 100,000
years to travel from one side to the other side. Mind boggling.

And it takes a multiple of 100,000 years to travel to the nearest
large galaxy Andromeda. Even several million years - just to the
nearest large galaxy! And billions of years to travel
to the other side/'far side' (if there is one) of our universe.

Many people think we are alone in our galaxy, even in our universe.
However I am convinced that life (biological reproduction)
was created via and in material processes, probably via
intermediate stages of self-reproducing and interlinking molecules
to self-reproducing organisms and then to more complex
organisms, etc. Nowhere is a unique all-powerful creator
needed. Given billions of material processes over billions
of years, statistically some arising molecular structures will by
chance have self-reproducing properties, which get propagated.
Via those properties these structures over time will
mushroom into billions of structures, etc., etc..

Wherever there is matter and the right environment and
millions or billions of years, life will evolve from matter.
That means we are not unique, not uniquely created by a single
all-powerful God: We are here by chance. With 20,000
billion billion stars and with the age of our universe
approximately 15 billion years, life evolved billions of times.

Why we are here by chance, why matter exists, why we made
from matter exist, cannot be answered. However, although
we cannot answer that question, we do not need to
invent a powerful creator to explain it. Not being able
to answer a mystery is no argument for the
existence of a single powerful creator.

As I am convinced life can evolve from material processes,
life is abundant in our galaxy and abundant in our universe.
Even intelligent life. As primitive life competes for
resources, the more primitive civilizations likely will be
violent. Many advanced civilizations that have reached
biological immortality may not be, but I am not sure.
(I'll read Asimov on this soon)

With regards,
Michael M. Terra