If life is normal... (Crossposted)

It occurred to me the other evening, that the universe is supposed to be
~14 billion years old. Life on Earth is supposed to be ~3.5 billion years
old. Human life is 1 million years.

At one time, people thought that they, and the Earth, were at the center
of the universe. However that perception changed to one in which the Sun is
the center of the Universe. And from there, the Sun became the center of the
Solar System, which became another part of the Milky Way, which became
another part of the known Universe. Instead of being at the center of
everything, we were in the middle of nowhere and were simply average.

A common conception of evolution put us at the head of the list of
species ('Created in the image of God'). As if the object of evolution is to
produce us and our kind. Now this is known to be false. We are just another
species competing for ground on this here green earth.

It seems that one of the results of Scientific progress is to disabuse
us of an infantile concept of ourselves as being the center of everything
and replace it with another conception in which we are merely average.

If this interpretation is correct then given the age of the Universe and
the variation about an average (say, our Earth's age) that would be expected
(this is essentially a guess), what possibilities might exist regarding life
in our Universe? In other words if we were to assume that we are not unique
what might be the actual age of life? Is it reasonable to guess, merely on
the basis of our (supposed) averageness that it could be much greater than
our own?

John Leonard

Dear John Leonard:

"John Leonard" wrote in message
...
....
If this interpretation is correct then given the age of the Universe
and
the variation about an average (say, our Earth's age) that would be
expected
(this is essentially a guess), what possibilities might exist regarding
life
in our Universe? In other words if we were to assume that we are not
unique
what might be the actual age of life? Is it reasonable to guess, merely
on
the basis of our (supposed) averageness that it could be much greater
than
our own?

If galactic structure is any guide, there are galaxies similar to the Milky
Way that are not much younger than the CMBR. So *life* (not necessarily
intelligent life) could be 11-12 Gy old, IMHO.

David A. Smith

[Note Followup-To:.]

"JL" == John Leonard writes:

JL It occurred to me the other evening, that the universe is supposed
JL to be ~14 billion years old. Life on Earth is supposed to be ~3.5
JL billion years old. Human life is 1 million years.
[...]
JL It seems that one of the results of Scientific progress is to
JL disabuse us of an infantile concept of ourselves as being the
JL center of everything and replace it with another conception in
JL which we are merely average.

JL If this interpretation is correct then given the age of the
JL Universe and the variation about an average (say, our Earth's age)
JL that would be expected (...), what possibilities might exist
JL regarding life in our Universe? In other words if we were to
JL assume that we are not unique what might be the actual age of
JL life? Is it reasonable to guess, merely on the basis of our
JL (...) averageness that it could be much greater than our own?

Yes. There has been a fair amount of speculation about this point.
The difficulty is that, with only one sample to study (us), it's
difficult to reach any definitive conclusions.

There seems to be widespread agreement among at least astronomers that
life originates easily and is widespread. (The ubiquity of
*intelligent* life is far less agreed-upon.)

Livio (1999, URL:
http://adsabs.harvard.edu/cgi-bin/np...pJ...511..429L
argues that it actually takes some time for the amount of "metals"
(i.e., elements heavier than helium) to build up to a point at which
life can arise. Lineweaver & Davis (2002,
URL:http://xxx.lanl.gov/abs/astro-ph/0209385) try to do a
statistical analysis, but, again, they are hampered by the fact that
they have a sample of one.

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