Life in the Universe (Are we alone?)

shootceaselessUrban and Civil

Nov 16, 2013 (3 years and 10 months ago)

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Life in the Universe

(Are we alone?)


Cosmic Evolution

There are 7 distinct steps to Cosmic Evolution:

1.


Particulate


no stars, no galaxies, just particles of dust and gas.

2.

Galactic


Clumps of this dust and gas collected.

3.

Stellar


Stars formed within the clumps of dust and gas.

4.

Planetary


Planets began to form around the young stars.

5.

Chemical


Chemical reactions began to occur.

6.

Biological


Primitive organisms formed and began changing to adapt to their environment.

7.

Cultural


Development of civilizations.

Basic characteristics of living t
hings:

1.


React to their environment and can heal themselves if damaged.

2.

Grow by taking nourishment from their surroundings.

3.

Reproduce and pass a long characteristics.

4.

Have a capacity for genetic change.

Although this “definition” doesn’t always apply, it is

a good starting point.

The case for extra
-
terrestrial life hinges on the Assumption of Mediocrity:

1.


Life on Earth requires just a few basic molecules.

2.

The elements making up these basic molecules are common to all stars.

3.

If the laws of science apply every
where, given sufficient time, life will emerge.

Opposition to the presence of Extra
-
terrestrial life:

Life on Earth is due to a series of fortunate accidents

whose occurrence in the correct order
would be very rare
:

1.


Astronom
ical

2.

Geological

3.

Chemical

4.

Biological

If we assume that the geological timeline of the Earth being about 4.5 billion years old, here is what the
break down looks like.


For the first billion years the Earth was barren, volcanic, and a generally violent place.
Outgassing from the pl
anet’s interior created an atmosphere rich in hydrogen, nitrogen, and carbon
compounds. As the Earth cooled ammonia, methane, carbon dioxide and water formed. Volcanic
activity, lightning and collisions with meteors and comets provided tremendous amount
of energy that
could have shaped the non
-
organic molecules into more complex molecules such as amino acids and
Life in the Universe

(Are we alone?)


nucleotide bases. These are the building blocks of life as we know it. Amino acids combined to form
proteins. Proteins combined to form DNA.

S
earch: Miller
-
Urey Experiment


Life in its most simple form is evidenced to have occurred some 3.5 billion years ago as algae. About 1.5
billion years later (2 billion years ago) one celled organisms like amoeba appeared. Multicellular
organisms appeare
d only about 1 billion years ago.

Life in our solar system?

Life as we know it means carbon based, originating from a liquid water environment. The only body in
our neighborhood (Mercury, Venus, Mars, and the Moon) that MIGHT be able to have once had liqu
id
water on its surface would be Mars. Mars lost its atmosphere and thus, liquid water due to the fact that
its core cooled sufficient to become solid. This did not allow for electromagnetic fields to shield the
planet from harsh doses of radiation. Cou
pled with its smaller mass and less gravitational attraction, its
atmosphere and liquid water was striped away. There is well documented evidence of water erosion on
the surface of Mars and ice caps at its poles.

The Jovian planets have no solid surfaces,

therefore, no possibility of life. Their moons however, just
might harbor an environment in which primitive life might exist. Jupiter’s moon Europa seems to have
evidence of ice covered oceans. Saturn’s moon Titan has been shown to have liquid on its s
urface,
probably liquid methane.

Intelligent Life in the Galaxy

The Drake Equation takes several questions and tries to answer logically regarding the number of
technological civilization NOW present in the galaxy.

Rate of star formation averaged over the
lifetime of the
Galaxy

X

fraction of stars having planets

X

average number of planets
in the “Goldilocks Zone”

X

fraction of those planets where life arises

X

fraction of
those life
-
bearing planets on which intelligence evolve

X

fraction of intelligent lif
e that develop a
technological society

X

average life span of a technologically competent society
.

Best Estimates

10 x 1 x 0.1 x 1 x 1 x 1 = 1

I
f the average lifespan of a technological society is about 1000 years, there
should be 1000 technological soc
ieties scattered throughout the Galaxy.