- what is it made of?
Water - the key factor
note that silicon-dioxide - sand, unlike carbon-dioxide, is not soluble
in water and is largely inert in the presence of most chemicals.
key constituent to the life process is something to act as a transportation
and suspension medium, to allow chemical processes to physically
occur. Liquids and gases are the obvious candidates for this.
Gas though, has the disadvantage that it allows heavier molecules
to settle out through the simple effects of gravity. This effectively
takes essential life-forming molecules out of play.
We may well have found this on Jupiter,
for no organic molecules were detected by the Galileo probe, when
it plunged into Jupiter's atmosphere a few years ago.
Jupiter, with the moon Io passing across its face.
Voyager 2 image. © NASA
energy levels - ie wind, that are required to remix settled-out
molecules into a solution, are so severe that they are likely
to destroy the structure of any potential living entity that might
be forming. Liquid suspensions, too, can suffer the effects
of gravity; however the remixing energies, such as convection
and evaporation, are gentle. It is therefore far more likely
that life will occur in a liquid environment, or at least in an
environment where liquids are relatively abundant.
most obvious candidate as a liquid medium is water. It is
the universal solvent. Many substances can go into
solution in water and this aids chemical processes in several
ways. It speeds them up, allowing new chemical units to
be brought into contact with one another, and it transports away
the results of the process - be it life itself, or the waste products
from life processes. Water is ideal for this. Like
carbon, it is universally abundant, and its unique ability in
bond-forming allows it to do some very helpful things for life
reason it is such a good solvent is due to its structure and internal
atomic bonding. As you will know, it is made up of
two hydrogen and one oxygen atom. The hydrogen atoms each
have a single electron, while the oxygen has eight electrons.
But the oxygen nucleus exerts a much stronger attraction to electrons
than does the hydrogen's. Even the hydrogen electrons are
attracted towards the oxygen end of the molecule. This causes
a charge imbalance within the water molecule. The oxygen
end consequently has a negative bias as the electrons, which carry
negative charge, spend most of their time in this area.
The hydrogen end, which is deprived of electrons, consequently
possesses positive charge. Thus, the water molecule is electrically
polar in nature.
a similarly-polar soluble material is now added to the water,
any free negative ends of that solute will link weakly with the
hydrogen atoms of the water, thus putting the solute into solution.
Those bonds are easily broken too, by evaporation or other processes.
So a ready, two-way reaction can take place, allowing the materials
of life to be moved around and worked with.
It does not constitute a good medium in life processes, which is another
reason for ruling out silicon as a basis for life.
what is the best base element for life?
Importance of Carbon
What Exactly Is It?- Discussion with Dr Stanley Miller
in the Universe
- Origins Investigation 13 Characterize the traits of the universal common
Research Findings Space Science Workshop 1996
and the Origins of life
Primordial Soup to the Prebiotic Beach
1999 Satellite Events Enterprises Inc.