17.1 Minimum Requirements for Life
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into and out of the planet, comes in with significant UV and visible light, and leaves
largely as infrared radiation from the upper atmosphere. Overall, this transformation
is entropy producing, as it must be. But some inflow of energy does work in making
complex molecules and performing necessary processes. The production of complex
molecules is entropy reducing in an open subsystem.
On the ocean floor, geothermal vents sustain life. There has been plenty of room
for order to form and for complexity to evolve in the open system which is the
Earth. That ordering selectively picks out pathways that allow further ordering and
that speed the process. This occurs simply from the fact that statistical interactions
between a variety of dispersed and diffusing molecules will encounter those
pathways if they exist. Once the system encounters a catalytic ordering pathway, it
undergoes a kind of phase change in the production of more ordered configurations.
The existence of the catalytic ‘shortcuts’ will be strongly dependent on the available
materials and the nature of the incoming energy.
When the system by these processes encounters molecular reproduction, Darwinian selection becomes operative, including the preservation of mutability balancing stability. Many of the molecules and processes used by life forms early in
evolution were so successful that we find them common in all analyzable past and
present life, including prokaryotes. This means that alternatives, if they existed, died
off early on. It also means that certain features of present life is strongly preserved.
To be adaptive, other attributes must be flexible and mutable.
We should not be too anthropomorphic by assuming life must be carbon based.
Silicon can also form long chains, although not quite as easily as carbon. Chains,
sheets, and three-dimensional structures of silicon and oxygen formed in the Earth’s
crust, with various mineral varieties created when an occasional silicon atom is
replaced by a metal atom. Boron also can form chain molecules with the boronnitrogen bond acting similarly to the carbon-carbon bond. Both water and ammonia
are highly polar molecules, and therefore can dissolve many salts and other polar
molecules. Perhaps a silicon-based life exists, with liquid ammonia as the solute.
Even more exotic life systems may exist, such as those formed secondarily by the
primary intelligent beings. Self-replicating robots would be an example.
In analogy and in parallel, an Asimov robot might run amok after a conflict with
‘The First Law’ directing no harm to humans, or robots may even evolve away from
strict rules.
A threshold in the evolution of order was passed when humans altered and made
organisms through genetic engineering. Humans will be tempted to improve their
own genes, to cure diseases and to enhance what might be considered favorable
characteristics. But if changed or created organisms supplant the natural ones, the
slow (millions of years) natural testing of viability of naturally evolved subsystems
is short-circuited. An engineered corn resistant to insects might replace all the wild
varieties, but later show fatal vulnerability to a rare virus, due to the changed DNA.
And if ‘super humans’ are created, new conflicts are bound to occur.
615
into and out of the planet, comes in with significant UV and visible light, and leaves
largely as infrared radiation from the upper atmosphere. Overall, this transformation
is entropy producing, as it must be. But some inflow of energy does work in making
complex molecules and performing necessary processes. The production of complex
molecules is entropy reducing in an open subsystem.
On the ocean floor, geothermal vents sustain life. There has been plenty of room
for order to form and for complexity to evolve in the open system which is the
Earth. That ordering selectively picks out pathways that allow further ordering and
that speed the process. This occurs simply from the fact that statistical interactions
between a variety of dispersed and diffusing molecules will encounter those
pathways if they exist. Once the system encounters a catalytic ordering pathway, it
undergoes a kind of phase change in the production of more ordered configurations.
The existence of the catalytic ‘shortcuts’ will be strongly dependent on the available
materials and the nature of the incoming energy.
When the system by these processes encounters molecular reproduction, Darwinian selection becomes operative, including the preservation of mutability balancing stability. Many of the molecules and processes used by life forms early in
evolution were so successful that we find them common in all analyzable past and
present life, including prokaryotes. This means that alternatives, if they existed, died
off early on. It also means that certain features of present life is strongly preserved.
To be adaptive, other attributes must be flexible and mutable.
We should not be too anthropomorphic by assuming life must be carbon based.
Silicon can also form long chains, although not quite as easily as carbon. Chains,
sheets, and three-dimensional structures of silicon and oxygen formed in the Earth’s
crust, with various mineral varieties created when an occasional silicon atom is
replaced by a metal atom. Boron also can form chain molecules with the boronnitrogen bond acting similarly to the carbon-carbon bond. Both water and ammonia
are highly polar molecules, and therefore can dissolve many salts and other polar
molecules. Perhaps a silicon-based life exists, with liquid ammonia as the solute.
Even more exotic life systems may exist, such as those formed secondarily by the
primary intelligent beings. Self-replicating robots would be an example.
In analogy and in parallel, an Asimov robot might run amok after a conflict with
‘The First Law’ directing no harm to humans, or robots may even evolve away from
strict rules.
A threshold in the evolution of order was passed when humans altered and made
organisms through genetic engineering. Humans will be tempted to improve their
own genes, to cure diseases and to enhance what might be considered favorable
characteristics. But if changed or created organisms supplant the natural ones, the
slow (millions of years) natural testing of viability of naturally evolved subsystems
is short-circuited. An engineered corn resistant to insects might replace all the wild
varieties, but later show fatal vulnerability to a rare virus, due to the changed DNA.
And if ‘super humans’ are created, new conflicts are bound to occur.