> >Detecting Earth-sized planets is hard enough but how does an
> >astrobiologist decide which of them are inhabited? Scientists
> >are now working to understand what signals life might give
> >off into space, so that when they do detect Earth-like
> >planets they know what to look for.
> >
> >Our radio and television broadcasts have been leaking into
> >space since the 1930s, when the first powerful emitters
> >were constructed. However, you can do things the other way
> >around as well. The Search for Extraterrestrial Intelligence
> >(SETI) has used radio telescopes to listen to the cosmos for
> >similar signals.
The problem with common approach used to look for other life in universe is
that it is too much homo-centric. It is only based on extrapolation
of how we look and what we do, and not on general definition of life.
To make an analogy, if bacteria wanted to look for other "life" in other
planets, they would try to find some signaling molecules, because it is
the only way of signaling they know.
Real search for life should start with defining "what IS life".
Definition should be given not based on analogy, but based on general physical
principles. Such definition can be given based on thermodinamical function of life
we know. What is it?
We know that all spontaneous processes are taking place if their result is
increase of entropy (2 LT). Moreover, if two processes involving the same resources
take place, the one which results in faster entropy increase will consume more resources.
Simple analogy here is the discharge through 2 parallel resistors. More current will
flow through smaller resistor. I stated this just to remind that not only entropy
increase is important for thermodynamics, but also its rate. Higher rate is favored and
supported by the system.
Now, many processes which by itself go with increase of entropy, are very slow.
For example, mix of oxygen and hydrogen can stay in certain volume for years without any
noticeable reaction, despite huge (explosive!) entropy increase which this reaction can
bring. Catalysts can accelerate many reactions, those satisfying thermodynamics push for
"faster" entropy increase. However, in many reactions only quite complex catalyst can give
noticeable reaction rate increase. Complex catalyst itself has low own entropy and therefore
has to decompose in correspondence with same law.
We have here a contradiction. On one side, thermodynamics favors fast entropy increase.
In many cases, complex catalyst is the only thing which can provide such. But - the more
complex is the catalyst, the faster it itself decomposes. The answer of the thermodynamics to this contradiction is life.
******
Life encompasses catalysts which are able to use part of the energy freed due to entropy
increase of the catalyzed reaction to apply work against its own decomposition.
******
This special class of molecules are different from other thermodynamical objects in the sense that they are semi-stable. They themselves have entropy too low to be stable in their environment (their decomposition has negative delta Gibbs potential) but in presence of reaction catalyzed by this molecules energy s generated equal to negative dG of molecules themselves, which as result makes the molecule stable _as long as catalyzed reaction takes place_.
Note that this definition of life is not restricted to chemical objects. "Catalyzed reaction"
providing catalysts stabilty can be of any kind - thermal exchange, nuclear, any process where entropy increase can be accelerated. Catalyst itself can be not only complex molecule, but complex electromagnetic pattern, a whirlpool in water, anything which is able to accelerate entropy increase and use part of the energy for own stabilization.
Conclusion from this in regard to search for life:
- life can be found in any place where entropy increase has taken very long time sufficient for evolution of complex catalysts
- life will be the more complex the more energy is involved in the catalyzed process.
Following this, the first place to look for life are very near to us - it is the inside
of any planet, where huge energy is dissipated by thermal exchange through the mantel,
and inside of any star which exist longer then any planet and where entropy increase process is incomparably more energetic then in any planet. Most advanced life will be found in the structures near black holes and quasars, where entropy increase rate is incredible. The nature of such life will likely be not even electromagnetic, but maybe based on nuclear forces.
Yes, this life will not look anywhere like our life - we are but a bacteria compared to
energy being converted by this more advanced life forms. And yes, it will most likely not
notice us or will be not in the slightest interested in "communicating" with us. And yet,
they are our only future. The only way how any life can progress is in the direction of
increase of the energy conversion. Any life forms which will become inefficient in this
increase will be replaced by others.
Regards,
Evgenij
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