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Life in the Universe

 

Is there life in the Universe?

Well, we are here, so yes.  Is there life anywhere else?  Enrico Fermi formulated this paradox:  given the number of stars and galaxies, there should be life elsewhere and even a lot of it.  But nobody has visited us, why not?

Against

On the other hand, the Anthropic Cosmological Principle(*) shows that life is very sensitive to the laws of physics:  if certain physical constants had just been very slightly different then biological, carbon-based life as we know it on Earth, would not be possible.  So maybe we are alone.

Another argument is as follows:  in order to build carbon-based organic life, we need chemistry of carbon, oxygen, hydrogen and nitrogen.  But these atoms, while sufficient to do organic chemistry, cannot exist on their own as "exceptions":  Nature (or God) built in fact a whole series of atoms.  It filled the periodic table of the elements by starting from the more basic building blocks of protons, neutrons and electrons.  Even if we need only atoms of H,C,N,O the protons, neutrons and electrons will also generate all the other elements of the periodic table.  Some are not important at all, and if more and more neutrons and protons are used to build nuclei, then after some size of nucleus there is no stability:  the atoms disintegrate by themselves.  Plutonium is a good example:  it did not exist on Earth before it was synthesized.  In other words, the other elements may be there only for completeness.  The only way to obtain H,C,N,O is to have laws of physics that as a side effect allow also the other elements.  Similarly, in order to get one single life-bearing planet, the only way may well be to create a complete universe filled with galaxies etc.  But this "rest of the universe" is only a frame, it has no use other than to complete the picture.  We are indeed alone.

In Favour

There are many other planets circling other stars, even quite close by.  There must be other places where life started.  We are not alone.

What is other life like?

We know that evolution has been working for several billion years.  About 60 million years ago, most interesting animal life was of the dinosaur type.  Then a catastrophe wiped them out and only the small creatures survived, among which the mammals.

Suppose the dinosaurs had not been wiped out by the asteroid incident.  Would they have produced intelligent beings?  No doubt:  there were very many different forms of dinosaur, and enough evolutionary pressure to be ever more intelligent.  Without the asteroid catastrophe, we might have seen intelligent life on Earth more than 50 million years ago!

Similarly, other planets in the Universe may have produced intelligent life many millions, even a billion years ago.  But this means also that physical appearances and technologies may have had equally large time spans to evolve.

Humans (homo sapiens) have been about for something like 500'000 to 1'000'000 years at most.  We have taken over the planet from the animals for only about 50'000 years and we have been doing agriculture for only 6'000 years.  Machine technology has existed only for 300 years.  We will probably build intelligent machines in the next decades (the electronic computer has been on the scene only since the end of the 1940s!).  Once intelligent machines are capable of building more of themselves and design themselves on the fly (no more Darwinian evolution!) we biological humans will lose control completely.  This will happen (or not) within the span of a few decades.  We humans end the line of biology and hand it over to technology.

But because of the famous asteroid that killed the dinosaurs, Earth may be 50 million years or more behind!

Assume that life always begins on planets, as biological (organic chemistry) forms, and then passes on into technology.  Let us call this the basic development-line:  from biology-over-intelligence-to-technology.

Other planets may have experienced this development line, and they may be superficially different:  millipede forms instead of bipeds, fish instead of land animals, whatever your imagination allows.  However, apart from accidents such as the ones that happened to the dinosaurs, many of these development-lines have come to their technological end many millions of years ago.  Once organic life gives rise to machine life, it disappears in favour of the machine(s).

When we humans want to go out into space, we need to protect ourselves with mechanical hulls.  We need instruments to observe what our organic bodies are incapable of sensing:  radiation, electric fields, gravity, speed.  We need computers to digest the data and present the results to our eyes.

But an intelligent machine would not need these prostheses:  it could re-build itself into a single unit which would be the spaceship, the computer and the sensors all rolled into one conscious entity.  It could autonomously go about its business in space, and it would probably try to avoid setting foot on planets with their large gravitational field from which it is costly to escape.

If such a machine arrived in the solar system, would we recognize it?  If such a machine travelled through interstellar (intergalactic?) space, would it protect itself from collisions with debris by using a comet or asteroid as bulk shield?  How would we know that we have not been observed or are being observed?

Would such machines not be indifferent to organic life, in the same way that we treat a forest or a lawn?  Nice to walk in, but we've seen it before. What use to try to talk to the ants?  More: "don't interfere with these places, let them be" might well be their ethic.

Only very few Sci-Fi authors have taken this topic seriously.  Fred Hoyle is one, Arthur Clarke, Stanislaw Lem and Olaf Stapledon are others.

This leads me to this critique of Sci-Fi movies:

Yet another sobering thought

There is a theory of the Multiverse:  many universes exist in parallel, all with different laws of physics.  We just happen to be in the one where life exists and the physical constants are what they are.  So there is no special reason for the "fine" tuning.  Perhaps, but then there must be universes in which life is possible, but intelligence never develops to a level able to cope with big problems (such as managing a planet instead of just a tribe).  Maybe we are in such a universe, therefore we will never be able to run the Earth properly and we will die of self-inflicted horrors.


* J. Barrow & F. Tipler, Oxford University Press, ISBN 0-19-282147-4
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