Exolife!
Jordon 179 asks an question worthy of endless debate in his blog, which I copy here to see if my readers also wish to discuss it. He asks about life in the universe:
Do you think that there is extraterrestrial ("not from this Earth," thus excluding astronauts, stray Earthly bacteria on probes, etc.) life anywhere in the Solar System? In the Universe?
Do you think that there is extraterrestrial sentience (higher animal level) anywhere in the Solar System? In the Universe?
Do you think that there is extraterrestrial sapience (ape to human level) anywhere in the Solar System? In the Universe?
Do you think that there is extraterrestrial technological culture (at least Paleolithic level) anywhere in the Solar System? In the Universe?
Finally, do you think that there is extraterrestrial civilization (at least agriculture + writing) anywhere in the Solar System? In the Universe?
And for each question — how common do you think it is?
My comment: It is an interesting question, more as a test of psychology than of fact. As far as we no, there is not even the smallest scintilla of evidence for the existence of life outside the earth’s atmo, except perhaps for one ambiguous rock from Mars, which hinted at microbes there.
It is a blank on which the imagination is free to paint whatever pictures it wishes.
But if you want to know what my imagination paints, it is a vast and universal blank. I am a pessimist, and so my psychology answers pessimistically. Even if there is something out there, we will never find it.
When I contemplate the distances that separate the stars, and the scientific, not merely the technical, miracles that would need to be performed to discover life even on very nearby stars — a starship even powered with theoretically perfectly efficient matter-antimatter fuel, or a sailing ship pushed by launching laser who left her fuel at home — no probe of ours could not reach even the nearest star in decades, or even centuries.
There are 400 billion or so stars in Milky Way alone, or 10^11. Let us suppose as many as ten thousand stars held planets containing bacterial life, or 10^4. That leaves us with 99,999,990,000 or so stars with no life. We have to sift through an entire beach to find the one grain of sand that is special.
If they are evenly distributed throughout the main disk, this is a volume some 70,000 to 100,000 light-years in diameter, and roughly 1000 light-years thick. On average, the nearest one will be ten thousand light-years away. Let us for the sake of argument say that Xi Persei, (1600 lightyears from Sol) is the lucky nearby candidate. On the second world, beneath a layer of ice, small cells have grown in the vents of sulfurous volcanoes pouring heat into a sunless sea. You would need a microscope to detect them.
Unless Einstein was fundamentally and radically wrong, and we can somehow slip something past lightspeed, the energy required to accelerate even one gram of mass to .9 lightspeed, and make it to Xi Persei in only a few millenniums, strain my calculator. It is something on the order of more joules than the entire human race, at present, controls. The long and the short of it is, the human race will never find it, never get out microscopes there to look.
That is assuming 5 thousand bacterium-bearing planets. In order for a world with life to be within the scientific range of our remote descendants, life would have to be considerably more densely packed in the universe than that.
How prevalent is extraterrestrial civilization? Let us suppose that not just millions, but tens of millions of worlds in the Corona Borealis galactic supercluster brought fourth life half a billion years ago. Let us further assume that they projected energy, either radio or something else, in sufficient magnitude to be detected by earthly instruments.
This happy event will take place half a billion years in the future, since Corona Borealis is one BILLION lightyears away.
The distance between here and Corona Borealis, according to current estimates of Astronomers, is perhaps one fourteenth of diameter of the universe. On that scale, it is a near neighbor.
But, in an utter absence of evidence, assuming every planet does and must hold bacteria is just as reasonable (or unreasonable) an assumption.
Assuming we are alone in the universe is just as reasonable (or unreasonable) an assumption.
Now, how many bacterial world develop into worlds with cats and dogs? Again, since we do not know whether evolution always goes from less complex to more in every world, the ratio is a complete unknown.
I simply see no reason, none, for assuming the process is inevitable.
Even in a game of cellular automata, the chances of generating a stable pattern of dots is not good. There are, of course, stable patterns in this game.
For hose of you not familiar with it, John Conway invented a math game see here with simple rules. You fill a grid with a pattern of cells. At each turn of the game, each cell with one or no neighbors goes blank. Each cell with four or more neighbors goes blank. Each cell with two or three neighbors remains. But each empty cell with three neighbors becomes populated. By these rules, a group of four squares will remain forever. Two cells will seem to oscillate like a propeller. Cleverly-designed enough systems of dots will produce stable systems, and more than one clever mathematician has found a pattern that will grow forever rather than collapsing into a stable form or vanishing.
On our world, unicellular life developed (or was corrupted, since unicellular life is immortal) into multicellular life. There in nothing in Darwins theory to make this inevitable, or even likely. Indeed, the example from the John Conway game seems to suggest that complex systems breaking down to simpler systems is a useful survival strategy: who is to say that the meek amoeba might not inherit the Earth, and the few moment of strange multicellular life be, in the grand scheme of things, an outbreak or aberration?
We also do not know how likely or how often primitive tribes of intelligent hunter-gatherers will settle down and build walls and roads and invent writing systems. Again, civilization does not seem inevitable, or even likely, but it does seem to have sprung up in two or three separate centers, in Ur, along the Yellow River, in Mohenjo-Daro. So for planets where the dominant species can survive by agriculture, or some other energy-gathering system requiring massive concentrations of population well organized, there may be strong tendencies that naturally create an incentive to build walls (or the equivalent) and invent writing (or some other long-term memory coding system).
For that matter, in real Earth history, one and only one culture ever developed the industrial revolution and the scientific world-view, and that culture is Christendom. The concept of a rational world that reacts to rational laws has no metaphyiscal underpinnings either in a pagan, a mystic, or a materialistic world-view.
If we are to judge from the history of the Earth, a civilization needs Christianity, with its unique blend of Hellenic and Jewish thought, to make the jump from caste-bound or Mandarin-run societies, to those with a rule of law, a free market, a university system, limits on monarchic powers, and so on. The "developing world" after all, is a euphemism, and a rather hopeful one at that, if you think about it.
Of course, this leads to an uncomfortable conclusion. But for someone who is skeptical of Victorian or Marxist notions of the "march of history", I see no warrant for assuming the life can emerge from non-life merely through random chemical accidents, no warrant for assuming life, once found, will necessarily mutate into sexual life. I see no warrant for assuming other worlds will have the mutation rate found on earth, for example. Some theorize mutation rates are caused by cosmic rays. If the ray count were lower, would the mutations be too infrequent to be of any use in the Darwinian accumulation of traits? I see no warrant for assuming other worlds with multi-cellular life will develop intelligence, or that intelligence will lead to civilization or anything like it, or that civilization will lead to technology or anything like it.
So far, we have heard no whisper of the radio noise one might expect if technological civilizations were common in this corner of the universe.
For that matter, we have yet to discover even a single organism outside the Earth’s atmosphere. Scientists are looking in places where there is water, such as Mars, or Io, but we have no results as yet.
The model that says life is utterly unique to Earth has yet to be disproved by a single counter-example. I am not saying this model is correct: time will tell. I am saying to assume it has been disproved is a reflection of a psychological reality, not a scientific one.
Neither believe is scientific or unscientific. The unwillingness to believe we are unique in the universe is just as unsupported and arbitrary as the willingness.