- Order from chaos. In other words - a repeating pattern, albeit a pattern that evolves over time. It is said that if you observe a chaotic system long enough, a repeating pattern will eventually emerge. This may be one clue to the origin of life. And if so, the possibility that it only happened once in this very large and rather old universe seems rather infinitesimal. Life, to exist and continue to exist and to evolve, has to be a repeating pattern arising out of the "chaos" of natural principles, laws, and constants.
- I place the word "chaos" in quotes because it is not an unlimited chaos. Think of a Shakespearean sonnet. It has a certain set of rules. These are the Shakespearean sonnet natural principles, laws, and constants: A Shakespearean sonnet is made up of three quatrains and a couplet (and can be expressed as a formula: 4+4+4+2. Math is everywhere folks!). It has a rhyme scheme ABAB, CDCD, EFEF, and GG. It has a rhythm as well, a repeating iambic pentameter. It normally shows a scene or tells a little story or vignette, and often ends, in the couplet, with a twist or irony. However, within those constraints, one can still have a wide range of possibilities - you can write it in any language, and describe any scene, or tell any kind of story, even a nonsensical one.
- Thus, universal biology will have its mathematical formula and algorithms, its principles, laws, and constants and still be able to describe a bewildering array of varieties of life. As the rules of the Shakespearean sonnet arose from the complex interactions of the nature of the human mind, so may the rules of universal biology be said to arise from the complex nature of interactions of the natural laws (chemical, physical, i.e.) that make up this universe.
What will the parameters for the Universal Life Sonnet? Biology is informed by chemical and physical laws and constants. As it is inevitable that galaxies, stars, and planetary systems arise from the original primordial chaos of the universe, so is it inevitable that life will form on planets that allow, at least, for liquid water.
Most scientists feel that life needs three things: organic chemicals (carbon based), water, and an energy source. That's it. That's all you need. As we are discovering, organic chemicals and energy sources are rather common in the universe. You don't need life to create organic chemicals (so this isn't a "which came first, the chicken or the egg" sort of paradox). But you do need organic chemicals to create life (at least life that we are familiar with). Energy sources can be the radiation from a star (like sunlight from the sun) or volcanism (including hydrothermal vents) to name but a couple. Thus, what we need to look for is a source of water. As detection improves with more advanced telescopes, we are increasingly finding extrasolar water, from water being detected in planetary atmospheres, to water "raining down" upon a young planetary disk (NGC 1333-IRAS 4B).
Think about our own solar system - how prevalent is water? Water exists in varying amounts on Mars, Venus, Jupiter (trace amounts), Saturn (also trace amounts), Uranus, Neptune, the Moon, the moons of Jupiter (most notably Europa) and Saturn (Enceladus, Titan), asteroids, comets, and Pluto. Water is theorized to exist even on Mercury! Seems water isn't that uncommon.
In other words, then, given enough time, life is bound to happen all across the universe.
Ah, but wait. There is a disclaimer, a caveat - life needs a couple of other things: a boring home - the more "boring" the better. A planet around a very dynamic, unstable star (with huge variables in light output) or a planet in a rather elliptical orbit, will experience dramatic extremes which would be disastrous to life, at least to higher forms of life. I suppose, however, that given enough time, as the lawyer in the movie Jurassic Park was found of say, "life will find a way." We are finding extremophiles on Earth that can survive conditions we once thought impossible for life to handle. There are even microbial lifeforms that can survive the rigors of space! Right now extremophiles are restricted to limited areas on the planet, while other lifeforms have found more efficient, more abundant, energy/food sources and have dominated the planet, but on a planet where things are reversed, the extremophile-type creatures may find themselves the dominant life form, and may possibly slowly evolve. I would predict that they would take a much longer time to evolve high level sentience than on a more "boring" planet, but I do not see it being impossible.
Another caveat - no solar system is completely boring. All stars vary in output, and all stars age and change. Gama ray bursts many light years away can wreak havoc on an unsuspecting system, destroying all or most life on any unlucky planet in the path of the beam (there is some conjecture this may have happened once to the Earth in the distant past). Meteors and comets abound, and occasionally collide with planets. If a supernova is near enough, it too can wreak devastation on a near-by system. The planets and moons themselves have dynamic events going on within them as well - earthquakes, volcanism, and atmospheric changes (changes in oxygen or methane content, i.e.) to name a few. While microbial life tends to survive major events, higher life forms tend to be more susceptible to being wiped out by them.
So it may be that while given enough time, life is bound to happen, high level sentient life may take even longer time, and be less common; there are more restrictions for the Universal Sentient Life Sonnet - it is a much harder sonnet to write. But it is a very big universe. At present scientists estimate there are over 100 billion galaxies in the universe. Each with billions of stars. However, the point of our speculations is not that the universe is teeming with sentient life, but that it does exist, even if it may be too far for us to ever have any real meaningful contact with (we may only be able to detect that a technologically advanced civilization exists, and "communicate" via 20, 100, or 1,000 year round trip communiques). Let us, then, speculate on alternative extrasolar biological, psychological, theological and societal realities that could exist.
Max-Planck-Gesellschaft. "Nano-assembly Mimics Origin Of Life? Molecules Organize Themselves Into Patterns." ScienceDaily 1 November 2007. 1 November 2007. <http://www.sciencedaily.com/releases/2007/10/071030105309.htm>.
Minkel, JR. "Water Found on Distant Planet." Scientific American. 11 July 2007. 1 November 2007. <http://www.sciam.com/article.cfm?articleID=B66E323B-E7F2-99DF-36D284B02192381C>.
Tinetti, G., et al. "Water vapour in the atmosphere of a transiting extrasolar planet." Nature. 12 July 2007. Excerpts at "Water, water everywhere - on an extrasolar planet. " ESA Portal. 11 July 2007. 1 November 2007. <http://www.esa.int/esaCP/SEMBDZI2O3F_index_0.html>.
"Water Vapor Seen 'Raining Down' on Young Star System." Spitzer - NASA. 29 August 2007. 1 November 2007. <http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20070829.html>.