Exobiology was the original term given to the sciences central to the question of life-in-the-Universe. It’s now been largely replaced by Astrobiology, but I’ll stick with the original. To investigate life-in-the-Universe one needs to look at what the most likely sort of extraterrestrial life will. Terrestrial life, extinct and past; or alive and present is amazingly diverse – in appearance anyway, but also in the environments they inhabit and the abilities they have to survive and thrive. But under the skin, our fundamental biochemistry, be you T-Rex, or be you a maple tree, or be you a bacteria, or be you, you, well you’re all as closely related as makes no odds. Extraterrestrial life will also be amazingly diverse – in appearance. However, the fundamental biochemistry that makes them, them, might be equally diverse relative to what makes you, you.
Life has to have some abilities, and life has to exist within an environment that’s fit for, well, life. Both abilities and environments go way beyond life-as-we-know-it, if by that we restrict life-as-we-know-it to the very everyday familiar life forms that we perceive around us – even then, surprises abound.
Abilities: When it comes to special abilities relative to ourselves, well fish gotta swim (but so do dolphins, a paramecium, squid, penguins, some turtles; even we humans make a rather feeble go at swimming but we’re not in the same league, far less the same ballpark as fish, etc.). And birds gotta fly (but so do bats and many insects; humans are natural flyers too – as long as it’s straight down). Clearly lots of organisms can move faster than we can. Many organisms have had abilities that have enabled them to survive for multi-millions of years; billions if you include microorganisms. We’ve got a long way to go before we start making it in that ‘Guinness Book of Records’. Your dog can hear higher frequencies than you; your cat has a better sense of smell; many birds have sharper vision and many organisms can ‘see’ parts of the electromagnetic spectrum that we can’t.
But, not to worry, at least we tend to come top of the pops in the I.Q. category! Now the natural question is, what sort of evolved abilities or capabilities might intelligent aliens have that haven’t been thought of in anyone’s philosophy, apart from perhaps being mental giants and putting us to shame in that I.Q. category?
Environment: When we think of the typical environment that life finds itself in, we tend to think of our own traditional environment, one that has a fairly narrow temperature range; predictable alternating daylight and darkness intervals; one relatively free of harmful radiation; a fairly narrow pressure range; also a very narrow range of an environment that’s not too acidic, not to alkaline; a near constant atmospheric composition, etc. We don’t often tend to think that life in general, terrestrial life in particular can survive, even thrive outside what’s comfortable to us. How wrong we are if we think that! Relatively few complex organisms exist in extreme environments, though examples would fill many an essay all by itself. We all know about animals that can live in Earth’s Polar Regions and in her ultra dry and hot deserts. We know that fish survive at the high pressure, eternally dark abyssal depths, and that some fish can bury into mud and cocoon themselves from drought for extended periods. Still, that’s peanuts compared to what some microorganisms can achieve. Without doing an exhaustive survey, you’ll find microbes surviving and thriving: high up in the atmosphere; kilometers beneath the surface of the earth; inside your digestive system; inside rocks; in battery acid equivalent environments; in extremely high saline environments; in extreme alkaline environments; in total darkness; in pressures that would crush you like an eggshell; in boiling water; in the near absence of water; in temperatures way below freezing; in toxic sludge; inside nuclear reactors; in environments totally free of oxygen. Some microbes can survive (but not thrive in) exposure to near absolute zero temperatures and the vacuum of outer space. The upshot is that the range of non-terrestrial planetary environments where we might detect, at least relatively simple life, has expanded to just about anywhere and everywhere.
Chemistry: Life-Not-As-We-Know-It: Humanoid, or non-humanoid life forms, with biochemistry very different from ours, is a reasonable rarity in science fiction. When such beings are depicted, they tend to be pure energy entities (fairly easily done via special effects), or something resembling terrestrial life forms albeit given an exotic biochemistry. Star Trek’s Horta are a case in point.
It’s going to be chemistry, not physiology that ultimately dictates life-not-as-we-know-it. Substitute liquid ammonia or ethane for water; silicon for carbon; copper for iron in the blood (Mr. Spock, anyone?), the literature of speculative astrobiology, not to mention the literature of science fiction as well as sci-fi TV series and films are relatively rare of really alien aliens, everything from pure energy beings to solid rock and crystalline life forms, but hardly non-existent. Alas, life-not-as-we-know-it, that is non-CHON (Carbon, Hydrogen, Oxygen & Nitrogen) life has been at best a ‘what if’ scientific and literary speculation of the purest kind. When subjected by biochemical specialists to critical examination, non-CHON biochemistries were found wanting as likely viable alternatives. For example, replacing carbon with silicon would have oxygen breathing aliens exhale not carbon dioxide but silicon dioxide – sand! Translated, we find the devil’s in the biochemical details as it were. While the possibility for alternative biochemistries can not be totally dismissed, we know CHON life can exist, so taking that certainty, we run with that first and foremost, when, in the first instance, looking for ET.
Really Far Out, Star Scout: Dark Life Composed of Dark Matter and Fueled by Dark Energy: However, while on the subject of life-not-as-we-know-it, you’re in for a bit of a surprise.
You are a minority, and it has nothing to do with your sex, age, blood type, religion, racial or ethnic characteristics, I.Q., or any other similar or related thing.
You are a minority, even a rarity, in that all the stuffs (matter and energy) that make you, you, and make you tick, is in itself a minority or a rarity in the cosmos, and it’s not because most of the cosmos is ‘empty’ space (not that in quantum theory space can ever be 100% empty). All that you experience (see, hear, feel, smell and taste) around you, be it from your immediate surrounds out to the farthest reaches of the cosmos is the result of just 4% (or thereabouts) of the ‘stuff’ we know and love – electrons and positrons, protons (composed in turn of quarks) and antiprotons, neutrons (again in turn composed of quarks) and antineutrons, neutrinos and antineutrinos, photons (electromagnetism), the theoretical to date undetected gravitons (gravity), gluons (the strong nuclear force), etc. And 4% of anything represents a minority, even approaches the definition of rarity.
The other 96% (or thereabouts) of the cosmos is made up apparently of both ‘dark matter’ and ‘dark energy’, which isn’t your run of the mill electrons, protons, neutrons, electromagnetism, gravity (although ‘dark matter’ exhibits a positive gravity akin to normal matter.), etc. yet can and does interact with the cosmos and its contents. It’s sort of like having a room full of 100 people, only 96 of them are ghosts, albeit physical enough to interact with the contents of the room (just like real ghosts allegedly do).
One needs to point out that thus far at least, there’s no actual known connection between ‘dark matter’ and ‘dark energy’ apart from the fact that neither is visible to us in the way that a star or light bulb is visible; thus, the common term ‘dark’. Both ‘dark matter’ and ‘dark energy’ have been detected by more indirect means, primarily their influences on the 4% of stuffs we can see.
The subject of astrobiology (as outlined above) deals mainly with the question of finding extraterrestrial life-as-we-know-it. That is, finding life like us based around traditional forms of matter and energy; life with similar chemistry, energy needs, and environmental requirements. However, astrobiologists do like to speculate and cast their minds far and wide and envision possible forms of life that fall in the category of life-not-as-we-know-it; life that makes use of exotic chemistries, unfamiliar energies, and (to us) extremely hostile environments.
So, the question proposed is could a form of ‘dark life’ originate and evolve out of some combination of ‘dark matter’ and/or ‘dark energy’? (This would be an ultimate life-not-as-we-know-it prize for astrobiologists.) Well, since we don’t really know what ‘dark matter’ is – its chemistry and other properties – and since we don’t have a handle on the nature of ‘dark energy’ either, one can’t conclude one way or another at this stage. Let’s just call it a whopping big “maybe”. Perhaps (the late) Sir Fred Hoyle’s Black Cloud concept as expressed in his sci-fi novel of that name, might not have been that far off the mark after all!
The major fly in this ointment is, I suspect, that ‘dark energy’ is a repulsive force, which at first glance, seems incompatible with life of any kind. Thus, for the moment, I’ll include it as a ‘dead end’. However, it’s early speculative days yet and there’s a long way to go before ruling anything either in, or out.
An idle thought however, we wonder what the missing 96% of the Universe is – just calling it ‘dark matter’ and ‘dark energy’ doesn’t tell us what it is. Perhaps a ‘dark energy/matter’ being wonders what the missing 4% of their Universe is composed of!
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