As a prelude to systematic analysis or discussion it’s often useful to set up some agreed upon definitions. Otherwise people usually just end up speaking past one other. That being said, definitions are also quite slippery. This is especially true when you venture outside of the mathematico-scientific realm and into the socio-cultural domain as every definition becomes contentious since it’s much more difficult to cleanly separate definition from conclusion-commentary. In short, definitions are at once problematic and inevitable. Thus in an effort to stimulate some discussion I offer the following definitions I find interesting (but don’t necessarily subscribe to), so as to incite, excite and cajole you into commenting. Some serious, some not so serious, but all dottering along magnificently.

(1) Life (see here): a self-replicating system in homeostasis with its environment.

(2) Conclusion: What one does when tired of thinking.

(3) Culture: A complex system of symbols.

(4) Feudalism: A system of government in which your Count votes.

(5) Science: A particular cultural form (see 3 above) which is distinguished by the institutionalization of revolution, and where the revolution in thought (symbols) is made complete by experimental verification.

(6) Haecceity (see this): Thisness; the essence that makes something the kind of thing it is and makes it different from any other.

(7) Religion (Clifford Geertz’s five-part definition): “(1) a system of symbols which acts to (2) establish powerful, pervasive, and long-lasting moods and motivations in men (sic) by (3) formulating conceptions of a general order of existence and (4) clothing these conceptions with such an aura of factuality that (5) the moods and motivations seem uniquely realistic.” (Geertz 1985: 4).

(8) Gleek (from UrbanDictionary.com): Building up saliva in the salivary glands using some stimulus, like sour food or yawning, and then pressing the tongue upon the glands, causing the saliva to shoot out, usually at an impressive distance.

(9) State: A group of thugs with an army and navy. Or equivalently Max Weber’s definition was something like an organization with a “monopoly on the legitimate use of physical force in a given territory.”

(10) Walnuts: 2008 Republican Presidential Nominee John McCain. See for example here and here.

(∞) Definition: … ?

   

Astrobiological musings

March 27, 2007

I was fairly astounded to find that astrobiology – the study of whether life exists elsewhere in the universe – is actually a respected field of study in academia. At its heart astrobiology is quite speculative, since we only have one notable data point of evidence that life occurs at all in the universe, namely good ol’ Mama Earth. There is however, a useful rule of thumb often attributed to Richard Feynman (who is incidentally also credited with a good portion of modern physics), that whatever is not forbidden in nature is mandatory. That is to say, if nature allows for the existence of self-replicating molecular systems on one rock around a fairly average star, then its not unreasonable to think life might exist elsewhere. The case for the commonality of life is strengthened further by the relatively recent discovery of so-called “extremophiles” thriving in the least likely of places on Earth: boiling water surrounding hydrothermal vents, underneath permafrost, and inside rocks to name just a few. Here’s an example of a particular extremophile.

A Pompeii worm colony near a hydrothermal vent.

This is a Pompeii worm colony near a hydrothermal vent. Needless to say, the existence of such extreme forms of life greatly reduces the number of necessary environmental criteria for life. Thus microbial life at least might very well be quite common in the universe.

In fact we might not need to look beyond our own solar system for other forms of life. Our very own Europa (one of Jupiter’s 63 moons!) might not only have liquid water beneath its icy surface but also have a significant heat source. That whole source of heat thing is not irrelevant when you consider that at Jupiter’s orbital distance the luminosity of the Sun isn’t that much greater than the background stars. The source of heat is unknown at the moment, but an intriguing possibility is the strong gravitational tidal flexing Jupiter’s large mass provides. There are actually two interesting bits of evidence for liquid water under the icy shell of Europa: 1) cracks in the ice crust appear to heal with time, and 2) the magnetic field around Europa is significantly smaller than would be expected since Jupiter has a substantial magnetic field. This happens near highly conductive bodies, such as a salty ocean perhaps.

The “heat plus water” equation seems to be more than enough for some of Earth’s extremophilic organisms, which bodes quite well for possible Europan biology. Given all of this it’s quite unfortunate that NASA somehow finds it more useful to waste oodles on a boondoggle to send humans to Mars rather than sending a much cheaper unmanned mission to Europa on a well-motivated search for extraterrestrial life. This despite the fact that we already have two wonderfully adept geologists on Mars right now living off of sunlight alone: the Mars Exploration Rovers Spirit and Opportunity. Here’s an example of two competing ideas regarding the Europan interior.

Alternative theories on the Europan interior.

Of course none of this says anything about the possibilities of complex or intelligent life. For that you probably need to satisfy much more stringent criteria such as the veritable Goldilock’s condition: a habitable planet must not be so far from its parent star that it gets too little light but also not so close that everything boils away. Getting the distance from the star just right is probably the most significant impediment to the development of intelligent life. Read more about the unfolding saga that is astrobiology here and here.

This might all be pure speculation since any would-be astrobiologist is forced to confront Fermi’s paradox regarding extraterrestrial life: if intelligent life is common why hasn’t it called us up yet? Or would it be too convenient for us to assume that another civilization would choose to communicate with us using radio-waves? Perhaps they’re so advanced that we can’t possibly hope to receive their communications given our limited technological capabilities? While although possible that’s not a falsifiable hypothesis and thus outside the bounds of science, but that won’t stop us from fun pontifications.