One might think a structured and serious approach to the subject of life should necessarily start with a working definition. To illustrate this is unwise; consider one of the traditional definitions for life, that says among other requisites that living organisms are capable of reproduction.
Then, one learns viruses are able to reproduce but lack the means to accomplish it by themselves and must borrow molecular machinery from a host to do it. If we accept this is still within reasonable tolerances, we must also accept computer viruses fill the same requisites and should therefore be declared living forms.
And then we should try to parch this slippage saying, "Oh, well, but they are not biological-based entities."
I guess you now get the idea we get deeper in the mess. What about an immaterial soul, if such thing is believed to exist?
Let's be content first with tracing the path traversed here on Earth, as fairly as we know, about what we tacitly accept as life. The long and improbable chain of circumstances that led clumps of stardust to - in this particular instance - be in front of a keyboard. In the last part, we'll speculate eventually with approaches to the concept of life in the light of things we learned mainly in the last century.
First find a place
The Universe at large is a place of extremes. Interstellar voids are so cold no organic reaction can take place but at the most sluggish of rhythms. Even assuming the process of life could anyway carry on there, most probably the Universe itself should not last long enough to get even to the most basic stages--barely distinguishable form featureless chemical chaos.
Star surroundings, on the other hand, are permeated with violent, energetic phenomena in the vast majority of cases leading to obliteration of any form of delicate chemical process that may be carrying on if venturing too near. Galaxies are not abundant with life favorable environments at large, being the zone of habitability generally restricted to a narrow ring and then pocked by forbidden zones where starbirth cradles emit copious amounts of deadly UV and other types of radiation.
There are a couple of good reasons the habitable zone is more or less ring-shaped and restricted. For organic life as we know it to rise, there must be a certain relative abundance of heavy elements like carbon, iron, nitrogen, etc. The outer galactic fringes are relatively thin and primeval in composition, having not had enough time for stars and supernovae to assemble and disperse them from the original hydrogen.
| Here's the follow-up discussion on this article: | View all related messages |
For a complete listing of article comments, questions, and other discussions related to Rodolfo Astrada's Astronomy topic, please visit the Discussions page.