why the universe isn't built for life
The universe is not "made for life" as is often said. Life just, uh, finds a way.
Illustration from Elegy For A Dead World
It seems that whenever we look at the universe, we find another place where life could exist or where all the ingredients for life could be abundant. We know that water ice, sugar molecules and amino acids are out there. We've even found a world that might have deep, liquid oceans just 20.5 light years away and we've only started looking at other solar systems. All this is making some people wonder whether our universe is built for life on the covers of some popular science magazines. But do they have the whole question backwards? Wouldn't it be more likely that life is evolving for this universe and not the other way around?
Natural selection dictates that only the organisms that can survive long enough to pass on their genes or whatever hereditary traits an alien might use, will be the only ones left. A fact that often gets ignored in these existential questions is just how many extinctions take place on a daily basis. More than 99% of all living things which ever lived on Earth alone, are now long gone. Many weren't around long enough to branch off into new lineages and have descendants.
Even today, countless organisms are going extinct and we somehow manage to overlook this systematic death, gaze at the stars and ask whether the whole universe is built to encourage living things. Isn't it odd that our incredibly hospitable world managed to witness nearly all life that ever spawned on it die while we're all busy discussing how suspiciously alive the universe must be?
Life, as we understand it today, is built on chemical reactions which help give rise to active, reproducing creatures. The environment of whatever world the living things in question call home will cull anything that can't survive its rigors in a very short time. The survivors will thrive and spread, changing and diversifying as they do, at least until their environment changes and those unable to cope with the shift in the conditions will be culled again.
If the universe is crawling with life, these are survivors, outcomes of countless evolutionary experiments on trillions upon trillions of worlds. The environment in which they live aren't uncannily suited to life, much less to them. These organisms just happened to persevere.
