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Simulation Pinpoints the Most Likely Spots For Life In the Milky Way (sciencemag.org)
sciencehabit writes: Our home galaxy isn't as hospitable to life as you might think. Cosmic radiation, supernova explosions, and collisions with small galaxies make much of the Milky Way too hellish for biology. But a detailed new simulation locates quiet and fertile cosmic neighborhoods, including a surprising locale: wispy streams of stars flung far beyond the main body of the Milky Way.
The simulation is probably accurate, the summary article not so much. The simulation answers a rather more nuanced question -- something like "where in the galaxy could Earth;s history possibly have been replayed?" Some places there aren't enough heavy elements, others there are too many supernovae, or near-misses with other stars. Yes, life could evolve in other places, maybe -- on a neutron star, or in the complex magnetic structures in gas clouds near the central black hole or ..... but, although the article suggests it, that is not really the question being answered by the simulation here. Also note that elements much heavier than iron are pretty rare everywhere. Even if you could identify a feasible biochemistry based on iridium or something, there is very unlikely to be enough iridium anywhere for it to evolve.
The research focuses on risks for life linked to cosmic radiation produced by supernovae (and massive stars in general).
This is only one of the risks. In dense regions of galaxies stars perturb the planetary orbits sufficiently frequently to destroy any climate stability. The solar system has been lucky not to have a star nearing the whole solar system in the last 4 billions years, such that even the outer planet orbits are near from circular.
On the other hand it is not difficult for life to screen strong cosmic radiation, such as
in the ocean and deep in the earth crust where most of the biomass exists. So the argument of cosmic radiation killing all life is probably wrong.
Well really bad scifi aside (Dr Who, star trek). A proper look at elemental abundance and chemical properties, something that we do know with a lot of accuracy, non carbon based life forms are a pipe dream. The only proposed element is silicon, and it is shit. Total shit. It simply does not form the range of compounds you need. Does not have any kind of useful solvent. doesn't naturally form anything interesting even in the slightest. And where you have silcon you have carbon. In fact silicon is far more prevalent on earth than carbon, yet life only uses it for shells of some diatoms.
Compare to carbon, where we have giant clouds of interesting organic molecules just floating around in space, that can bond to itself and other elements in an infinite range of ways with and equally diverse range of properties. Water is a *very* good and strong solvent and highly polar. But in a pinch i guess say methane may work as a solvent. But it wouldn't be as good as water.
In short there are very good reasons to believe all life in this universe will be carbon based. But lets not forget, that gives a huge scope for varation from what we see here on earth. With equal certainty all alien life will not be biocompatible with us. If we found anything with DNA, RNA etc, it would be very strong grounds to suspect common origin.
Some people i work with here, are astrobiologist. Honestly carbon is as impressive as a bable fish.
If information wants to be free, why does my internet connection cost so much?
If the premise of the study is to highlight the risks of near stellar neighbors and cluttered neighborhoods, of COURSE the conclusion will be that remote systems are 'safer'.
This is like asking a cancer doctor where it's safest to live, and getting the answer "in a sealed lead-lined vault"....yes, disregarding the need for air, water, and food, and only focusing on the cancer risk, that's probably great.
While we simply don't KNOW the primary drivers of life generation (or the Drake equation would be a lot less hand-waving), and while yes, there's a danger of nearby stellar events, one might also consider:
- our solar system didn't just appear ex nihilo: the heavier elements present suggest that our system formed from nova or supernova remnants. A more cluttered stellar neighborhood is going to have more of such events. While these events would be indeed dangerous (likely exterminatory) for nearby life, life might regrow with such staggering frequency that the stellar scales are outmatched
- radiation: dangerous, sure, but we exist because of mutations. LIFE is based on mutation. (And hell, there's persuasive evidence here on earth that living with higher level of background radioactivity actually increases life span; then again, that could also be a raised average due to selective weeding by same.) A higher-radiation environment is not necessarily inherently bad for life, and may actually accelerate the mutative processes.
These are just a couple of reasons that inner regions might be better. A lot of it is simply guesswork at this point.
-Styopa