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submitted 1 day ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] bstix@feddit.dk 9 points 23 hours ago

There's also a theory that we're too late, and that our existence is like the remaining microbes in a puddle of water in a desert.

The universe used to be lukewarm with conditions for life to exist everywhere, until it expanded and started cooling.

On a positive note, this could also mean that life lies dormant everywhere just waiting for the right conditions, so that anywhere that has the right conditions also has life.

[-] CatAssTrophy@safest.space 2 points 1 hour ago* (last edited 1 hour ago)

IMO it is more likely that we're more early than late (though an argument can be made that there's a sweet spot in between the two).

When the universe was lukewarm, I don't think the conditions existed for life to exist everywhere because there hadn't been enough stellar nucleosynthesis for there to be astrophysical metals (i.e. anything heavier than helium, with the possible exception of lithium at a very low concentration). Not much useful chemistry can be done with just hydrogen and hellium.

Additionally, planetary systems surrounding earlier generation stars are much rarer than those of the same class at the Sun. Planets that formed around earlier generation stars did not have access to a high enough variety of astrophysical metals to create the complex chemistries that chemical life requires and their host stars were likely too short lived to make advanced evolution possible, even if they had planetary systems.

Planets formed around stars younger than/with higher metallicity are much more likely to be gas giants that would have their own set of issues with the evolution of chemical life (e.g. much lower carbon presence).

The "optimal" time frame for the development of complex life on a planet would theoretically vary by its position compared to the galactic bulge its star formed in, i.e. earlier closer to the galactic center and later further out. Being closer to galactic core makes for a higher chance of being blasted by a supernova or other extremely high energy astronomical event, making for a higher chance of mass extinctions.

If most stars/planets formed much before our sun lacked sufficiently complex chemistry, and those formed much after it lack sufficient carbon and provide a host of gravitational/pressure issues that would inhibit technological development even if evolutionary life did arise, it seems likely that most planets potentially with advanced civilizations are of similar ages. With some slightly older examples nearer the galactic core and some slightly younger ones deeper into the spiral arms.