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"Earth-like"
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this post was submitted on 26 Nov 2023
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I wouldn't be particularly surprised to find out Venus has life. Complex life, probably not, but something like the life we have around undersea volcanic vents seems more than possible.
I really don't see how. Yes there is life at undersea volcanic vents on Earth, but they don't live like in the vent itself. It's where the temperature gets lower there is life.
As far as I know nothing can survive boiling temperatures for long and Venus has been way above boiling for millions of years. There are extremophiles that survive a little above boiling, but 400+ degrees I really don't see how.
There is a chance in the atmosphere where there are parts with reasonable temperatures and pressures. But there is also a lot of acids floating around, which is sorta incompatible with life. If some photosynthetic life was present in the atmosphere, floating around and living on sunlight, we would have seen it by now. There would be seasonal blooms, similar to plankton in the oceans on Earth.
It's cool to think about and I remember reading old sci-fi with Venus as a forest planet, since it's so like Earth in a lot of ways. But in reality it's dead dead.
Same for Mars I feel like. We might find indications life once lived there, which would be a huge deal. But as far as actual current life, I think chances are slim to none.
The mean surface temperature of Venus is only 464C.
But, with 93x the atmospheric pressure of earth, water boils at around 300C.
So…what is it that makes it difficult to thrive beyond 100C? Is it strictly the temperature, or is it the properties of water at that temperature? If it’s the latter, I wouldn’t be so surprised.
Also keep in mind that photosynthesis was a genetic accident that just happened to work really, really well, and the ability to process sunlight directly into energy was what allowed microorganisms to move away from thermal vents.
That same genetic accident could play out in a different world. Or a different genetic accident that’s more suited to their environment. Or no genetic accident at all, and life never moves past small, very secluded regions.
It's the temperature, a lot of chemistry doesn't work at higher temperatures because everything is too unstable. There is simply too much energy messing things up. This is why having a surface temperature that allows for liquid water to be present is such a good indicator for life. A lot of chemistry for life as we know it works at liquid water temperatures and water does play a big part as well.
The pressure would be less of an issue, there is plenty of life on Earth that thrives at huge pressures.
I'm pretty sure life on Earth evolved at the surface (or even in the atmosphere, it is thought lightning plays a part) and only adapted to use the vents later on. I'm not sure life could get started at those volcanic vents.
I think their point was that the pressure "balances out" the temperature - so that enough of these chemistry does remain stable even though the temperature is high. For example - the water remains liquid because of the pressure, so that's one requirement for life that gets fulfilled.
Life finds a way...
Pretty sure there are though
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6476344/
The article you post specifically states the observed lifeforms to be limited to 130 degrees C (and even then they don't live long) with a theoretical max of 150 degrees C. Life as we know it (in all its wonderous forms) cannot exist above that temperature. The processes needed simply can't work and the structures can't exist. Maybe there's some lifeform that uses a neat trick to remain alive trough a short stint of say 200 degrees, but that's a far cry from living at 400+ all the time. Extremophiles usually can't live at boiling temperatures for long, they can only tolerate it for short durations, living most of their lives in less than 100 degrees. Which is still really cool, since most lifeforms die at half that temperature.
Now there could be some form of exotic stuff that may be called life, but that's well into speculation and science fiction.
Personally I'm not convinced by extremophiles, yes they can exist in very harsh environments, but they are always specialized forms of life that evolved in simpler conditions. It's not clear whether life can make the jump from mild to extreme or even start out in an extreme environment. My bet is that's not possible. So that could mean stuff on Mars, since we know it was probably very mild in the past and extremophiles may have persisted that can live in the current environment since that time (unlikely, but possible). But probably not on places like Venus where as far as we know it's been super hot for ages now, too long for anything to survive if it was even habitable to start with.