demagogue on 16/9/2020 at 03:55
I'm not an astrobiologist by any stretch of the imagination, but I remember reading once that the general opinion seems to be if life can exist on a planet it practically has to exist. So my knee jerk instinct is even earth microbes surviving a probe landing might be associated or probative of indigenous life. The thing that's interested me is that video someone posted recently about sugar & amino acid, etc, chirality (right vs. left handedness created by a kind of biological natural selection) where one punchline was that Mars had the same "biology-based" chirality as the earth has in some molecules that suggested that life among the inner planets was already contaminating one another ostensibly by hitchhikers on asteroids and the like blasted off the surface of one planet by whatever cataclysmic event or another.
Edit: Wait, no, the reason it's probably not earth contamination in this case though is because the Venus signature is for anaerobic life, the kind of thing you only find on earth in incredibly harsh anaerobic environments like deep sea geysers & hydrothermal vents, Yellowstone-like hot springs, around volcanoes and the like, and rarely anywhere else aerobic where it couldn't survive. So it's very unlikely to find itself in a Russian lab and hitchhike it's way to Venus on a space probe. And aerobic & anaerobic life is ... well in the DNA tree of life they'd be separated really early on -- I think I even read once that they may be on completely separate trees altogether, as in independent spontaneous creation and evolution -- so it's not the kind of thing where one would just evolve from the other in a few decades, I don't think.
Pyrian on 16/9/2020 at 05:06
We don't even know how life arose here, nevermind how it'd arise anywhere else.
For the record, though, there are plenty of aerobic microbes that can also survive anaerobically - and some of those eat sulphur.
demagogue on 16/9/2020 at 05:12
But do they make phosphine in high quantities? That's really the key point here, and I'm too dumb to word it properly.
Pyrian on 16/9/2020 at 05:27
I dunno, but I'm like 99.99% certain that none of the described species would remotely survive in Venus' atmosphere anyway.
Fun fact: We know almost nothing about why there's phosphine around certain types of microbes on Earth. I have a suspicion, though, that they produce it as a defense against larger organisms, as it's widely used as a rat poison. But the current hypothesis seems to be that it's just something they give off when they die and decay.
BTW, phosphine can be produced by placing metallic phosphides in acid, and Venus has plenty of acid, so I'm guessing that might have something to do with it.
EDIT: Reading a little more, it seems it's the decay of dead anaerobic microbes that produces phosphine. So, that's interesting. If an anaerobic bacteria were thriving anywhere on Venus, it could potentially lead to the observed effect.
Kolya on 19/9/2020 at 00:22
If we find life on another planet that didn't originate from earth, that means our abiogenesis is nothing special. It's bound to happen a lot then.
Given the size and age of the universe + likelihood of life developing, there should be many advanced civilizations out there. And we should have heard from them. So life on Venus might just be another hint that there's a great filter.
I know there are other explanations of the Fermi paradox. But if you look at this world, then the idea that we'll wipe ourselves out and leave only a dusty dead planet behind, doesn't seem too far fetched. Not making it to a type I civilization could be the great filter.
Nicker on 19/9/2020 at 03:26
As much damage as humans can do to the planet there will be life here until the sun explodes. We talk about having planet killing capability but that's just hubris. We can clearly make a huge fucking mess but the earth has suffered worse before.
Humans are one of the most successful life forms. Even with just basic technology, humans have occupied every continent and ecology from arctic to tropics. I don't think we have the capability to destroy our species, let alone all life. We might never colonize off world but our direct ancestors will persist here until a non-terrestrial threat sterilizes the planet.
Marecki on 21/9/2020 at 13:38
Quote Posted by Kolya
Given the size and age of the universe + likelihood of life developing, there should be many advanced civilizations out there. And we should have heard from them.
I can't for the love of Xenu remember where I've read it or who the author was but one of the contemporary cosmologists has written a short paper arguing that even our universe will have throughout its lifetime seen a significant number of technical civilisations, the chance of two of them actually finding out about one another is very nearly zero. To begin with, the time scales involved are so large that two such civilisations actually existing at the same time is unlikely - and then you start adding all the difficulties associated with the speed-of-light limit for information transfer (or if you assume that there ARE ways of working around this, the fact a civilisation must be even more advanced for being able to do it), that accidental detection outside the period from when a civilisation begins to leak radio frequencies into space till when they have the means to make transmissions more directional (which it will in all likelihood do because not radiating all that energy off-planet is simply cheaper) considerably more difficult, and so on. A depressing but, sadly, logical read.
Sulphur on 21/9/2020 at 13:58
That really is the most common-sensical explanation. Given the size of the universe and the hard limit of the speed of light, even if there were a bunch of advanced civilisations able to travel and look for intelligent life (assuming they'd actively want to, we can't just blanket-ascribe our gregarious motivations to that of the fundamentally alien), the signs of intelligence you're looking for still have to travel at the speed of light. And when did we start sending out actual transmissions as indicators of an advancing civilisation? When we started bouncing radio signals around. Given ~125 years of that, (
https://www.sciencealert.com/humanity-hasn-t-reached-as-far-into-space-as-you-think) here is how far they would have reached into the Milky Way by now.
If there is alien life out there, chances are that it'll take a while to find us. We're an impatient species. The universe works on timescales beyond our individual mortal reckoning.
Gryzemuis on 21/9/2020 at 16:35
[video=youtube;3CKmZUd6Epo]https://www.youtube.com/watch?v=3CKmZUd6Epo[/video]
