Remember Venus is a Earth like planet and even relatively close to the habitable zone (depending on your definitions and error bars). Just because it's a planet like Earth, doesn't mean it would support life.
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.
I mean, isn't the entire concept of the Fermi paradox that given the universe is so large and old, it seems surprising that we see no signs of aliens anywhere, and therefore some explanation must exist for why we have not? That's more focused on intelligent life than extraterrestrial life of any sort I suppose, but given it's even named a paradox in the first place, someone must find it surprising
In addition to the other helpful replies, one of the major flaws of the Fermi paradox is that it fails to account for the vastness of time. Our failure to observe spacefaring intelligent life is the metaphorical equivalent of a baby born at some point in human history somewhere on earth, opening it's eyes only long enough to blink, and not observing Cher. It doesn't mean that Cher doesn't exist, or even that Cher should be observable given that humanity is so large and old.
My argument of that is that we've only just started looking in a massive, massive, massive universe. Like, the other day. The big bang theory is less than a hundred years old and we only just discovered cosmic background radiation in 1964
We JUST started looking and we probably have no idea what we are looking for or at.
Also, these earth like planets are a fucking guess, a giant maybe. They make their host star, which we make assumptions of about their size, make a tiny hardly perceptible dip in light and we measure the wavelengts that were filtered out.
The more I learn about how this science is done, the more it all just looks like a big fucking maybe that someone spouts so confidently as fact. Like, the track record for fact is pretty thin in science.
I guess people tend to look to astronomers for information about space, while the Fermi paradox probably borders more on philosophy than on astronomy. And in a lot of people minds philosophers are not real scientists, unlike astronomers.
It could just be that they're just so far that we're looking at these planets millions/billion of years in the past, meaning there may may be life there but we can't see it yet.
Earth looked pretty icy when it was "snowball Earth" and early Earth's surface was full of molten rocks.
The Milky Way galaxy is "only" 100.000 light years across, so any planets we see around stars in our galaxy we would only see about at most 100.000 years in the past. So it would be very unlikely there would be detectable life now, where there wasn't 100.000 years ago. And even if there were, it wouldn't be complex life.
The most distant exoplanet we've found to date is 27.710 light years away, so we see that planet as it was 27.710 years ago. We've had humans running round for at least a 100.000 year on Earth, so if there are any aliens on that planet we would see them.
It's worth mentioning that we can't "see" any exoplanets at all. We know they are there by the gravitational lensing that occurs when a planet passes in front of the star it orbits. Once we calculate the position and orbit, we can track the planets and listen for any radio waves or radiation that would indicate life. We are also getting better as guessing the chemical composition of the planets, but it's not like we can scan the surface for plants and animals.
Yeah I didn't know we were mostly looking at planets in the Milky Way, but it makes sense. Rocky planets are very tiny compared to other stuff in the universe so it's gotta be hard detecting them millions of light years out.