The fermi paradox makes sense within "just" the milky way, so the size of the entire observable universe or the speed it expands doesn't seem relevant.
You mean the collection of stars that's 100,000 light years across?
How long has life existed on Earth?
Of that time, how long has life on Earth been generating signals that could be detected elsewhere?
How much of the Milky Way has recieved those signals by now?
50,000 light year radius squared (let's favor your argument by calculating the milky way disc as 2D area) = 2.5 billion square light years
Area our signals could have reached in the milky way over the past century of broadcasting: ~10,000 square light years
So the intelligent life here and now, only a fraction of the life that's existed (much of which has had some degree of intelligence) has only reached about 0.0004% of the Milky Way by now, to say nothing for the drop of signal to CMB noise as it propagates.
There's extensive discussion about the fine tuning argument for Earth regarding our gravity/propulsion to even be able to enter outer space, a threshold other intelligent life on a different planet may never be able to cross.
Fermi's Paradox is silly when you dive into the nuances.
>Of that time, how long has life on Earth been generating signals that could be detected elsewhere?
Earth has a magnetic core and there are million things that generate EM radiation. Earth would have started radiating the moment it was created. It has a magnetic core as well. Now as per if somebody could read it 100000 light years away? Well the Sun was way hotter then and it would have obscured anybody looking this way.
Why aren't we seeing signs now, well maybe the signals are on their way but it may take another 20000 years to get them. I hope there is somebody here to receive and respond back.
Earth is young in the milky way, 4.5 billion years, compared to 13+ billion year galaxy. There's lots of stars in the milky way that are billions of years older. You can limit your question to "just" those stars and ask, why didn't any of them produce life that expanded all over the galaxy (or why can't we see it if they did?)
But what if he was overestimating the the frequency of intelligent life emerging? Yes, it's quite possible that there are many simple lifeforms spread throughout the galaxy, but what if we're the only intelligent life that's emerged in the galaxy? Sure there could be intelligent life elsewhere in the universe but we'd never find know about it because the distance between galaxies is so large.
> But what if he was overestimating the the frequency of intelligent life emerging?
I don't understand there to be any such estimation at all. The paradox is that ONE of the pieces of the equation has to be so improbable that it basically doesn't happen. That's absolutely allowed to be the piece that is nearly impossible to happen.
There are hundreds of billions of galaxies in the observable universe. Imagine if most of them were teaming with interstellar civilizations, but we happened to be stuck in one of the few where such a thing was rare.
You mean the collection of stars that's 100,000 light years across?
How long has life existed on Earth?
Of that time, how long has life on Earth been generating signals that could be detected elsewhere?
How much of the Milky Way has recieved those signals by now?
50,000 light year radius squared (let's favor your argument by calculating the milky way disc as 2D area) = 2.5 billion square light years
Area our signals could have reached in the milky way over the past century of broadcasting: ~10,000 square light years
So the intelligent life here and now, only a fraction of the life that's existed (much of which has had some degree of intelligence) has only reached about 0.0004% of the Milky Way by now, to say nothing for the drop of signal to CMB noise as it propagates.
There's extensive discussion about the fine tuning argument for Earth regarding our gravity/propulsion to even be able to enter outer space, a threshold other intelligent life on a different planet may never be able to cross.
Fermi's Paradox is silly when you dive into the nuances.