They are implying the great filter is actually the current step (advancing towards colonization explosion). The next step would be colonization explosion (aka colonizing space or other planets), but that could be cut short due to civilization eradicating itself. This is thought to happen either via climate change, nuclear war, or artificial intelligence wiping us out.
I personally am not a fan of the AI destruction theory because I'd expect AI to replace us and expand into the solar system. If it got to the point where it could kill all organic life, then I'd bet it's unlikely for AI to die off with us as well. Just my opinion though...
I think it’s plausible an AI could be able to wipe out humanity before it is able to secure its own indefinite existence. So there’s a scenario in which is wipes out all Earthly life/intelligence.
It could be as simple as a microbe that eats an elementary molecule in our bodies that is so foreign our immune system can't spot it. No need to target us directly.
Quite likely; we’re pretty closely related to those, and multiple species viruses show up all the time. It would be more surprising, though, to find a virus which was pathogenic to, say, both us and archaea, and any Venus life is probably more different to us than archaea are.
A bacteria analogue is possibly more of a risk; those can be less fussy.
We get infected by bird viruses all the time, and they're not even mammals. A virus that evolved in mammals infecting different types of mammals is very likely.
Toby Ord's book The Precipice does a good job evaluating them. Top contenders are AI, bioengineered viruses, nuclear war, and climate change, with natural disasters that we fail to avert/mitigate, like asteroid impact or supervolcano eruption as a distant aslo-ran.
That could be it, but it also could be just that all the low hanging fruit is all taken. Like Newton is a genius for coming up with an equation for making delta-x really small, I could have come up with that and I don't even dabble in alchemy.
The space shuttle was meant to be reusable - it was built 40 years ago in 1980.
I'm not saying there is no new tech, it just all seems incremental, not revolutionary. When I was younger every day it seemed there was something new. Today, not so much.
You might just need to pay attention to the right things. Genetics is making steady progress and promises to revolutionize almost everything. Machine learning seems to be applicable to most things and if only suffering from a lack of optimization. The road to space is opening and we’re about to find out just how many new technologies will be made possible with unlimited solar power, microgravity, and untapped resources.
