This seems to leave out don't fail steps. That is steps where you need to avoid having some low (per year) probability event occur. For instance avoid having a civilization destroying nuclear war or the like. Depending on how low that probability is that could easily be the even better solution to 5.
The emergence of the Eukaryote by Hydrogen Hypothesis (Nick Lane, mitochondria) is likely the "filter" inhibiting the rise of intelligent life in the universe.
Don't we think it took longer to go from Eukaryotes to multicellular life than from prokaryotes to eukaryotes? And it certainly took far longer to go from Eukaryotes to technologically capable intelligence along with a body plan able to take advantage of it. So why wouldn't you identify one of those things as the more likely filter?
The scarcity of grabby aliens might also be explained by the anthropic principle: if there were any grabby aliens nearby, we wouldn't be here. So we may have simply gotten very, very lucky to evolve in a part of the universe without them.
My layman's sense has always been that there are no hard steps, just that things develop as they do along multiple axes (geological, chemical, environmental, astronomical, etc) and that all of these have to line up perfectly by accident for anything interesting to happen. So there is no hard step or 'Great Filter' really. The next step is always easy if conditions are right. It's just improbable that conditions will be right when the next step becomes available and this is true for every step, leaving none much harder than any other intrinsically. Like I said, I'm a layman so this might be easily disproven.
There are a significant number of people who do not see your #4 as a fact. I like it better when you properly describe it as an assumption for your model. I believe it was Dr. Wright who made the comment that we make observations of the Universe which allow us to say "Aliens don't do that." It's not everything, but it's interesting to be able to say that out of the nearest 100,000 galaxies, there don't seem to be any with 90% of their starlight is converted to infrared.
I understand that you do not want to model unobserved present aliens, but you have given it a decent shot over the past 5 years and I encourage you to keep doing so. My hunch is that it will be more productive than extrapolating 20th century technology across 10 orders of magnitude. Because it doesn't seem like aliens do that.
"4. Our empty universe says the chance of grabby life per planet must be crazy low." Grabby is defined so as to be visible, and we don't see them for a long distance. Therefore the rate at which they appear must be very low. How is that speculative or an assumption?
Also, the distinction between try-try steps and enable steps seems a bit blurry. I mean is waiting for Oxygen an enable step (you are waiting for something to change) or a try-try step (wait for some organism to evolve that produces oxygen at scale).
Ok, I get the distinction if you demand that the thing you are waiting for is roughly constant time but now that's a wait steps not an enable step. Am I missing something?
This seems to leave out don't fail steps. That is steps where you need to avoid having some low (per year) probability event occur. For instance avoid having a civilization destroying nuclear war or the like. Depending on how low that probability is that could easily be the even better solution to 5.
The emergence of the Eukaryote by Hydrogen Hypothesis (Nick Lane, mitochondria) is likely the "filter" inhibiting the rise of intelligent life in the universe.
Don't we think it took longer to go from Eukaryotes to multicellular life than from prokaryotes to eukaryotes? And it certainly took far longer to go from Eukaryotes to technologically capable intelligence along with a body plan able to take advantage of it. So why wouldn't you identify one of those things as the more likely filter?
The emergence of the Eukaryote occurred only once in our history. This suggests it being a genuinely rare event.
Seems at least as plausible that intelligence simply requires a threshold in organism size, evolution increases size at an almost constant rate (in log time), but almost all planets simply fail to remain habitable long enough to allow large enough beings to evolve https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/abs/longevity-of-habitable-planets-and-the-development-of-intelligent-life/20433F5178D6B2C7CDD2E8E1BDE292DF
The scarcity of grabby aliens might also be explained by the anthropic principle: if there were any grabby aliens nearby, we wouldn't be here. So we may have simply gotten very, very lucky to evolve in a part of the universe without them.
I lack some context. Is “Grabby is defined so as to be visible” the full definition?
You could follow the link: http://grabbyaliens.com
My layman's sense has always been that there are no hard steps, just that things develop as they do along multiple axes (geological, chemical, environmental, astronomical, etc) and that all of these have to line up perfectly by accident for anything interesting to happen. So there is no hard step or 'Great Filter' really. The next step is always easy if conditions are right. It's just improbable that conditions will be right when the next step becomes available and this is true for every step, leaving none much harder than any other intrinsically. Like I said, I'm a layman so this might be easily disproven.
What’s your opinion on Fermi’s paradox?
There are a significant number of people who do not see your #4 as a fact. I like it better when you properly describe it as an assumption for your model. I believe it was Dr. Wright who made the comment that we make observations of the Universe which allow us to say "Aliens don't do that." It's not everything, but it's interesting to be able to say that out of the nearest 100,000 galaxies, there don't seem to be any with 90% of their starlight is converted to infrared.
I understand that you do not want to model unobserved present aliens, but you have given it a decent shot over the past 5 years and I encourage you to keep doing so. My hunch is that it will be more productive than extrapolating 20th century technology across 10 orders of magnitude. Because it doesn't seem like aliens do that.
"4. Our empty universe says the chance of grabby life per planet must be crazy low." Grabby is defined so as to be visible, and we don't see them for a long distance. Therefore the rate at which they appear must be very low. How is that speculative or an assumption?
Because the universe is quite obviously not empty. Whether it's full of aliens or not, well I don't have a telescope good enough to look.
Also, the distinction between try-try steps and enable steps seems a bit blurry. I mean is waiting for Oxygen an enable step (you are waiting for something to change) or a try-try step (wait for some organism to evolve that produces oxygen at scale).
Ok, I get the distinction if you demand that the thing you are waiting for is roughly constant time but now that's a wait steps not an enable step. Am I missing something?