Epistemic status: exploring implications, some of which feel wrong.
If SIA is correct, you should update toward the universe being much larger than it naively (i.e. before anthropic considerations) seems, since there are more (expected) copies of you in larger universes.
In fact, we seem to have to update to probability 1 on infinite universes; that’s surprising.
If SIA is correct, you should update toward there being more alien civilizations than it naively seems, since in possible-universes where more aliens appear, more (expected) copies of human civilization appear.
The complication is that more alien civilizations makes it more likely that an alien causes you to never have existed, e.g. by colonizing the solar system billions of years ago. So a corollary is that you should update toward human-level civilizations being less likely to be “loud” or tending to affect fewer alien civilizations or something than it naively seems.
So SIA predicts that there were few aliens in the early universe and many aliens around now.
So SIA predicts that human-level civilizations (more precisely, I think: civilizations whose existence is correlated with your existence) tend not to noticeably affect many others (whether due to their capabilities, motives, or existential catastrophes).
So SIA retrodicts there being a speed limit (the speed of light) and moreover predicts that noticeable-influence-propagation in fact tends to be even slower.
If SIA is correct, you should update toward the proposition that you live in a simulation, relative to your naive credence.
Because there could be lots more (expected) copies of you in simulations.
Because that can explain why you appear to exist billions of years after billions of alien civilizations could have reached Earth.
Which of them feel wrong to you? I agree with all them other than 3b, which I’m unsure about—I think it this comment does a good job at unpacking things.
2a is Katja Grace’s Doomsday argument. I think 2aii and 2aiii depends on whether we’re allowing simulations; if faster expansion speed (either the cosmic speed limit or engineering limit on expansion) meant more ancestor simulations then this could cancel out the fact that faster expanding civilizations prevent more alien civilizations coming in to existence.
I deeply sympathize with the presumptuous philosopher but 1a feels weird.
2a was meant to be conditional on non-simulation.
Actually putting numbers on 2a (I have a post on this coming soon), the anthropic update seems to say (conditional on non-simulation) there’s almost certainly lots of aliens all of which are quiet, which feels really surprising.
To clarify what I meant on 3b: maybe “you live in a simulation” can explain why the universe looks old better than “uh, I guess all of the aliens were quiet” can.
I deeply sympathize with the presumptuous philosopher but 1a feels weird.
Yep! I have the same intuition
Actually putting numbers on 2a (I have a post on this coming soon), the anthropic update seems to say (conditional on non-simulation) there’s almost certainly lots of aliens all of which are quiet, which feels really surprising.
Propositions on SIA
Epistemic status: exploring implications, some of which feel wrong.
If SIA is correct, you should update toward the universe being much larger than it naively (i.e. before anthropic considerations) seems, since there are more (expected) copies of you in larger universes.
In fact, we seem to have to update to probability 1 on infinite universes; that’s surprising.
If SIA is correct, you should update toward there being more alien civilizations than it naively seems, since in possible-universes where more aliens appear, more (expected) copies of human civilization appear.
The complication is that more alien civilizations makes it more likely that an alien causes you to never have existed, e.g. by colonizing the solar system billions of years ago. So a corollary is that you should update toward human-level civilizations being less likely to be “loud” or tending to affect fewer alien civilizations or something than it naively seems.
So SIA predicts that there were few aliens in the early universe and many aliens around now.
So SIA predicts that human-level civilizations (more precisely, I think: civilizations whose existence is correlated with your existence) tend not to noticeably affect many others (whether due to their capabilities, motives, or existential catastrophes).
So SIA retrodicts there being a speed limit (the speed of light) and moreover predicts that noticeable-influence-propagation in fact tends to be even slower.
If SIA is correct, you should update toward the proposition that you live in a simulation, relative to your naive credence.
Because there could be lots more (expected) copies of you in simulations.
Because that can explain why you appear to exist billions of years after billions of alien civilizations could have reached Earth.
Which of them feel wrong to you? I agree with all them other than 3b, which I’m unsure about—I think it this comment does a good job at unpacking things.
2a is Katja Grace’s Doomsday argument. I think 2aii and 2aiii depends on whether we’re allowing simulations; if faster expansion speed (either the cosmic speed limit or engineering limit on expansion) meant more ancestor simulations then this could cancel out the fact that faster expanding civilizations prevent more alien civilizations coming in to existence.
I deeply sympathize with the presumptuous philosopher but 1a feels weird.
2a was meant to be conditional on non-simulation.
Actually putting numbers on 2a (I have a post on this coming soon), the anthropic update seems to say (conditional on non-simulation) there’s almost certainly lots of aliens all of which are quiet, which feels really surprising.
To clarify what I meant on 3b: maybe “you live in a simulation” can explain why the universe looks old better than “uh, I guess all of the aliens were quiet” can.
Yep! I have the same intuition
Nice! I look forward to seeing this. I did similar analysis—both considering SIA + no simulations and SIA + simulations in my work on grabby aliens