I’m not going to give a very full explanation here, but since nobody else has explained at all [EDIT: actually apparently Matt explained correctly below, just not as a top-level answer] I’ll at least give some short notes.
Most people on LW absorbed the usage you describe via osmosis, and probably don’t understand the accurate underlying interpretation.
In particular, in the context of usage like e.g. “the worlds where the alignment problem is relatively easy vs the worlds where the alignment problem is really hard”, the “multiple-worlds” aspect has approximately nothing to do with the many-worlds interpretation of quantum mechanics.
Instead, the “worlds” in question are best interpreted as outcomes of a probabilistic world model.
For example, suppose we take a Solomonoff-style view: we imagine the world as having been generated by some program, but we don’t know which program a priori. We have a prior which assigns a probability to each program, and we update on what the “true” generator-program might be as we see new data.
Then, in that Solomonoff-style view, we can view each program as a “possible world we could be in”, in a Bayesian sense. That’s roughly the way that LWers typically use the phrase.
So the relevant “multiverse” is the set of “worlds” compatible with our information in a Bayesian sense, roughly speaking. (I say “roughly speaking” because really humans also use e.g. logical uncertainty and other things technically not captured by Bayesianism, but in a way that preserves the core concepts of the explanation given above.)
I’m not going to give a very full explanation here, but since nobody else has explained at all [EDIT: actually apparently Matt explained correctly below, just not as a top-level answer] I’ll at least give some short notes.
Most people on LW absorbed the usage you describe via osmosis, and probably don’t understand the accurate underlying interpretation.
In particular, in the context of usage like e.g. “the worlds where the alignment problem is relatively easy vs the worlds where the alignment problem is really hard”, the “multiple-worlds” aspect has approximately nothing to do with the many-worlds interpretation of quantum mechanics.
Instead, the “worlds” in question are best interpreted as outcomes of a probabilistic world model.
For example, suppose we take a Solomonoff-style view: we imagine the world as having been generated by some program, but we don’t know which program a priori. We have a prior which assigns a probability to each program, and we update on what the “true” generator-program might be as we see new data.
Then, in that Solomonoff-style view, we can view each program as a “possible world we could be in”, in a Bayesian sense. That’s roughly the way that LWers typically use the phrase.
So the relevant “multiverse” is the set of “worlds” compatible with our information in a Bayesian sense, roughly speaking. (I say “roughly speaking” because really humans also use e.g. logical uncertainty and other things technically not captured by Bayesianism, but in a way that preserves the core concepts of the explanation given above.)
Thanks!