The MWI doesn’t necessarily mean that every possible event, however unlikely, “exists”. As long as we don’t know where the Born rule comes from, we just don’t know.
Worlds in MWI aren’t discrete and completely isolated from each others, they are more inkstains on paper, not clearly delimited blobs, where “counting the blobs” can’t be defined in non ambiguous way. There are hytpothesis (sometimes called “mangled world”) that would make worlds of too small probability (inkstains not thick enough) unstable and “contaged” from “nearby” high probability world.
But the main issue is that as long as we don’t have a formal derivation of the Born rule inside MWI, we can’t make any formal analysis of stuff like QI. We are left with at best semi-intuitive analysis of what “MWI” does mean, but QI being highly counter-intuitive, a semi-intuitive analysis breaks down there.
We don’t know how to derive the Born Rule in MWI, or even if it is possible to derive it. However, uncertainty goes both ways, and that’s definitely no way to dismiss QI. Is there any actual reason to suspect that MWI is true, but QI isn’t (apart from, maybe, mangled worlds)?
Because I lack the necessary mathematical understanding, I’ve never really understood what mangled worlds actually says. What does it mean when you say that a world’s probability is “too small”, and does mangled worlds say that these worlds never actually come into existence, or just that they eventually disappear?
The MWI doesn’t necessarily mean that every possible event, however unlikely, “exists”. As long as we don’t know where the Born rule comes from, we just don’t know.
Worlds in MWI aren’t discrete and completely isolated from each others, they are more inkstains on paper, not clearly delimited blobs, where “counting the blobs” can’t be defined in non ambiguous way. There are hytpothesis (sometimes called “mangled world”) that would make worlds of too small probability (inkstains not thick enough) unstable and “contaged” from “nearby” high probability world.
But the main issue is that as long as we don’t have a formal derivation of the Born rule inside MWI, we can’t make any formal analysis of stuff like QI. We are left with at best semi-intuitive analysis of what “MWI” does mean, but QI being highly counter-intuitive, a semi-intuitive analysis breaks down there.
We don’t know how to derive the Born Rule in MWI, or even if it is possible to derive it. However, uncertainty goes both ways, and that’s definitely no way to dismiss QI. Is there any actual reason to suspect that MWI is true, but QI isn’t (apart from, maybe, mangled worlds)?
Because I lack the necessary mathematical understanding, I’ve never really understood what mangled worlds actually says. What does it mean when you say that a world’s probability is “too small”, and does mangled worlds say that these worlds never actually come into existence, or just that they eventually disappear?
Also, is there something wrong with Sean Carroll’s attempt?
It works only in a very limited setting. Here’s my analysis.