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You have to dig down to the 2nd page of comments on his previous post about these articles to learn that when he says "multiverse" he isn't referring to the man

You have to dig down to the 2nd page of comments on his previous post about these articles to learn that when he says "multiverse" he isn't referring to the many worlds interpretation of QM: http://www.math.columbia.edu/~woit/wordpress/?p=9027&cpage=1#comment-224637 http://www.math.columbia.edu/~woit/wordpress/?p=9027&cpage=1... It's very confusing and I can't help but assume he doesn't mind misleading people.

conistonwater 10y ago
Is it confusing? Is there a specific reason to think that the multiverse is related to the many worlds interpretation? I didn't know people thought they were the same thing.
- akvadrako 10y ago
  From https://en.wikipedia.org/wiki/Many-worlds_interpretation https://en.wikipedia.org/wiki/Many-worlds_interpretation > MWI is one of many multiverse hypotheses in physics and philosophy.
  - conistonwater 10y ago
    I see your point, but Wikipedia isn't super reliable on the more unsettled parts of theoretical physics. For example, a cursory search gives me https://www.technologyreview.com/s/424073/multiverse-many-worlds-say-physicists/ https://www.technologyreview.com/s/424073/multiverse-many-wo..., but while I can't judge https://arxiv.org/abs/1105.3796 https://arxiv.org/abs/1105.3796 on my own, it does appear the idea is new, and for something as new, and as vaguely defined as the multiverse (MWI itself is quite old), I probably should ask for more than a Wikipedia summary. I mean, it's fine by me if there's some kind of disagreement within physics, but to assume they are the same thing would require more, no?
  - musgravepeter 10y ago
    I find that a bit mis-leading. While IAAP, this is not my area. My understanding is the at the big bang there are a HUGE number of universes (the Multiverse) that are causally dis-connected, with different coupling constants for the forces and very different physics. Within our universe we have our physics, which includes QM, and one way of viewing QM is the many-worlds view.
musgravepeter 10y ago
I don't think there is any intent to be misleading. I agree that reading this blog by itself is jumping into the middle of the conversation, and terms are not explained. The multi-verse has been discussed there for years, so occasional readers may assume it is the many-worlds stuff, but it is a very different beast.
yk 10y ago
"Multiverse" can have several different meanings, causally disconnected regions of spacetime in General Relativity, landscape ideas in String theory or all the worlds of the many worlds interpretation. However, since non of them so far produced actual, that is observable, physics, it is probably not important to distinguish between these meanings in a popular discussion.

conistonwater 10y ago

Is it confusing? Is there a specific reason to think that the multiverse is related to the many worlds interpretation? I didn't know people thought they were the same thing.

akvadrako 10y ago
From https://en.wikipedia.org/wiki/Many-worlds_interpretation https://en.wikipedia.org/wiki/Many-worlds_interpretation > MWI is one of many multiverse hypotheses in physics and philosophy.
- conistonwater 10y ago
  I see your point, but Wikipedia isn't super reliable on the more unsettled parts of theoretical physics. For example, a cursory search gives me https://www.technologyreview.com/s/424073/multiverse-many-worlds-say-physicists/ https://www.technologyreview.com/s/424073/multiverse-many-wo..., but while I can't judge https://arxiv.org/abs/1105.3796 https://arxiv.org/abs/1105.3796 on my own, it does appear the idea is new, and for something as new, and as vaguely defined as the multiverse (MWI itself is quite old), I probably should ask for more than a Wikipedia summary. I mean, it's fine by me if there's some kind of disagreement within physics, but to assume they are the same thing would require more, no?
- musgravepeter 10y ago
  I find that a bit mis-leading. While IAAP, this is not my area. My understanding is the at the big bang there are a HUGE number of universes (the Multiverse) that are causally dis-connected, with different coupling constants for the forces and very different physics. Within our universe we have our physics, which includes QM, and one way of viewing QM is the many-worlds view.

musgravepeter 10y ago

I don't think there is any intent to be misleading. I agree that reading this blog by itself is jumping into the middle of the conversation, and terms are not explained. The multi-verse has been discussed there for years, so occasional readers may assume it is the many-worlds stuff, but it is a very different beast.

yk 10y ago

"Multiverse" can have several different meanings, causally disconnected regions of spacetime in General Relativity, landscape ideas in String theory or all the worlds of the many worlds interpretation. However, since non of them so far produced actual, that is observable, physics, it is probably not important to distinguish between these meanings in a popular discussion.