- #106
DennisN
Gold Member
2023 Award
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Hi, I just read some things I thought I might share in this thread.
Frank Wilczek's paper "Multiversality" has caused some debate (abstract, paper):
After reading and thinking about this, I'm starting to realize that one of the main problems (perhaps the main problem at the moment) seems to be that people can't even agree on what multiverse means. So, in my view, the multiverse can't be considered a hypothesis - it is a set of hypotheses. So we've got ourselves a multitude of multiverses, oh dear.
I'm trying to sum up the main ideas as I understand them; multiverse can be
1 and 2 are versions that can not interact, so we will not get any observational support from them. 3 and 4 are versions that can interact, so this will boil down to what we mean by same/different physics - and - how we define a universe. Should a universe be defined as
Frank Wilczek's paper "Multiversality" has caused some debate (abstract, paper):
- http://www.sciencenews.org/view/generic/id/352421/description/Belief_in_multiverse_requires_exceptional_vision (Tom Siegfried comments on Wilczek)
- "Belief in multiple universes requires exceptional vision. So does belief in telepathy." * (Ashutosh Jogalekar comments on Siegfried)
- "Belief in multiverse requires exceptional vision" (Peter Woit comments on Siegfried)
- "Multiversing around" (Sabine Hossenfelder's blog post, mentioned in the Woit comment thread)
After reading and thinking about this, I'm starting to realize that one of the main problems (perhaps the main problem at the moment) seems to be that people can't even agree on what multiverse means. So, in my view, the multiverse can't be considered a hypothesis - it is a set of hypotheses. So we've got ourselves a multitude of multiverses, oh dear.
I'm trying to sum up the main ideas as I understand them; multiverse can be
- a set of universes that have different physics, and can not interact with each other
- a set of universes that have the same physics, and can not interact with each other
- a set of universes that have different physics, and can interact with each other
- a set of universes that have the same physics, and can interact with each other
1 and 2 are versions that can not interact, so we will not get any observational support from them. 3 and 4 are versions that can interact, so this will boil down to what we mean by same/different physics - and - how we define a universe. Should a universe be defined as
- everything that obeys the same set of physical laws and physical constants
- everything that belongs to the same spacetime continuum
- or both 1 and 2?