Yesterday, the media buzzed with the revelation that Stephen Hawking had completed a paper two weeks before his death. This paper supposedly contains some breathtaking insight.
About the multiverse (parallel universes).
The paper is based on an old idea by Stephen Hawking and Jim Hartle called the “no-boundary” proposal. In the paper, the authors employ a new method to do calculations that were not previously possible. Specifically, they calculate which type of universes a multiverse would contain if this theory was correct. The main conclusion seems to be that our universe is compatible with the idea, and also that this particular multiverse which they deal with is not as large as the usual multiverse one gets from eternal inflation.
It’s not entirely uninteresting if you are into multiverse ideas, because then you need this information to calculate the probability of our universe. But it is also a very theoretical paper that does not say anything about observational consequences.
Hawking’s recent death robbed the multiverse of key aspect, Big Cool. Another rock star scientist will need to get behind it to keep it lodged in the popular imagination such that a science writeranjust assume that everyone believes it is true and go on to psit some theory about, say, identical you’s or Boltzmann brains.
Theoretical physicist have proposed some thousand ideas for what might have happened in the early universe. There are big bangs and big bounces and brane collisions and string cosmologies and loop cosmologies and all kinds of weird fields that might or might not have done this or that. All of this is pure speculation, none of it is supported by evidence. The Hartle-Hawking proposal is one of these speculations. More.
Hossenfelder is doubtless right, but she is taking a lot of risks, one suspects, in so openly supporting reason, evidence, and common sense in a Po-Mo world.
And what would we do without people like her?
Note: Hossenfelder is the author of the forthcoming Lost in Math: How Beauty Leads Physics Astray (June, 2018)
See also: Did Stephen Hawking discover a means of detecting parallel universes just before he died?
This sounds a lot like grief talking but we’ll see.
After the multiverse, the… multiworse? Hossenfelder is one of those theoretical physicists who thinks that science should make sense. Wish her well. So may would just love to slip the bonds of reason…
The multiverse is science’s assisted suicide