On Friday, September 27, 2019 at 2:56:42 AM UTC-5, Bruce wrote: > > On Fri, Sep 27, 2019 at 5:01 PM Quentin Anciaux <[email protected] > <javascript:>> wrote: > >> >> And you forgot 3- it's always the same matter in w0 and w1, just seen >> from another POV, like a circle in a 2d plane could be thought to be from a >> sphere or a cylinder intersecting a 2d plane, so if you see the many 2d >> planes intersecting the cylinder, they see each a part of it, no new circle >> are created on each plane. >> > > That seems similar to the view of Chad Orzel: > > https://scienceblogs.com/principles/2008/11/20/manyworlds-and-decoherence > > His idea is that there aren't many worlds, just the wave function of the > universe. So there is no splitting and no multiplication of worlds, there > is just the wave function. And our world is just our path through this wave > function. This is, therefore, a single world interpretation since we see > only one world. The other parts of the wave function may exist, but they > are not worlds like ours. > > Bruce >
Philip Ball talks about Hossenfelder's take, then Orzel's take: https://philipball.blogspot.com/2019/09/just-how-conceptually-economical-is.html : ... *Sabine Hossenfelder*: "Many Worlds in and by itself doesn't say anything about whether the parallel worlds "exist" because no theory ever does that. We infer that something exists - in the scientific sense - from observation. It's a trivial consequence of this that the other worlds do not exist in the scientific sense. You can postulate them into existence, but that's an *additional* assumption. As I have pointed out before, saying that they don't exist is likewise an additional assumption that scientists shouldn't make. The bottom line is, you can believe in these worlds the same way that you can believe in God.” I have some sympathy with this, but I think I can imagine the Everettian response, which is to say that in science we infer all kinds of things that we can’t observe directly, because of their indirect effects that we can observe. The idea then is that the Many Worlds are inescapably implicit in the Schrödinger equation, and so we are compelled to accept them if we observe that the Schrödinger equation works. The only way we’d not be obliged to accept them is if we had some theory that erases them from the equation. There are various arguments to be had about that line of reasoning, but I think perhaps the most compelling is that there are no other worlds explicitly in any wavefunction ever written. They are simply an interpretation laid on top. Another, equally tenable, interpretation is that the wavefunction enumerates possible outcomes of measurement, and is silent about ontology. In this regard, I totally agree with Sabine: nothing compels us to believe in Many Worlds, and it is not clear how anything could ever compel us. In fact, *Chad Orzel* suggests <https://www.forbes.com/sites/chadorzel/2019/09/17/many-worlds-but-too-much-metaphor/> that the right way to look at the MWI might be as a mathematical formalism that makes no claims about reality consisting of multiple worlds – a kind of quantum book-keeping exercise, a bit like the path integrals of QED. I’m not quite sure what then is gained by looking at it this way relative to the standard quantum formalism – or indeed how it then differs at all – but I could probably accept that view. Certainly, there are situations where one interpretational model can be more useful than others. However, we have to recognize that many advocates of Many Worlds will have none of that sort of thing; they insist on multiple separate universes, multiple copies of “you” and all the rest of it – because their arguments positively require all that. Here, then, is the key point: you are *not* obliged to accept the “other worlds” of the MWI, but I believe you *are* obliged to reject its claims to economy of postulates. Anything can look simple and elegant if you sweep all the complications under the rug. @philipthrift -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/5250a11c-77be-466d-aeef-4adc9a2062b7%40googlegroups.com.
