Q. Can you talk about the future of many-worlds? What would have to be true, or what milestones would have to be achieved for the majority of the physics community to adopt many-worlds as a proper model of foundational physics?He goes on to say the second thing, which is that someone has to find some practical utility to many-worlds, and no one has found any yet.
A. I think there's two things going on, one is already happening. Which is, you just need to appreciate the need for a proper model of foundational physics, a proper model of quantum physics in particular. You know we have been muddling along with the Copenhagen Interpretation, which is hilariously ill-defined for a very long time now, but as technology improves, and as physicists are paying more attention to truly quantum phenomena, especially entanglement and measurement, and so forth, they are becoming easier to convince that we need to get quantum mechanics right. So whether it is many-worlds or something else, first we need to convince physicists that it is worth spending the effort to think carefully about the foundations of quantum mechanics.
I do not see how a respectable professor can say anything so ridiculous.
QM is not a new or immature theory. Its worldwide impact is about a trillion dollars a year, counting all the semiconductors, lasers, liquid crystals, etc. Those products are built with an understanding of the basic science from textbooks on the Copenhagen interpretation of QM.
Physicists need to be convinced to get it right? What about all those people invested in that trillion dollar economy? Don't they want to get it right?
Carroll is telling them that they need to give up their theory for some many-worlds nonsense that has never shown any practical utility whatsoever.
Got that? On the one hand, a theory worth a trillion dollars a year. On the other, one worth zero. And Carroll is trying to get people to jump to the latter theory.
This is like saying: What would it take for people to stop driving cars, and using wormholes for transportation instead?
And the eminent professor answering: We need two things, to convince everyone that cars are hilariously ill-defined, and to find a way to use wormholes for transportation.
In a sense, he's right, in that people would use wormholes if they became more useful than cars. But there is no chance of that ever happening.
Here is a new article on many-worlds (MWI) being unscientific:
We show, in fact, that a whole class of theories -- of which MWI is a prime example -- fails to satisfy some basic tenets of science which we call facts about natural science. The problem of approaches the likes of MWI is that, in order to reproduce the observed empirical evidence about any concrete quantum measurement outcome, they require as a tacit assumption that the theory does in fact apply to an arbitrarily large range of phenomena, and ultimately to all phenomena. ...I do believe that many-worlds is completely contrary to everything we know about science. Believing in it is more backwards than believing in astrology or witchcraft.
The unblemished success of the theory in such ample range of phenomena is really staggering. Precisely because of that, it is suicidal to leave our best comprehension of such rounding success in hands of any interpretation that, due to its soaring ambition, is incapable of building itself on any concrete empirical ground, and therefore cannot but fall apart sooner or later. ...
In the specific case of MWI, there seems to be an almost religious sentiment that animates its supporters by believing that everything that exists is a single, “simple”, immutable, elegant mathematical object, which supposedly lives in an abstract Hilbert space. In this view, everything we observe and experience, including the space in which we move and live, would just be emerging from the only “real” entity – the universal wave function . With the arguments exposed in this article, we then join Heisenberg here who, to similar claims put forward by Felix Bloch, once simply replied: “Nonsense, space is blue and birds fly through it.”