The multiverse is misguided: a review of David Deutch’s views on quantum mechanics and reality

In short: the theory described in his Fabric of Reality constitutes an impressive effort but suffers from huge leaps of logic and if you don’t accept the many worlds (multiverse) interpretation of quantum mechanics you won’t accept his broader theory

The multi-verse concept has become rather popular recently in pop culture and in the academy. Where does this idea come from? It’s not new but one of its primary proponents today is David Deutsch, a professor at Cambridge University in England.

This is a short review of David Deutsch’s 2010 book, The Fabric of Reality: The Science of Parallel Universes and Its Implications, and the broader concept of the multiverse that is part of parcel of his approach.

I appreciate Deutsch’s efforts and obvious intellect. It’s not very often that an intellectual will have the moxie or the time to create a “theory of everything.” In this case, Deutsch attempts just this, injecting some degree of humility in claiming that he is merely prodding us toward a theory of everything (while I believe that he believes he has proffered just such in this book).

I’ve read many philosophers’ and physicists’ theories of everything over the years, including Whitehead, Schopenhauer, Russell (not collected into one book, but the collected works fairly constitute a theory of everything), and David Bohm. Bohm’s writings are perhaps least deserving of being called a theory of everything, yet he is one of a handful of physicists who have written extensively on topics outside of pure physics.

Deutsch’s idea of a theory of everything certainly encompasses more than “mere” physics, so any purely physical “theory of everything,” such as quantum gravity, doesn’t fit the bill Deutsch is trying to fill. Deutsch writes of the “four strands” that weave his nascent theory of everything: Popperian epistemology, the Turing theory of computation, the Darwinian-Dawkinsian theory of evolution and multiverse quantum mechanics. I believe Deutsch is FAR too conclusive from the get-go in concluding that quantum evidence such as the double slit experiment and half-silvered mirror experiments REQUIRE accepting the multiverse (“many worlds”) interpretation of quantum mechanics (QM). This is, as Deutsch might say, nonsense.

Deutsch barely mentions Bohm’s rich interpretation of quantum mechanics, known as Bohmian quantum mechanics, the “causal interpretation” or the “ontological interpretation.” As these names suggest, it’s all about interpretation: almost no one questions the mathematics of QM because they have been shown to be empirically accurate to a very high degree in almost all situations.

So while Deutsch is a very strong advocate of the multiverse interpretation, in which interference phenomena at the quantum level can ONLY be explained by the presence of an infinite number of “shadow” particles for every single particle in our particular universe, it is simply not the case that this is the only rational interpretation. I don’t pretend to understand the dozens of interpretations offered over the years for the QM formalisms. However, I have read Bohm’s books and feel I have a decent grasp of his interpretation. Bohm’s interpretation rests upon the presence of a “guiding wave” for every particle in the universe. The guiding wave always accompanies each particle. The guiding wave is part of the “implicate order” that undergirds our reality, the explicate order. The particle itself is part of the explicate order.

So there is an epistemological (but not an ontological) dualism in Bohmian QM because we cannot know the implicate order directly. We can only infer it by its impacts in the explicate order — our world. I think of each particle as a tiny boat pushed along the sea surface of the implicate order by the guiding waves in the implicate order. Bohmian QM explains very well the strange interference phenomena of the double slit experiment and other quantum phenomena.

Deutsch’s whole intellectual edifice rests upon the certitude of the multiverse interpretation. But this foundation is by no means certain. To say that Bohmian QM is more parsimonious than the multiverse interpretation is an understatement of infinite magnitude. This is the case because under the multiverse interpretation there are literally an infinity of universes at every point in our space-time, existing in parallel to our universe. No universe is the “real” universe — they’re all real and all exist already (somehow).

This is philosophical profligacy at its worst. I can’t say it’s wrong because at this level of explanation nothing can really be called “wrong.” It’s simply no where near as parsimonious or as elegant an explanation as Bohmian QM, to cite one alternative explanation.

Bohmian QM is itself inspired by Alfred North Whitehead’s own awesome intellectual edifice. Whitehead, in 1929’s Process and Reality and a number of other scientific and philosophical works written during the course of this intellectual giant’s long career, described a philosophical system that is itself a theory of everything.

Where Deutsch’s theory generally ignores the need to explain consciousness and its role in the universe, as well as the existence of mystical and spiritual experience as valid phenomena, Whitehead offers a detailed and comprehensive theory of consciousness. For Whitehead, all real things are “drops of experience.” Each “actual entity,” his term for the most basic unity of matter, is also the most basic unit of consciousness — that “atoms” of consciousness, if you will. Whitehead is thus a panpsychist. And panpsychism is a sword of unparalleled sharpness for cutting through Gordian Knots in countless fields.

In sum, Deutsch is overly dismissive of alternative interpretations of QM (the foundation of his edifice), particularly Bohmian QM, which he mentions in passing only twice in the whole book; fails to offer any theory of consciousness or spiritual experience, and thus fails to offer a convincing or satisfying theory of everything.