"The fabric of reality" and the theory of everything

These days I am reading the essay "The fabric of reality" by physicist David Deustch, well known for example by his works in the field of Quantum Computation. In this essay Deutsch proposes his own version of a "Theory of Everything", a theory that has all the ingredients to understand and explain all the reality as we experiment it. It is a rather ambitious proposal based on four basic scientific theories: quantum theory, biological evolution, epistemology and computational theory.

I have just read the very first chapters, so let me just comment on a couple of points that seem of interest to me. First of all Deutsch points out that a"Theory of Everything" cannot in any case be interpreted in the reductionist way some theoretical physicists think about it, like string theorists like to name their loved theory. Indeed, Deutch argues that even in in the future a theory that unifies all fundamental particles and forces is discovered, this will not be in any case a complete theory of Reality, since most of the features of nature cannot be derived from its fundamental components, that is, one cannot derive the theory of evolution from fundamental physics. This is what in recent times has been advocated as an "emergent" view of physical reality rather than an "reductionist" view.

Second is that according to Deutsch the only possible real understanding of quantum teory is Everett's Many Worlds interpretation, according to what there exists an infinite number of parallel universes just like ours, with "ghost" (for us) particles which however can interact with our own universe particles to form the characteristic interference patters that are one of the most astounding features of quantum mechanics. This interpretation seems at least controversial, however the canonical interpretation of quantum mechanics in terms of propagation of "wave functions" is also not the most intuitive concept in the world. I am a bit skeptical about the real existence of this "multiverse", my feeling is that more work on the foundations on quantum mechanics (or a deeper theory) should bring us a better understanding of the in any case extremely surprising quantum world.

More as I go on with this interesting essay in the short future ...