I have to admit that I haven't read Tegmark's book. (Nor am I really motivated to.) But that being said, I get the impression that Tegmark is promoting a very strong version of old-time Platonism. Mathematical truths 'exist' in some mysterious abstract way that accounts for their objectivity ( the fact that mathematicians around the world agree with each other about the validity of particular proofs). That's not all that controversial (most mathematicians are Platonists I think) and it's something that I'm inclined to agree with). But as I understand it, Tegmark seems to go further than that, by insisting that this hypothetical Platonic abstract world of mathematics is all that really exists. (Plato himself probably would have agreed.) Everything else is reducible to it. When we look at physical objects, what we are really looking at is mathematics. While that idea does resemble currently trendy structural realism in metaphysics, I'm not entirely prepared to buy it. I'd like to know how Tegmark explains how particular mathematics is somehow instantiated in particular physical events, while other mathematics isn't and remains entirely conceptual among the mathematicians. And what about all of life and reality that doesn't seem so easily quantifiable? (Maybe I should read the book, eh?) I've said before and I continue to believe that a lot of this is an artifact of how theoretical physicists are trained. What they are taught in their classrooms is all mathematics, Hamiltonians and Lagrangians and Hermitians so on. If they encounter a physical problem, the procedure they are taught is to plug the variables in the problem into their mathematics, turn the crank and produce a solution. So it's probably natural to start thinking that the mathematics is what's most truly real and most fundamental in reality, and the world of experience just kind of emerges from the mathematics somehow. I'm not aware of how, or even whether, Tegmark works consciousness into his speculations. The quantum tubules and the cell-biology stuff isn't Tegmark's as far as I know. That's W4U channeling Hameroff. Tegmark and Hameroff are W4U's big ideas at the moment, and he's trying to work them together even if they don't quite fit. In Tegmark's version, our physical reality seems to be an emanation, the physical instantiation, of the abstract realm of mathematics that theoretical physicists are always scrawling on their chalkboards. (Remember RPenner's posts?) I'm reminded of Neoplatonism, where physical reality and consciousness all kind of emanate from higher metaphysical planes of being, each of which is more real than the ones below it. The Neoplatonists thought that there were a number of "higher planes" (we see that idea in modern occultism), ascending through a World Soul or a 'Demiurge' that creates our reality, up to a higher Plato-inspired level of the timeless unchanging Forms (mathematics seems to originate here). And finally even the multiplicity of forms emanate like light out of their transcendent Source, the single indescribable "One". I'm not sure that Tegmark and his supporters are even aware that he, and theoretical physics along with him, are distant descendants of a much older intellectual tradition that also gave rise to a great deal of the Western occult tradition. The two are one and the same thing in his mind. It's his grand idea. The tables and the chairs are mathematics, made solid. Solidity is just physical interaction, simply more mathematics in his scheme and he no doubt has equations to "prove" it.