I focus on fiction, sci-fi, fantasy, science, history, politics and read a lot. I try to review everything I read.
Great ideas and great narration makes this a great audio book. The last quarter of this book has some of the most interesting ideas in physics I have heard. I think these ideas are, by far, the most likely to lead to progress in physics. The first three-quarters is good, but is just a nice rehash similar to a bunch of other speculative physics books covering a brief history of cosmology leading to the theory of inflation and various levels of multiple universes, Boltzmann brains and such, finally culminating in the Measure Problem (one cannot assign consistent probabilities to infinite sets). Then the book gets really interesting! The author proposes that math does not model the universe, but that math IS the universe. The relations defined by a mathematical structure is all that is needed for us to believe all we see and feel is real. Nothing physical is needed. I really thought I was alone in being a strong proponent of this Mathematical Universe idea, so I have quite pleasantly surprised to find this excellent presentation. I was led to my conclusions by a much different path (Bell’s Theorem & Bell Test Experiments) and take these ideas to even greater extremes than Tegmark, but this is the best (the only?) popular presentations of these ideas I have seen.
It may just be awkward editing or just these ideas are heady stuff, but by the end of the book Tegmark seems a bit schizophrenic. He seems to reject continuums and infinities and randomness as unreal (which is what I think), but then he continues to refer to, and use, these as if they were real. Also a good new model in fundamental physics should address multiple issues in physics, but Tegmark does not use his ideas of the Mathematical Universe to clarify the understanding of quantum mechanics (particularly Bell’s Theorem) and the problem linking General Relativity and Quantum mechanics. I think Tegmark underestimated the depth of the Measure Problem. The underlying problem is in any reality, it is simply not possible to take a random sample from an infinite set. Thus any assignment of probability to such constructs is nonsense. Tegmark seems to still be hoping for a resolution of the Measure Problem.
The author has a really pleasant way of covering the history of cosmology, making the story like a mystery novel, using detective work to explain one mystery after another. Yet what makes this book really worth reading is the last quarter where the ideas about the Mathematical Universe are explored. I suspect that in a few hundred years the conception of the Mathematical Universe will be considered the great turning point leading to a final, simple and beautiful, Theory of Everything.
Being a layman interested in quantum theory I found this book important, and even touching. There is trouble with physics and it is wonderful that a very few scientists are pointing it out. I agree with Smolin that the trouble with physics is deeper and more insidious than run of the mill historical scientific dogma. New physicists are being encouraged to research an un-testable theory and actively discouraged from investigating any other underlying foundations of quantum physics. Smolin does not offer any answers, but demonstrates the problem, and encourages more open inquiry. Unfortunately the trouble with physics is very deep. Some of the greatest minds of the twentieth century spent entire careers on open inquiry to understand the fundamentals of physics, yet failed utterly. It is understandable that most advisers, after seeing decades of wasted genius, discourage their gifted students from such pursuits. Yet such pursuits may be the only path to true progress in physics.
This book does not stand on its own really well, it is dependent on having some grounding in the history of quantum theory, so I would suggest reading Lindley’s Uncertainty (and maybe some others), before this reading this book.
Hopefully this book will encourage some unknown non-professional, like Einstein, to ignore the conventional wisdom and see the simple and obvious truth that every professional physicist has missed for a century.
Smolin is brilliant and an excellent writer. I really enjoyed, appreciated, and mostly agreed with his hypotheses in his The Trouble with Physics. Time Reborn is a good book and well worth the read. The narration is expressive and excellent. The first half of Time Reborn is a particularly well written account of why Smolin feels Time should be reborn. The second half of the book is more technical, less well written, quite speculative, and has weak foundations that seems to render the main conclusions invalid.
I think the fundamental weakness is the author’s self-limitation by acceptance of quite a few false dichotomies. The most important of these false dichotomies is regarding Bell’s Theorem. Smolin says Bell’s Theorem proves quantum theory must be non-local. This is not so. Bell’s Theorem proves that no local theory can explain quantum correlations. There could be some novel theories that are neither local nor non-local and are able to explain quantum correlations without violation of Bell’s theorem. Accepting this false dichotomy leads Smolin down a chain of reasoning culminating in a rejection of the relativity of synchronicity.
The second dichotomy I found invalid is any theory without time must yield a deterministic world that would necessarily have fixed laws, fixed constants, fixed particles, would lack novelty, and would be a stranglehold upon thought. All this is ridiculous. It is quite easy to imagine non-Newtonian deterministic theories without time that allow constants and particles to evolve deterministically with causation as a time-like partial ordering. Such a universe would seem as open and novel to an observer as any open universe.
Smolin kind of explains why giving up the relativity of synchronicity is really not a good idea, then tosses it out anyway. This seems really unwise and weakens his ideas depending upon elimination of this well tested feature of special relativity.
I had a number of other minor nits with this book. Smolin, who should know better, called non-locally in QM an “effect”. There is no non-local quantum effect (that would transmit information from the cause), but instead there is a subtle influence, incapable of transmitting information of any kind.
Another nit, but still annoying, Smolin describes the path of a thrown object as a parabola. Not so, it is an elliptical segment; which becomes clear if one imagines what would happen if the path continued without hitting the Earth, going into orbit (not flying off parabolically into space.)
I agreed strongly with Smolin’s trouble with physics, and that trouble almost certainly involves a fundamental invalid assumption we are making. Dragging back the theory of universal time seems very unlikely resolve this invalid assumption issue, since that old theory, until recently, was held by almost everyone, and has been extremely well examined.
Smolin also seems to contend that questions like “Why is there something rather than nothing” are outside the scope of scientific questions. I instead like Hawking’s quote from In A Brief History of Time “if we discover a complete theory, it should in time be understandable by everyone, not just by a few scientists. Then we shall all, philosophers, scientists and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to that, it would be the ultimate triumph of human reason -- for then we should know the mind of God."
You can never get a cup of tea large enough or a book long enough to suit me.” ― C.S. Lewis
Either this book gives evidence to parallel Universes or proves that no matter how absurd an idea is you can make it sound reasonable if you are skilled enough. Anyway the book is interesting. Its ideas excite interest. The narrator does a great job with the material. I recommend.