Time Reborn: From the Crisis in Physics to the Future of the Universe (英語) ペーパーバック – 2014/5/29
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Nothing seems more real than time passing. We experience life as a succession of moments. But just as some of us see God as eternal, so physicists understand the truths of mathematics and the laws of nature as constant, transcending time. These laws dictate how the future will evolve: there is no freedom, no uncertainty about the future at all.
Yet, argues Lee Smolin, this denial of time is holding back both physics, and our understanding of the universe. We need a major revolution in scientific thought: one that embraces the reality of time and places it at the centre of our thinking. Time, he concludes, is not an illusion: indeed, it is the best clue that we have to fundamental reality. Time Reborn explains how the true nature of time impacts on us, our world, and our universe.
One of the most original living theorists ... He challenges not only Einstein's relativity, but also the very notion of natural laws as immutable truths (Economist)
Brilliant and persuasive (Ray Monk Guardian)
Provocative and stimulating ... Smolin reconceives the universe (Christopher Potter Sunday Times)
Lee Smolin is a theoretical physicist who has made important contributions to the search for quantum gravity. Born in New York City, he was educated at Hampshire College and Harvard University. Since 2001 he is a founding faculty member at Perimeter Institute for Theoretical Physics. His three earlier books explore philosophical issues raised by contemporary physics and cosmology. They are Life of the Cosmos (1997), Three Roads to Quantum Gravity (2001) and The Trouble with Physics (2006). He lives in Toronto.
I have read the author’s books: "The Trouble with Physics" (2006, Penguin Books) and "The Life of the Cosmos" (1997). Very much educative, though I don’t like the idea of “Cosmological natural selection,” because Darwin’s idea of Natural Selection seems to have been scientifically demolished according to the modern molecular biologists. See "What Darwin got Wrong" by J.A. Fodor & M. Piattelli-Palmarini (2010) & "Darwin’s Doubt" by Stephen C. Meyer (2013). Sorry, I have digressed from the subject.
Now, no need for me to explain the contents of this book, which was published 4 years ago; someone should have given a good review. Hence, I would like to place here a certain piece of information on “Consciousness” in relation with author’s writing about consciousness in Epilog.
The author writes about “consciousness” in pp. 267 – 271. Let me get to the point: The author writes (p. 269), “Here’s another way to ask it: Suppose we mapped the neural circuits in your brain onto silicon chips and uploaded your brain into a computer. Would that computer be conscious? Would it have qualia? Yet another question serves to focus our thoughts: Suppose you could do that without harming yourself. Would there now be two conscious beings with your memories whose futures diverge from there?”
So far there has been no actual case of a computer, being so manipulated as in the author’s supposition, which has “two conscious beings with a human’s memories whose futures diverge from there.” However, if we replace the computer with a living human being who has experienced a successful heart transplant from a brain-dead donor, then there have been actual cases of heart-transplanted people who have two conscious beings with donor’s memories (as well as characteristics & tastes) whose futures have definitely diverged from there.
I cite the following three references which describe the actual situations:
 Stephen E. Braude, “Immortal Remains – The Evidence for Life after Death,” Rowman & Littlefield, 2003, Chap. 7: Lingering Spirits.
 Claire Sylvia, “A Change of Heart – A Memoir,” Warner Books, 1997.
 Paul Pearsall, Ph.D., “The Heart’s Code,” Broadway Books, 1999.
創発される量子的な面積と体積をもち背景独立な理論であるループ量子重力理論には、このようなスモーリンの根本思想が潜んでいたわけである。非局所性（簡単に言えば瞬間移動）についてはスピンネットワークなどにおけるnon-local linkによって、逆問題（量子重力理論で宇宙全体を形作ることができるか）はmatrix model of string theory, causal-dynamical triangulation modelなどで解決できるという。
But the claim that "there is no timeless truth" itself is timeless! It is obviously a self-defeating claim. The author probably wants to say there are no timeless *physical laws*. This might be true. But on more than one occasion he seems to deny the principle itself.
The author repeatedly asserts that, if the laws of the universe are like computer programs, then the future is perfectly decided. He writes (location 989): "A deterministic physical theory can be likened to a computer. ... Given the input and the program, the output is completely determined."
For some reason, the author overlooks the results of Turing, Post, Rice, and other logicians, about uncomputability. They show that, for any sufficiently rich computer program, there is no systematic way to decide (by inspecting the program as such) if the output of the program has a certain non-trivial property. This means that a rich computer program may very well produce unexpected (and uncomputable) output. If the author is endeavoring to introduce uncertainty, novelty, and unpredictability into the Newtonian paradigm, this has already been done via the theorems of Gödel and Turing, among others.
The author criticizes the "block universe" view as timeless while time is an undeniable fact that we observe. But, if we follow the author's own approach, the block universe is a view for the universe as a whole. The block-view is unobservable from within the universe. Thus, there should be no contradiction in principle between a timeless block universe and time-dependent events inside the universe. These are two different views from different perspectives that need not be matched.
Overall, the book is provocative and forces the reader to think and rethink in novel manners. Despite some shortcomings highlighted in other reviews, it is an indispensable volume in the science library.
Based upon the author's previous work and publications, I picked up this book expecting a discussion of the problem of time in quantum gravity. What I found was something breathtakingly more ambitious. In essence, the author argues that when it comes to cosmology: the physics of the universe as a whole, physicists have been doing it wrong for centuries, and that what he calls the “Newtonian paradigm” must be replaced with one in which time is fundamental in order to stop speaking nonsense.
The equations of general relativity, especially when formulated in attempts to create a quantum theory of gravitation, seem to suggest that our perception of time is an illusion: we live in a timeless block universe, in which our consciousness can be thought of as a cursor moving through a fixed, deterministic spacetime. In general relativity, the rate of perceived flow of time depends upon one's state of motion and the amount of mass-energy in the vicinity of the observer, so it makes no sense to talk about any kind of global time co-ordinate. Quantum mechanics, on the other hand, assumes there is a global clock, external to the system and unaffected by it, which governs the evolution of the wave function. These views are completely incompatible—hence the problem of time in quantum gravity.
But the author argues that “timelessness” has its roots much deeper in the history and intellectual structure of physics. When one uses Newtonian mechanics to write down a differential equation which describes the path of a ball thrown upward, one is reducing a process which would otherwise require enumerating a list of positions and times to a timeless relationship which is valid over the entire trajectory. Time appears in the equation simply as a label which causes it to emit the position at that moment. The equation of motion, and, more importantly, the laws of motion which allow us to write it down for this particular case, are entirely timeless: they affect the object but are not affected by it, and they appear to be specified outside the system.
This, when you dare to step back and think about it, is distinctly odd. Where did these laws come from? Well, in Newton's day and in much of the history of science since, most scientists would say they were prescribed by a benevolent Creator. (My own view that they were put into the simulation by the 13 year old superkid who created it in order to win the Science Fair with the most interesting result, generating the maximum complexity, is isomorphic to this explanation.) Now, when you're analysing a system “in a box”, it makes perfect sense to assume the laws originate from outside and are fixed; after all, we can compare experiments run in different boxes and convince ourselves that the same laws obtain regardless of symmetries such as translation, orientation, or boost. But note that once we try to generalise this to the entire universe, as we must in cosmology, we run into a philosophical speed bump of singularity scale. Now we cannot escape the question of where the laws came from. If they're from inside the universe, then there must have been some dynamical process which created them. If they're outside the universe, they must have had to be imposed by some process which is external to the universe, which makes no sense if you define the universe as all there is.
Smolin suggests that laws exist within our universe, and that they evolve in an absolute time, which is primordial. There is no unmoved mover: the evolution of the universe (and the possibility that universes give birth to other universes) drives the evolution of the laws of physics. Perhaps the probabilistic results we observe in quantum mechanical processes are not built-in ahead of time and prescribed by timeless laws outside the universe, but rather a random choice from the results of previous similar measurements. This “principle of precedence”, which is remarkably similar to that of English common law, perfectly reproduces the results of most tests of quantum mechanics, but may be testable by precision experiments where circumstances never before created in the universe are measured, for example in quantum computing. (I am certain Prof. Smolin would advocate for my being beheaded were I to point out the similarity of this hypothesis with Rupert Sheldrake's concept of morphic resonance; some years ago I suggested to Dr Sheldrake a protein crystallisation experiment on the International Space Station to test this theory; it is real science, but to this date nobody has done it. Few wish to risk their careers testing what “everybody knows”.)
This is one those books you'll need to think about after you've read it, then after some time, re-read to get the most out of it.