From the Crisis in Physics to the Future of the Universe
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From one of our foremost thinkers and public intellectuals, a radical new view of the nature of time and the cosmos
What is time?
This deceptively simple question is the single most important problem facing science as we probe more deeply into the fundamentals of the universe. All of the mysteries physicists and cosmologists face—from the Big Bang to the future of the universe, from the puzzles of quantum physics to the unification of forces and particles—come down to the nature of time.
The fact that time is real may seem obvious. You experience it passing every day when you watch clocks tick, bread toast, and children grow. But most physicists, from Newton to Einstein to today’s quantum theorists, have seen things differently. The scientific case for time being an illusion is formidable. That is why the consequences of adopting the view that time is real are revolutionary.
Lee Smolin, author of the controversial bestseller The Trouble with Physics, argues that a limited notion of time is holding physics back. It’s time for a major revolution in scientific thought. The reality of time could be the key to the next big breakthrough in theoretical physics.
What if the laws of physics themselves were not timeless? What if they could evolve? Time Reborn offers a radical approach to cosmology that embraces the reality of time and opens up a whole new universe of possibilities. There are few ideas that, like our notion of time, shape our thinking about literally everything, with huge implications for physics and beyond—from climate change to the economic crisis. Smolin explains in lively and lucid prose how the true nature of time impacts our world.
From Publishers Weekly
© Publishers Weekly
A must read that must be read carefully
Time Reborn is a must read for anyone interested in physics, cosmology, and/or spacetime. It presents a good overview of the state of the current wall against which physics appears to have hit, and proposes that the only reasonable way through the wall is to assume that “time” is a fundamental quality/quantity of the universe. In fact Smolin may be completely correct and the book may give readers an amazing glimpse into a future scientific revolution.
The first part of the book is dedicated to convincing us that science has accepted time as an illusion. Those familiar with the block universe derived from relativity will be receptive to the idea that a block universe is a “timeless” universe. However it seems, at least to me, that Smolin overstates (as I believe he does throughout the book) when he says that the consensus among physicists and philosophers is that time is an illusion. Perhaps a better statement would be that most realize the implications of a block universe, but few are willing to accept that there is no flow of “time”.
Smolin is right to press for the logical conclusion that a block universe is likely to be a timeless universe, and that relativity favors a block universe, but he jumps too far when he suggests that the canonical view is that time does not exist. Indeed it would seem fairer to say that while theoretical physicists may feel that a timeless conclusion is inevitable, most scientists and philosophers don’t even consider the possibility that the past, present, and future are literally fixed. Whether they should do so or not is not the issue, rather it is the statement that the “illusion” of time is universally accepted that is overbroad, were it not so Presentism would have already faded into the past.
For time to be reborn it must have been killed off by science. In fact both intuition and Quantum theory have prevented that from happening. Schrodinger’s equation argues for a fundamental time of sorts, and even relativity leaves room for solutions that preserve a robust temporality. Smolin seeks to resurrect time by first killing it. His arguments that the current state of our knowledge have already done in time may be based on his acknowledged deep understanding of cosmology, if so he does not effectively disclose the secrets he has uncovered.
The problem is that even though he warns us that his ideas are in their formative stage, Smolin jumps from argument to conclusion to argument to conclusion, making it seem that we can, indeed should, reach no other logical answer than that time is fundamental. When he speaks of the initial conditions of our universe he says that “These properties are extraordinarily unlikely, were the solution that describes our universe to be picked randomly.” Penrose and almost everyone else agrees, but he then jumps to the conclusion that multiverses are not the answer because they cannot be observed and therefore our universe must be the result of natural selection or a “principal of precedence”. He does not explain how natural selection of initial conditions is significantly, or at least satisfactorily, more likely to produce a fine tuned universe than an initial big bang, which frankly we have very little understanding of in the first place.
Furthermore Smolin is dismissive of the possibility that time is derived, and not fundamental. He glosses over the fact that most people (not including Barbour) who argue that time is derived and not fundamental would not dispute that the universe evolves in a temporal fashion. The difference is that they believe that Relativity and Quantum theories may be harmonized within the framework of mathematics.
The physicist Carlo Rovelli states it best, Rovelli does not say that there is no (t)ime, he says that there is no fundamental variable (T)ime. Small (t) time is derived from state evolution in an essentially atemporal universe. Everything that Smolin says about an arrow of time is allowed in Rovelli’s view of causation, but his causation is a result of some form of presymplectic mechanics without a fundamental (T). I believe that Rovelli would agree with many of Smolin’s arguments, (t)ime exists and flows in his model, it simply is not a fundamental quantity (T).
Rovelli understands the quantum arrow of (t)ime to be based on the Heisenberg and not the Schrodinger equations, as he states in one of his articles "Some of these quantities may express the value of certain variables 'when and where' certain other quantities have certain given values... These quantities describe evolution in a way which is fully invariant under the parameter time, unphysical gauge evolution. The corresponding quantum operators are Heisenberg operators. There is no Schrodinger picture, because there is no unitary time evolution. There is no need to expect or to search for unitary time evolution in quantum gravity, because there is no time in which we should have unitary evolution. A prejudice hard to die wants that unitary evolution is required for the consistency of the probabilistic interpretation. This idea is wrong."
The point is that Smolin lumps all concepts of time into a single entity, and then appeals to our intuition of the passage of time to argue that time must be fundamental. Again he may be right, but I do not believe he is any more successful in presenting his case than are the thoughtful people who believe that relative position, and perhaps shape, is all that is fundamental in our universe. My favored view is that only a small bounded atemporal portion of spacetime (a type of “present”) represents physical reality, with something like John Cramer’s transactional interpretation of QM providing non-locality. Smolin notes that “It is so easy to make stuff up, and the bookshelves are full of metaphysical proposals”. We simply do not have enough present knowledge to know if this book belongs on that shelf.