Time Reborn: From the Crisis in Physics to the Future of the Universe

Early in his career, the author received some unorthodox career advice from Richard Feynman. Feynman noted that in physics, as in all sciences, there were a large number of things that most professional scientists believed which nobody had been able to prove or demonstrate experimentally. Feynman's insight was that, when considering one of these problems as an area to investigate, there were two ways to approach it. The first was to try to do what everybody had failed previously to accomplish. This, he said, was extremely difficult and unlikely to succeed, since it assumes you're either smarter than everybody who has tried before or have some unique insight which eluded them. The other path is to assume that the failure of numerous brilliant people might indicate that what they were trying to demonstrate was, in fact, wrong, and that it might be wiser for the ambitious scientist to search for evidence to the contrary.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.

Although I'm not a physicist, I loved this book. I am fortunate to have enough familiarity with the topics--the nature of time, the "finely tuned universe," the hidden-variables interpretation of quantum mechanics, and so forth--to know that the questions Smolin tackles are worth asking. I also have enough skepticism about traditional scientific thinking to entertain his suggestions for new answers.I have been interested in the problem of time ever since reading the articles in Physics and the Ultimate Significance of Time, published in 1986. They taught me how much scientific thinking conflicts with our deepest intuitions about the unfolding of reality in time, in particular the idea that time flows from a settled past to an as-yet non-existent and indeterminate future, by way of a unique present. Einstein was uncomfortable that he couldn't find a scientific basis for such a belief. Smolin thinks that by emphasizing the timeless to the detriment of the temporal, physics has reached a kind of explanatory dead-end with regard to understanding the universe as a whole.What scientists have been good at is "doing physics in a box." They focus on a subsystem of the universe, describe it as a configuration space of possible states, and discover laws expressible in the timeless language of mathematics that account for the changes of state. There's nothing unique or creative about the present; it's just another application of the same timeless laws. Relativity theory seems to deprive the idea of NOW of any objective meaning, since observers' frames of reference affect which events they experience as occurring simultaneously. "Observers in motion with respect to each other will reach different conclusions about whether two events are simultaneous or not when those two events are distant from each other." Without an objective NOW, we seem to lack a point at which to separate the past from the future, and all points in time become equally real in the "block universe." Some theories of quantum cosmology treat the universe as a single quantum state in which all possible configurations exist at once, and so the passage of time becomes a complete illusion.Smolin believes that these conclusions result from the "cosmological fallacy" of trying to extrapolate the physics of subsystems to the universe as a whole. "When we attempt to scale up our standard theories to a cosmological theory, we are rewarded with dilemmas, paradoxes, and unanswerable questions. Among these are the failure of any standard theory to account for the choices made in the early universe--choices of initial conditions and choices of the laws of nature themselves." Smolin's attempts to answer questions about the universe as a whole have led him to the view that time is fundamental, and that "the laws of nature emerge from inside the universe and evolve in time with the universe they describe." Our universe must also have evolved out of some previous universe, and it may give rise to others, in his theory of "cosmological natural selection." He believes that a theory of this kind is potentially testable, since the universe can contain evidence of its past. He regards as unscientific and untestable the theory postulating a multitude of simultaneously existing universes simply in order to claim that the special conditions of our universe exist entirely by chance.Smolin suggests that quantum mechanics is only an approximation to a larger cosmological theory, and that's why it's predictions are only probabilistic. "The missing information needed to determine what a quantum system will do might still be present somewhere in the universe, so that it comes into play when we embed a quantum description of a small subsystem into a theory of the universe as a whole." This leads him to consider a "hidden-variables" interpretation of quantum, despite its apparent contradiction of relativity theory. He argues that the theory of "shape dynamics" reformulates relativity theory to resolve this problem:"In general relativity size is universal and time is relative, whereas in shape dynamics time is universal and size is relative. Remarkably, though, these two theories are equivalent to each other, because you can--by a clever mathematical trick...--trade the relativity of time for the relativity of size...Thus, shape dynamics achieves an accord between the experimental success of the principle of relativity and the need for a global time demanded by theories of evolving laws and hidden-variable explanations of quantum phenomena. As noted, one quantity not allowed to change when you expand and shrink scales is the overall volume of the universe at each time. This makes the overall size of the universe and its expansion meaningful, and this can be taken for a universal physical clock. Time has been rediscovered."I'm not qualified to evaluate such a claim. But my studies in science and philosophy have convinced me that scientists are much more likely to be right about little things than about big things such as the nature of time. New ideas about big things should be welcome, especially if they help reconcile scientific knowledge with lived experience.

Physics has a curious relationship with time. Most laws are time-reversible; famous ones that aren’t, like the Second Law of Thermodynamics, are approximate and emergent from underlying reversibility; in relativity a universal time cannot be defined consistently, and instead provides us with a static space-time. It’s almost as if physics doesn’t believe time exists.Smolin is having none of that. For him, time is the fundamental property of the universe, whatever else may emerge. We are not flies caught in the amber of a static space-time; time itself is real.How can he say this, when all the physical theories seem to point in the other direction? His argument is that those theories are local, and cannot be simply extended to apply to the entire universe. Those theories assume that crucial parts of the process must be outside the region they describe. This is what Smolin dubs the traditional Newtonian paradigm of doing “physics in a box”. It rests on some underlying assumptions: (1) the configuration space is timeless; (2) the forces, and hence the laws the system is subject to are timeless. If all the possible states of the system are predefined, and the laws under which the system evolves are predefined, then time does seem to be nothing more than an accounting variable: which of those states the laws say the system is currently occupying. What if the possible states of the entire universe aren’t predefined, because its laws aren’t predefined?Smolin argues that this Newtonian paradigm, powerful as it is, cannot be extended to provide a theory of the entire universe. It is not a simple task to make a truly universal theory: one that doesn’t just apply to every part of the universe, but that applies to the whole universe at once.He also argues that our current theories are approximations: physicists pretend that the system inside their box is an isolated system, unaffected by the rest of the universe, and they go to a lot of experimental effort to make that approximation as good as possible. Good approximations make effective theories, but they are only as good as their assumptions (energy ranges, for example). These approximations inevitably break down whenever a theory is extended to encompass the entirety of the universe.So the timeless nature of isolated, local, approximate theories cannot be taken to imply that the universe itself is timeless.Having argued that the laws cannot be extended naively to imply a timeless universe, Smolin also argues that there is no reason to assume that the laws themselves are timeless: "To make laws explicable, we must consider them as much a part of the world as the particles they act on. This brings them into the purview of change and causality."Smolin explicitly links this view with his proposal for an evolutionary universe, where a new universe is born in each black hole, with its laws of physics being a mutation of its parent’s laws, as explained in his earlier work, The Life of the Cosmos. Smolin is a Leibniz fan: as well as following Leibniz’ relational view, he uses the Principle of Sufficient Reason: that everything must have a reason or cause, to show that the laws must also have a cause, an explanation. I wonder: do random mutations to the laws of physics obey this principle? (In passing: I was amused to discover that Smolin was introduced to Leibniz’ ideas by Barbour, but has come to rather different conclusions!)This mutational view does not mean that Smolin thinks the laws, despite being changeable by mutation, are set at the beginning of the universe, and fixed thereafter. He gives an example of how a quantum system might be free to choose a result in a situation for which there is no precedent. Smolin suggests that this principle of precedence could be subject to experimentation, by preparing some genuinely novel quantum states, and measuring them. I’m not sure of the scope of the system’s freedom, however. What about all those more advanced alien races who have already done these experiments? Do those set precedents? Also, the second time a measurement is done, there is only a single precedent from which to select randomly; this seems to imply determinism.I like his idea of explicable evolving laws; although I still wonder, does a random choice fit with the principle of sufficient reason? And I must admit, I’m not sure why these “principles”, of sufficient reason, of precedence, of whatnot, are allowed to be timeless and universal, when nothing else is. He mentions the need for meta-laws, laws to say how the laws change, but doesn’t go into this as deeply as I wanted. Are the meta-laws timeless? If so, why? If not, what governs their change? I didn’t get the answers here: Smolin refers his book with philosopher Unger, The Singular Universe and the Reality of Time; maybe the answers will be there. For the time being, I have a few new ideas for student projects: growing cellular automata or graphs with rules that depend on configurations, and only deciding on the rule when a new configuration is seen.Smolin finishes up with more social concerns. He explains that our notion of the fundamental laws of nature as being timeless leads to a damaging distinction between the timeless natural (hence good and right being changeless) and the ephemeral artificial (hence bad and wrong being change). Rather, everything changes and evolves, and we should embrace that fact.This is a clearly written and thought-provoking book. It makes plain some issues with physics, and its thesis, about time and change, opens up some fascinating possibilities. Well worth the read.

A boy writes his telephone number on a tennis ball and throws it to a stranger, who catches it. If you want to know more, you'll need to buy the book. The story exemplifies Smolin's easy fluent narrative style. This is a book with no formulae, and the easiest way into special relativity that I've seen in a pop science book. At the same time, Smolin is generally true to science, and he lets you know when his ideas are reaching into conjecture and metaphysics.The parable of the tennis ball elegantly shows the two views of time that Smolin contrasts in this book. The flight of the ball follows a parabola, following Newton's laws of motion, which Einstein's General Relativity generalises. These laws treat time as another static dimension. There is no "now" or flow of time, or even a direction -- a movie of a tennis ball in flight would look the same run forwards or backwards. This static timeless view of the world is what this book is arguing against.What happens at the ends of the ball's flight exemplify the other view of time, which Smolin is trying to bring back into physics, a view that gives time direction and flow, and cannot simply be treated as another dimension. The boy who writes the phone number is deciding to change his future, and is transmitting information forward in time.Conventional physics has only the second law of thermodynamics to offer, that disorder increases, but this law leaves many questions unanswered, such as why everything was so well-ordered in the first place, or the apparent direction of causality, or the strange time-asymmetric "collapse" of the wavefunction in quantum mechanics. In particular, if there is such a concept as "before the big bang", time has to be more than just some emergent property of the known universe.Smolin does not so much answer these questions as pose them, but I think he does well to do so. He criticises the multiple universes or Goldilocks theory on the grounds that it is unverifiable. However, some of his own conjectures strike me as being metaphysical in the same way. Surely the way to determine whether the universe is finite or closed is through experiment, rather than metaphysical argument.I find Smolin rather too vague about the detail of what he means by time that is independent of space -- a time that can exist before the Big Bang, and which could define the ordering of the two ends of a EPR experiment. (I do not think it is necessary to define an ordering in that case, and the concept of direction of causation is all he needs in general. But what do I know.)Smolin's theory of the evolution of universes via black holes, though contentious, does have the benefit of being testable. If it proves true, it surely wins Smolin a Nobel prize, and also confirms him as one of the most visionary physicists of our generation.

Lee Smolin is a researcher at the Perimeter Institute in Canada and considers low level issues in physics like why it's so hard to formulate gravity in a quantum framework. He's also a bit of an outsider because he thinks modern physics hasn't really progressed in 30 years. Sure we have light emitting diodes and smartphone but there's been no change in fundamental physics. For example, the theoretical under-pinnings of the recently discovered Higgs boson were written down 50 years ago.So in the book Smolin advances his view of a possible alternative formulation of fundamental physics which he believes will allow progress to be made. Core to this alternative formulation is our perception of time as an eternal, outside constant. This is why the book has the name it does. He's not proposing to rewrite general relativity or quantum mechanics he's just suggesting looking at these pillars from a different perspective.If you are into physics and want a non-establishment view of current ideas and research in physics this will be a good read for you.

This is a deep and thought provoking book by an expert in the subject who is also something of a heretic (since he has doubts about certain implications of General Relativity). At the same time I found it lacking in certain respects. Smolin does not really go into what (our notion of) time is and in particular does not distinguish sharply between time as succession and time as duration.The disappearance of time in modern physics is alarming from the human point of view since it endangers the very concept of personal liberty and choice (because In the GR block-universe model everything that can happen has in some sense already happened). But Lee Smolin deliberately skips these aspects and implications, precisely those that would interest the general reader the most. The book is a wide ranging non-mathematical but nonetheless strictly scientific study. There is little questioning of science itself as the one and only path to firm knowledge. It is dreadful to think we are in some sense dependent on a small elite of mathematical physicists for what we can know about reality (including the 'future' which is no longer the future). The implications of General Relativity are even worse than those of Quantum Mechanics, almost I prefer the latter since there is at least uncertainty. But while registering some reservations, Lee Smolin does not really show what's wrong with the GR block universe picture which I can only hope to God is not completely true. Galada

The concept that "Time is real" is not completely original to Smolin and his collaborators. The idea was central to the thought of the philosopher Henri Bergson, and I'm amazed Bergson goes unmentioned in the book, especially since Smolin prides himself on the breadth of his philosophical studies.There are superficial flaws which make the book average. The prose frequently loses focus, as when Smolin attempts to enliven his writing with personal anecdotes in the manner of Nassim Taleb's popular works, but Smolin lacks Taleb's gift for discursive narrative. The excursion into climate change and economics theory towards the end adds little to the book and it comes across as an exercise in scientific megalomania.The author also continually asserts that his thesis undermines the need for metaphysics. Yet the tradition he is writing against shares the same disdain for metaphysics too; Smolin is confused on this issue, assuming that the idea that Time is an illusion is inherently Platonic and supportive of traditional ideas of God and the ideal as Timeless. However, there has been a great deal of work in theology in recent years which opens up the concept of God as being involved in Time - such as Keith Ward's work on the Trinity. Henri Bergson understood that Time is real yet he also wrote metaphysics.Overall, I was disappointed by the quality of the book, but the central concept is important.