Quantenwelt: Wie wir zu Ende denken, was mit Einstein begonnen hat

by Lee Smolin, Jürgen Schröder (Translator)

Die Zukunft der Quantentheorie von einem der führenden Physiker unserer Zeit

Die Quantenphysik ist das Lieblingskind der modernen Wissenschaft. Sie ist das Fundament für unser Verständnis von allem was sich abspielt zwischen den Elementarteilchen bis hin zum Verhalten von Materie aller Art. Die Quantenphysik ist aber auch ein Problemkind: Ihre Erfinder können sich noch nicht einmal ‎auf ihre Grundlagen einigen, sie ist gefangen in seltsamen Paradoxien, und was sie ausmacht, klingt eher erfunden als erforscht. Warum das so ist, zeigt uns Lee Smolin in seinem neuen Buch: Die Probleme der Quantenphysik sind ungelöst und unlösbar aus einem einzigen Grund: Die Quantentheorie ist unvollständig. Er zeigt uns, wie wir zu einem wirklich neuen Verständnis von Natur und Universum kommen können, indem wir die Theorie vervollständigen und zu Ende denken, was mit Einstein begonnen hat.

Genres: Science, Physics, Nonfiction, Philosophy, History, Audiobook, Space

401 pages, Kindle Edition

First published January 1, 2019

About the author

Lee Smolin is a theoretical physicist who has made influential contributions to the search for a unification of physics. He is a founding faculty member of the Perimeter Institute for Theoretical Physics. His previous books include The Trouble with Physics, The Life of the Cosmos and Three Roads to Quantum Gravity.

Reviews

[BlackOxford · Rating 3 out of 5]

Do Scientists Make Good Philosophers?

I am confused. Not (inordinately) by quantum physics: Smolin is an excellent populariser of an almost impossible subject. But by his philosophy, which appears self-contradictory. Either I don’t understand his philosophical argument or he doesn’t. Either way, it’s not a terribly convincing exposition of his point of view.

Smolin begins in a way that makes my heart sing: “To explain the world to ourselves we make up stories and then, because we are good storytellers, we get infatuated by them and confuse our representations of the world with the world itself. This confusion afflicts scientists as much as laypeople; indeed, it affects us more, because we have such powerful stories in our tool kits.” A scientist who takes seriously the centrality of story-telling to everything connected with human beings is a rare and beautiful bird.

He then increases my admiration by recognising the essentially conventional character of not just science but all human inquiry: “To have a scientific mind is to respect the consensus facts, which are the resolution of generations of dispute, while maintaining an open mind about the still unknown.” Some people know more than others about certain things, like physics. Groups of these people argue continuously about what they know about those things. Their concurrence is the best view, for the moment, that we’re likely to have about those things, even if the unknown remains... well, unknown.

And finally, Smolin recognises the validity of what I call metaphysics or what others think of as religion, that intellectual realm beyond language and beyond at least current experience. “It helps to have a humble sense of the essential mystery of the world, for the aspects that are known become even more mysterious when we examine them further.” In many ways the mystery of the ‘beyond’ increases the more we know. Existence itself, we begin to realise, is not something we are able to measure and evaluate. The closer we get to this descriptor-which-is-not-a-property, the less sure we are about everything else. So that “The simplest facts about our existence and our relationship to the world are mysteries.”

But then Smolin starts to get a bit eccentric. He says, “Behind the century-long argument over quantum mechanics is a fundamental disagreement about the nature of reality—a disagreement which, unresolved, escalates into an argument about the nature of science.” But he has already implied that he doesn’t want to fight about reality but rather who has a better story. It is at this point that he gets swept into metaphysics not as a scientist, or even merely as a thinker, but as a polemicist, that is, someone with an ideological axe to grind, with a story that he takes to be more than a story. He wants to tell me, and you, and his fellow scientists what’s really there. And it is here that we part company.*

Smolin‘s world is divided between realists, people like him who believe that there is a world that exists independently of our experience of it; and purported anti-realists, those who believe that our knowledge of the world, particularly our knowledge of atoms, radiation and elementary particles, is not just a matter of convention but ONLY a matter of convention. That is to say, that what we know about is solely the language in which we know it, and that’s the end of the matter. He claims that most scientists today are anti-realists and that this attitude represents a kind of ideology which is inhibiting a solution to the big problems of contemporary quantum physics.

This distinction between realists and anti-realists, however, is a parody and a slur; and in the context of his argument, it is fraudulent. To understand why, it is necessary to define metaphysics a little more carefully. Immanuel Kant, the 18th century thinker, is the go-to guy when it comes to what we mean by metaphysics in the modern world. For Kant, metaphysics is not about religious revelation or mythical accounts about how the world came into being. Rather it is a purely rational endeavour for discovering what might lie beyond language, beyond our immediate experience and what allows us to connect the two. Our experience is certainly of reality; it’s the getting of that experience into language which causes the disjunction between reality and story.

The intellectual technique which Kant developed for metaphysical inquiry is called Transcendental Deduction. In simple terms this technique tries to establish what things must be the case in order for us to connect our experiences with the language we use to express that experience. These ‘transcendentals’ are things that we employ instinctively as human beings to make sense of what we casually call reality. Since we cannot even conceive of something called reality without them, however, we are never able to communicate about reality itself, only reality filtered or constructed through this human faculty. Since communication about this reality can only take place through language, we are constantly tempted, as Smolin admits, to confuse language with reality.

Even these transcendentals are parts of stories however. Kant suggested, for example, that reality must have certain characteristics if it were to appear to us as it does, even through our human filters. Space and time, he said, are two such characteristics. These are the kind of things that must be there in light of our experience. But about a century after he wrote, it became clear that he was wrong. It is not space and time that are elements of reality, but space-time, an entirely different metaphysical, as well as scientific category. Space-time is part of a contrasting story. As such it is yet another deduction about the world, not necessarily a ‘thing’ in the world. It is a word, a concept, that is connected to other words and concepts, and not to that vague unknown called reality.

And Smolin is undoubtedly correct: something is missing from current quantum theory. Perhaps, as he suggests, time generates space, which might then explain quantum entanglement. But neither Kant nor any other ‘idealist’ thinker, scientist or layperson, would deny the existence of reality as something independent of human perception or experience. What they are likely to deny is that the language we use to express this reality is ever any kind of permanent truth. Among other things, our deductions about what is actually ‘there’ are changing more or less continuously. And we know that the language we use to describe what is there, however scientific, is not the reality of what is there. The map is not the territory. Smolin’s story may turn out to be better by the standards of his colleagues but it will never be any more real.

Regardless of its elusiveness, indeed its inherent unattainability, reality is a necessary transcendental category for all scientific inquiry. Perhaps it is the only one that really matters. Without a presumption that there is something ‘there’ to be inquired about, inquiry would not take place. Without the failure of scientific stories to achieve what we hope to achieve, knowledge could not be distinguished from self-interested boast. Reality is a permanently receding horizon which doesn’t get any nearer the more precise our measurements or the more inclusive our theories become. To even suggest that some scientists claim that reality doesn’t exist is simply a tendentious ploy on Smolin’s part. It’s a ridiculous assertion. And it needlessly undermines his own position.

It is perfectly possible and respectable for scientists to differ about the best transcendental deductions to be made about reality. Or indeed for scientists to simply decline to make such deductions and ‘get on with calculating.’ And there are better and worse deductions to be made depending upon how inclusive they are of alternative deductions, that is to say, scientific stories about the world. Smolin’s story isn’t one of these; it is only about the possibility of one of these - that he apparently wants assistance in writing. He claims his story might be better once it gets finished. Sure, and I might have been a world-wide celebrity with Stephen Hawking’s intellect and Rock Hudson’s looks. Shoulda, woulda, coulda, as my mother used to say. Until his story is told, it has no status except that of dream.

The literary parallel is to me inescapable: Can you imagine a Jane Austen who instead of exposing the misogynistic mores of contemporary English culture in her work, wrote instead about the reprehensible lack of critical fiction among contemporary authors and solicited allies in her cause for ‘real’ fiction? Or perhaps a Cervantes who instead of creating the genre of the novel, complained about the absence of untrue but meaningful narratives about human beings trapped in their own imaginings? I think it’s clear that neither of these imaginary figures would be taken seriously by history.

So despite his overtly Kantian epistemology, which makes the distinction between stories and reality, what it is that Smolin wants to replace current quantum mechanics, is at best only something temporarily better not something definitive, true or even necessarily a closer approximation to reality. Instead of slinging intellectual mud, perhaps he just ought to get on with it. I regret my conclusion because Smolin is a fan of Leibniz, as am I; but he’s not doing himself or Leibniz justice with this fruitless rant about realism.**

=====================

* Smolin contradicts his initial assertions about science both implicitly and explicitly throughout the book. Here is one example:

“I want to uncover a world beyond quantum mechanics. Where quantum mechanics is mysterious and confusing, this deeper theory will be entirely comprehensible. I can make this claim because we have known since the invention of quantum mechanics how to present the theory in a way that dissolves the mysteries and resolves the puzzles. In this approach, there is no challenge to our usual beliefs in an objective reality, a reality unaffected by what we know or do about it, and about which it is possible to have complete knowledge. In this reality, there is just one universe, and when we observe something about it, it is because it is true. This can justly be called a realist approach to the quantum world.”

Note the sudden appearance of ‘complete knowledge’ and ‘truth’ and the disappearance of ‘mystery’. Smolin clearly reckons he is on the trail of ultimate reality itself. Note also that he is particularly concerned not to challenge our ‘common-sensical’ beliefs. Yet in the previous paragraph he wants us to dump our common sense understanding of what physicists call ‘locality,’ that is, the impossibility of two objects sharing properties at a distance. So much for the distinction between stories and reality.

** inspired by Leibniz, Smolin imagines a universe of entities called ‘nads’ which are similar to Leibniz’s ‘monads’. These nads are defined relationally to each other, an idea perhaps borrowed from the Christian doctrine of the Trinity in which each Person is defined entirely in terms of its relations to the other two. Nads are ‘events’ rather than things in Smolin’s conception. Interestingly, this idea has been previously put forth by Philip Caputo in his Theology of the Event. See: https://www.goodreads.com/review/show...

But this idea makes no sense in terms of Leibniz’s Monadology since each of his monads is ‘windowless,’ that is, has no perception of anything but it’s own isolated state. The only relation the monad has is with God. The monad’s perception is in fact supplied entirely by God who also ensures that the collectivity of monads is coordinated in their perceptions and actions. Smolin seems dangerously close to this theology when he suggests that there are ‘hidden connections’ among nads which defy locality restrictions and explain quantum entanglement. That may be interesting poetry but it is not compelling science... or theology.

[Brian Clegg · Rating 4 out of 5]

You wait years for a book on the interpretations of quantum theory and then they appear in droves. In reality though, it's a good thing - each of them has brought its own slant and approach, and never more so than in Einstein's Unfinished Revolution from theoretical physicist Lee Smolin.

Although Smolin takes us on a tour of the best-known interpretations, he sets out his intention from the beginning - he is a realist and wants an interpretation that incorporates realism. That might not seem much of an ask - surely everyone in science wants realism? - until you realise that the long-prevailing approach, the Copenhagen interpretation is anti-realist. This is because we're dealing with a particularly theoretical physics view of the world. It's not that those who have held the Copenhagen interpretation don't think the world as a whole is real. Rather that the requirement that, say, a quantum particle has no location, just probabilities, until it interacts with something means that quantum theory is not a description of something 'real' in the usual sense.

The lack of realism was one of the reasons that Einstein became so uncomfortable with the way quantum theory was developing, making his famous remarks about playing dice, and Smolin plays this up as a defender of Einstein's position, particularly in the preface to the book. I found the way this was done a trifle disingenuous, as Einstein was also unhappy with non-locality, the idea that, say one quantum particle can influence another instantly at any distance - and it's impossible to have realism in quantum theory without non-locality. But this is only a passing irritation.

Smolin comes down firmly on the side of realism, more it seems for intuitive reasons than anything else, and accordingly looks at the possible approaches that embrace this. He gives an excellent overview of the deBroglie-Bohm pilot wave interpretation, which he clearly likes - in it, particles are real, always having a specific location - but is honest about issues with it, notably his dislike of the way that particles are steered by the pilot waves, but the particles can't influence the waves. He then takes us through the Many Worlds approach, which he impressively shreds (rather beautifully referring to it as 'magical realism'), before introducing one or two more esoteric possibilities.

Up to this point, Smolin has done what others have done, and does it very well, managing all this without any mathematics and with clear, approachable language. But then he faces the problem square on. No approach is totally satisfactory. And, for that matter, no one has managed to bring general relativity and quantum theory together despite decades of trying. He suggests, then, that we need to take a step back and start from scratch, giving us an overview of some, at the moment very toy, approaches to doing this.

This section is much harder to follow than the rest. When Smolin outlines his current ideas involving networks* of 'nads', what strikes me is both fascination and sadness. Fascination to see how such an edifice is constructed, but sadness because, for me, what he constructs seems far further from any idea of a comprehensible worldview than even the Copenhagen anti-realism. This is the only place where I got the feeling of a theoretical physicist detached from the rest of us, except when Smolin makes the assertion that the anti-science efforts of climate change deniers and some religious extremes reflects a lack of trust in science because of anti-realist quantum interpretations. This seems a very parochial worldview that, dare I say it, suggests theoretical physics has more influence in the world than it really has.

That isn't the end, though. Although very inward looking, it's well worth persevering with Smolin's short epilogue in which he explains the difficulties of making the leap away from the standard approaches at a fundamental level and starting over within the confines of the academic system, and ponders whether to make the leap - I found this genuinely moving.

Overall, while more effort was needed to make the nads comprehensible (and particularly seeming anything like reality), the book is an excellent contribution to thriving debate on what to do about the elderly enfant terrible of physics, quantum theory.

* Purists: I know they're not strictly networks, but it's alliterative.

[D · Rating 5 out of 5]

A convincing, intuitive and reasonably clear exposition on why the author, who is a world class theoretical physicist, believes that quantum theory is incomplete, even without considering the problem of unifying it with gravity.

Not being a physicist, I was always baffled by the standard Copenhagen interpretation as it claims that reality changes (the wave function collapses) just because it is observed. So I was very happy to read that, according to the author, I am a 'realist' like him because I agree that physics should explain the universe, irrespective of there being humans to observe it.

The book considers some alternative theories/interpretations such as pilot wave, objective-collapse models and the Everettian many-worlds interpretation; all of them the author considers to be more or less unsatisfactory. The book then ends with a stimulating sketch of a new (2018) theory that takes time, but not space, as a given, and is based on (energetic) causal sets of events.

I learned a lot, even without any formulas in sight. Highly recommended.

[India M. Clamp · Rating 5 out of 5]

This book gently encourages us to look at our world from the perspective of donning a different pair of glasses, allowing us to see and imagine our world on an atomic scale. To do so, Smolin recommends using a Schrödinger’s cat rationale (a thing that may be dead or alive) or a belief that the world is not really in existence independently of our observations of it. Its' in this way quantum reality comes into view (observation and interaction).

"But the quantum state is only indirectly related to what we observe when we make a measurement--and that relation is not deterministic. The relation between the quantum state.”
—Lee Smolin

Werner Heisenberg (deduced via mathematics) without observation, reality simply does not exist. “The idea of an objective real world whose smallest parts exist objectively in the same sense as stones or trees exist, independently of whether or not we observe them ... is impossible." John Wheeler, too, used a variant of the double-slit experiment to argue “no elementary quantum phenomenon is a phenomenon until it is a registered (‘observed,’ ‘indelibly recorded’) phenomenon.” So without seeing, observing or interacting, there is no reality. Smolin asserts, "everything is uncertain until it is observed, and that observation inevitably alters reality."

[Ryan Boissonneault · Rating 5 out of 5]

To understand the enigma that is quantum physics, it’s best to start with the relatively easier problems of classical physics.

Classical physics was invented by Galileo, Kepler, and Newton to deal with everyday macroscopic objects that you can see with the naked eye or with the assistance of telescopes. Classical physics—equipped with calculus and its associated equations—can describe the precise location, speed, direction, and trajectory of any visible object, from airplanes and cannonballs to stars and planets.

If you were to take a snapshot of the solar system at this moment in time, you could measure, using the equations of classical physics, the position and velocity of each planet and could predict the precise location of any one planet at any future time (within a small margin of error up to a limited but significant amount of time). The mechanics of the equations are complex, but the problems are fully soluble.

As Lee Smolin explains in his new book, Einstein’s Unfinished Revolution, this turns out to not be the case at the smallest of scales. When you start asking what matter is made of—atoms, protons, electrons, photons, quarks, etc.—a new type of physics is required, quantum physics. Quantum mechanics was invented in the early twentieth century to explain quantum physics, and seeks to describe how quantum particles behave and interact with each other.

If you think of the atom as a miniature solar system (with the nucleus as the sun and the electrons as planets), you would expect quantum mechanics to be able to chart the trajectory of an electron in the same way classical physics charts the trajectory of a planet. But this is not what you find, because electrons (along with atoms and other subatomic particles) do not behave like planets (or any other macroscopic object). Experiments have confirmed that particles exhibit the following odd behaviors and properties:

1. Superposition - quantum particles exhibit weird dualities: electrons, for example, can be in two different places and embody two different properties simultaneously. Electrons are both particles and waves. And if you measure an electron’s exact position, you can’t precisely measure its speed and direction. Conversely, if you measure its speed and direction, you can’t precisely measure its location (this is the uncertainty principle). Electrons pop into and out of existence and change their properties at random. Two electrons may start out in identical states and end up in different positions. That means that you only ever have half of the information you need to make predictions that are anything more than probabilistic. This is contrary to classical physics, and is analogous to being able to only calculate the position or velocity of a vehicle but not both. Imagine driving a car and having no method available to know where it will end up based on its speed and direction. (Here’s a great video that further explains superposition.)

2. Entanglement - classical physics relies on the concept of locality. This means that objects cannot influence other objects unless they directly impact them or transmit a force over distances. Distant objects can communicate with each other, but not faster than the speed of light. Enter quantum mechanics, where two particles can influence each other instantaneously at large distances faster than the speed of light. This is the principle of nonlocality. It would be like the earth suddenly reversing its rotation and having an instantaneous impact on the rotation of Mars.

3. The Measurement Problem - In classical physics, we can measure the speed and position of objects without altering their course. Each object has a definite position and velocity. Not so in quantum mechanics. Particles only have a definite position after we measure them, and exist in a superposition of possibilities prior to measurement. Further, each measurement impacts the quantum state we’re trying to measure. It would be like the act of measuring the orbit of Mars actually changing Mars’s orbit.

So what are we supposed to make of this? We know that even though quantum mechanics has weird properties and paradoxes and can only speak in probabilities, we also know that it makes extremely accurate predictions and is responsible for the development of many technologies.

It would seem that we have two choices. One is to accept the findings of quantum mechanics as they are, admitting that the underlying reality at the quantum level is unknowable. Quantum mechanics is a shorthand, a useful way to make predictions but that is incapable of describing a reality that either does not exist independent of our minds or that is beyond our comprehension.

Another approach is simply to say that if quantum mechanics disagrees with our deepest intuitions, perhaps quantum mechanics is wrong—or at least incomplete.

The first approach was adopted by the likes of Niels Bohr and Werner Heisenberg, who, along with others, developed the “Copenhagen interpretation” of quantum mechanics, which essentially states that quantum mechanics is complete and that we have to deal with whatever it tells us, even if we don’t like it. This is the anti-realist position. Here’s how Smolin describes the philosophy (in which he does not agree, as we’ll see in a minute):

“Bohr called the new philosophy complementarity. Here is how he talked about it: Neither particles nor waves are attributes of nature. They are no more than ideas in our minds, which we impose on the natural world. They are useful as intuitive pictures that we construct from observing large-scale objects such as marbles and water waves. Electrons are neither. Electrons are microscopic entities that we cannot observe directly, and so we have no intuition about them. To study electrons we must construct big experimental devices to interact with them. What we observe is never the electron itself; it is only the responses of our big experimental devices to the tiny, invisible electrons.”

This interpretation dominated physics for the entirety of the twentieth century, despite the existence of other plausible theories that are starting to be taken more seriously today.

The alternative view, espoused by Einstein, Schrodinger, Smolin, and others, simply states that quantum mechanics is incomplete. In this view, there IS an underlying reality that makes sense, we’ve just yet to find it. This is the realist position, which states that there is a reality that exists independent of the mind, that we can understand it, and that it is the job of science to create intelligible explanations.

Most of Smolin’s book seeks to convince the reader of the realist position and that it is a tragedy that the anti-realist position (the Copenhagen interpretation) was adopted dogmatically for an entire century. Smolin’s main argument is that we have to move beyond quantum mechanics to develop a realist model that is experimentally accurate and coherent. To this end, promising lines of realist research include pilot-wave theory (which proposes the existence of both particles and waves, with the waves guiding the location of the particles) and various collapse models. None have yet proven entirely satisfactory.

So which view is correct? The realist or anti-realist (Copenhagen) interpretation?

While the quantum puzzle remains unsolved—and may remain unsolved indefinitely—I find myself sympathetic to Smolin’s views. To be a realist only requires that you think 1) there is a universe that exists independent of the mind, and 2) that we can understand it in coherent terms.

Regarding the first premise, it is quite egocentric to think that the universe only exists when we contemplate it. As evolved primates, human beings are relative newcomers; the universe existed for billions of years without us and there’s no reason to suppose that it will cease to exist when we’re gone. Our evolution implies an environment available for us to evolve within and adapt to, hence an independent reality. (Of course, perhaps we’ve adapted only to navigate the macroscopic world and therefore have no capacity to comprehend the world at its smallest scales. If that’s the case, then the anti-realist position is, in fact, true, not in the sense that there is no independent reality, but in the sense that we can’t comprehend it, like a person born blind not being able to comprehend sight. We cannot discard this as a possibility, but let’s move on.)

Second, science has made tremendous progress under the realist philosophy. If you chart the progress of science, if something didn’t make sense, we continued to investigate it until it did. If a theory was incoherent, that meant it was wrong.

Think about it this way. You can construct a theory of the universe that has the earth at the center and still make relatively accurate predictions about things like the motions of planets and the predictions of eclipses. But, despite these otherwise accurate predictions, the theory is still wrong; our earth-centered solar system doesn’t describe reality independent of the model.

It seems, to me, that quantum mechanics is like the earth-centered model of the solar system. We can make calculations and predictions with it, but this doesn’t, in itself, mean that the theory accurately describes reality.

(A side note: for all of those people who like to invoke quantum mechanics in support of whatever bizarre supernatural theory they’re peddling, they are doubly confused. First, quantum properties do not apply to macroscopic or emergent properties, so even if quantum mechanics is correct, the effects don’t scale up to macroscopic phenomena or emergent properties like consciousness. Second, quantum mechanics could be wrong itself, even in its descriptions of the quantum world. So, remember this: anytime a non-physicist brings up quantum mechanics during a non-related topic, your bullshit meter should be going haywire.)

Still, the anti-realist position could be right, and if it is, then we will never have a coherent theory, and we will be searching forever in vain. The anti-realist position declares the quantum state unknowable, so if that’s true, we will never understand quantum reality, but we will also never get to the point where we know that we can’t understand quantum reality with certainty. This discouraging possibility cannot be ruled out.

But there’s some reason for hope. We’ve encountered difficult problems before, problems that defied explanation. And out of those problems came theories like calculus and relativity, theories that both make accurate predictions and are coherent. In that respect, along with Smolin and in the true spirit of science, I’m holding out hope that we will one day coherently solve the quantum puzzle.

[James F · Rating 3 out of 5]

One thing is axiomatic -- Lee Smolin's books are always fascinating. He is a prominent physicist with legitimate credentials, but always somewhat outside the mainstream. One of his main concerns is with trying to reconcile what we know about quantum physics with a realist philosophy that assumes there is a real world independent of human consciousness.

This book, just published, reviews the development of quantum physics with an emphasis on the realist alternatives to the Copenhagen interpretation(s) of quantum mechanics, such as the pilot wave theory proposed by deBroglie and later revived by Bohm, spontaneous physical collapse theories, and the multiple worlds theory with its variations.

Smolin then suggests a possible way of going beyond quantum mechanics to something more fundamental -- a theory he calls "energetic causal sets" which sees the world as composed of causal networks of events which create spacetime through their "views". He likens this account to Leibniz's theory of monads.

While I am not a physicist and certainly do not have the background to judge these theories (which are presented here without the mathematics necessary to really understand them anyway), I did find it interesting to learn that there are such approaches to going beyond the current views of quantum mechanics.

[Nitica]

Got my signed copy after Lee's talk here at PI. Pertinent to the area of Quantum Foundations, Lee argues for the need of a realist theory. Excited to go through it!

[Miriam · Rating 3 out of 5]

Interesantă!

[Brandon Hensley · Rating 4 out of 5]

I encountered Lee Smolin around the same time I was introduced to Speculative Realism and was immediately gripped by Smolin's accessible readability paired with his insistence that the human observer is far too privileged in quantum mechanics. Far too often we read about developments in the field of quantum mechanics that are accompanied with taglines like "It's quantum mechanics; you're not meant to understand it." Smolin rejects this idea in favor of the quantum being articulated simply and elegantly according to realist terms. After introducing the history of the theory of quantum mechanics, he critiques it calmly without polemicizing his position. Smolin then explores realist interpretations of quantum physics such as pilot wave theory and spontaneous collapse. Illustrating problems with all these realist interpretations, Smolin bridges the gap between professional theoretical physics and lay understanding. One of the key components of philosophical realism is that everything remains largely incomplete. There is always more to discover, and we must always use what we know to highlight what we don't so that we can investigate further. Smolin leaves us understanding that quantum mechanics is incomplete but a dead end with nowhere to go, and then leaves us in a lurch on the realist alternatives without making us feel that the search in that direction is hopeless. The one criticism I would give is that he does a fantastic job concisely introducing quantum mechanics, and then repeats himself fairly constantly throughout the rest of the text. It could be a case of simply hedging the technical side of things to ensure that he doesn't lose the reader, but I found it jarring to his otherwise conversational prose. I highly recommend this book to anyone who has ever read highly publicized breakthroughs in quantum mechanics and thought "This feels off somehow and I can't place it." Smolin is here to tell you why.

[Gendou · Rating 4 out of 5]

This book gives a good survey of the search for a unification between QM and GR. It shines a light on the measurement problem and does a good job evaluating the pros and cons of the several interpretations of quantum mechanics we have today. Unfortunately, Smolin plays favorites and I think he really checked his objectivity at the door in this book. That's not always a crime, but it did leave me very guarded as a reader. You should be, too.

Smolin is an uncompromising philosophical realist. Now, that's great. For him. But his approach to this book is to shove it in the reader's face, without adequate justification. He simply declared by fiat, "Realism is always to be preferred in science." Um, but like why, though? He rejects several interpretations of quantum mechanics merely on the basis that they aren't "real" enough for him (Copenhagen, Many Worlds, etc.) and seems to think this is in line with the philosophy of science. I just can't agree with his holding realism as a sacred tenant of science. There is no justification on offer for this.

Don't get me wrong. I love Smolin. But he did make one other mistake worth mention. He says that the Many Worlds Interpretation poses "ethical quandaries" and adherence to it is "inimical to the common good". He says that "believing in the existence of all these copies lessens my own sense of moral responsibility." This is a bald-faced appeal to consequences.

[Stephen Sowle]

New Scientist: “IN AN obvious if rather lovely irony, quantum physics has always led a double life. It fundamentally shifted our world view by building a new picture of life at the subatomic level, explaining everything from elementary particles to the behaviour of materials. But it also created bitter divisions over which interpretation best describes our world.
For a few years now, theoretical physicist Lee Smolin, a pioneer of the theory of loop quantum gravity (one of the big hopes for developing a quantum theory of gravity), has thought he has an answer. The reason quantum physics is still so contentious is that the theory is incomplete, that quantum mechanics doesn’t provide an explanation for what happens at a larger scale because it leaves out aspects of nature needed for a true description. In Einstein’s Unfinished Revolution, Smolin works through alternative interpretations, from pilot wave theory to the many worlds interpretation – only occasionally, becoming textbooky. He ends up with his own theory – and that, as your parents might have said, you will have to discover for yourselves.”

[Jean-Pascal · Rating 3 out of 5]

Un essai assez difficile qui exigerait une relecture pour passer à quatre étoiles. Les propositions finales sont assez excitantes et touchantes les déceptions de l'auteur que l'on lit entre les lignes. Le livre aurait sans doute gagné à être plus épais avec des résumés et des points d'étapes où se reporter.
En tout cas, une découverte des points de vue réalistes.

[Odo · Rating 3 out of 5]

3.5/5.0

[Vegeta · Rating 5 out of 5]

Physics is like a college campus in which every building is named after someone. The uncertainty principle is named after Werner Heisenberg and the constant is named after Max Planck. "Physics gives rise to observer-participancy; observer-participancy gives rise to information; information gives rise to physics". Through this book Lee Smolin says that despite we have failed so far but we are on the right track. Smolin elucidates complex science without equations which is quite appreciable. He is an extremely creative thinker. I like how he simplifies and explains the theory by giving basic examples.

Einstein’s theory of relativity delivered an accurate explanation of space, time, and matter for most of the universe, but it breaks down at the level of atoms: the quantum world. Quantum mechanics works beautifully but only by postulating paradoxes and nonsensical behavior such as an electron being both a particle and a wave depending on the experiment. Einstein insisted that this didn’t make sense, but most colleagues had no objection. Smolin reminds readers that this is an argument between realists and nonrealists. Quantum physics is indeed the golden child of modern science. It is the basis of our understanding of atoms, radiation, and so much else, from elementary particles and basic forces to the behavior of materials. But for a century it has also been the problem child of science. This is a philosophical debate that has disturbed thoughtful scientists for a century. The details are complex however the ideas are fundamental.

I like how he explained each theory with ease and without any complex equations. I like his straight view about that he is not afraid to confess that no issue in quantum foundations has been more challenging and more painful to him personally than the issue of Everett, where he find himself in disagreement with friends and colleagues for whim over years he have grown to have great respect. However our job is to figure out how the world is, and it is not up to is to impose our personal likes and dislikes. I like his idea where he says that others are free to do anything but he chose to invest his time in developing cosmologies that inspire us to look for new particles, new phenomena, new physics, over the scholastic contemplation of the lives of copies of ourselves. The book is mainly about the debate between realists and anti realists and history of quantum physics and various theories in the favour as well as against it. Realism indeed, in any version, has a price. I believe, as expressed by Lucien Hardy, many physicist would prefer realism to operationalism, and would take an interest in the discovery of realist approach to quantum theory that over came the weakness of existing approaches. The question is only what price we have to pay to get a new theory that makes complete sense and describe nature correctly and completely.

The rest of the book is about the future of the realist approaches to the quantum physics. There are many different ways to express how the quantum world differs from the classical world of Newtonian physics. If you are happy taking an anti realist point of views, there are range of options: you can adopt bhor's radical denial also quantum bayesianism. Another option is to embrace a purely operational perspective. There is much more that could be said about these recent non realist and magical realist perspectives. But the bottom line is that if your interest is pragmatic and you want to use quantum theory to understand questions other than those arising from quantum foundations any of these will serve to frame your calculations and explaination you draw from them. But if you want to solve the measurement problem in a way that give a detailed description of what goes on in an individual physical process, nothing but a realist description will do.

According to me, the most interesting chapters were chapter 13, 14 and 15; where he explained various theories and gave his opinion about them. Also various principles like background independence, space time relation, casual completeness, reciprocity and the identity of indiscrenibles.

The main message of this book is that however weird the quantum world maybe, it need not threaten anyone's belief in commonsense realism. It is possible to be a realist while living in the quantum universe. For the realist, quantum mechanics cannot be the final story. There is still more to discover. Nonetheless, nature is comprehensible. I am optimistic that the universal power of reasoning that each of us has, together with our vast powers of imagination and our ability to invent novel ideas, will suffice to comprehend the universe. I agree with lee where he finds himself deeply frustrated by our lack of definite progress on fundamental physics during this last half century, however i am optimistic about the long run. I am confident that in the future we will know vastly more about nature than we do. It would be fortunate indeed if we already have among our library of ideas and the answer to how to complete Einstein's twin revolutions as long as we keep the great adventure of science alive.

This book is definitely worth to re-read and i took quite a large amount of time reading and re-reading this amazing book, full of extraordinary ideas and the best explaination yet of what has yet to be explained. Also well written and engaging.

[David · Rating 3 out of 5]

My rating of "liked it" reflects appreciating that I got an update on aspects of physics and learned about efforts to find alternatives to current quantum physics' "magical" aspects. On the other hand, I wasn't impressed by the alternatives that still tend to depend on "wave functions" guiding particles and/or collapsing superpositions (although not as a result of human observation.) While Smolin doesn't necessarily object to these factors, he does not consider any of the alternatives (including his own ideas) to be ready for prime time. So, the book is more about developing a framework within which to search for better alternatives.

As a scientific person who didn't specialize in physics, I had thought the "wave-particle duality" might have been a result of something like the old story of several blind men feeling different parts of an elephant and drawsing different impressions of what an elephant was like. Maybe a "blind man" testing one part of a quanta gets the impression of a particle, but another testing a second part gets the impression of a wave. But in reality, it's not quite either. The book gives little encouragement for such a view.

The book made me ask myself questions and made me realize I had viewed physics with a shallow conception of some elements (which I now must question.)

[Jake · Rating 4 out of 5]

This is a small history of the puzzles of quantum mechanics, but actually, it is more so just a call to arms for physicists to re-look at the fundamentals of their subject as a whole. Smolin claims that the type of reflection that he advocates for, has become out of vogue post-Copenhagen's rise of hegemony within universities.

We must, in smolin's views, re-look at the principals of physics and QM to finish Einstein's revolution and make sense of physics. Ya know. In the Logical Laplacian- Newtonian - Galileoian- Spanozaian - platoian -but - actually - pythagorian type of way

The later chapters are much better than the initial ones, overall it was pretty good. Boring at times - only cause many of us have heard it all before. AT the end though, smolin gets a bit original.

Recommended for :
- Those unsettled with the state of quantum mechanics who need a kick of inspiration.
- philosophers of science
- physicists
- young scientists confused by Heisenberg and Schrodinger

[Cecil New · Rating 5 out of 5]

Great read! I think Smolin's sense of things has the ring of truth, but, please, I'm less than an amateur.
- that QM is incomplete and that realism will win-out
- that time is fundamental and space is emergent.

Two links:
http://backreaction.blogspot.com/2019...
http://backreaction.blogspot.com/2019...

This is also the first completed book where I used a book log (https://bulletjournal.com/blogs/bulle...). See my comment to that article to see how I modified the presented technique to suit me.

[Mitch Allen · Rating 5 out of 5]

Stunning

I have read numerous books on quantum physics. For awhile now, I have been searching for a book like this, one that would confront the lack of a complete quantum theory and offer an idea on how to fill that void. One that would tell the whole story of quantum theory, including rather than rejecting the “dissidents”. One that would develop a forward-looking vision and suggest that we pursue that vision with deliberate pace. This is that book.

Clear, accessible and engagingly written. It left me satisfied, intrigued and inspired.

[Serdar · Rating 4 out of 5]

I gave this a second read recently, and I like it even more on revisiting it now that I have some additional context (further readings in the state of QM, etc.) I still think it's likely to be of the most interest to people who are fiercely interested in this subject by default, so no "Brief History Of Time"-level accessibility here, but still - we need more work that tries to look beyond the abysmal failure of string theory to produce a single testable prediction, and to suggest more complete explanations for the way our universe behaves. More Smolin, please.

[Justin · Rating 1 out of 5]

Did not finish. I expected to learn a lot about quantum physics and how the field is advancing. Instead I got an entire book length rant from an author about why everyone else is wrong and he is right. I couldn't make it past 50 pages and I skimmed farther on to see if it got better and it didn't so I gave up. Maybe I'm just not the target audience, or maybe this book promised too much and was marketed poorly.

[Arno Mosikyan · Rating 5 out of 5]

Always loved contrarian views in science, those keep mainstream in check, and pose discomforting questions for the latter for the benefit of her majesty Science. Lee Smolin is a brave fellow.

[Nilesh Jasani · Rating 3 out of 5]

Unfinished Revolution is a book with convoluted motives. One is never sure what its true intentions are.

Unlike traditional popular science books, this one does not expand or expound or explain quantum physics/relativity or their history. Unlike the author's other books, this one is also not about the alternate theories that might marry the two sciences someday, like the author's favorite loop quantum gravity.

The author spends a vast stretch of the book trying to assert that quantum physics is an incomplete theory. Despite his attributions of the otherwise, those who hold diametrically opposite views on quantum physics interpretations, say the author's anti-realists, are unlikely to disagree. Not discounting the successes of the two giant theories or expositions like no local hidden variables, almost everyone agrees that deeper sciences/explanations are waiting to be unearthed to resolve numerous contradictions between what we observe versus what the theories predict. That the two theories do not come together well is another reason why almost everyone believes that neither of them is complete. One does not have to beat up certain quantum physics anti-realists' assertions to conclude that these sciences are incomplete as they stand now.

The author strongly asserts that anti-realists' assertions about quantum physics assertions are mostly wrong. Realists, like Einstein and the author, believe that there is a real-world in existence out there irrespective of our measurements and models. Anti-realists feel that the only world we feel is the world we obtain with our measurements, which is a mere outcome of the myriad of potential worlds that stay in existence until our probes. While neither side assertions are so simple, and neither has too many who agree with others of the same camp, the author makes valid philosophical points.

It is easy to sympathize with the assertion that measurements do not maketh a reality. It is far better to believe that things do not spring into existence only with measurements while staying only as a potential until then (or the proposition that what we observe is only because of the questions we ask). That said, at some level, existence and all models describing them, are irrational. They contain equation parameters, operators, interrelations, or even interpretations that do not have further rational antecedents. In other words, as compelling as realist interpretations may appear in a specific rational framework, existence or scientific laws do not have to follow such what we deem reasonable.

Quantum Physics has not lent itself to conventional mathematics with its reliance on random operators and various "dualities," with the dualities implying characteristics adopted from two different/conflicting categories of existential modes. Consequentially, we must be ready to accept that its human language interpretation could be mind-bending as well. Anti-realists' explanations might be inadequate, but don't have to be. It is also conceivable that sciences at the root are not explainable in human languages, even if mathematics may take us far closer to the essential elements, far beyond the points where human language interpretations collapse.

One example of such a phenomenon is machine-learning driven programs that beat any human being in a game like Go. The programs - aka, equations - that provide such results exist, but there are no complete human language explanations of what these programs do to attain such invincibility.

Mr. Smolin conceptualizes a new type of science from a primal element called "nad," defined by its relationships with other nads, and having entanglement with similar other nads anywhere in the world. What the author hypothesizes in the framework to build the quantum units of space-time is not less fantastical that ancient philosophers in their thinking of atoms, basic elements, or various interrelationships. There is no reason to have only one basic unit - whether nomenclaturally a nad or a string is a matter of language preference. It is far more likely that these nads' characteristics are as variegated and complex as those of atoms or electrons and other fundamental particles in current sciences than what the author imagines.

In summary, Mr. Smolin is exceptional in criticizing many quantum physics interpretations, but he has done this no less brilliantly a handful of times in the previous books. Most readers are likely to struggle with the speculative "nads" section where he fails in verbally explaining the lattice he conceptualizes and from there to the construction of space-time as they become apparent in both relativity and quantum physics.

[Vanessa Ortiz · Rating 2 out of 5]

This book is basically an analysis of various theorems and gaps in knowledge in the world of quantum physics. Aside from the technical science, the main take away from this book is the importance of scientific advancement. Specifically, the idea that there is no cookie cutter way to achieve this - and that sometimes unconventional methods are those that produce the greatest results. I was also intrigued by his commentary on the state of the scientific and academic community and their reticence to go against the grain and fear of failure.

I am quite impressed with the author's ability to simplify these advanced topics by cutting back on jargon (when possible) and using basic analogies and figures to get some points across. Although the author did a pretty good job of describing these technical topics to the layperson, I still think the reader may need a more advanced background in science/physics to understand some of the topics discussed - there were several instances where he lost me for a bit. I do appreciate the inclusion of footnotes, a basic glossary, references, and a list of further recommended readings. Although I love all things science, physics is not at the top of my list or expertise. I appreciated the content presented and learned some new things but this was not the most enjoyable reading experience for me. If you are really into physics, I think would enjoy this book.

[Naeem · Rating 5 out of 5]

This a fantastic overview of the map of current physics with all its controversies, all its theorists, and all its most meaningful questions. Smolin has a clear understanding of the average reader's needs and abilities. He tells his story from the point of view of a scholar/theorist who is in the middle of the great debates. He is a partisan for what he calls "realism" -- a unified theory that depends on the existence of a knowable world that exists outside of our concepts (against the relativism of the Copenhagen School). So we get two points of view: a overview of the overall cosmos but also a position he takes with which to convince the reader.

I cannot say that I was able to follow every twist and turn in the theoretical presentation. But I got most of it and would happily read this book again. Great job, Lee. (We were colleagues of sorts in his short stint at Syracuse University).

[Mishehu · Rating 4 out of 5]

4 stars for the passion and precision of the writing, and the ideas. Less one star for failing, beyond a certain point, to guide the lay reader. This is not your standard popular science treatment. True, it lacks math. But for all that Smolin very ably describes the dominant strains of quantum theory, he does a much poorer job of describing cutting-edge revolutionary thinking (his own included) in this area. The last third of the book was akin to an entrancing prose poem — highly suggestive but hardly clarifying of the concepts/theory/models at stake. After a certain point, Smolin seems to have abandoned the notion that he was writing for an interested lay readership, and instead began writing a kind of ‘lay treatment’ for scientific sophisticates. I don’t regret reading this book. What it does well it does very well. And the material I had a tough to impossible time following I nonetheless found highly intriguing. That said, I’m ready to move on.

[Steve · Rating 3 out of 5]

Smolin does a good job of shedding light on the shadowy world of quantum mechanics in a way that lay people can grasp, but doesn't go much deeper than the information that is readily available from many sources. Rather, he spends a good deal of time discussing the theories that may fill in some of the holes in quantum theory. Without a deeper understanding of what physicists have already figured out about quantum mechanics, however, I found it very hard to follow his arguments.

[Fabrizio Valenza · Rating 5 out of 5]

Ottimo lavoro, le cui conclusioni sono superiori alle aspettative create dalla partenza. Inoltre, riconosce il giusto spazio a Leibniz. Infine, la teoria finale proposta da Smolin ha ottimi e suggestivi punti di contatto con alcuni principi fondamentali della Filosofia mistica della conoscenza.

[charlie · Rating 5 out of 5]

wirklich tolles buch und sehr verständlich erklärt :)

[Steven H · Rating 5 out of 5]

IS TRADITIONAL QUANTUM MECHANICS AN ‘INCOMPLETE THEORY”?

Lee Smolin (born 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the philosophy department at the University of Toronto.

He wrote in the Preface to this 2019 book, “The best understanding of what … atoms and electrons are, is expressed by … quantum physics. But, as it seems everyone knows by now, that is a realm full of paradox and mystery. Quantum physics describes a world in which nothing has a stable existence… This is great for popular culture, which has made ‘quantum’ a buzzword for cook, geek mystification. But it’s terrible for those of us who want to understand the world we live in… a theory called ‘quantum mechanics’ … has been… the golden child of science… It has also been… a troubled child. From its beginning… Some expressed shock and misgivings, even outrage. Others declared it a revolutionary new kind of science, which shattered the metaphysical assumptions about nature and our relationship to it that previous generations had thought essential…

“I hope to convince you that the conceptual problems and raging disagreements that have bedeviled quantum mechanics since its inception are unsolved and unsolvable, for the simple reason that the theory is wrong. It is … incomplete. Our task… must be to go beyond quantum mechanics to a description of the world on an atomic scale that makes sense. This task might seem overwhelmingly difficult, were it not for … an alternative version of quantum physics that does make complete sense… The scandal… is that this alternative form of quantum theory is rarely taught… There are several alternative formulations of quantum physics that make consistent sense. The challenge now is to build on these to find the right way to understand quantum physics…Problems such as quantum gravity and the unification of the forces… are, I believe, foundering because at the foundations of our theorizing is an incorrect theory.”

He outlines, “Behind the century-long argument over quantum mechanics is a fundamental disagreement about the nature of reality… Two questions underlie the schism. First off, does the natural world exist independently of our minds? … does matter have a stable set of properties in and of itself, without regard to our perceptions and knowledge? Second, can those properties be comprehended and described by us? Can we understand enough about the laws of nature to explain the history of our universe and predict its future?... People who answer ‘yes’ to these two questions are called realists. Einstein was a realist. I am also a realist. We realists believe that there is a real world out there, whose properties in no way depend on our knowledge or perception of it.” (Pg. xix)

He explains, “This book has three purposes. First, I want to explain to lay-people just what the puzzles at the heart of quantum mechanics are…. I will not stay impartial… .I side with Einstein. I believe that there is a layer of reality deeper than that described by Bohr… Thus, my second purpose is to advocate a point of view about the puzzles of quantum mechanics… I can make this claim because we have known since the invention of quantum mechanics how to present the theory in a way that dissolves the mysteries and resolves the puzzles. In this approach, there is no challenge to our usual beliefs in an objective reality, a reality unaffected by what we know or do about it… I have been thinking about the question of how to go beyond quantum mechanics since the mid-1970s, and I’ve never been more excited and optimistic about the prospects for success. So this is my third reason for writing this book, which is to bring to a wider audience a report from the front in our search for the world beyond the quantum.” (Pg. 10-13)

Of the acceptance of quantum mechanics by most physicists, he comments, “One of the hardest lessons to learn in academic life… is the speed with which a radical insurgency can become orthodoxy. In just a few years a generation of students championing a dangerous new idea are elevated by an initial success into professorships. From these positions of influence they form a powerful network … which they use to ensure the continuation of the revolution. Such was the case with the generation of quantum revolutionaries.” (Pg. 94)

He recounts, “[An] obvious solution to the challenge of the wave-particle duality was thought up by Louis de Broglie. He worked it out in detail and called it the ‘pilot wave theory.’ … The core of pilot wave theory was… that the electron is actually two entities, one particle-like and one wave-like. The particle is always located some particular place and always follows some particular path. Meanwhile, the wave flows through space, taking simultaneously all the possible paths or routs through the experiment.” (Pg. 98) He laments, “Few quantum physicists mentioned de Broglie’s theory … after its presentation in 1927… no textbooks mentioned it for decades after. It is not that there were Copenhagen textbooks and pilot wave textbooks. There were only Copenhagen textbooks.” (Pg. 103) He continues, “if someone raised the possibility of a realist version of quantum mechanics, the response… [was] ‘von Neumann proved there is no alternative.’ One can imagine it would have changed things … if Grete Hermann’s paper showing that no, con Neumann hadn’t proved anything, had been known. But it simply wasn’t.” (Pg. 106)

He asserts, “The pilot wave theory explains everything that ordinary quantum mechanics does, without the awkwardness… What is new is that there is a particle that moves according to its own law, guided by the wave function… pilot wave theory explains what quantum theory does not. It gives a complete description of what goes on in every individual process… It explains where the uncertainties and probabilities come from… And it solves the measurement problem because there is no need to distinguish experiments from other processes.” (Pg. 116-117)

He states, “The wave function surrounds where I am now, but it also has other branches where I might be, but am not… the one branch that guides me now is that only one branch coincides with, and guides, the atoms that make me up. The myriad other branches flow on, empty… there is basically no chance that the empty branches representing the loves we didn’t live and the choices we didn’t make will have any effect on our futures… So for all practical and moral purposes, if pilot wave theory is right, we can ignore the empty branches. We are real only once, and live out that life on that one occupied branch. We need care about, and be responsible for, only what the one real version of each of us does.” (Pg. 126-127)

He says of Hugh Everett III’s ‘Many Worlds Interpretation,’ “it turned out to be a bit naïve, as it ran into several big problems. The first problem … is that he suggested that the branching happens when a measurement is made. But this makes measurements appear to be special, whereas it is a basic tenet of realism that measurements are ordinary interactions to be treated like any others… To avoid making experiments special, the universe must split each and every time there is an interaction which has more than one possible outcome. But this is happening literally all the time… Moreover, the interaction that causes the splitting can happen anywhere in the universe. So while you are reading this sentence you are splitting a vast number of times, into a vast number of versions of yourself. This is a lot to ask someone to believe… A second problem is that … the branching … must be irreversible… A third big problem… [is that] Everett’s version of quantum mechanics tells us only that every possible outcome occurs. Not with some probability, but with certainty… There is no sense in which some branches are more probable than other branches… So we seem to have lost an important part of quantum mechanics---that part which predicts the probabilities that different outcomes occur… Yet another problem with Everett’s original formulation … was that slitting the quantum state into branches is ambiguous… There is one branch in which … the cat is alive and another branch in which … the cat is dead. But why these and not some other quantities?... You have not solved the mystery of why macroscopic observers see definite outcomes.” (Pg. 149-152)

He asserts, “[there is no] empirically based argument that would require us to prefer Everett over other approaches. Despite some provocative claims to the contrary, there is no experimental outcome that cannot be explained as least as well by the other realist approaches.” (Pg. 174)

He suggests, “The existence of all these copies of ourselves would then seem to me to present a moral and ethical quandary. If no matter what choices I make in life, there will be a version of me that will take the opposite choice, then why does it matter what I choose? There will be a branch in the multiverse for every option I might have chosen, There are branches in which I become as evil as Stalin and Hitler and there are branches where I am loved as a successor to Gandhi… believing in the existence of all these copies lessens my own sense of moral responsibility.” (Pg. 178)

He summarizes, “The main message of this book is that however weird the quantum world may be, it need not threaten anyone’s belief in commonsense realism… However, simple affirming realism is not enough. A realist wants to know the true explanation for how the world works… Thus the next question to ask is whether any of the available realist versions of quantum physics are compelling as true explanations of the world…. Unfortunately, I believe the answer is that, so far, none of the well-developed options are convincing. All the realist approaches that have so far been studies have serious drawbacks.” (Pg. 205) Later, he admits, “No problem in physics has given me more pain, and kept me up more nights, than this conflict between commonsense realism applied to the atomic domain and the principles of special relativity… There is more work to do to discover a realist completion of quantum mechanics that avoids the pitfalls of the existing theories while offering solutions to the other key questions in physics.” (Pg. 215-216)

He suggests, “I propose three hypotheses about what lies beyond spacetime and beyond the quantum: ‘Time, in the sense of causation, is fundamental.’ This means the process by which future events are produced from present events, caused CAUSATION, is fundamental. ‘Time is irreversible.’ The process by which future events are created from present events can’t go backward. Once an event has happened, it can’t be made to un-happen. ‘Space is emergent.’ There is no space, fundamentally. There are events and they cause other events. So there are causal relations. These events make up a network of relationships. Space arises as a coarse-grained and approximate description of the network of relationships between events. This means that locality is emergent. Nonlocality must then also be emergent.” (Pg. 236)

This book will be of keen interest to those seeking alternative approaches to quantum mechanics.

[Ania · Rating 4 out of 5]

A lot could have been left out from this book, from the endless historical recounting to the overly personal philosophical tangents on which theory describes ‘reality’ the best. Despite this (in certain moments of clarity that Smolin has) i can say that i am walking away with an idea of what quantum theories have evolved as well as a new sense of what reality means to me