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Philosophy of Physics: Quantum Theory
A sophisticated and original introduction to the philosophy of quantum mechanics from one of the world’s leading philosophers of physicsIn this book, Tim Maudlin, one of the world’s leading philosophers of physics, offers a sophisticated, original introduction to the philosophy of quantum mechanics. The briefest, clearest, and most refined account of his influential approach to the subject, the book will be invaluable to all students of philosophy and physics.Quantum mechanics holds a unique place in the history of physics. It has produced the most accurate predictions of any scientific theory, but, more astonishing, there has never been any agreement about what the theory implies about physical reality. Maudlin argues that the very term “quantum theory” is a misnomer. A proper physical theory should clearly describe what is there and what it does—yet standard textbooks present quantum mechanics as a predictive recipe in search of a physical theory.In contrast, Maudlin explores three proper theories that recover the quantum the indeterministic wavefunction collapse theory of Ghirardi, Rimini, and Weber; the deterministic particle theory of deBroglie and Bohm; and the conceptually challenging Many Worlds theory of Everett. Each offers a radically different proposal for the nature of physical reality, but Maudlin shows that none of them are what they are generally taken to be.
250 pages, Kindle Edition
Published March 19, 2019
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Displaying 1 - 14 of 14 reviews
August 9, 2021
The Copenhagen interpretation of quantum mechanics has been notoriously hard to understand, Bohr even stated that there is no quantum world. As per the Copenhagen interpretation which a lot of physcists seem to have accepted as dogma, it makes no sense to even talk about the physical world outside of measurements. So questions like 'where was the electron before the measurement?' is simply absurd within the Copenhagen context. And this famously led to those jokes along the lines of 'does the moon exist when nobody is looking?'.
One of the first physicists to question the validity of this entire formulation (Besides Einstein, of course) was David Bohm. But Bohm achieved what other skeptics hadn't, he came up with an alternate mathematical formulation that was equivalent to the Schrodinger wave mechanics, but it dealt very elegantly with the measurement problem and that very important question: what are the limits of the quantum laws? Where do they stop being pertinent? What Bohm originally called the pilot-wave theory (although it was De Broglie who first proposed it, but he didn't work on it further because he was discouraged by his inability to answer the questions posed by Pauli, Heisenberg and Bohr during one of those Solvay conferences - oh you know it, that black and white picture with those famous European male physicists and Marie Curie? Yep, that one) is now the broader Bohmian mechanics and much of this book deals with that.
This book also explains bits of Bell's local beables theory, and the GRW collapse theory although not as extensively. It completely ignores the Copenhagen interpretation though, except for discussing its shortcomings.
Physicists and philosophers seem to be slowly growing disenchanted with the Copenhagen interpretation, which makes sense in 2021 given that the quantum mechanics that we study in universities sometimes completely disregards cause-and-effect, and locality. Even if Bell's theorem and experimental results proved that quantum mechanics is inherently non-local, with the rise alternative theories, the Copenhagen interpretation has been harder to accept for the simple reason that it does not provide a consistent description of reality. I myself seem to be straying away from it even though it's all I've been taught. Might even be 'just a phase', we'll see. But for now, I have to giggle at and agree with this quote from my favorite physicist John Stewart Bell:
Was the world wavefunction waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some more highly qualified measurer—with a Ph.D.?
One of the first physicists to question the validity of this entire formulation (Besides Einstein, of course) was David Bohm. But Bohm achieved what other skeptics hadn't, he came up with an alternate mathematical formulation that was equivalent to the Schrodinger wave mechanics, but it dealt very elegantly with the measurement problem and that very important question: what are the limits of the quantum laws? Where do they stop being pertinent? What Bohm originally called the pilot-wave theory (although it was De Broglie who first proposed it, but he didn't work on it further because he was discouraged by his inability to answer the questions posed by Pauli, Heisenberg and Bohr during one of those Solvay conferences - oh you know it, that black and white picture with those famous European male physicists and Marie Curie? Yep, that one) is now the broader Bohmian mechanics and much of this book deals with that.
This book also explains bits of Bell's local beables theory, and the GRW collapse theory although not as extensively. It completely ignores the Copenhagen interpretation though, except for discussing its shortcomings.
Physicists and philosophers seem to be slowly growing disenchanted with the Copenhagen interpretation, which makes sense in 2021 given that the quantum mechanics that we study in universities sometimes completely disregards cause-and-effect, and locality. Even if Bell's theorem and experimental results proved that quantum mechanics is inherently non-local, with the rise alternative theories, the Copenhagen interpretation has been harder to accept for the simple reason that it does not provide a consistent description of reality. I myself seem to be straying away from it even though it's all I've been taught. Might even be 'just a phase', we'll see. But for now, I have to giggle at and agree with this quote from my favorite physicist John Stewart Bell:
Was the world wavefunction waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some more highly qualified measurer—with a Ph.D.?
July 24, 2025
getricked in filosofie te lezen door de meest jobless guy van de Oude luikerbaan
October 4, 2021
Professor Maudlin is one of the leading philosophers of physics and his book on Quantum Theory is exceptionally good. He offers the most clear approach to a very difficult subject - the physical meaning of a quantum theory. Maudlin argues that the word "theory" is not even adequate in some cases since a true "theory" should provide an ontology (what there is) and a consistent set of equations for the dynamics (what it does, or how the ontology will evolve in time) and some interpretations of the quantum theory (like the famous "Copenhagen Interpretation") don't care to explain what is really happening - they just use well know rules (dubbed as "the quantum recipe" by Maudlin) to (successfully) obtain results and adopt the "shut up and calculate" attitude.
On the other hand, there are other approaches which Maudlin consider as "legitimate theories" in the sense of providing an ontology and the equations for it's evolution (dynamics). In particular, Maudlin gives a very well written account of three quantum theories: The GRW (Ghirardi-Rimini-Weber) spontaneous collapse theory, where the collapse of the wavefuncion is indeterministic, the Pilot Wave Theory (David Bohm), and the (very strange but mathematically consistent) Many World's interpretation (by Hugh Everett).
Each of these three candidates are "proper quantum theories" by Maudlin's account of what a legitimate physical theory should be, yet each one of them offers a very different view for the nature of physical reality. Nevertheless, all these theories are nonrelativistic, meaning they are based on a classic view of space and time which an absolute notion of simultaneity. The Theory of Relativity must be somehow taken into account in the search of a more realistic quantum theory. One theory of this kind is the very beautiful (and also mathematically challenging) Relativistic Quantum Field Theory (QFT), which Maudlin address in Chapter 7. In QFT, "elementary particles" are not fundamental entities, they emerge as excitations of quantum fields. Unfortunately even the powerful QFT approach cannot be still a complete account of reality since gravity is still left aside. In the quantum gravity approach to this problem (as proposed by Carlo Rovelli, Lee Smolin and others) spacetime should also treated as a quantum field, so the entire world would be made by just one single ingredient: covariant quantum fields.
Philosophy of Physics: Quantum Theory
On the other hand, there are other approaches which Maudlin consider as "legitimate theories" in the sense of providing an ontology and the equations for it's evolution (dynamics). In particular, Maudlin gives a very well written account of three quantum theories: The GRW (Ghirardi-Rimini-Weber) spontaneous collapse theory, where the collapse of the wavefuncion is indeterministic, the Pilot Wave Theory (David Bohm), and the (very strange but mathematically consistent) Many World's interpretation (by Hugh Everett).
Each of these three candidates are "proper quantum theories" by Maudlin's account of what a legitimate physical theory should be, yet each one of them offers a very different view for the nature of physical reality. Nevertheless, all these theories are nonrelativistic, meaning they are based on a classic view of space and time which an absolute notion of simultaneity. The Theory of Relativity must be somehow taken into account in the search of a more realistic quantum theory. One theory of this kind is the very beautiful (and also mathematically challenging) Relativistic Quantum Field Theory (QFT), which Maudlin address in Chapter 7. In QFT, "elementary particles" are not fundamental entities, they emerge as excitations of quantum fields. Unfortunately even the powerful QFT approach cannot be still a complete account of reality since gravity is still left aside. In the quantum gravity approach to this problem (as proposed by Carlo Rovelli, Lee Smolin and others) spacetime should also treated as a quantum field, so the entire world would be made by just one single ingredient: covariant quantum fields.
Philosophy of Physics: Quantum Theory
April 21, 2026
Tim Maudlin's Philosophy of Physics: Quantum Theory is a hard book. It is hard in the way that doing the work should be hard, and the author offers few concessions to readers who wander in, hoping for a smooth tour of quantum weirdness. This has its virtues. It also means that anyone approaching the book without either prior training or a patient guide will find stretches that feel closer to a mathematics seminar than to popular science. What rewards the effort is a clear demonstration that the epistemology of quantum physics is a genuinely different subject from the physics itself. The equations are assumed settled. The question of what they describe is not.
The book lays out the main interpretational candidates with care, and any serious reader will finish it with opinions. Those opinions will almost certainly be shaped by what the reader happened to find clear, what they found opaque, and which gaps in their own understanding they are most willing to tolerate. Mine are no exception. What follows is a reviewer's preference, not a verdict, and should be seen as a reflection of what I understood and failed to.
Before arriving at preferences, though, a word on fascination. Quantum physics has countless strange properties and manifestations that remain astonishing no matter how many times one returns to the same canonical examples. The Mach-Zehnder setup is the case in point. Take a beam of electrons all prepared spin-up along the Z axis. Send them through a magnet oriented along X. The beam splits, as expected. Now recombine the two paths without looking at which path any particle took, and send the result through another Z magnet. Every electron emerges spin-up, as if the X magnet never happened. But if you block one of the X paths, or if you simply measure which path was taken without blocking anything, the final Z measurement gives a fifty-fifty split. The act of knowing, or the act of interrupting, reaches back into the experiment and changes what the universe is willing to deliver. One can read this description a hundred times, and it never stops being strange.
The equations predict all of this to staggering precision. What they do not do is tell us what is happening. This is the gap the interpretations try to close, and it is where the author does his most important work. He presents GRW-style spontaneous collapse, pilot-wave theory, and the many-worlds view with sufficient rigor that the reader can see what each one buys and what each one pays.
My own reaction, after working through the book, is that two of the three dominant options feel like forced closures on a question that should stay open. The GRW flash, the spontaneous localization event with its tuned rate and tuned width, has the shape of a proposal written in an afternoon to make a problem go away. That is not a dismissal of the decades of careful work around it. It is an observation that the mechanism, as posited, sits at the armchair end of the space of possible nonlinear modifications to quantum dynamics. Reality rarely conforms to proposals that look like the minimum viable patch. Many-worlds, in turn, asks us to accept an unbounded ontology of branching realities to avoid modifying an equation, trading a conceptual economy for a cosmological extravagance. Both theories survive partly by retreating from measurement: the branches are unfalsifiable by construction, and GRW's parameters live just below current experimental sensitivity. Parsimony is supposed to cut between explanations, not provide hiding places for the complexity one wishes to avoid.
The position I find more honest is incompleteness. Collapse, or whatever we should call the transition from superposition to the single world of beables we inhabit, is real. It happens here, to these objects, and our existence is evidence of it. The mechanism is almost certainly some nonlinear, interaction-driven process operating through decoherence dynamics that we understand only crudely. Our grasp of how waves interact, how entanglements propagate in dense matter, how recoherence behaves on axes complementary to the ones that have settled, is probably at a stage that will look, from a future vantage, roughly as primitive as Aristotelian physics looks to us. Maudlin himself concedes near the end that extending this philosophical project to relativistic quantum theory or quantum field theory would compound the difficulties enormously. We are interpreting an approximate theory and calling the interpretations fundamental.
Given that, the philosophical price of spontaneous flashes or proliferating worlds seems high for what we get. Bohmian mechanics, with its explicit nonlocality and its commitment to real beables, is incomplete in its own ways, and no one should expect closure in our lifetimes. But the disposition it encourages, that the measurement problem is a research problem being answered badly rather than a pseudo-problem to be dissolved by clever metaphysics, is the right one. The razor was meant to cut explanations, not hiding places. Keep looking, and do not mistake the placeholders for the answer.
What makes the book worth the struggle is that it forces exactly this kind of thinking. It will not satisfy casual readers, and it does not try to. For readers who actually want to wrestle with what quantum mechanics might mean, rather than being handed a tidy story, it is one of the better provocations available. The fact that a book can leave a non-expert reader with strong, defensible objections to positions held by eminent physicists is itself a sign of how much thinking the text unlocks.
The book lays out the main interpretational candidates with care, and any serious reader will finish it with opinions. Those opinions will almost certainly be shaped by what the reader happened to find clear, what they found opaque, and which gaps in their own understanding they are most willing to tolerate. Mine are no exception. What follows is a reviewer's preference, not a verdict, and should be seen as a reflection of what I understood and failed to.
Before arriving at preferences, though, a word on fascination. Quantum physics has countless strange properties and manifestations that remain astonishing no matter how many times one returns to the same canonical examples. The Mach-Zehnder setup is the case in point. Take a beam of electrons all prepared spin-up along the Z axis. Send them through a magnet oriented along X. The beam splits, as expected. Now recombine the two paths without looking at which path any particle took, and send the result through another Z magnet. Every electron emerges spin-up, as if the X magnet never happened. But if you block one of the X paths, or if you simply measure which path was taken without blocking anything, the final Z measurement gives a fifty-fifty split. The act of knowing, or the act of interrupting, reaches back into the experiment and changes what the universe is willing to deliver. One can read this description a hundred times, and it never stops being strange.
The equations predict all of this to staggering precision. What they do not do is tell us what is happening. This is the gap the interpretations try to close, and it is where the author does his most important work. He presents GRW-style spontaneous collapse, pilot-wave theory, and the many-worlds view with sufficient rigor that the reader can see what each one buys and what each one pays.
My own reaction, after working through the book, is that two of the three dominant options feel like forced closures on a question that should stay open. The GRW flash, the spontaneous localization event with its tuned rate and tuned width, has the shape of a proposal written in an afternoon to make a problem go away. That is not a dismissal of the decades of careful work around it. It is an observation that the mechanism, as posited, sits at the armchair end of the space of possible nonlinear modifications to quantum dynamics. Reality rarely conforms to proposals that look like the minimum viable patch. Many-worlds, in turn, asks us to accept an unbounded ontology of branching realities to avoid modifying an equation, trading a conceptual economy for a cosmological extravagance. Both theories survive partly by retreating from measurement: the branches are unfalsifiable by construction, and GRW's parameters live just below current experimental sensitivity. Parsimony is supposed to cut between explanations, not provide hiding places for the complexity one wishes to avoid.
The position I find more honest is incompleteness. Collapse, or whatever we should call the transition from superposition to the single world of beables we inhabit, is real. It happens here, to these objects, and our existence is evidence of it. The mechanism is almost certainly some nonlinear, interaction-driven process operating through decoherence dynamics that we understand only crudely. Our grasp of how waves interact, how entanglements propagate in dense matter, how recoherence behaves on axes complementary to the ones that have settled, is probably at a stage that will look, from a future vantage, roughly as primitive as Aristotelian physics looks to us. Maudlin himself concedes near the end that extending this philosophical project to relativistic quantum theory or quantum field theory would compound the difficulties enormously. We are interpreting an approximate theory and calling the interpretations fundamental.
Given that, the philosophical price of spontaneous flashes or proliferating worlds seems high for what we get. Bohmian mechanics, with its explicit nonlocality and its commitment to real beables, is incomplete in its own ways, and no one should expect closure in our lifetimes. But the disposition it encourages, that the measurement problem is a research problem being answered badly rather than a pseudo-problem to be dissolved by clever metaphysics, is the right one. The razor was meant to cut explanations, not hiding places. Keep looking, and do not mistake the placeholders for the answer.
What makes the book worth the struggle is that it forces exactly this kind of thinking. It will not satisfy casual readers, and it does not try to. For readers who actually want to wrestle with what quantum mechanics might mean, rather than being handed a tidy story, it is one of the better provocations available. The fact that a book can leave a non-expert reader with strong, defensible objections to positions held by eminent physicists is itself a sign of how much thinking the text unlocks.
September 13, 2023
It's a good book, but barely touches on any philosophy of science. We're told from the start to dismiss antirealist construals of quantum physics without any argument, and that we should desire from a physical theory a realist ontology and dynamics. But this seems backwards - we hope that there's an ontology and dynamics for quantum theory because we've been successful at designing ontologies and dynamics for theories at higher levels; but if we're committed to reductionism, e.g. that the contents of our higher level theories are emergent and that the "real stuff" they're made out of exists only at the fundamental quantum level, then our desires are completely misaligned. We have no reason to expect that the nonreferring, idealized, and approximated descriptions of our higher level theories correspond to fundamental reality.
This book also doesn't really motivate how we would settle Many Worlds vs Bohmian Mechanics vs Objective Collapse models. The empirical equivalency of these theories is overlooked, and no appeal to theoretical virtues is even attempted, which is odd because realist physical theories appeal to theoretical virtues and inference to the best explanation all the time. You're left wondering "Who cares?" and edging closer to siding with the shut-up-and-calculate physicists as the book fails to deliver any decisive answers, or even sketch out how one of these theories would be falsified. The only constraint the author enforces is that the interpretations recover the quantum recipe. Some paragraphs are wasted explaining high level mathematics that could instead be spent on situating this work in a historical or philosophical or pragmatic context.
Overall, the book is mostly devoid of philosophy. If you're interested in learning about QM intepretations, this book will definitely be an aid, but if you're interested in thinking critically about what we're doing in quantum theory, then it isn't too helpful, and ironically parrots the same shut-up-and-calculate attitude except towards pursuing seemingly unsettleable metaphysical questions.
This book also doesn't really motivate how we would settle Many Worlds vs Bohmian Mechanics vs Objective Collapse models. The empirical equivalency of these theories is overlooked, and no appeal to theoretical virtues is even attempted, which is odd because realist physical theories appeal to theoretical virtues and inference to the best explanation all the time. You're left wondering "Who cares?" and edging closer to siding with the shut-up-and-calculate physicists as the book fails to deliver any decisive answers, or even sketch out how one of these theories would be falsified. The only constraint the author enforces is that the interpretations recover the quantum recipe. Some paragraphs are wasted explaining high level mathematics that could instead be spent on situating this work in a historical or philosophical or pragmatic context.
Overall, the book is mostly devoid of philosophy. If you're interested in learning about QM intepretations, this book will definitely be an aid, but if you're interested in thinking critically about what we're doing in quantum theory, then it isn't too helpful, and ironically parrots the same shut-up-and-calculate attitude except towards pursuing seemingly unsettleable metaphysical questions.
May 21, 2019
This is a remarkable book. The author is focussing on physical theories of what he calls the "quantum recipe" (ie the mathematical and predictive elements of quantum mechanics). As such, he does not consider theories that are not physically possible, ie the Copenhagen interpretation. Rather he considers 3 nonrelativistic theories and briefly touches on quantum field theory. His main concerns are: what are the fundamental ontologies of these theories? how do they relate to the wavefunction/quantum state? how do they relate to violations of Bell's inequality? and how do they account for the relationship between macroscopic objects and microscopic particles?
One concern I have is with the easy dismissal of categorization (per Aristotle's categories) for the quantum state. The author states that this is not at all necessary for something as unique and mind boggling as the quantum state; rather, we should consider it ontologically basic. I found this justification odd and I am not convinced by it.
Although it is an introduction, it definitely has to be read very very carefully. A book worth revisiting, if only for how the author presents the 8 basic experiments of quantum physics.
The author apologetically acknowledges that relativistic theories are important, but justifiably believes that the main concerns of physical theories of quantum mechanics can, for pedagogical purposes, be better approached through the nonrelativistic theories presented. I am inclined to agree with him.
Note that there are many many resources on the Copenhagen interpretation out there, so it's nice to read a work that doesn't focus on it (for once). Also this isn't a work of the history of science; you're better off reading that elsewhere (eg Cushing).
One concern I have is with the easy dismissal of categorization (per Aristotle's categories) for the quantum state. The author states that this is not at all necessary for something as unique and mind boggling as the quantum state; rather, we should consider it ontologically basic. I found this justification odd and I am not convinced by it.
Although it is an introduction, it definitely has to be read very very carefully. A book worth revisiting, if only for how the author presents the 8 basic experiments of quantum physics.
The author apologetically acknowledges that relativistic theories are important, but justifiably believes that the main concerns of physical theories of quantum mechanics can, for pedagogical purposes, be better approached through the nonrelativistic theories presented. I am inclined to agree with him.
Note that there are many many resources on the Copenhagen interpretation out there, so it's nice to read a work that doesn't focus on it (for once). Also this isn't a work of the history of science; you're better off reading that elsewhere (eg Cushing).
June 22, 2024
Let me share my thoughts on Tim Maudlin's book on quantum theory—a work that truly stands out in its ability to unravel the complexities of quantum physics with clarity and depth.
Maudlin navigates through the enigmatic realm of quantum theory with an adeptness that makes even the most intricate concepts comprehensible. Whether discussing the dual nature of particles, the phenomenon of entanglement, or the philosophical implications of quantum mechanics, he strikes a balance between scholarly rigor and engaging narrative.
What distinguishes Maudlin's approach is his willingness to delve into not only the scientific intricacies but also the profound questions that arise from them. He deftly explores the implications of quantum theory for our understanding of reality and consciousness, offering readers a thought-provoking journey into the fundamental nature of existence.
The prose is elegantly crafted, making complex ideas accessible without compromising on depth. It feels as though one is engaged in a stimulating conversation with a knowledgeable companion, where every explanation is meticulously thought out yet presented with a conversational ease.
For anyone seeking a comprehensive exploration of quantum theory that is both intellectually stimulating and accessible, Tim Maudlin's book is an indispensable read. It not only clarifies the mysteries of quantum mechanics but also invites readers to contemplate the profound implications of these discoveries on our perception of the universe.
Maudlin navigates through the enigmatic realm of quantum theory with an adeptness that makes even the most intricate concepts comprehensible. Whether discussing the dual nature of particles, the phenomenon of entanglement, or the philosophical implications of quantum mechanics, he strikes a balance between scholarly rigor and engaging narrative.
What distinguishes Maudlin's approach is his willingness to delve into not only the scientific intricacies but also the profound questions that arise from them. He deftly explores the implications of quantum theory for our understanding of reality and consciousness, offering readers a thought-provoking journey into the fundamental nature of existence.
The prose is elegantly crafted, making complex ideas accessible without compromising on depth. It feels as though one is engaged in a stimulating conversation with a knowledgeable companion, where every explanation is meticulously thought out yet presented with a conversational ease.
For anyone seeking a comprehensive exploration of quantum theory that is both intellectually stimulating and accessible, Tim Maudlin's book is an indispensable read. It not only clarifies the mysteries of quantum mechanics but also invites readers to contemplate the profound implications of these discoveries on our perception of the universe.
April 2, 2022
captivating
It is refreshing to see someone dismiss in a few words the So called Copenhagen Interpretation as something not even worth discussing. And to take physicists to task for their frequent naive misuse of well established terms such as … well ‘realism’.
The author then outlines the methods of (non relativistic ) quantum mechanics - the quantum recipe as he calls it - and then asks for real physical theories that would provide some account of the recipe and its success.
Pilot waves, many worlds etc.
There are some technical details but not really enough if you don’t already know them. A common problem with books of this type.
There are some good references to more advanced works.
He dismisses statistical and epistemic theories and advocates openly for ontological ones. There is no nonsense about conscious observers and not even a heavy emphasis on ‘measurement’ as such.
We are left asking, ‘so what is the quantum state of an object or system, and how can it be so implicitly non-local’ and how can it behave the way it does.
It is refreshing to see someone dismiss in a few words the So called Copenhagen Interpretation as something not even worth discussing. And to take physicists to task for their frequent naive misuse of well established terms such as … well ‘realism’.
The author then outlines the methods of (non relativistic ) quantum mechanics - the quantum recipe as he calls it - and then asks for real physical theories that would provide some account of the recipe and its success.
Pilot waves, many worlds etc.
There are some technical details but not really enough if you don’t already know them. A common problem with books of this type.
There are some good references to more advanced works.
He dismisses statistical and epistemic theories and advocates openly for ontological ones. There is no nonsense about conscious observers and not even a heavy emphasis on ‘measurement’ as such.
We are left asking, ‘so what is the quantum state of an object or system, and how can it be so implicitly non-local’ and how can it behave the way it does.
July 11, 2025
A very interesting (though highly introductory) book, which seems to be completely free of common misconceptions and presents its subject matter in an exceptionally clear and rigorous manner. (Of course that is a thoroughly stereotypical thing to write, but it's also true.) That being said there is one very irritating thing about it. Maudlin ends book 1 in the series, on space & time, with some very interesting considerations of the arrow of time, but he leaves them unresolved on the grounds that answering those questions would require quantum mechanics; I believe the last sentence in the book is a promise to return to the subject in the next book. But he has apparently completely forgotten that promise; not only does he fail to discuss the topic, he doesn't even apologize for leaving it out.
April 15, 2021
Quite an interesting book on the ontological and interpretational aspects of Quantum Mechanics. It mainly tackles three 'schools' of Interpretations : Collapse Theories (GRW, Local Beables etc), Pilot Wave Theory and the Many World Theory. The author(s) have done quite a good job of explaining how each of these interpretations can be equipped with an individual ontological foundation that connect the bras and the kets to physical, tangible entities and phenomena. A possible ontology for Quantum Field Theory is discussed in the last chapter.
January 28, 2022
One of the best introduction to your humanities friends about why quantum mechanics is "weird" or unintuitive. The actual interpretations falls off quite a bit and Maudlin fails to really articulate why they're so unsatisfactory. Relativity chapter is also lacking, but pretty insightful for an analysis without any math
July 23, 2025
Not for your average Joe
I had hoped this book would help me better understand quantum mechanics, but it left me more confused than before. It’s clearly written for students of the subject, not for general readers.
I had hoped this book would help me better understand quantum mechanics, but it left me more confused than before. It’s clearly written for students of the subject, not for general readers.
Want to Read
December 27, 2023Anbefalt av Einar og Viro
January 18, 2026
Definitely one of the best introductions to and clarifications of the issues that riddle the current understanding of quantum mechanics written so far. Concise, to the point, and exposed systematically, from the introduction of 8 emblematic experiments to the presentation of the "quantum recipe", and finally the description of a selection of attempts to make sense of the recipe with proper theories (collapse theories, pilot wave, many worlds). Maudlin does not abide to the historical order and rather puts the developments in logical order, presenting the formalism first and not shying away from admitting that quantum mechanics, as typically taught, is just an operational recipe, if to be sure one of unprecedented success in accounting for experimental data. It cannot be ranked as a theory, given that its components (assignment of a wavefunction to the system under study, evolution of the wavefunction in time, assignment of probabilities to the predictions extracted from the "measurement") are in themselves not rigorously justified (the first and third stage typically require evoking classical mechanics analogies), nor linked to an ontology. Maudlin is then particularly in the look out for a local ontology for a theory, following on the steps of John Stewart Bell and his "local beables". Therefore, he does not dwell on quantum bayesianism and other observer-centered theories, nor on Rovelli's relational interpretation of the recipe in the vein of Heisenberg. Maudlin also shortly discusses the extension of the non-relativistic versions of the theories to the relativistic domain of quantum field theories, where instantaneity is not given and the number of particles is not fixed. In view of this, collapse theories are those closer to the recipe though admittedly phenomenologic in spirit (and perhaps ad hoc, given the introduction of 2 new constant of nature; pilot wave theories add particles to the ontology, but suffer in the extension to relativistic theory due to the use of absolute simultaneity and fixed particle count; and many worlds remain plagued with the transition from wavefunction to beables in spite of being easily extended to a relativistic version given that they do not contemplate a wavefunction collapse.
The author does not open new ground, nor seem to be suggesting a preferential development in any single direction - except for pilot wave theories, where he defends as legitimate the possibility that a global foliation be introduced in space-time to complement and complete its structure (admittedly proposed before the evidence for violations of Bell's inequality), which would make the theory solve one big issue though at the expense of a perceived step back from the main claim of relativity theory. Rather, Maudlin devotes effort to polishing and cleaning up the discussion on the ontology of the theories and stimulating further work (also in many worlds, in spite of explicitly mentioning several reservations on its probability problem and decision-theoretic solution(s) and the local beable problem). A concluding chapter with a summary and explicit comparison among the theories would have made the book even stronger.
The author does not open new ground, nor seem to be suggesting a preferential development in any single direction - except for pilot wave theories, where he defends as legitimate the possibility that a global foliation be introduced in space-time to complement and complete its structure (admittedly proposed before the evidence for violations of Bell's inequality), which would make the theory solve one big issue though at the expense of a perceived step back from the main claim of relativity theory. Rather, Maudlin devotes effort to polishing and cleaning up the discussion on the ontology of the theories and stimulating further work (also in many worlds, in spite of explicitly mentioning several reservations on its probability problem and decision-theoretic solution(s) and the local beable problem). A concluding chapter with a summary and explicit comparison among the theories would have made the book even stronger.
Displaying 1 - 14 of 14 reviews