The Emergent Multiverse presents a striking new account of the many worlds approach to quantum theory The point of science, it is generally accepted, is to tell us how the world works and what it is like But quantum theory seems to fail to do this taken literally as a theory of the world, it seems to make crazy claims particles are in two places at once cats are alive and dead at the same time So physicists and philosophers have often been led either to give up on the idea that quantum theory describes reality, or to modify or augment the theory The Everett interpretation of quantum mechanics takes the apparent craziness seriously, and asks, what would it be like if particles really were in two places at once, if cats really were alive and dead at the same time The answer, it turns out, is that if the world were like that if it were as quantum theory claims it would be a world that, at the macroscopic level, was constantly branching into copies hence the sensationalist name for the Everett interpretation, the many worlds theory But really, the interpretation is not sensationalist at all it simply takes quantum theory seriously, literally, as a description of the world Once dismissed as absurd, it is now accepted by many physicists as the best way to make coherent sense of quantum theory David Wallace offers a clear and up to date survey of work on the Everett interpretation in physics and in philosophy of science, and at the same time provides a self contained and thoroughly modern account of it an account which is accessible to readers who have previously studied quantum theory at undergraduate level, and which will shape the future direction of research by leading experts in the field

14 thoughts on “The Emergent Multiverse: Quantum Theory According To The Everett Interpretation”

Hard in places but still worth the read for anyone who has already read digestible books such as the two by David Deutsch which discuss the multiverse I found I could gloss over the difficult technical mathematical bits but still enjoy reading the rest.

This is probably the first textbook account of the Many Worlds interpretation that has appeared in the literature In that sense it performs a useful guide for those who want to know about this particular interpretation Wallace along with his colleague Simon Saunders have done much to develop the interpretation over the past 15 years or so However whilst it is useful I remain totally unconvinced by the intepretation or its motivation.The first chapter tries to motivate it by claiming that there is a problem with the standard interpretation of quantum mechanics and an outline of the measurement problem It is curious that most physicists are not really concerned with the measurement problem and it certainly does not prevent them from using the formalism of quantum mechanics to make ever predictions about the quantum world This activity is relatively independent of any interpretation and one would think that is telling us something about quantum mechanics.The so called foundational issues seems to have been left to philosophers whilst physicists get on with the job of explaining the properties of solids, cosmology, astrophysics and particle physics.For my part I see nothing wrong with the minimalist view that the so called wave function is a complex probability state vector whos modulus squared gives rise to a probability density function via the Born Rule Indeed it is quite instructive to recast the language of classical physics in the language of quantum physics One can write down a wave function for a dice and by application of the Born rule one will get the correct probabilities Ok in quantum physics one needs to extend classical probability to include complex numbers whose modulus squared gives rise to the probabilities relevant to the situation.Such a pragmatic viewpoint does not seem to satisfy people like Dave Wallace who wish to give the wavefunction some sort of physical meaning One way of doing this is via the Everrett interpretation which implies the generation of a whole new universe every time a measurement is made This view borders on science fiction and seems to stem from a perspective which wishes to associate every mathematical concept with something out there Yes if you wish to take the wavefunction as corresponding to some element of reality you will probably end up with something like the Everrett interpretation but the price is to high One can t test the existence of other universes I dare any one who is tempted by the Everrett interpetation to play quantum suicide because in one of the many branches it is alleged that you will still be alive.On a constructive note it is useful to have in one book a fairly definitive account of the interpretation On the other hand it would seem to paraphrase Bernard Shaw those who can do physics do physics those who cant interpret it.

This book defends the controversial idea that when certain events happen, like the decay of a radioactive atom, the world divides into branches where in one the atom has decayed and in the other it hasn t A person observing the decay in a Geiger counter also branches into copies of him or herself, each observing a different decay result.The author justifies this idea, first propounded by Hugh Everett III in his PhD thesis, against a multitude of alternative proposals for explaining what happens without calling upon branching The author insists that the Everett approach is not just an interpretation of quantum theory, but IS quantum theory without any need for embellishment It helps reading the book to have some knowledge of quantum theory, decision theory, and the philosophy of science Nevertheless, I found it possible to skip over most equations and appreciate the scholarship of the author and the profound consequences of Everett s ideas figuring out what to do with trillions of lives.

Excellent Although the rendering is technical at times the explanations are amply focused and self explanatory Highly recommend it for anyone interested in this fascinating story.

Depuis la fin des ann es 1990 et les travaux de Deutsch, Saunders, Wallace et quelques autres, l interpr tation d Everett est consid r e par de nombreux philosophes analytiques comme une des interpr tations les plus labor es et les plus cr dibles de la m canique quantique Malheureusement, les adversaires de cette interpr tation ignorent la plupart du temps ces derniers d veloppements et basent leurs critiques de la th orie partir d une vision assez na ve de ce qu est une th orie physique en g n rale, et d une vision caricaturale de ce qu est la th orie d Everett en particulier C est particuli rement vrai en France, ou m me les rares d fenseurs de cette interpr tation n ont souvent pas suivi les d veloppements de leurs coll gues d Oxford, et ne prennent pas en compte l importance de la d coh rence et l int r t des approches de la th orie de la d cision pour r soudre les deux plus gros probl mes qui se posent la th orie d Everett, savoir le probl me dit de la base pr f r e et celui des probabilit s.Le livre de Wallace est le livre qu il faut avoir lu pour pouvoir juger de la consistance de la th orie d Everett On ne peut aujourd hui tout simplement pas en rester aux travaux originaux d Everett ou ceux de Brice DeWitt pour pouvoir l valuer.Pour d fendre sa th se, Wallace propose un cadre interpr tatif fonctionnaliste des th ories physiques et des rapports entre diff rents niveaux de descriptions th oriques, bas s sur la notion d instanciation, qui a un grand int r t en soi c est dire au del des probl mes d interpr tation de la m canique quantique notamment sur les questions d mergences et du r ductionnisme, qui vite la fois l cueil des versions trop simplistes du r ductionnisme tout en ne tombant pas dans cette forme de mysticisme qui apparait si souvent entourer certains discours obscurs en faveur de l mergentisme.Le livre n est pas tr s difficile, et est raisonnablement accessible aux personnes qui ont un bagage assez solide en m canique quantique standard, niveau master 1 Les chapitres les plus difficiles, qui concernent les preuves rigoureuses donn es ses r sultats sur le probl me des probabilit s peuvent tre saut s sans dommage car l auteur propose en amont d autres preuves moins rigoureuses, mais plus intuitives et moins formelles, qui donnent d j une id e pr cise de comment l auteur parvient r soudre le probl me.Excellent livre.

This is the definitive book for anyone interested in the Everett, or Many Worlds, formulation of quantum theory David Wallace is a leading philosopher of physics, with an incredibly deep understanding of the underlying physics.It isn t a popular level book this is a scholarly work, aimed at professional philosophers, physicists, and students Wallace gives a thorough discussion of the main issues confronting the contemporary Everettian decoherence, the emergence of classical worlds, pointer states, the origin of the Born Rule for probability, and time asymmetry The style is uniformly clear and engaging Readers will certainly come to the work with a wide variety of opinions on the plausibility of Many Worlds, but everyone should get a lot out of reading this book.

I have been looking for a book that explains Everett s Many Worlds Interpretation of Quantum Mechanics in a way that is authoritative, thorough, rigorous, and understandable to a person like myself who is a scientist in a different field This is it Wallace uses a combination of mathematics, and verbal explanation of both physics and philosophy to make all the issues accessible He writes very clearly and precisely, summarizes as he goes along and does not avoid in fact, faces squarely the common criticisms of MWI This is by no means light reading, but rewards the careful reader with a much improved understanding of what MWI is and is not.

This book is technical than I expected and is requiring me to revisit largely forgotten parts of quantum theory It is carefully argued and to me very convincing A most valuable work resulting from many years study Not for the faint hearted

I purchased this book with anticipation and money I have given much time to the study of quantum mechanics and to the Many Worlds Theory of Hugh Everett III However, I am not now nor have I ever been a physicist, so you can factor that into my review Having devoted considerable attention to the issue of scientific materialism versus scientific idealism or non materialism, I have opted for the Copenhagen Interpretation, which ultimately supports physicist John Wheeler s dictum that there is no out there out there Disappointingly for me, Wallace s book comes down squarely in the scientific materialist camp It s a big book and offers much to chew on in that regard In sum, it argues that there IS an out there out there and that we should be happy about that Actually, it supports Everett s view that there are an infinite number of out there s out there and that they are all equally of a material nature, demonstrating that they are not created out of wave potential by human consciousness One of my favorite physicists, Dr Edward Close, in his book, Transcendental Physics, makes this comment The many worlds and transactional interpretations were each offered, by Everett and Cramer, as conceptual aids to understanding quantum reality In fact, they are perfect examples of the way we tend to ignore mathematical results that do not correspond to our preconceived notions of reality But both Everett and Cramer, like Wheeler and Bohr .were careful to stick to the party line of the paradigm of scientific materialism and disallowed the involvement of consciousness in the actualization of physical phenomena from the spectrum of possible states of the wave equations Wheeler, it seems, had mixed feelings about the materialism of science issue and adopted conflicting stances depending upon how much peer pressure was being brought to bear on his current position.If you are looking for an extensive defense of the materialist position in terms of Everett s Many Worlds Theory, Wallace is your man I guess that because I am not a physicist, I can afford to play fast and loose with the theories, not really having a dog in the fight in so far as my career is not dependent upon my choice of a materialist or non materialist paradigm I have many worlds of wiggle room.

This guy gets it Wallace references Dr David Deutsch and does an excellent job of showing why the Everett interpretation is the only understanding that makes no B.S sense in other words, Everett is reality.

Parallel Universes, Quantum Theory and Quantum Computing all go hand in hand The Emergent Multiverse clears up several topics which have been less than clear For example the quantum basis of probability theory at a level where a lay technical person with a curiosity of how our universe works can find useful and informative.

I liked this book a lot It had parts which were very technical it is quantum physics after all but the main thread of the argument is easy to follow and convincing The idea argued for is the Everettian or Many worlds interpretation of Quantum Mechanics To bolster his argument he applies the equations of the theory which can be quite technical but then he usually goes on to explain philosophically the justification of the interpretation I suggest people who are not familiar with the mathematics of QM treat the equations like sentences from another language inserted into the text to make the author look smart and focus on the English translation which is the argument The book is very comprehensible without the equations but it is a rigorous text and I think Wallace felt compelled to include them.

Hard in places but still worth the read for anyone who has already read digestible books such as the two by David Deutsch which discuss the multiverse I found I could gloss over the difficult technical mathematical bits but still enjoy reading the rest.

This is probably the first textbook account of the Many Worlds interpretation that has appeared in the literature In that sense it performs a useful guide for those who want to know about this particular interpretation Wallace along with his colleague Simon Saunders have done much to develop the interpretation over the past 15 years or so However whilst it is useful I remain totally unconvinced by the intepretation or its motivation.The first chapter tries to motivate it by claiming that there is a problem with the standard interpretation of quantum mechanics and an outline of the measurement problem It is curious that most physicists are not really concerned with the measurement problem and it certainly does not prevent them from using the formalism of quantum mechanics to make ever predictions about the quantum world This activity is relatively independent of any interpretation and one would think that is telling us something about quantum mechanics.The so called foundational issues seems to have been left to philosophers whilst physicists get on with the job of explaining the properties of solids, cosmology, astrophysics and particle physics.For my part I see nothing wrong with the minimalist view that the so called wave function is a complex probability state vector whos modulus squared gives rise to a probability density function via the Born Rule Indeed it is quite instructive to recast the language of classical physics in the language of quantum physics One can write down a wave function for a dice and by application of the Born rule one will get the correct probabilities Ok in quantum physics one needs to extend classical probability to include complex numbers whose modulus squared gives rise to the probabilities relevant to the situation.Such a pragmatic viewpoint does not seem to satisfy people like Dave Wallace who wish to give the wavefunction some sort of physical meaning One way of doing this is via the Everrett interpretation which implies the generation of a whole new universe every time a measurement is made This view borders on science fiction and seems to stem from a perspective which wishes to associate every mathematical concept with something out there Yes if you wish to take the wavefunction as corresponding to some element of reality you will probably end up with something like the Everrett interpretation but the price is to high One can t test the existence of other universes I dare any one who is tempted by the Everrett interpetation to play quantum suicide because in one of the many branches it is alleged that you will still be alive.On a constructive note it is useful to have in one book a fairly definitive account of the interpretation On the other hand it would seem to paraphrase Bernard Shaw those who can do physics do physics those who cant interpret it.

This book defends the controversial idea that when certain events happen, like the decay of a radioactive atom, the world divides into branches where in one the atom has decayed and in the other it hasn t A person observing the decay in a Geiger counter also branches into copies of him or herself, each observing a different decay result.The author justifies this idea, first propounded by Hugh Everett III in his PhD thesis, against a multitude of alternative proposals for explaining what happens without calling upon branching The author insists that the Everett approach is not just an interpretation of quantum theory, but IS quantum theory without any need for embellishment It helps reading the book to have some knowledge of quantum theory, decision theory, and the philosophy of science Nevertheless, I found it possible to skip over most equations and appreciate the scholarship of the author and the profound consequences of Everett s ideas figuring out what to do with trillions of lives.

Excellent Although the rendering is technical at times the explanations are amply focused and self explanatory Highly recommend it for anyone interested in this fascinating story.

Depuis la fin des ann es 1990 et les travaux de Deutsch, Saunders, Wallace et quelques autres, l interpr tation d Everett est consid r e par de nombreux philosophes analytiques comme une des interpr tations les plus labor es et les plus cr dibles de la m canique quantique Malheureusement, les adversaires de cette interpr tation ignorent la plupart du temps ces derniers d veloppements et basent leurs critiques de la th orie partir d une vision assez na ve de ce qu est une th orie physique en g n rale, et d une vision caricaturale de ce qu est la th orie d Everett en particulier C est particuli rement vrai en France, ou m me les rares d fenseurs de cette interpr tation n ont souvent pas suivi les d veloppements de leurs coll gues d Oxford, et ne prennent pas en compte l importance de la d coh rence et l int r t des approches de la th orie de la d cision pour r soudre les deux plus gros probl mes qui se posent la th orie d Everett, savoir le probl me dit de la base pr f r e et celui des probabilit s.Le livre de Wallace est le livre qu il faut avoir lu pour pouvoir juger de la consistance de la th orie d Everett On ne peut aujourd hui tout simplement pas en rester aux travaux originaux d Everett ou ceux de Brice DeWitt pour pouvoir l valuer.Pour d fendre sa th se, Wallace propose un cadre interpr tatif fonctionnaliste des th ories physiques et des rapports entre diff rents niveaux de descriptions th oriques, bas s sur la notion d instanciation, qui a un grand int r t en soi c est dire au del des probl mes d interpr tation de la m canique quantique notamment sur les questions d mergences et du r ductionnisme, qui vite la fois l cueil des versions trop simplistes du r ductionnisme tout en ne tombant pas dans cette forme de mysticisme qui apparait si souvent entourer certains discours obscurs en faveur de l mergentisme.Le livre n est pas tr s difficile, et est raisonnablement accessible aux personnes qui ont un bagage assez solide en m canique quantique standard, niveau master 1 Les chapitres les plus difficiles, qui concernent les preuves rigoureuses donn es ses r sultats sur le probl me des probabilit s peuvent tre saut s sans dommage car l auteur propose en amont d autres preuves moins rigoureuses, mais plus intuitives et moins formelles, qui donnent d j une id e pr cise de comment l auteur parvient r soudre le probl me.Excellent livre.

Good intro to Quantum Mechanics

1957 20 David Deutsch David Wallace BB 2008 500 3 4 a b

This is the definitive book for anyone interested in the Everett, or Many Worlds, formulation of quantum theory David Wallace is a leading philosopher of physics, with an incredibly deep understanding of the underlying physics.It isn t a popular level book this is a scholarly work, aimed at professional philosophers, physicists, and students Wallace gives a thorough discussion of the main issues confronting the contemporary Everettian decoherence, the emergence of classical worlds, pointer states, the origin of the Born Rule for probability, and time asymmetry The style is uniformly clear and engaging Readers will certainly come to the work with a wide variety of opinions on the plausibility of Many Worlds, but everyone should get a lot out of reading this book.

I have been looking for a book that explains Everett s Many Worlds Interpretation of Quantum Mechanics in a way that is authoritative, thorough, rigorous, and understandable to a person like myself who is a scientist in a different field This is it Wallace uses a combination of mathematics, and verbal explanation of both physics and philosophy to make all the issues accessible He writes very clearly and precisely, summarizes as he goes along and does not avoid in fact, faces squarely the common criticisms of MWI This is by no means light reading, but rewards the careful reader with a much improved understanding of what MWI is and is not.

This book is technical than I expected and is requiring me to revisit largely forgotten parts of quantum theory It is carefully argued and to me very convincing A most valuable work resulting from many years study Not for the faint hearted

I purchased this book with anticipation and money I have given much time to the study of quantum mechanics and to the Many Worlds Theory of Hugh Everett III However, I am not now nor have I ever been a physicist, so you can factor that into my review Having devoted considerable attention to the issue of scientific materialism versus scientific idealism or non materialism, I have opted for the Copenhagen Interpretation, which ultimately supports physicist John Wheeler s dictum that there is no out there out there Disappointingly for me, Wallace s book comes down squarely in the scientific materialist camp It s a big book and offers much to chew on in that regard In sum, it argues that there IS an out there out there and that we should be happy about that Actually, it supports Everett s view that there are an infinite number of out there s out there and that they are all equally of a material nature, demonstrating that they are not created out of wave potential by human consciousness One of my favorite physicists, Dr Edward Close, in his book, Transcendental Physics, makes this comment The many worlds and transactional interpretations were each offered, by Everett and Cramer, as conceptual aids to understanding quantum reality In fact, they are perfect examples of the way we tend to ignore mathematical results that do not correspond to our preconceived notions of reality But both Everett and Cramer, like Wheeler and Bohr .were careful to stick to the party line of the paradigm of scientific materialism and disallowed the involvement of consciousness in the actualization of physical phenomena from the spectrum of possible states of the wave equations Wheeler, it seems, had mixed feelings about the materialism of science issue and adopted conflicting stances depending upon how much peer pressure was being brought to bear on his current position.If you are looking for an extensive defense of the materialist position in terms of Everett s Many Worlds Theory, Wallace is your man I guess that because I am not a physicist, I can afford to play fast and loose with the theories, not really having a dog in the fight in so far as my career is not dependent upon my choice of a materialist or non materialist paradigm I have many worlds of wiggle room.

This guy gets it Wallace references Dr David Deutsch and does an excellent job of showing why the Everett interpretation is the only understanding that makes no B.S sense in other words, Everett is reality.

Parallel Universes, Quantum Theory and Quantum Computing all go hand in hand The Emergent Multiverse clears up several topics which have been less than clear For example the quantum basis of probability theory at a level where a lay technical person with a curiosity of how our universe works can find useful and informative.

I liked this book a lot It had parts which were very technical it is quantum physics after all but the main thread of the argument is easy to follow and convincing The idea argued for is the Everettian or Many worlds interpretation of Quantum Mechanics To bolster his argument he applies the equations of the theory which can be quite technical but then he usually goes on to explain philosophically the justification of the interpretation I suggest people who are not familiar with the mathematics of QM treat the equations like sentences from another language inserted into the text to make the author look smart and focus on the English translation which is the argument The book is very comprehensible without the equations but it is a rigorous text and I think Wallace felt compelled to include them.