Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime

I'm late to the party, I know; the book was published almost a year ago. But I swore I wouldn't buy another book on Quantum Theory. Every author claims they will explain it, but of course they can't. All I wanted to do was understand quantum mechanics before I died, but to use an oxymoron, Carroll made it blindingly clear that wasn't going to happen. Not the dying part, the understanding part. Don't misunderstand - this is a superb book. It's well written, insightful, and entertaining. It's on the other extreme of the spectrum of useful explanations from, say Roger Penrose. Penrose is reputed to be one of the smartest living scientists, but his writing is impenetrable and should not be marketed to the general public. Maybe 100 people in the world understand him. I suspect most physicists lie and never finish his books. I knew there was a problem with quantum theory when I tossed the problem of quantum entanglement to my 9 year old grandson and he couldn't solve it. He's a really smart kid. My experience has been the drunker I get the more sense theories seem to make. Problem is, I could never get drunk enough for quantum mechanics to make sense. When I read that if the wave function of the universe simply obeys the Schrodinger equation it will undergo decoherence and branching I think to myself tell me something I don't know. No I don't. I think is this going to be on the test? Is it too late to drop the course? What sustains me is the famous Feynman quote. Don't feel bad if you don't understand quantum physics. Nobody does. But exploring the many manifestations of quantum theory with witty conversations and amusing anecdotes is not enough. String theory, the many worlds, the numerous other quantum theories Carroll explains reminds me of what Hossenfelder said in her recent book Lost in Math. Theoretical physicists are collectively delusional, unable or unwilling to recognize their unscientific procedures. As Unger and Smolin said in The Singular Universe and the Reality of Time, if a theory makes no predictions and is unfalsifyable it's no longer science. The more time that passes after the establishment of the Standard Model in the 1960's and 70's with very little progress, the more philosophical and metaphysical science seems to have become. The thing I can't get past is nonlocality. Neither could Einstein. Having remote particles instantly affect each other when one of them changes is what Einstein called spooky action at a distance. No explanation I've seen is convincing. I think some of the critiques of Carroll's book are a tad harsh. I think the problem lies with quantum physics- trying to explain it is pretty heroic. Despite my criticism, if Sean Carroll writes another book I'll probably buy it. A parting note - I would have submitted this review earlier, but towards the end of the book I was seriously injured by a collapsing wave function.

It’s an amazing book covering the fundamental questions of quantum mechanics, something that is not often honestly discussed in courses. It discusses what any student (and professional) would really struggle with, conceptually and fundamentally, while learning its techniques. Anyone trying to understand the field should read the book. It’s would be hard for me to guess how someone not at all familiar with quantum mechanics would read it, but I’d imagine it would be a rich experience as well, although one would miss the excitement of getting the questions engaged and answered that would have been bothering one while learning the techniques.

I'm not one to review books, or even review anything at all, however, I wanted to give my two cents about this one. I read Something Deeply Hidden through and through. The information Carrol presents and reciprocates in his book is great, not gonna lie, and helped me add knowledge to my understanding of Quantum Theory. However, there are some quarrels about the author himself. To any piece of literature, whether that be non-fiction or fiction, the author reveals themselves within their writings, to which reveals who they are as a person. That being said, Carrol appears as a pretentious know-it-all that adheres to the prowess of knowing and teaching Quantum Theory. Not only does he remind you of that fact here and there, he begins the book with a warning and a history lecture, the latter being a third of the book as a whole. Both of which are not necessary as one looks to books that present Quantum Theory for the information and not for a lesson on how it got there. SDH is then like every other mainstream book about science that many physicists praise. If what you're looking for is the information, you would find it dead center of the book, excluding the fact that you know the workings of Hawking and Rovelli or that you don't mind a spiel about the metaphysical aspects of Q.T. (more on that later) Once you look past the character that is Carrol, you run into another problem. When explaining the concepts of entanglement and such, one would have to use an analogy to fully grasp them. What Carrol does is he formulates an analogy, but then drops it a paragraph later. Leaving the reader to pick up after the man who is 'teaching' you. Going back to when I mention the spiel on metaphysics. Completely unnecessary to the avid reader and actually blurs the knowledge trying to be obtained. Carrol somehow brought philosophy and went about it for a good chunk of time, which is understandable, to a certain degree, but irrelevant. All in all, the information present is not at all bad nor is it false. SDH is a great tool to add to your quantum theory toolbar. In essence, what matters is what is present and how well it is being understood. TL;DR: Carrol is arrogant but not in a bad way. Good info in most parts. 35% is a history lesson. 5% is a rant on Philosophical intentions, 25% is Carrol showing off, 15% is the juicy knowledge you're looking for, 20% is analogies that try to help.

The Many-Worlds idea has proven a source of inspiration to science fiction writers and has many of us thinking about what alternative versions of ourselves might be like. But it has been taken by the general public as a fringe idea – interesting but one on the borderline between science and fiction. This book puts Many-Worlds into the center of the debate about how to interpret the results of quantum physics. Carroll’s expertise in quantum fields has been firmly established over the years and his ability to explain ideas, as he did in his superb courses for The Teaching Company, makes this the best book available to explain what the Many-Worlds hypothesis is and what it means. After laying the background in the first third of the book, Carroll uses part two to spell out the strengths and weaknesses of Many-Worlds and why he holds to it. Carroll’s approach is “materialistic” but not in the old way of meaning that word. Materialism in the old sense of everything in reality being reduced to what we can check out by our five senses is absurd in the light of quantum theory. What Carroll means is that the Many-Worlds approach ignores things like consciousness or “mental” effects in the understanding of what is happening at the quantum level. Results like the “observer effect” and entanglement can be explained by a straightforward evidence-based hypothesis that takes the wave equation of Schrödinger and the experimental processes as the foundation of the theory. To agree with Carroll we have to accept the reality of “many worlds” and Carroll goes over the problems we have with that. But Many-Worlds is in an important way the simplest explanation (in the Occam’s Razor sense) of the strange results in quantum experiments. The third part of the book explores how the Many-Worlds hypothesis ties into explaining the origin of the universe and the origin of space and time. Carroll goes over three other possible theories and discusses Hawking’s cosmological ideas. As a non-physicist I found some parts of the third section more difficult but this does not detract from the overall clear and readable writing in the bulk of the book. This book and ones like it being produced today are starts toward convincing us that understanding the quantum level by the categories of our macroscopic reality needs to be replaced by understanding our macroscopic reality by the realities of the quantum level. The foundation of it all is there. As Carroll says, everything is quantum.

Many folks have expressed their thoughts about the discussion of the Many Worlds/Everettian interpretation of Quantum Mechanics contained in this book, but I'd like mention another aspect of this extraordinary book. Namely its excellent description of the so-called "Measurement Problem" of QM; that is the exploration of how QM describes the "Realism" (in the technical sense) of the phenomena underlying the results of laboratory experiments. Or, phrased another way, whether such "real" actual objects and interactions actually exist (as denied, for example, by the standard "Copenhagen" interpretation of QM). The discussion of the so-called "Many Worlds Interpretation" is, of course, excellent. And the book should be praised for presenting an intelligent, detailed --and serious-- discussion of the topic, accessible to any thoughtful, careful reader. But to my mind, the book is equally (or, perhaps more) valuable for laying out and explaining the actual underlying questions that underlie this whole topic; moreover, the issue that the "Many Worlds Interpretation" intends to address and, perhaps more to the point, a topic that is almost never seriously addressed even in university courses in QM. (If I may suggest another book that covers much of the same material (i.e. concerning the "Measurement Problem"), but with additional focus on the detailed history of the discussion, the reader may wish to take a look at Adam Becker's "What is Real?")

This is a really easy-to-read book to get started with Quantum Mechanics. When you are finished, you’ll have a good starting point to move on to more advanced texts, or a solid high-level understanding of the topic if that is what you’re looking for.

In this book, Sean Carroll does a good job explaining quantum mechanics for persons not schooled in this subject. But when it comes to his arguments in favor of the Many-Worlds interpretation (MWI) of quantum mechanics, I believe he falls well short of what could be termed “full disclosure.” MWI is an interpretation favored by materialists because it retains determinism and seems to avoid the need for some sort of non-physical entity such as mind or consciousness to collapse wave functions. And Carroll is certainly one of the most outspoken proponents of the materialist worldview (although he labels himself a “poetic naturalist”). So it is natural that he might favor this interpretation of QM that was first postulated Hugh Everett III in the 1950s and says that every time we make an observation the world branches, and there is another copy made—one in which, for example, the electron is spinning clockwise and another where it is spinning counterclockwise. Therefore each of us exists in countless worlds, all real, but slightly different. Some of the implications of MWI are as follows: • This universe is constantly splitting into a stupendous number of branches (perhaps as many as 10 to the 100th power)—resulting from measurement-like interactions between the myriad components of the universe. Moreover, every quantum transition that takes place in every corner of the universe is splitting our local world on Earth into countless copies of itself. • Although MWI predicts an awful lot of universes, these cannot interact with one another, and therefore there is no way to know if they actually exist. Hence, it is untestable and unfalsifiable, which makes this interpretation of QM speculation, not science. • MWI denies a singular self. Our notion of self is also split, and we exist in multiple worlds. Our self can be considered a tree with countless branches. Each version is slightly different with different life experiences and outcomes. The further we go from this moment in time the greater the differences in the life histories of our various selves. Our perception of only existing in one universe is illusory. The reality is that we exist in countless worlds. • The wave function is real—not just a theoretical thing in abstract mathematical space. We might think of atoms as real, but true physical reality is the wave function. In addition, there is a wave function for the universe and it is real. Therefore, everything in the universe is entangled. • MWI appears to violate Occam’s razor, which states “entities are not to be multiplied without necessity.” On the other hand, Carroll argues it is a simplified interpretation of quantum mechanics because it eliminates the disappearance of the unobserved possibilities described by the wave function. Some of the problems with the MWI that Carroll does not talk about are as follows: • MWI presupposes a multiplicity interpretation for quantum superpositions. The basic assumption being made is that quantum superposition by default equals multiplicity. However, when you use ordinary probabilities, you are not obligated to believe that every outcome exists somewhere. For example, an electron’s wave function really may be describing a single object in a single state, rather than a multiplicity of them. • MWI tries to eliminate the need for a human element in bringing physical objects into reality by saying that splitting can occur spontaneously. However, each branch of the Many-Worlds requires a measurement at the point of bifurcation or splitting and this implies an observer. Indeed, human observation does cause splitting and the “observation problem” is not really solved by MWI. It is also obvious that spontaneous splitting is unobservable. • Experiments prove that it is not measurements that cause wave function branching (or collapse) but information about the measurement. And this information may be obtained retroactively. If measurement-like interactions are occurring all the time in the universe then exactly who is “informed” about them? This need to include the role information plays in MWI branching implies that the universal wave function postulated by the theory has a mental component. • Another problem with the MWI is that we have been split into countless worlds with their separate realities, but we are aware of only this one world. The existence of other worlds, if they were to exist, is irrelevant—we can only deal with the world we know. What this theory may actually be describing are the myriad possibilities that exist for us depending on our choices. As we make a choice, we go down one path. A different choice would lead us down another, and so forth. A choice takes us down one of the possible branches predicted by the MWI of quantum mechanics—but we only experience a single reality since it depends on the choice we make. Accordingly, there is no need for multiple realities. However, MWI is thoroughly materialistic and logically we are nothing but a bag of particles—free will is impossible. Hence, choice doesn’t enter the MWI equation. In conclusion, Carroll does not outline these faults with MWI nor point out that the theory is unfalsifiable with no scientific evidence supporting it. Hence, it would be better to call it science fiction than a scientific theory. Secondly, because it denies a singular self, MWI is best described as a metaphysical oddity. Finally, by introducing a universal wave function as the foundation for reality, it argues in favor of a cosmology of oneness, which is the hallmark of spiritual ideology. In other words, it is ironic that MWI, which is favored by many materialists because it tries to eliminate consciousness from the equation, actually hypothesizes that the universe is characterized by wholeness in which everything is connected and there are no truly separate parts—just wholeness.

Carroll show that one can carefully explain many aspects of reality---in his case the physics particles and the cosmos---without using any math. The math is important many to make sure that what you say without it is actually correct. It's like when you read the label of ingredients in a food product, they don't tell you how they verified their truth in the lab, but you can usually believe them. Carroll does a very good job of this. Now Carroll has a candidly expressed goal of convincing you of the Many Worlds interpretation of quantum mechanics (QM). Well, I don't believe it for a moment, but I still liked the books a lot. It's like reading St. Thomas Aquinas or Martin Buber. Or like having a double bourbon at the end of a long day. Somehow... There is not a grain of support for the Many Worlds (MW) interpretation. Not a grain, for or against. It is pure metaphysics to believe or disbelieve. Carroll argues that MW is just taking the Schrodinger equation (SchrE) seriously, without 'collapse.' First of all, this is just false. The SchrE describes the evolution of a wave equation is Hilbert space. But we live in four dimensional spacetime, not Hilbert space. Attributing 'reality' to the wave equation, and alternative 'worlds' to the entities that are entangled and superimposed in the wave equation is a monster leap of faith for which there is no compelling argument. The major illegitimate assumption of MW is that every physical system has a Hamiltonian. Once you admit that you are gone. The decay of a particle, for instance, can be registered by a macro instrument (or Wigner's friend), and since the latter has a Hamiltonian, the whole system goes into superposition. But why must the instrument have a Hamiltonian? There is no reason in QM. QM assumes the system under study has a Hamiltonian. In many cases, we can find the Hamiltonian and show that the Schrodinger equation predicts. But there is no formula for finding the Hamiltonian of a system. Does my computer have a Hamiltonian? I doubt it. No one has ever found such a thing. QM seems to work universally because whenever we can find a plausible Hamiltonian, it works. But we mostly can't eve come close to finding a Hamiltonian for a complex system. We can create fake cardboard Hamiltonians by. say, representing the NY State lottery as a mechanism with a million integer outcomes. But that is not the NY State Lottery. There really is a classical world. We all live in it. There really is also a quantum world. How they fit together is one of the great mysteries of modern thought. We just don't know, and theologies like the Many Worlds approach impede our progress towards a real understanding.

Muchas gracias voy a empezar a leerlo llego 1 dia antes y esta grueso. Buen material (

Great book, not that easy to understand and requires deep thinking. As per the book, there are thousands of copies of me being created while I'm typing this review :D. I completed the book and still not convinced of the many worlds interpretation of Quantum Mechanics, however, it is fascinating to read about QM and the various interpretations of it. And the fact the MW interpretation is actually the one with less assumptions i.e. more natural interpretation of them all.

Sean Carroll's nouveau livre est un guide vers la mécanique quantique la plus poussée qui est accessible par tout le monde, peu importe leurs connaissances acquises en mathématique, physique classique ou physique quantique. C'est de plus un ouvrage qui explore les conséquences philosophiques d'un monde complètement différent du monde qu'on expérience tous les jours, et qui néanmoins semble être le monde dans lequel on vit.

Great book

In Something Deeply Hidden, the equation Schrödinger developed...rules the discussion (the book helpfully provides a stripped-down layman’s version of this equation, which will thoroughly baffle most of those laymen) ... Carroll’s book is so comprehensive, and he’s such a fantastic teacher ... As a smart and intensely readable undergraduate class in the history of quantum theory and the nature of quantum mechanics, Something Deeply Hidden could scarcely be improved. Carroll has a natural teacher’s knack for democratizing the conversation without sacrificing his own authority. I don’t believe for one femtosecond that possibility is the same thing as actuality; I don’t believe in ghost worlds and don’t think there’s a single word in Carroll’s book that should make anybody else believe in them ... [but] it sure is fun to imagine.