Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime By Sean Carroll

Sean Carroll Ò 6 Summary

As you read these words, copies of you are being created.

Sean Carroll, theoretical physicist and one of this world’s most celebrated writers on science, rewrites the history of 20th century physics. Already hailed as a masterpiece, Something Deeply Hidden shows for the first time that facing up to the essential puzzle of quantum mechanics utterly transforms how we think about space and time. His reconciling of quantum mechanics with Einstein’s theory of relativity changes, well, everything.

Most physicists haven’t even recognized the uncomfortable truth: physics has been in crisis since 1927. Quantum mechanics has always had obvious gaps—which have come to be simply ignored. Science popularizers keep telling us how weird it is, how impossible it is to understand. Academics discourage students from working on the dead end of quantum foundations. Putting his professional reputation on the line with this audacious yet entirely reasonable book, Carroll says that the crisis can now come to an end. We just have to accept that there is more than one of us in the universe. There are many, many Sean Carrolls. Many of every one of us.

Copies of you are generated thousands of times per second. The Many Worlds Theory of quantum behavior says that every time there is a quantum event, a world splits off with everything in it the same, except in that other world the quantum event didn't happen. Step-by-step in Carroll's uniquely lucid way, he tackles the major objections to this otherworldly revelation until his case is inescapably established.

Rarely does a book so fully reorganize how we think about our place in the universe. We are on the threshold of a new understanding—of where we are in the cosmos, and what we are made of. Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime

Rather than the confusing publisher's blurb, I recommend starting with the author's essay about his book:

I struggled with Carroll's book, which doesn't make a whole lot of sense to this (physics-impaired) old geologist. He writes well, and the history of the hostile reception to new research on the roots of quantum theory is deeply disturbing. Make no mistake, no one doubts that quantum mechanics works. And is deeply weird. Feynman once said something like I think I can safely say that nobody understands quantum mechanics. Still true, sfaict.

Carroll prefers Many-Worlds as the best theoretical basis for QM. And he is a physics prof at Cal Tech, Feynman's old home base. But gosh: one wave function for the entire universe? And a new world is created every time there's a subatomic interaction? The number of new worlds created would far exceed the number of atoms in the universe.... And no way to experimentally test any of this? Good grief. Angels dancing on the heads of pins?

Well. Since the book is already overdue, I think I'll call it good and go on to something else. I read about half of the book, and kept getting lost, rereading sections and trying again. My usual problem with trying to understand theoretical physics. 2.5 stars for what I read, rounded up for the good writing, interesting science history and provocative philosophizing. Do note that I'm not qualified to judge the physics -- but I do have a finely-tuned BS detector, which kept going off in this book.

Here's Manuel Antão's fine review, pointing out these problems (and many more!), which is when I realized I should give up:
He is better qualified than me to judge the physics. Well-read guy, too.

Nature's review:
Six decades on, the theory is one of the most bizarre yet fully logical ideas in human history, growing directly out of the fundamental principles of quantum mechanics without introducing extraneous elements. It has become a staple of popular culture, although the plots of the many films and television series inspired by it invariably flout the theory by relying on contact between the parallel worlds, as in the 2011 movie Another Earth.

In Something Deeply Hidden, Carroll cogently explains the many-worlds theory and its post-Everett evolution, and why our world nevertheless looks the way it does. Largely because of its purely logical character, Carroll calls Everett’s brainchild “the best view of reality we have”. . . .

Carroll argues that the many-worlds theory is the most straightforward approach to understanding quantum mechanics. It accepts the reality of the wave function. In fact, it says that there is one wave function, and only one, for the entire Universe. Further, it states that when an event happens in our world, the other possibilities contained in the wave function do not go away. Instead, new worlds are created, in which each possibility is a reality. The theory’s sheer simplicity and logic within the conceptual framework of quantum mechanics inspire Carroll to call it the “courageous” approach. Don’t worry about those extra worlds, he asserts — we can’t see them, and if the many-worlds theory is true, we won’t notice the difference. The many other worlds are parallel to our own, but so hidden from it that they “might as well be populated by ghosts”. . . .

Something Deeply Hidden is aimed at non-scientists, with a sidelong glance at physicists still quarrelling over the meaning of quantum mechanics. Carroll brings the reader up to speed on the development of quantum physics from Max Planck to the present, and explains why it is so difficult to interpret, before expounding the many-worlds theory. Dead centre in the book is a “Socratic dialogue” about the theory’s implications. This interlude, between a philosophically sensitive physicist and a scientifically alert philosopher, is designed to sweep away intuitive reservations that non-scientists might have. . . . English Scientific Revelation

There is more than a hint of theological method in modern physics. Carroll confirms this in his insistence that quantum physics is, in his words, not an ‘epistemic’ but an ‘ontological’ discipline His claim is that current quantum theory is a description of the way the world really is not merely a way of understanding the world. This is the traditional position of theologians who would like us all to consider God as the ultimate reality even if we find this reality to be not what we perceive it to be.

In fact Carroll defines science in general, not just physics, in theological terms. For him, the essential presumption of science is the intelligibility of the universe. This implies not just that there is a pre-existing order to be discovered but also that such order in some sense wants itself to be discovered. These implications are precisely those of what is called fundamental theology, the study of how God can be known about at all.*

The similarity between Carroll’s view of quantum physics and fundamental theology is important because in both there is no distinction possible between epistemology and ontology. How we know about the world, or God, is indistinguishable from what the world, or God, actually is. Theology has a term for referring to this knowledge of being (or Being) - revelation. Essentially, you either get revelation or you don’t. It can’t be argued about because the presuppositions about what constitute both existence and knowledge about existence are contained simultaneously within it.

Thomas Aquinas is perhaps the most well-known theologian to defend the presuppositions of revelation. In doing so, his preferred approach is cosmological, that is, treating the entire universe as an entity to be explained in terms of its existence and its history. At such a level of analysis, ordinary logic (like that of cause and effect and their priority in time) start to break down. Thus, Aquinas asks, if every effect must have a cause, what is the ultimate cause? And if human beings exhibit free will and purpose as an effect of that ultimate cause, is it not reasonable to attribute will and purpose to that cause. QED, the universe is a consequence of divine action with some divine purpose toward which it is drawn.

Carroll makes a parallel case for quantum physics and the Many-Worlds theory of Hugh Everett, formulated in the 1950’s. First, just like Aquinas, he adopts a cosmological position. The universe, he says, is one vast quantum state, a wave function of enormous complexity. This is not inconsistent with the theory of quantum physics even if it could never be empirically verified. And it fits with the strange results of quantum experimentation. QED, reality is composed 0f an indeterminate number of simultaneous universes. In other words, Everett’s theory qualifies as a revelation.

If this is the case, then this wave function will evolve according to the mathematics of the Schrödinger equations, just as it has always done. Not according to the logic of Newtonian (or Aristotelian) cause and effect but the logic of probability and entanglement. This wave function is not something temporary or local that might transform into something else, say a particle, or ‘collapse’ upon observation. Within it is not only the universe we know about but an infinite number of others that exist simultaneously.

The wave function, in other words, is the very stuff, the ultimate reality of the universe; and it doesn’t make distinctions between observer and observed or between possible and actual. Our brains and the farthest galaxies as well as everything in between, including any number of other worlds, must be part of this wave function, since there can be nothing else. So the conventional ‘Copenhagen interpretation,’ despite its usefulness, is wrong. The wave function is the Alpha and the Omega, the source and giver of not just life but also existence, the Ground of Being (as modern theologians like to say). If it explicitly isn’t called godly, it’s only because the divine has suffered a significant reduction in brand-value in recent centuries.

That all sounds logically fine, if more than a tad baroque. But the reason it all sounds fine is the same reason that Aquinas sounds fine to the Pope. Once ontology and epistemology are conflated, that is, when that which is is presumed to confirm that which we know, we have entered the realm of religion. At that point, we simply assume a cosmological guarantor in what we take as revelation. Revelation is its own assurance; it proves itself. And at that point Aquinas is about as credible as Carroll

* The most important Christian theologian of the 20th century, Karl Barth, devoted himself almost exclusively to this issue. The intellectual machinations he had to employ in order to establish the intelligibility of God are really important for scientists like Carroll to consider before casually presuming an even more diffuse source of such an attribute.

Postscript 16Sep19. Another view: English This book is about the Many-Worlds hypothesis of quantum mechanics. It is a deep description of the hypothesis, and its context in quantum mechanics. Quantum mechanics does not violate logic; its precise predictions are correct, and among the most accurate of any scientific theory. But its foundations are still quite controversial, especially when it comes to understanding the role of gravitation.

The Many-Worlds hypothesis is a simple way to explain some of the seeming paradoxes of quantum mechanics. There are alternative hypotheses, and the book covers these as well.

I can't say that I learned anything (I am a physicist), but the book did focus my attention on a few key ideas. First, it is incorrect to say that atoms are made up mostly of empty space; particles are not tiny points, but are wave functions that are spread out in space.

Another example: The Heisenberg Uncertainty Principle does not say that the act of measuring a quantity disturbs the system. In addition it does not say that you cannot simultaneously measure position and momentum perfectly at the same time. Instead, it says that a definite position and momentum (velocity) do not even exist simultaneously. The wave function solution to the Schrodinger Equation acts as a wave, and so it can be analyzed like a Fourier Transform. Think of a sudden audible transient--like a click. The click occurs at a definite point in time, but it has no specific pitch because its spectrum is broadband. Likewise, a pure audible tone must occur over a span of time; it does not occur at a specific, definite time.

Here's the problem with the book. Like many technical books that are aimed at non-specialists, it gets deep into jargon and concepts that are totally unfamiliar. The non-specialist can understand all the words, and maybe even entire sentences. But it comes off sounding like a foreign language. And, there is an additional problem with this book. Much of the book focuses on the Schrodinger Equation, which is a typical type of partial differential equation. But unless you have studied similar equations, you cannot really understand the physical concepts described in this book. A general form of the equation is written in the book, but it is so simplified, that to a mathematician it doesn't convey much of anything, and to a non-mathematician it is gibberish.

This book is an excellent attempt at explaining some of the deepest mysteries of quantum mechanics. But the fundamentals are not covered well enough for a general reader to grasp all the arguments presented here. English I think I can safely say that nobody understands quantum mechanics.
- Richard Feynman

Shut up and calculate.
- David Mermin

Sweet is by convention, bitter by convention, cold by convention, color by convention; in truth there are only atoms and the void.
- Democritus

As an amateur, I love physics. I think there is something in my brain that associates the bleeding edge of physics with poetry and art. I'm not the only one. Authors like Thomas Pynchon and Cormac McCarthy are constantly using physics as a springboard into literary ideas and explorations. I think one of the big connections between theoretical physics and literature is the fact that both seek to explain the world through imagery and metaphor. Physics are hard science's poets.

Sean Carrol does a fantastic job of describing the many-worlds interpretation (MWI) as initially suggested by Hugh Everett. The entire price of admission to this book was paid when I discovered in this book that Hugh Everett is the father of EELS' lead singer and song-writer Mark Oliver Everett (also known as E). Talk about convergence.

Anyway, the book was well written, carefully laid out, and like other topics I've flirted with (Knot theory), I'm pretty sure I just walked off with a pip of knowledge, but I'll keep coming back to the damn fruit of the tree of knowledge. English In this book Carroll fully embraces the reality of quantum mechanics. He doesn’t accept that it’s just useful for calculations. Carroll says that the quantum world is the real world. Rather than proceed from classical physics to explain the quantum world Carroll starts with the quantum world to find out how it builds the world described by classical physics. Carroll’s approach leads to what many consider outlandish conclusions.

Carroll is a theoretical physicist at Caltech and an award winning author of physics books. Here he makes a case for the Many-Worlds theory of quantum mechanics calling it “the most promising formulation of quantum mechanics”. Quantum mechanics is proven science. It is fundamental to the way the universe works. But what it tells us about the nature of reality is disputed. The different takes on this question have been commonly called interpretations, but Carroll considers this term misleading since it implies the answer is subjective. He uses the more recent description, the foundations of quantum mechanics. Here, I’ll stick with the more familiar and less cumbersome word, interpretation.

The Many-Worlds interpretation of quantum mechanics was first espoused in 1957 by physicist Hugh Everett in his PhD thesis under the guidance of Noble Prize winner John Wheeler. The Many-Worlds interpretation was at first widely dismissed as nonsense but has gained more support over time. In the quantum state particles are in superposition meaning they are in a combination of positions all at the same time, both here and there, an electron spinning both up and down, a photon both vertically and horizontally polarized, etc. While strange we know it is true. Quantum computers are being built that operate taking advantage of those extra states to process calculations at unheard of speed.

Every quantum object has a wave function which tells us the probability of finding it in a particular state. When we measure we get a distinct answer. But what is the fundamental reality, the quantum state of superposition or the measurement yielding a specific position? Carroll believes it is the quantum state. The measurement is just what we observe. This belief pits Carroll against the standard theory also known as the Copenhagen interpretation.

Carroll says the Many-Worlds theory is consistent with the science while the traditional interpretation is not. First Many-Worlds avoids the measurement problem that plagues the Copenhagen interpretation. The Copenhagen interpretation holds that the wave function collapses when we measure yielding a specific value. Carroll holds there is no reason to believe that the wave function does collapse. Physicists commonly accept that the evolution of the wave function is defined by Schrodinger’s equation. That equation does not indicate the collapse of the wave function. Nor is there any other support for the collapse. According to Carroll it was just made up to explain why measurement gives a specific outcome.

An implication of the Copenhagen interpretation is that particles in the quantum world only become real when they are measured. This makes no sense. Carroll holds that all the possible outcomes are real, but in different universes. The Many-Worlds theory holds that for every possible outcome the universe splits accommodating each. Carroll believes there is one wave function for the universe and we are all in superposition with it. So if we are betting on a coin toss, in one universe we win but in another we lose. We are entangled with the coin and go together in both universes, each universe forever completely separate from the other.

A second problem with the Copenhagen interpretation is that it claims the quantum world only exits at the micro level of fundamental particles, even though experiments now show that larger objects display quantum characteristics. So where is the dividing line between where quantum mechanics rules and classical physics rules. Any such line is arbitrary. Carroll considers the entire universe to be part of the quantum world defined by a quantum wave function, just as are fundamental particles. He holds that the everyday world we encounter, the universe described by classical physics, is an emergent property of the universe’s wave function. Carroll says that the Many-Worlds interpretation best explains the reality of the quantum. There is no measurement problem, no arbitrary distinction between quantum and classical worlds, and no mysterious making something real by measuring it. Every outcome is real and consistent with the quantum world.

Carroll points to entanglement, an idea that came out of quantum mechanics that has been proven in experiments. When two particles become entangled they become one quantum system, a change in one means the other also changes instantaneously even if they are light years apart. Carroll believes every object can become entangled. For example the equipment or people measuring particles or anything else become entangled with them and also are in superposition with them. Photons, electrons or other particles will inevitably interact with a macroscopic object. Thus macroscopic objects are necessarily entangled with their environment and thus with the entire universe and are part of its wave function.

The Many-Worlds formulation also offers an explanation for the famous two slit experiment. When electrons pass through both slits of the testing apparatus they hit a screen forming an interference pattern because they are waves. But when we set up a detector to measure them they pass straight through to the screen showing up as if they were particles. Carroll holds that this is because any interaction including measurement, in this case between the detector and electron, causes what is known in quantum mechanics as decoherence. The electron’s quantum state has been altered. In the Many-Worlds theory decoherence causes the electron and its shared wave function with the universe to branch into different universes thus the electron can no longer interfere with itself as it passes through the detector.

Carroll briefly explores some alternative quantum theories: the GRW theory of dynamical collapse, the Bohmian mechanics model using pilot waves and QBism an epistemic model that holds the wave function is purely informational and not real. Carroll sticks with Many-Worlds calling it “simple and elegant” but indicates he will switch if something better comes along. In the final chapters he explains quantum field theory describing quantum fields that fill the universe creating locality and becoming entangled. In a fascinating discussion he shows how entanglement of quantum fields could yield space. He also discusses the search for quantum gravity and looks at black holes from a quantum perspective. These sections were quite involved, but I enjoyed his unique presentation.

Central to all of Carroll’s thinking is starting with quantum mechanics to create the world of classical physics. In his own words:

Nature is quantum from the start, described by a wave function evolving according to an appropriate version of the Schrodinger equation. Things like ‘space’ and ‘fields’ and ‘particles’ are useful ways of talking about that wave function in an appropriate classical limit. We don’t want to start with space and fields and quantize them; we want to extract them from an intrinsically quantum wave function.

From a Many-Worlds perspective that treats quantum states as fundamental and everything else as emergent, this suggests that we should really turn things around, ‘positions in space’ are the variables in which interactions look local. Space isn’t fundamental; it’s just a way to organize what’s going on in the underlying wave function.

I don’t have any idea whether Many-Worlds turns out to be a great contribution to physics or just a bizarre dead end. But I don’t dismiss an idea just because it sounds crazy. Regardless of the fate of Many-Words, I learned much about quantum mechanics from Carroll’s presentation. For example, he offered the clearest explanation I have read for why it is not possible to measure position and momentum at the same time in quantum mechanics. I’ve read several of Carroll’s books and enjoyed them all. In this one I found myself frequently paging back and forth. It definitely is for someone with a strong interest in the subject and an open mind.

This was definitely one of Carroll's more technical works. While his language as always as simple as it can be for the layman, there's only a certainly level of simplicity to which quantum theory can be broken down. That said, Carroll does good work interspersing all of the necessary technicalities with a more story-form description of the ideas behind quantum gravity, Many Worlds, and quantum physics, so if only half of the book sticks with you, you're still bound to learn something. Carroll's trademark humor, too, shines through in a lot of places, and serves as a good anchor point to bring even the most baffled reader back from the brink. Definitely not for beginners to the ideas behind quantum theory, but an excellent book to build on what a fan of popsci might already know. English This book is like taking acid, be warned—it's a total trip.

Not that I'd know, but I'm guessing based on Rick and Morty episodes I've never watched.

In other words, don't take my word for it, I need to brush up on my quantum mechanics apparently.

“On the other hand, in the memorable words of Richard Feynman, 'I think I can safely say that nobody understands quantum mechanics.'”

“Should the branching of our current selves into multiple future selves affect the choices we make? In the textbook view, there is a probability that one or another outcome happens when we observe a quantum system, while in Many-Worlds all outcomes happen, weighted by the amplitude squared of the wave function. Does the existence of all those extra worlds have implications for how we should act, personally or ethically? It’s not hard to imagine that it might, but upon careful consideration it turns out to matter much less than you might guess.” English TL;DR

Sean Carroll’s Something Deeply Hidden tackles the difficult many worlds theories of quantum mechanics. It’s weird; it’s funny; it’s deeply philosophical and worth reading. Highly recommended.

Disclaimer: I received a free copy of this as an ebook from the publisher in exchange for an honest review. Find this and other reviews at my website


According to quantum mechanics, it’s entirely possible that there are multiple copies of you reading multiple copies of this review. The many worlds approach to quantum mechanics says that the world decoheres into various branches. Branching reality is a difficult subject, but it is one that makes sense when interpreting exactly what quantum physics represent. Physicist, author, and podcaster, Sean Carroll attempts to explain these subtle and difficult philosophical questions in his latest book, Something Deeply Hidden, from Dutton. This is a book of big ideas explained to an audience of anyone. It doesn’t spoon feed the reader answers, but nor does it put concepts too far out of reach. For anyone interested in quantum mechanics, this is a must read.

Review: Something Deeply Hidden

I’m a fan of Sean Carroll. I like his podcasts and his appearances on Joe Rogan’s podcast. He’s entertaining while still conveying complex knowledge. So, this review is biased from the start. I don’t understand quantum mechanics, and for most of my studies, I’ve been told I don’t need to understand it because the math works. It’s an odd way to approach physics. To quote Richard Feynman, “…I think I can safely say that nobody understands quantum mechanics.” Certain physicists like Sean Carroll have decided to change that. Something Deeply Hidden largely succeeds for our current best understanding. It doesn’t rely on the fact that the math works out; it attempts to explain reality, which was physics original purpose.

The book reads well; it’s not full of equations, though there are some. Dr. Carroll’s style of explanation is clear enough without equations. He’s funny and fills the book with good examples and easy to follow illustrations. Dr. Carroll lays down a foundation of quantum mechanics history before moving onto cutting edge physics and then to the weird stuff. Something Deeply Hidden is an intensely philosophical book that I’m still thinking about.

The book focuses on Schrödinger’s equation and the Everettian interpretation, which is also known as the many worlds interpretation. In short, Schrödinger’s equation describes the wave function of the universe, and there is no collapsing of the equation. Instead of superpositions collapsing into a measured reality, the measurement causes a branching of the universe. Let me repeat that a branching of the universe. One where outcome A happens and another where outcome B happens. And guess what, we branch when the universe does as well.

The Many Worlds Interpretation

Decoherence, branching, and superposition are difficult concepts to understand. Honestly, I’m not sure I grasp it fully. Dr. Carroll does a good job explaining it in a way that I could start to understand. (This is a book that I will have to reread.) The idea that the universe branches has long been a popular idea in science fiction (see the TV show Sliders). But it’s much more complex than simply a person’s decision causes the universe to split. In fact, Dr. Carroll deliberately debunks this idea. The universe branches, but an individual’s decision doesn’t cause the branching.

Dr. Carroll explains the many worlds interpretation in plain terms that at the same time make you scratch your head. In Chapter Seven, Dr. Carroll writes a short story that’s a dialogue between father and daughter physicists. In a way, it reminded me of What We Talk About When We Talk About Love by Raymond Carver. This chapter was unexpected yet effective in conveying difficult topics around probability. It was an odd chapter in a physics nonfiction book, but it helped convey the information. Something Deeply Hidden is well written.

Part Three

Something Deeply Hidden is organized into three parts with a prologue, epilogue, and appendix. I kept up easily with part one; part two stretched the limits of my intellect; and part three simultaneously blew my mind and broke my brain. I don’t think I can adequately review this section without reading it again. And I will definitely read it again. In my review copy, one of the chapters in part three is titled, “Breathing in Empty Space.” A chapter title like that deserves re-reading.

Multiple Me's

One consequence of branching is that when the universe decoheres and branches, so does the person.
In other words, there are many copies of each of us on various branches out in the multiverse. Maybe. Dr. Carroll treats this as no big deal, and really after thinking about it for a while, it isn’t. Since we can’t interact with these other branches, contemplating the other me’s that exist is much the same as contemplating how many angels dance on the head of a pin. But I never did shake the weirdness of me branching with the universe.

This branching has direct consequences to conservation of energy and the concept of entropy. I’m not entirely convinced of the answer provided, but it’s an interesting answer. This is one of the rare moments in the book where I don’t think the answer conveys a physical meaning. Or, at the very least, one that I can understand. If the universe branches enough, does that mean it’s possible to lower the energy of the many worlds to almost zero? If so, what happens to all the me’s in those branches?

Competing Theories

Dr. Carroll states plainly that he subscribes to Hugh Everett III’s interpretation of quantum mechanics. But he does devote time to competing theories and gives them fair treatment. Then, he explains why he thinks the alternate interpretations are wrong but in respectful manner. Maybe I’ve been reading too much politics lately, but this was really refreshing. It’s important to see a thoughtful summary of and argument against a competing philosophy without a need to ‘win’ – whatever that means in physics circles.

This section also serves as a starter for investigating more about the interpretation of quantum mechanics. In this section, I learned the phrase quantum Bayesianism, which is just fun to say. Dr. Carroll’s description is quite interesting, and I might look into the topic in the future.


Sean Carroll’s Something Deeply Hidden broke my brain in the best way possible. This insightful, philosophical book explains difficult, complex concepts in understandable language. Based on the arguments, I’m now an Everettian convert. Somewhere out in the multiverse, there’s an Eric writing a better review of this book. In a different branch, there’s an Eric who didn’t get to read this book, and he’s all the poorer for it.

9 out of 10!
English I eagerly waited for this book for a year. Having read Deutsch, Albert, Aaronson, Becker, I had very high expectations about the insights Carroll would add.

The book fell short on introducing and justifying quantum concepts. Entangled pairs are presented without the obvious comparison to correlated classical objects (like two pieces of a torn card, as soon as I look at mine the one you have is determined faster than the speed of light ;) Bell’s theorem is not explained at all, when there are so many simple examples. Basically if you didn’t know why the world has to be different from our classical conceptions, you still wouldn’t know after reading this book. Becker’s book does a better job at this.

I also have a beef with some of the terminology that is not specific to this book. I don’t know why physicists still use the word “measurement” when it has confused so many generations - wouldn’t “interaction” work just as well without invoking conscious observers in lab coats? Similarly “wave function” misleads when you are not talking about the position of a single particle: in what way does the spin of an electron wave? How about just calling it a “state vector”? Aaron’s book does a better job at this.

I would recommend this book for the speculative but provocative ideas about tying quantum theory with spacetime.

It is a pity, Sean is usually such a great explainer. I suspect some draft of the book had parts that gave good intro insights but were somehow voted off. I wish I had access to earlier drafts. English First third is fantastic! The latter bits get quite meandering... It seems I am always very curious about the scope of Carroll’s books but never quite getting what I expect.

Nowhere near as engrossing as Rovelli’s stuff. So... a very reserved recommendation. English