This took a while to get through. Carroll's explanations are lucid, and helpful, but the material is occasionally a bit opaque and--frankly--mind-blowing. What this book lacks completely is sensationalism. Carroll lays out a case rationally, calmly, completely. This is a must-read for anyone who's interested in how the world(s) works.

I thought I would try something different.... but then realized why I never liked science in school.

Brilliantly written and so intriguing, but it missed the mark for what I prefer to read.
I DNF'd this one.

Thank you to the author, publisher and NetGalley for my complimentary ARC in exchange for an honest review. Please excuse my tardiness in posting my review as my TBR continuously grows and I keep finding so many book with so little time!

So much gratitude for this copy shared with me, always xo

I was granted an ebook ARC of Something Deeply Hidden by Sean Carroll by the Publisher Dutton on Netgalley to provide a fair and honest review.

Video review in progress
You can read my full review on my blog!

Introduction
I am beyond grateful to be offered the opportunity to review this book. I just recently finished one of Carroll's older books, and it is one of my favorites of the year. I know this book is already out. Nevertheless, the copy I was granted expires on the 31st of December, so intend to finish it before then to provide feedback for the copy I received. When I reviewed From Here to Eternity, I tried to review each part of the book. I think the result was a bit of mess; it was also a lot of work. Here, I will stop after each chapter to very briefly summarize his points and to discuss how effective it was as a chapter. Summarizing it will help me get a sense of how well I really understand it. Basically, I'm blogging my entire experience with the book. When I'm done, I'll summarize my thoughts above my blogging experience (right after this).

Final Thoughts
I absolutely adored this book. I am so grateful to NetGalley for providing me with an e-ARC of this. I didn't even realize it was already out, and I ended up using the audiobook (also amazing) to read the book. I still am happy I got the ARC because I may not have read it otherwise. I have only just started on NetGalley. I am a fan of Carroll, so I wanted the chance to review his newest book early. Even if it was already out, I may not have read it without the ARC because that was really the biggest motivator (the need to provide a review).
Otherwise, I might have read a different book by him because I was honestly very afraid of this book. The first time I saw the synopsis (prior to finding it on NetGalley), I read quantum mechanics and thought this was not for me. I have never understood it and was unlikely to start trying now. Then, with the added incentive, I decided to give it a try. Dear Sagan am I happy I did. I left this book feeling as though I actually understand quantum mechanics. Then add on the extra benefit of being beyond fascinated, intrigued, and excited by his discussion of Everett's Many World's hypothesis. I go in depth in my thoughts on that in my live blogging where I responded after each chapter. I would refer you there, jjoshh.com !, if you are interested in reading that.

All in all, this book did everything I want from a science book. It challenged my fundamental way of thinking all the while in a clear and structured manner. What's more, it is one that doesn't shy away from the tough parts of science while not creating a story that completely hinges on your reader to have an expert level understanding to follow along. I highly recommend this book and Sean Carroll (and his podcast Mindscape). This will probably be one of my top 10 books of the year. 5/5 stars

Rating Break Down
Writing Style: 10/10
Content: 10/10
Structure: 10/10
Summary: 9/10
Engagement: 10/10
Enjoyment: 10/10
Comprehension: 8/10
Pacing: 9/10
Desire to Reread: 10/10
Special: 10/10
Final Rating: 4.785/5
Note, each rating is weighted based on personal importance (see blog for more details).

I received a free digital copy of this book from NetGalley in exchange for an honest review.

I really like books like this because you learn while being entertained. I like Sean Carrol. I am a long time listener to his podcast. I really enjoy his entertaining way of explaining things that really should go over everyone's heads.
The book reads well. I really enjoyed it. I was a bit nervous to start this title. It seemed a bit daunting and complex. I do not have a background in science, so I was worried that this would all just go over my head but Carrol has a unique way of helping you understand super complex things.

Overall this is a great and intense read that we should all pick up.
Thank you to the author, the publisher, and NetGalley for allowing me to review this title.

Physics necessarily conducts rather reductive science. Psychology emerges from biology, which in turn emanates from chemistry, which itself functions as physics writ large. Some physicists find it possible (and desirable) to explain this emergent narrative to a wide, non-specialist audience, a formidable task without employing the underlying numbers and equations.

The issue at hand concerns the nature of the world itself — world qua everything that exists, the universe and everything in it, the cosmos. Thinkers before Plato tried to determine the fundamental components of our world, and the urge to build upon this understanding with greater and greater specificity has continued to this day, creating a sort of physical refinery within the natural sciences.

At least since physics laid claim to the atom, scientists have been searching for ever more underlying substances and/or principles at work. The thinking goes that these more fundamental constituents are what really exists, while the rest simply emerges from these materials.

A computer or television monitor produces images made up of dots that combine to form a picture we see on the screen. The video then is “really” just a series of dots in a certain configuration.

The same holds true for physicists at the forefront of modern science. In fact, such has been the case for at least the last century, perhaps much longer, depending on one’s viewpoint. As far back as the 1800’s, John Dalton used the notion of atoms to explain certain features of elemental reaction. Today, physicists work largely in the realm of quantum mechanics, but the principles remain the same: to determine ever-deeper constituents of space, time, and matter.

Sean Carroll, of the California Institute of Technology, has written numerous books for lay audiences on these and other subjects from a physicist’s perspective. He writes clearly and with an essential dose of humility, an element glaringly missing in some treatments of the subject. Carroll sets out in Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime (Dutton, 2019) to explain the current state of quantum physics for interested non-physicists, as well as to elucidate some of the more speculative ideas that arise when moving from experimentation to theoretical world-building.

While all books in the “quantum” category deal with a related batch of subjects, most of them attempt to answer or provide solutions to the tricky matter of measurement, which is inextricable from that locality and entanglement — or why particles seem connected even lightyears apart from each other. What Heisenberg and Bohr argued in Copenhagen about the collapse of the wave-function came to be accepted as Truth. This interpretation of the quantum problem of measurement does fit the math in many ways, but it fails to explain much else about the universe that further experimentation and equation-solving have brought to light. As Carroll himself writes,

“What exactly a measurement is, and what happens when we measure something, and what this all tells us about what’s really happening behind the scenes: together, these questions constitute what’s called the measurement problem of quantum mechanics. There is absolutely no consensus within physics or philosophy on how to solve the measurement problem, although there are a number of promising ideas.”

For his part, Carroll is a proponent of one promising idea called the Many Worlds Theory, an interpretation of quantum mechanics stating that each time someone makes a quantum measurement a new world branches off from the current timeline. If you’re like me, this explanation might strike you as a clear violation of Occam’s razor. It seems to introduce far more complexity than ought to be warranted. Carroll isn’t blind to this: “[A] proliferating tree of multiple universes...is arguably not very simple at all.”

Despite this, throughout most of the book, he propounds the Many Worlds Theory (also called Everettian, after the theory’s founder). He goes to great lengths not only to explain the theory in great detail, but to lay bare the difficulties this claim makes, as well as the problematic nature of any of the many theories attempting to explain the perennially thorny measurement problem in relation to the whole of the cosmos and its foundational aspects.

Ultimately, what we discover is that the Many Worlds Theory actually, at least in Carroll’s explanation, provides arguably the simplest interpretation of quantum mechanics. If nothing else, this ought to impress upon the astute reader how tricky the problem of measurement actually is. On the face of it, the very notion that a new “world” splits off each time someone takes a quantum measurement is anything but simple or straightforward. But, again and again, Carroll takes great pains to explain how this is almost certainly the case, amplifying the magnitude of uncertainty involved in this particular scientific and theoretical endeavor.

As we know, Newton laid out the foundations of classical mechanics and calculus, which explain to a high degree of accuracy most of what we experience in the world on a macroscopic scale. By the early 20th century, however, physicists like Heisenberg and Bohr, Schrodinger and Einstein, and many others, turned this idea on its head. While large objects obey the laws of classical mechanics, the world isn’t really classical: it’s quantum.

In other words, quantum mechanics describes everything we experience in the world, too, only to a much higher level of precision than classical, Newtonian physics. Carroll writes that the world is, in fact, quantum in every way, from top to bottom, even if we don’t always experience it as such. This notion is so antithetical to intuition that it’s hard to grasp, even for the physicists themselves; hence, the ever-present measurement problem.

Carroll’s explanation — in short — goes as follows: the universe and everything in it can be explained by something fundamental, namely, the Schrodinger equation as it describes the evolution of the wave function. He writes: “Schrodginer’s wave function works; you have a single function that depends on the possible positions of all the particles in the universe.” Sounds a lot like classical mechanics. Except he goes on: “It’s that simple shift that leads to the world-altering phenomenon of quantum entanglement.” And just like that, the world ceases to be Newtonian.

Most are familiar with Schrodinger through his famous cat experiment, in which a box contains both one cat that is somehow both alive and dead, at least before we open the box to measure it. As soon as we measure, the cat is either alive or dead. In the Copenhagen interpretation, the measurement is what — more or less — causes the cat to be in that state. Something mysterious seems to be going on, there’s no doubt about that.

But Carroll says that the Everettian Many Worlds Theory solves this problem in a novel way. Instead of measurement causing the cat (standing in for the “wave function”) to be alive or dead (standing in for “collapse of the wave function”), measurement actually produces two distinct timelines, one in which the cat is alive and another in which the cat is dead. According to Carroll, while it’s far from certain or accepted in the physics community as a whole, much of the math makes this at least a little difficult to dispute.

Of course, my short appraisal here does not do justice to the theory (or include any of the equations). There is much more to be said on entanglement at great distances, black holes and their horizons, entropy, the emergence of space-time, and perhaps the biggest bugbear of all, gravity. Carroll makes each of these topics readily understandable to the reader willing to focus on the task. This does not mean they are easily understood, of course, only that Carroll’s text works admirably to make it so.

While we may not have a complete and full understanding of the universe, physicists labor away, crunching the numbers and building ever-larger particle colliders in the hopes that one day, quantum mechanics will include everything we are able to measure in the world without any spooky action at a distance. Either way, the search continues, and Carroll’s book is a phenomenal place to get an in-depth look at the cutting edge, as well as all the progress made so far.

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.

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.

Review

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.

Conclusion

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!

Something Deeply Hidden is that rare science nonfiction book that’s both easy to understand and incredibly complex. This is quantum mechanics laid out in an understandable fashion. With a combination of history, basic explanations, and visual aids that simplify its complexities, Carroll presents an essential guide to this mysterious field.

I’ll admit I was nervous as I started reading the book. At first glance, the subject matter seems too dense for a basic human without any scientific background. As you read, it slowly starts to make sense until you’re nodding along at things you never thought you’d learn. One of the most fascinating aspects of the book is the history of how the field came to be. It’s nearly impossible to imagine a group of people coming up with these kinds of theories but here we are.

Above all, you’ll learn so many things about the mysteries of the universe. I continue to have trouble wrapping my head around this fascinating field of science but I feel a big step closer after reading this thoughtfully written guide to everything quantum mechanics.

Sean Carroll of Caltech is an excellent writer and he has produced a wonderful book that everyone who has a solid science background must read. That said, "Something Deeply Hidden" is not for everyone. The general public should avoid this book. It is a bear to read with concepts like Hilbert space and countless other very technical issues and concepts. I give it five stars for those in the scientific community and those who possess a firm footing in classical relativity and the shift to quantum mechanics over the last 100 years. For everyone else -- Please avoid this fine book.