On Gravity: A Brief Tour of a Weighty Subject

by A. Zee

A brief introduction to gravity through Einstein's general theory of relativity



Of the four fundamental forces of nature, gravity might be the least understood and yet the one with which we are most intimate. From the months each of us spent suspended in the womb anticipating birth to the moments when we wait for sleep to transport us to other realities, we are always aware of gravity. In On Gravity, physicist A. Zee combines profound depth with incisive accessibility to take us on an original and compelling tour of Einstein's general theory of relativity.

Inspired by Einstein's audacious suggestion that spacetime could ripple, Zee begins with the stunning discovery of gravity waves. He goes on to explain how gravity can be understood in comparison to other classical field theories, presents the idea of curved spacetime and the action principle, and explores cutting-edge topics, including black holes and Hawking radiation. Zee travels as far as the theory reaches, leaving us with tantalizing hints of the utterly unknown, from the intransigence of quantum gravity to the mysteries of dark matter and energy.

Concise and precise, and infused with Zee's signature warmth and freshness of style, On Gravity opens a unique pathway to comprehending relativity and gaining deep insight into gravity, spacetime, and the workings of the universe.

Genres: Science, Physics, Nonfiction

200 pages, Hardcover

First published January 1, 2018

Reviews

[Manny · Rating 4 out of 5]

This charming little book, which I zipped through in a few hours, is basically an extended trailer for the author's more substantial works on the same subject. Zee says he's addressing the members of the audience who've read some popular science books and are now wondering if they could transition to the real thing. He does a great job of giving you a feel for what it would be like to read a proper physics book, without actually throwing you in the deep end; if physicists were pilots, you could call it a flight simulator. The math is presented schematically, and you're gently encouraged to look at equations and size them up. What does the left hand side mean? What does the right hand side mean? This expression is the sum of three smaller expressions. Where does each one come from? What are the physical intuitions underpinning the mathematical argument?

En route, he makes sure you're entertained. He has a good line in acid asides - I get the impression that he does not love string theory - and there are plenty of stories I hadn't seen before, particularly from the gravitational wave detection community. It sounds like the LIGO collaboration had to traverse an unusually arid desert to reach their land of milk and Nobel Prizes. And you can't help feeling sorry for poor Joseph Weber, doggedly maintaining that his detector could pick up gravity waves and nearly hitting Richard Garwin, who cruelly announced at a conference that he'd built a replica of Weber's machine to prove that it couldn't in fact detect anything.

I actually have read some real physics books, but Zee makes me want to read more of them. In particular, I must get to grips with his notoriously inaptly named "In a Nutshell" series. Too bad that my copy of Quantum Field Theory in a Nutshell is currently sitting on our Australian bookshelf...

[Bernhard · Rating 4 out of 5]

“Gravity is absurdly weak compared to the electromagnetic force”. Well, that’s not very surprising and I think most people who have read about physics would know this. To me, the most surprising thing is the following: “Electromagnetism is stronger than gravity by a factor of 10^36”. That’s a value of 1 followed by 36 zeros and simply put, sits outside human comprehension.

This book is aimed at readers who have read their fair share of popular science books, and are not afraid of some equations, or who have studied physics using mathematics. It also suits readers who want to get a glimpse at relativity before reading some textbook. Personally, this book was a natural choice for me, as I had recently read the latest book from The Theoretical Minimum series.

On Gravity isn’t only about general relativity though. The author, A. Zee, also writes about other stuff that might be related to Einstein’s gravity, such as basic field theory, gravitational waves, the possible relation between relativity and quantum mechanics, black holes, dark matter and dark energy, etc. And it’s all worth it. The writing is compelling and entertaining, mixing A. Zee’s humorous style with lots of stories and fun facts.

The action principle, in particular, is brilliantly described and I believe even readers who haven’t learned about it before will get a good idea of what it means and its importance in physics. Reading about the action for general relativity, or as it is known, the Einstein-Hilbert action was the highlight of the book.

At the end of book there’s also an appendix illustrating how spacetime is described using simple mathematics. This is a great addition, especially if you’ve never seen curved spacetime in equation form, to an equally great book.

[Brian Clegg · Rating 3 out of 5]

This is the first book I've read where I had to force myself to stop thinking about the author's name - and specifically from asking myself if his middle name is 'To' (I bet he hasn't heard that one before) - to be able to concentrate on the subject. It's the second book I've read on gravity and gravitational waves in the last few weeks, and it didn't work for me as well as the Pierre Binétruy title Gravity! In part it's down to A Zee's writing style, which is extremely mannered (not to mention constantly referring to his other books), but the content also simply didn't put the information across very well.

Things start in a promising way (despite the style). The first lines of the prologue give a suitable feel: 'Finally, finally, the long wait was over: we the human race on planet earth collective heard the song of the universe. Yes, we, a rather malevolent but somewhat clever species, can now proudly say we have detected the ripples of spacetime...' (i.e. gravitational waves). Sometimes the wording is a little odd, and the tone can be irritatingly breezy, but what we get to begin with is exactly what we are promised - an introduction to gravity that is not too technical, but above the trivial level. Admittedly, the use of end notes for what should be footnotes - usefully expanding on a point rather than providing reference information - is irritating as you either painfully flick back and forth or (more likely) simply miss some of the best content, but things are going quite well.

However, a couple of chapters in, Zee falls for the classic error of a scientist writing for the general public (especially common when they're writing for a university press). Probably without even noticing that he's done it, he changes gear and suddenly we've gone from popular science to the level of accessibility of an introductory textbook (though still with the same odd tone). This means that much of the material on electromagnetism, relativity and more becomes increasingly impenetrable as you read on.

What is particularly sad is that the transition happens before Zee gets on to the principle of least time/action (and action in general). He covers this at considerable length (pointing out, for example, that it makes Einstein's field equations for general relativity in some ways a simpler concept) and that is brilliant. This is by far the most interesting and original part of the book as far as a general audience goes, because it's something that is usually only touched on (often in reference to Richard Feynman), but unfortunately it is virtually incomprehensible in the way it's put across.

Overall, then, a strange book that seems sadly to be poorly matched to its audience.

[Veronika Sebechlebská · Rating 1 out of 5]

Jeden odsek za všetky: Zatím jsem se musel vyjadřovat trochu neurčitě, ale princip akce umožnuje upřesnit, co znamená obrat "struktura fyzikální reality." Různí pozorovatelé musi pracovat s touž akcí. Kdyby ne, extremalizovali by odlišné akce a dostávali by odlišné fyzikální zákony ...Chskym? ??? A predovšetkým, v termeni júnovom či júlovom??

Jednoduché veci vysvetlené zložito, zložité veci nevysvetlené vôbec. Asi najhoršia kniha na túto tému, akú som kedy čítala. Ale možno je to len tým, že som sa stala povrchnou a otupejvávam.

[Onur Yz · Rating 5 out of 5]

Kitabı çoktan okudum bitirdim lakin "kişiselleştirmeden" yorum yazabilir miyim diye günlerdir düşünüp duruyorum. En sonunda anladım ki benim bunu yapabilmem mümkün değil. Zira kitap yorumları iki türlü oluyor, ilki kitabın geniş bir tanıtımı şeklinde (az önce bir arkadaşın bu şekilde bu yorumunu okudum, kitabı müthiş şekilde özetlemiş). Bu benim yapmak isteyeceğim son şey olur herhalde, asla da yapmam. Başarıyla yapanlara sözüm yok ancak benim herhangi bir şeyi değerlendirme tarzıma hiç uymayan bir şey. Diğer yorumlar ise bir review şeklinde oluyor, özet değil, şu şöyle demiş bu böyle demiş, şöyle değerlendirilmiş falan filan. Eh review yapacaksam zaten bu işi profesyonelce yapardım, tabii kendi uzmanlık alanımda.

Geriye elimde kalan tek şey kendi hislerimi, kendi duygularımı aktarmak. Elbette bunu yaparken abarttığım oluyor ama fark ettim ki en sevdiğim şey de bu. Bunun ne kadar ilgi çektiğini hiçbir zaman ölçme verim olmadı elimde. Like (beğeni) bana etkili ve değerlendirilebilecek bir veri vermiyor.

Yine kişisel bir yazı oldu ama bu konuyu bir açıklığa kavuşturmam gerekiyordu. Buradaki değerlendirmelerde kitabı sevemedim, çok sevdim, bayıldım gibi ifadeler de yüzde yüz kişiselleştirmedim, onu da atlamayalım. Hobi duyduğum alanlarda bir şeyler ifade etmeye, yazmaya, çizmeye ve coşkumu ifade etmeye çalıştığım zamanların ileri bir döneminde hep büyük kötülüklerle karşılaştım. (bu konuda yazacak o kadar çok şeyim var ki) Bu nedenle hayat bana bir şey anlatmaya çalışıyor ve ben o mesajı nihayet almaya başladım. Uzlet...

Bu esere gelirsek, kafamda yıllardır oluşan bir sürü boşluğu kapatmama yardımcı oldu. Zira bu kitaptaki bazı konular zaten profesyonel hayatımın bir parçasını oluşturuyordu. Ancak büyük resimi görmek (çok klişe oldu ama doğru tabir de bu) açısından son derece ufuk açıcı oldu. Bir klişe daha gelsin; başucu kitabım olacak diyeceğim ama önce kitabın orijinalini de okumak için ateşten gömleği giymem gerekiyor.

Ve umarım yazarın diğer kitapları da çevrilir. Zira kitabın içinde diğer kitaplarına çok referans veriyor ve kalan boşlukları da doldurabilmek için önemli bir şans bu. Sabırsızlıkla bekliyor olacağım.

[R Nair · Rating 5 out of 5]

Among the many well explained concepts in this book the highest ranked would be the explanation of Einstein's field equations of general relativity based on the principle of least action. The action principle doesn't appear in many books on physics for the general reader for some reason but here it is explained in relative depth which is great. This may not be a good book for lay readers completely unfamiliar with modern physics but it is definitely a pleasure to read for those who have at least a passing familiarity.

[John Gribbin · Rating 3 out of 5]

I did a double review of two books for the Wall Street Journal, so posting it under both titles!

The Ascent of Gravity
Marcus Chown
Pegasus
On Gravity
A. Zee
Princeton

Gravity has become a hot topic in science, with the discovery of gravitational waves, ripples in the fabric of space coming from colliding black holes and neutron stars. Both The Ascent of Gravity and On Gravity mention those discoveries, but neither book focuses on them. Rather, they provide the background to our understanding of this fundamental force of nature, a force which is the weakest one known but which paradoxically, because of its long range, is the most important one in the Universe at large.
The first person to appreciatee the literally universal importance of gravity was Robert Hooke, who realised that gravity is a universal force possessed by every object in the Universe, which attracts every other object. Hooke, a slightly older contemporary of Isaac Newton, was both an experimenter and observer, and a theorist.  His insight about gravity came partly from his telescopic observations of the Moon.  He studied lunar craters, and noticed that they are formed of nearly circular walls, around a shallow depression.  They looked, in his words “as if the substance in the middle had been digg’d up, and thrown on either side.”  So he carried out experiments, dropping bullets onto a mixture of water and pipe-clay, making miniature craters which, when illuminated from the side by a candle, looked just like lunar craters.  He realised that the material thrown up from the centre of the craters of the Moon was pulled back down by the Moon’s own gravity, independent of the Earth’s gravity.  He pointed out that apart from small irregularities like craters, the Moon is very round, so that “the outermost bounds. . . are equidistant from the Center of gravitation”, tugged towards the center by gravity, and concluding that it had “a gravitating principle as the Earth has.”  This was published in 1665, when Newton was just completing his degree at the University of Cambridge.  Hooke went on to suggest that planets are held in orbit by an attractive gravitational force from the Sun.
The two books considered here both fill in what has become known about gravity since Hooke’s day, but they are very different, both in approach and style. Marcus Chown is a science writer, and a very good one. He favours the historical approach, starting with Newton’s work on gravity and taking us through Albert Einstein’s contribution to the mysterious world beyond Einstein where physicists hope to find a theory that will explain gravity and quantum physics in one package. He eschews equations, but provides clear explanation with a useful guide to further reading at the end of each chapter. The result feels easy and natural, like the author talking to you, although I suspect it took a lot of hard work to produce that effect.
By contrast, A. Zee (who only uses the initial) is a professor of physics who has previously written an epic tome on gravity, and is now trying to “bridge the gap between popular books and textbooks.” He is only partially successful. Some of his attempts to be “popular” seem forced, as with sentences such as “Ah, the glory days of trial and error experimental physics!”, and the logical structure of his arguments is sometimes faulty, as when (in a book about gravity!) he tells us that “just about the only commonplace example of a force acting without contact is the refrigerator magnet.” He does provide equations, and diagrams, and is on secure footing there. But the sloppiness of his writing is highlighted by comparing his mention of the myth that Galileo dropped weights from the Leaning Tower of Pisa with Chown’s. Chown correctly identifies this as a legend; Zee presents it as a fact “we all learned in school”. Maybe we did learn the story there, but it is definitely legend, not fact.
A particularly delightful feature of The Ascent of Gravity is the inclusion of several fictional vignettes in which the author imagines how the big ideas came to his protagonists – for example, a story of the young Einstein walking out with his girlfriend Marie Winteler under a moonlit sky, and having a sudden insight about the way light travels across space. Fantasy, but fun – and no real surprise that it should work so well, since Chown is also a successful writer of science fiction (on some of which, long ago, I collaborated with him). Chown’s great achievement is to make his discussion of such bizarre phenomena as the way rotation distorts space just about as intelligible and entertaining as the fantasy.
Zee’s great achievement is to provide the clearest explanation I have seen of the physical principle known as “action”, which among other things explains why light travels in straight lines – or, more accurately, why light travels along the path that takes least time. Action is arguably the most powerful tool in the physicist’s box of tricks. In Einstein’s own formulation of the general theory of relativity he required a set of ten equations to explain the interaction between matter and spacetime; but the whole thing can be described much more simply in terms of a single action. I was also particularly pleased to see Zee emphasising the point that Einstein did not prove that Newton was incorrect. Newton’s version of physics is perfectly adequate for things moving much more slowly than light in weak gravitational fields, and Einstein’s version includes Newtonian physics within itself. The famous headline in the London Times of 7 November 1919 proclaiming “Newtonian Ideas Overthrown” was just plain wrong. Science does not progress by revolutions, but by building, brick by brick, on what has gone before.
The latest brick in the edifice is, of course, the discovery of gravitational waves, and it is unfortunate that these books are unable to give much space to this. The Ascent of Gravity was written a little earlier than Zee’s book, and gives the discovery only passing mention. On Gravity was written, the author tells us, after the first detection was announced, but even so gives it a rather cursory mention. I was baffled by the fact that although Zee mentions plans for a gravitational wave detector to be built in India, he does not mention the one already built in Italy (and a curious footnote suggests that he is unaware of its existence). If you do want the full story of gravitational wave research, it is covered by Marcia Bartusiak in her excellent book Einstein’s Unfinished Symphony.
If you are looking for a good read and a chance to absorb painlessly some ideas about the force that controls the Universe, Marcus Chown is the man for you. If you think you already know a little bit about the topic, and are not afraid of a few equations, then On Gravity will take you deeper; if you are very brave, the Appendix will explain the meaning of curved spacetime. If I had a magic wand, I would wave it to put Zee’s diagrams into Chown’s book, and get the best of both worlds.

[Sebastian · Rating 2 out of 5]

I was about to write a rather scathing review of this book before I read the appendix. Now that I have, I will say this – if you are really interested in gravity above a popular science book level, but below a textbook level, skip the main part and just read the appendix. It does in a dozen pages what the rest of the book fails to do in a hundred plus some.

The author is really quite certain that he has an awesome sense of humor and that it will help get his points across. Consequently, he bogs the text down with funny quips, asides, digressions, and BLOODY ENDLESS footnotes and endnotes that add little to the subject matter, ultimately making the whole thing nearly unreadable. Perhaps this approach works really well in a live teaching environment, but on paper it can only “work” with people who already understand the subject matter sufficiently well to not really need the book – a sort of written conference presentation for colleagues to nod along to.

Had I not been familiar with the subject matter before reading this, I would have been dumbfounded by the labyrinthine exposition. Like oh so bloody many professors trying to write to a (more or less) lay audience, Zee overexplains the simple stuff, and underexplains the really complicated stuff, producing a work that has no clear audience. I’m afraid that if you want to truly understand the topic beyond popular science level, but below textbook level, you are much better off investing (quite) a bit more of your time with something like Susskind’s Theoretical Minimum series that will actually provide you with a systematic ground-up understanding, complete with warty formulae and all.

[Deepanshu Bisht]

The book is light and fun, but suitable for a physics undergrad rather than a complete layperson, mainly because of the lack of in-depth explanations. The special relativity section, in particular, is too rushed.

Zee lays out standard (but fascinating) facts and concepts quickly in plain English, sometimes with unconventional but helpful analogies and all the time with his characteristic humour-filled sentences and endnotes. Zee's emphasis on the action formulation is an impressive choice for a popular-level book.

The book lacks original/personal insights, which could have appealed to more knowledgeable readers.

[Miles Hanson · Rating 3 out of 5]

3.5/5

[Logan Carter · Rating 3 out of 5]

This is a good book for beginners with little to no experience in physics. I think I underestimated the simplicity of explanations that this book has. I should have gone for a more mathematically developed explanation, though this is perfect for somebody interested in gravity who doesn’t know the math.

[Ceyda Şimşek · Rating 5 out of 5]

her yerde bulamayacağınız detaylar okuyucuyu dinamik tutuyor, şahane bir çeviri ile.

[Julius · Rating 5 out of 5]

This is a second book by A. Zee that I read in close succession (first was Quantum Field Theory: As Simply As Possible). Some of the chapters overlapped with QFT book, but not enough to make it boring. This book is definitely about gravity, and while QFT surfaces here and there, it's not the main thing.

I really appreciate A. Zee's ability to simplify complex things without dumbing them down. He describes things in simple analogies, or builds the knowledge up from the basics, without going into the weeds, but with a razor sharp focus on the important parts.

His writing is also entertaining. Here's one paragraph that made me giggle:

> Interestingly, the solution describing the curved spacetime outside a massive object was first obtained, not by Einstein, but by Karl Schwarzschild within months of publication of Einstein's theory. Schwarzschild's achievement is truly remarkable, since he did it while under heavy artillery fire serving in the German army on the Russian from in World War I. (He died a year later.) I always tell my students that for sure they should be able to solve for the Schwarzschild black hole, as it is now known, in the peace and quiet of their rooms.

Speaking of scientists other than Einstein, Zee also does a magnificent job interleaving history throughout his book (this and QFT) and showing how the current physics understanding came from small incremental improvements and insights into previously known theories, by many people. Sure, it culminated with Einstein's theories, but they would not have been possible if others did not provide their own insights. Incidentally, the author also notes on a couple of occasions how Einstein went off on a red-herring. Even the genius was not infallible.

Finally, this book has even less math-y symbols than QFT book, except for Appendix, which is wholly optional to read. I read it with a notebook and a pen, following the explanations, and honestly, it is fantastic. In only a couple of pages Zee builds up from flat space (starting with Pythagoras theorem) to curved spacetime, to defining a formula for a gravitational wave. Sure, noone's going to become a PhD from doing this, but the scary looking formulas may become less intimidating. And that is a good thing.

[Rama Rao · Rating 5 out of 5]

The cosmic origins of gravity (five stars)

According to Newton, an object falling down to the ground experiences gravitational force from earth. This force represents the earth pulling the object, and also the object pulling the earth up. According to Einstein, the force is not “force” perse, but it is due to the curvature of spacetime (space and time are amalgamated into a malleable spacetime.) Spacetime warps around the object, and when it is falling down to earth, it seeks to extremize its action, that is, find the shortest distance to earth, which is also surrounded by curved spacetime. But according to quantum field theory, the curved spacetime is due to gazillions of gravitons (particles of gravity) sweeping around. When an object is falling, gravitons zing back and forth like crazy between the falling object and the earth. This constant exchange of graviton between the two bodies (falling object and earth) produces the observed gravitational force. This is similar to the constant exchange of photons between two charged particles that produces electromagnetic force. These are two of the four fundamental forces observed in the cosmos. Electromagnetic waves are produced by quantum fields such as light. They consist of both waves and particles. Similarly gravitational fields which are also quantum fields have gravitational waves, and particles called gravitons.

The author has a unique style of writing to describe gravitational physics that takes us on a tour of general relativity, quantum physics, quantum field theory, spacetime, gravity and black holes. This math-free book is a good introduction to quantum gravity and has a lot of interesting history. He is a good physicist and a great writer. The book simply demonstrates that our knowledge of spacetime at its most fundamental level is inadequate. This is brutally an honest story written with some passion and humor. Highly recommended to anyone interested in gravity, black holes, and the nature of spacetime.

[James F · Rating 3 out of 5]

Zee states in the Preface that he intended this book as a bridge between popularizations (such as his own An Old Man's Toy) and textbooks (such as his own Einstein Gravity in a Nutshell), neither of which I have read, so I expected something similar to Leonard Susskind's Theoretical Minimum series, but it was not at that level. The first half was a fairly low-level, virtually math-free popularization of waves, electromagnetism, the idea of a field, and special relativity; the book then jumps to the concept of action and becomes filled with integrals and other equations which I probably wouldn't have understood without having read the Susskind books earlier (although despite the equations, it remains basically a qualitative though high-level popularization.) What links the two halves is the discovery and explanation of gravity waves. Some of the discussion was useful, such as the explanation of how the differential, laws-of-force approach to physics we all learned in high school or early undergraduate physics courses and the least action approach used here (and in more depth in the Susskind books) are related, and why the latter is preferred by people doing advanced physics. The book is very up-to-date, if somewhat conservative. On the negative side, like many popularizers he tries too hard to be funny.

[Les · Rating 4 out of 5]

I wish I knew the author. A. Zee (!!) is very good at making complex physics concepts understandable and, dare I say it, entertaining. Zee takes the reader on a ride, exploring what gravity is and isn't, how the various theories of gravity throughout history build upon one another, and where most physicists think it's going: toward unification with quantum mechanics. (Personally, I think we might just be kidding ourselves on that last one. But I'm only an applied physicist and would NOT claim to be anywhere close to as knowledgable on the subject as Zee.)

The book is fairly short and well worth reading. But be warned, to get the most from it, you should really have a grounding in college physics.

[Amanda · Rating 3 out of 5]

I don't feel right reviewing this because I understood such a small amount of it. Zee tells you, right off the bat, that it's more than popular non-fiction about science, kind of between that writing and a textbook, and he's not kidding. But the parts I did understand were interesting, as if I were attending a disciplinary lecture and so understood the simpler parts. Zee is entertaining and is able to explain complicated subjects -- but in this he also goes ahead and works through some of the basic math, which is way beyond my own math. If you got further in physics than I did, I bet this is a pretty awesome book. For someone like me just curious about gravity, it was over my head. I'll try his more popular-culture version next.

[Nicholas Mcgranahan · Rating 4 out of 5]

A little hard to understand unless given enough time to fully analyze and think about what the author is talking about. It’s a great learning source which gives just enough of the fundamentals of theoretical physics to understand just how mysterious and potentially confusing the world around us is.
As a physics student I truly enjoyed diving in and imagining the stories of the universe being laid out before me. There’s also a great appendix in the back of the book if any clarification is needed!

[Robert Pinto · Rating 5 out of 5]

This was a very fun and exciting book to read. I highly recommend this book on physics to an outsider like myself. Even though I am not an expert in physics and have not studied physics in school I personally found this book very easy to read. A Zee presents different example of physics throughout this book with its main focus being on gravity. I enjoyed Mr. Zee's presentations as well as his humor throughout the book. If you are a interested in quick learning about physics I highly recommend this book.

[Walter · Rating 2 out of 5]

There is a nauseating amount of footnotes/figures that do not provide meaningful context/elaboration, their main purpose appears to be to reference one of his other books. His other books appear to be the main source for a significant amount of the information in this book, they make up a quarter of the books in the bibliography. Since he pulls heavily from his own works, I could not determine why this book was needed. All of that said it is an alright book, though I do not plan on rereading it in the future.

[Pamela · Rating 5 out of 5]

I wrote a review before; Where is it.? Oh well. Deal with gravity and get mysteries.

Informative book,well written and even lyrical at times. Even though gravity
is often described as weak at times, it can be a heavy subject.

[Mary T · Rating 3 out of 5]

We do not need this book: it's patched together with passages from previous books plus a little on gravity waves. This our author does not hide. I assume his publisher wanted something on gravity waves and A Zee obliged.

[William · Rating 3 out of 5]

Brief and helpful

[Pat Nelson · Rating 2 out of 5]

Noy exactly sure why but I had trouble connecting with this book.

[Steve · Rating 4 out of 5]

Interesting introduction to the topic. Good drawings and a very good bibliography in the back for further reading.

[Shuhei Kagawa · Rating 3 out of 5]

Easy to read, but I wanted it to be a bit more specific.

[Ben · Rating 4 out of 5]

Really thought-provoking. Does a great job building up conceptual structures (even if I doubt that I’ll retain much).

[Gregory Netols · Rating 4 out of 5]

Quick read, helped me identify a few other topics I wanted to read about.

[Randall Scalise · Rating 3 out of 5]

Contains material recycled from his others books.

[wyn · Rating 1 out of 5]

Even as someone who watched TBBT 3 times, I didn’t manage to grasp a single concept mentioned. Not sure how to rate this book, hence the 1 ⭐️… It could be a good book, I just wouldn’t know.