The Quark and the Jaguar: Adventures in the Simple and the Complex

by Murray Gell-Mann

From one of the architects of the new science of simplicity and complexity comes an explanation of the connections between nature at its most basic level and natural selection, archaeology, linguistics, child development, computers, and other complex adaptive systems. Nobel laureate Murray Gell-Mann offers a uniquely personal and unifying vision of the relationship between the fundamental laws of physics and the complexity and diversity of the natural world.

Genres: Science, Physics, Nonfiction, Philosophy, Popular Science, Biology, Mathematics

392 pages, Paperback

First published April 1, 1994

About the author

American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. He was the Robert Andrews Millikan Professor of Theoretical Physics Emeritus at the California Institute of Technology, a Distinguished Fellow and co-founder of the Santa Fe Institute, Professor in the Physics and Astronomy Department of the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California.

Reviews

[Ushan · Rating 2 out of 5]

People make positive statements more often than negative ones and want to clearly distinguish between the two; therefore, it makes sense for a language to have a "not" morpheme. A language usually has 10 to 100 phonemes; even if there are some languages that go outside these bounds, no human language has a million phonemes: no one could ever learn it. Latin had three grammatical genders; most Latin-derived Romance languages have two, with the neuter merging into the masculine, and Romanian retains all three, but no Romance language has developed twenty-some gender-number combinations like Bantu languages have, including the plant gender and the abstract nouns gender. Living Indo-European languages are much more grammatically diverse than Romance languages, but they still retain some vestiges of Proto-Indo-European grammar; none of them are like Chinese grammatically. It is possible that likewise, all human languages have shared features that remain from the last shared human languages. If we look at linguistic universal and near-universals, some of them will be adaptive, some will follow from human biology, and some will be "frozen accidents". The same will be true not just for language but for any complex adaptive system such as life. That life is built of carbon and not silicon probably follows from the chemistry of these elements; that all life uses a particular genetic code with extremely minor variations is probably a frozen accident; that most mutations are either neutral or only slightly detrimental to the organism, and may be beneficial in changed circumstances is probably adaptive. Now, how do you distinguish between these cases?

Gell-Mann is an elementary particle physicist who did pioneering work in the theory of strong and weak interaction, most famously coining the term "quark", and received the 1969 physics Nobel prize. While traveling in South America, he saw a jaguarundi, which is a small wild cat, and was struck by how different it is from the quark. The jaguarundi is an animal that consists of organs, which consist of tissues, which consist of cells, which consist of organelles, which consist of molecules, which consist of atoms, which consist of electrons and nuclei, which consist of nucleons, which consist of quarks. Modulo a few quantum numbers, all quarks are the same; each jaguarundi is a different individual. The behavior of the quark is predictable as much as anything is predictable in quantum physics; that of the jaguarundi is unpredictable. The jaguarundi adapts to its environment; the quark doesn't. Somehow when you travel up the ladder of levels of abstraction, these properties emerge. In order to tackle this mystery, Gell-Mann tries to run through all of science in less than 400 pages, mentioning things like Bell's inequalities from quantum physics, the ecology of different desert biomes, grammatical universals and near-universals from linguistics, spontaneous symmetry breaking from quantum field theory, and more. I don't know who this book is written for. In order to understand the physics part, you need a Ph.D. in high-energy physics, but then you'll know this material already; I doubt that an average biophysicist knows what Gell-Mann is talking about when he says, "Quantum flavor dynamics and quantum chromodynamics [...] belong to the same class of theories - so-called gauge theories of Yang-Mills theories (as generalized by Shelly Glashow and me long ago.)" and does not give any further explanations. A reader who is not a physicist certainly won't know what Gell-Mann is talking about. This book mentions in passing Joseph Greenberg's theory of linguistic universals, and says that some universals may be adaptive, some are basic consequences of human biology, and some may be "frozen accidents" remaining from the first human language that no generation of speakers could ever alter, but no examples are given. So this is basically an ego trip in book form. We already know that a Physics Nobel laureate must be smart, and know a lot; why write a book about it?

[DJ · Rating 2 out of 5]

Gell-Mann is a very intelligent man with wide-ranging interests but his attempts to treat so many of these interests at once really hinder ‘The Quark and The Jaguar’.

At times, this book presents fascinating and powerful new ways of looking at the world. Gell-Mann shines when he’s in his element. His introduction to complexity & randomness and complex adaptive systems is excellent and has given me a new lens to view the world through. Also, his introduction to modern physics (Gell-Mann is a Nobel Prize winner who basically built QCD, an essential piece of the current standard model) is one of the clearest I have encountered and debunks the pop culture misinterpretations of quantum mechanics that pervade most discussions.

At other times, I felt like I was in one of those dreams where you’re sitting in class minding your own business and, suddenly… your pants are gone! In trying to jump from interest to interest so often, Gell-Mann has to drop introductions to the fundamental background needed to understand what he’s discussing, leading to confusing situations in which the reader has no idea where they are and how they got there.

There are certainly interesting nuggets here but this book could do with some editing.

Note: 2 stars doesn’t mean I thought this book was “bad”. I follow Goodreads convention and 2 stars means “it was ok”. If I believed in inflated scores for every book, it’d be on Amazon right now.

Book Notes

* Defining Complexity
o coarse/fine grain - level of detail
o length of description - possible measure
o context dependent - f(vocab, shared knowledge)
o algorithmic info content (AIC) - shortest program that produces a string
+ compressibility - inverse of randomness
+ AIC = measure of randomness, not complexity
* Meaning of Random
1. incompressible (defined by result)
2. generated by chance (defined by process)
o let’s call 1 random and 2 stochastic
o pseudorandom - generated using chaotic or messy process to imitate chance
* Complex Adaptive Systems
o Method
+ old data –> construct theory
+ present data –> predict
+ new data –> test & revise
o compress regularities in observation into schema
o revise defn. of complexity by length of schema (since only regularities produce schema)
o external complexity - book description (good approximation but subject to academic tone, audience experience, etc)
o internal effective complexity - brain representation [in native speaker] (better approximation as it is truer to the source)
o usefulness = f(observer skill & size of observed set)
o regularities identified by class (no algorithm can identify all regularities - Godel?)
o high complexity = balance between order & disorder and simple & random (mid-range AIC)
o species learning - mutations (variation) present before challenge
o brain learning - ideas (variation) created in response to challenge
* More on Complexity & Randomness
o self-organized criticality - natural attraction of a system to a critical value
o depth - difficulty of moving from compressed program/schema –> full description of result
o crypticity - difficulty of moving from full description of result –> compressed program/schema
o individuality - bits to describe object > bits to enumerate group
* Intro to Modern Physics
o bootstrap principle - assume particles are already there and they give rise to and sustain themselves (*like recursive programming in Scheme!)
o QCD differs from QED because gluons are electrically charged and interact with each other unlike photons (so color force doesn’t die with distance and traps quarks)
o photons/gravitons transfer energy/motion while W+- bosons seem only to transform particles into their antiparticles
o charged particles interact through photons
o colored particles interact through gluons
o flavored particles interact through W bosons
o weak force (W bosons) change flavor AND charge (since W bosons are electrically charged)
o renormalization - isolating a portion of a theory to stand on its own as a good approximation (can lead to arbitrary constants dependent upon rest of theory)
o superpartners - fermions for bosons & bosons for fermions
o supergap - mass difference between superpartners caused by SSB
o force unity - extrapolate experiments and gluonic, EM, and weak interactions almost converse at high energies (early BB perhaps?)
o action [=] energy * time
* Time
o frozen accident - chance events with many long-term consequences
+ more of universe’s AIC and effective complexity results from accidents than laws
+ can lead to SSB when chance occurrence is one among a symmetrical set of possibilities
+ provide regularity –> higher effective complexity
+ responsible for many environmental & biological conditions
o coarse-grained history - class of all fine-grained histories that meet its class reqs (equivalence of properties in focus, set of all possible alternatives for properties ignored)
+ ignored properties are ’summed over’
+ when interference terms disappear, histories ‘decohere’
+ asymmetry between past & future:
# radiation (energy flows out)
# records (only of past)
# entropy (energy of macrostate = bits to represent a microstate)
* Biology, Evolution, and Fitness
o evolution (intermingling of species & environment) can be modeled as a movement toward equilibrium of information (like the intermingling of hot & cold gases)
o gateway events - dramatic biological events that open new options (photosynthesis, eukaryotes, etc)
o fitness landscape - topological representation of biological fitness (as depth)
+ local minima similar to potential wells (false optimization)
+ noisy, random path allows movement in/out of wells
+ basin of attraction - watershed for a well
o inclusive fitness - factors in survival/reproduction of related organisms, weighting the most related most heavily (related to the selfish gene)

Questions
* How does the nuclear force arise from the color force?
* How does gluon interaction result in the color force not dying with distance?
* Do W bosons transfer a ‘force’ or just transform particles to antiparticles?
* What makes the fundamental units fundamental? (i.e. fundamental length, mass, etc)
* What is Hawking’s ‘initial condition of the universe’ that Gell-Mann repeatedly refers to?
* Has anyone made a program that evolves its strategy intelligently based on a predictive brain algorithm?
* What about a system that meta-evolves its strategy (i.e. evolves it process for evolving)? Perhaps it shifts from neural net to genetic algorithm, etc.

Conclusions
* I’m still rooting for Einstein’s ‘hidden variables’ alternative to QM
* Complexity is not a well-defined idea but its a very alluring topic and this offers a nice framework to begin thinking about it
* ‘Fitness landscapes’ are an incredibly fun way to look at biology through the lens of someone trained in physics but show how reliant we are on space for our models and analogies. This may be a fault for certain problems but heck, I’m a sucker for geometric interpretations.
* The deeper you go, the simpler & more elegant physics gets
* I still don’t understand entropy nor am I convinced of the second law. I will (skeptically) read more.
* Frozen accidents are ubiquitous mysteries peppered throughout our world (and identifying them is a great way to entertain yourself).
* Complex adaptive schema are very powerful and should be a fun thing to toy with when I improve my programming.
* Coarse-graining is another ubiquitous principle that I’ve overlooked. Graining is a built-in assumption that we make at all times and must be considered in any analysis.

[Paul Brogan · Rating 3 out of 5]

Unless you're a whiz at maths and physics, the first part of this book will be heavy going for you. Fortunately, I have always had a fascination for quarks and quantum theory, Einstein and Heisenberg, calculus and statistical theory, so I found great reward from getting inside the methodical brain of a man such as Gell-Mann, winner of the 1969 Nobel Prize for Physics. (Indeed, it was he who coined the term 'quark', among others.)

By the time he moves onto to a discussion of the complex (biological evolution, creativity, superstition, environmental protection, and world futures), however, I suspect that even the technical maladroit would find something of immense value from his thorough and analytical musings on the state of both humankind and our planet. This said, I was glad I took the trouble to plough through those early chapters, without which I may have missed the precision that he uses to describe terms such as order and disorder, randomness, simple and complex, depth, and entropy, and without which I think I may have lost much of the beautiful logic of his conclusions.

This is an ideal book to lend to your favourite scientist or engineer friend. When finished, invite him or her for dinner, drinks, and plenty of debate over Gell-Mann's ideas. It would be animated, I'm sure, but stimulating. While the universe is in essence quite simple, humans and our society are complex, and that's worth celebrating.

[Brian Godsey, now on thestorygraph · Rating 5 out of 5]

I got this book as a prize from the math department of my college when I was a freshman or a sophomore. Though I liked the idea of learning more about quarks, I had a habit of not reading anything that wasn't required of me. So, The Quark and the Jaguar sat on my shelf for almost a decade before I took it seriously, and I'm glad for that---both that I took it seriously and that I waited so long.

I'm glad that I [finally] took the book seriously because there's a ton of good information and ideas in there. I'm glad that I waited because I think that even a couple of years ago I would not have fully understood or appreciated most of it. Four years ago, I had only basic knowledge of physics, biology, genetics, evolution, machine learning, probability, and political science, all of which are discussed in this Nobel Prize winner's book. In these last four years, I've learned a lot about all of these topics, not that it's really necessary for understanding the book; it definitely helps appreciate its importance, though.

Strictly speaking, The Quark and the Jaguar is about learning, albeit three distinct types of learning: (1) humans learning about our world and universe, (2) our world and universe learning what laws, rules, and configurations can function in the long run, and (3) computers designed by humans learning from data. Learning type (1) is obviously what Gell-Mann has done for most of his lifetime as a theoretical physicist and general applied scientist. Learning type (2) is what Gell-Mann has discovered in his lifetime as a scientist: that every system in our universe---from quantum physics to genetic evolution to economics---is an example or result of that system having tried many possibilities and settling on the few that work. The theory and literature on learning type (3) provide the necessary framework and terminology with which we can discuss learning types (1) and (2), since, in essence, all three types are one and the same, but with different physical objects at the center. Gell-Mann calls these objects "complex adaptive systems" and demonstrates how a machine learning algorithm can be very much like the process of evolution, the training of a dog, or even the settling of our cosmos into the physical laws we know and accept today.

The breadth of this book is incredible---especially since it's less than 400 pages---and what's even more amazing is that my only complaint about this book is that it was sometimes redundant and written at a level below my current scientific knowledge. It's clearly a book written for people who are not experts in any of the aforementioned fields, but Gell-Mann manages to make it relevant also for them. The only scientifically difficult subject matter is on information theory or quantum physics, and these pages are by no means necessary to the rest of the book.

The best aspect of the book, though, which is referenced throughout but becomes clear near the end, is that Gell-Mann tells people in no uncertain terms to look at the big picture, an action that seems incredibly uncommon in the world at large. Not only does he stress this for science, but he tells us how to do it in our everyday lives---work, community, environment, and politics included. There's even a concise summary chapter at the end in case you missed the message in between the examples throughout the book.

What I'm left with in the end is a strong feeling that the world and universe are largely a product of learning and chance, the two aspects of every valuable complex adaptive system. I am a product of this universe, and I operate the same way. If I learn how to learn and convince others to do the same, I can be successful or change the world, or both, whichever I prefer.

[Remo · Rating 2 out of 5]

Decepción. Yo creía que el libro iba a tratar sobre los quarks y su descubrimiento (por algo el autor fue quien tuvo la mayor parte del mérito) y resulta que el libro es un conjunto de visiones personales sobre complejidad y simplicidad de sistemas. EN algunos momentos se hace realmente ininteligible (al hablar de decoherencia en historias no detalladas con detalles integrados, sin ir más lejos). Hay partes buenas e interesantes; otras son imposibles. El libro no está mal pero no me ha llamado la atención.

[Czarny Pies · Rating 2 out of 5]

"The Quark and the Jaguar" is an engaging account of the life-long intellectual pilgrimage of Murray Gell-man , winner of 1969 Nobel Prize for Physics. Gell-mann was the first person to postulate the existence of Quarks and ranks as one of the all-time greats in the field of quantum mechanics. In 1984, he co-founded the Santa Fe institute which is dedicated to the physical, computational, biological, linguistic and social components of complex adaptive systems. The jury is still out on the accomplishments of this initiative which unfortunately occupy most of the this book.
Above-all, "The Quark and the Jaguar" seems dated. Gell-mann wrote the book at a time when the discipline of quantum mechanics had arrived at plateau. In the last 50 years, the scientific community has come a long way in explaining quantum mechanics to high school students and members of the general public. The general reader can now find better explanations elsewhere. The passages on complex adaptive systems suffer from the inverse problem. The discipline was in its infancy at the time Gell-mann was writing and his comments in this area are not terribly enlightening at this point in time twenty-five years after the publication of the "The Quark and the Jaguar."
"The Quark and the Jaguar" is a ghastly muddle for any lay reader wishing to educate himself or herself about either quantum mechanics or complex adaptive systems. What it does offer the reader interested in the history of quantum mechanics is access to the personality, charm and thinking processes of one the great physicists of the 20th century.

[Jorge Zuluaga · Rating 3 out of 5]

Este libro es de todo menos de física. Y esa es una buena o una mala noticia dependiendo del lector, o utilizando las categorías del autor dependiendo de si el lector es "apolíneo" u "odiseico" (y un poco de "dionisíaco").

Para el lector "apolíneo" (que prefiere la lógica, la aproximación analítica y el peso desapasionado de la evidencia), que posiblemente consiguió el libro buscando leer unas buenas piezas divulgativas de física, escritas por uno de los físicos más importantes de la segunda mitad de los 1900, es una mala noticia.

El libro apenas si aborda explicaciones completas de algunos conceptos difíciles de la física moderna; ni siquiera lo hace con aquellos en los que el autor contribuyo de forma decisiva.

Si bien la segunda parte del libro lleva por título sugestivo "El universo cuántico", la mayor parte del material contenido en estos capítulos es difícilmente comprensible por una persona que no sepa ya bastante de física (yo soy físico y me vi a gatas para comprender los capítulos decisivos sobre la mecánica cuántica).

El libro tiene sus añitos y por lo tanto da demasiada importancia a una teoría que que hoy no goza ya de tantos adeptos, la teoría de cuerdas.

Sin embargo, para el lector "odisíaco", que ama la ciencia, toda la ciencia, la ciencia sin barreras y sin compartimientos, el hecho de que "El quark y el jaguar" no sea un libro de física es una excelente noticia.

¿Por qué iba a serlo al fin y al cabo? ¿solo podemos esperar de los físicos que hablen de física? ¿ya el título o el subtítulo "aventuras en los simple y lo complejo" no dejaba adivinar que la aproximación del libro era justamente una aproximación integradora, una que busca conexiones en las que otros solo ven disciplinas diferentes?

Si bien al empezar el libro yo me catalogaba entre el primer tipo de lectores (los dionisíacos, los que están ávidos de leer de física) y página tras página fue defraudándome al punto de querer abandonar la lectura, al terminar el libro completo (todavía soy de los lectores que no renuncia... y hasta ahora ningún libro me ha defraudado), mis sentimientos se acercaron más al segundo grupo (los odisíacos, que agradecen que no todo sea física).

Solo en el último capítulo comprendí el proyecto total del libro (llámenme lento) y estoy seguro que en mi segunda lectura lo disfrutare completo sin ninguna duda (inclusive los crípticos capítulos de física, que leeré con mucha más atención).

Si pudiera resumir en un párrafo el proyecto del libro diría:

En el universo hay sistemas complejos no adaptativos y adaptativos. Los últimos son difíciles de entender, su comportamiento es caótico (con perturbaciones de origen cuántico ¡a todas las escalas!) y no solo depende de leyes simples (como creemos los científicos) sino también de la historia (el azar), razón por lo que no se puede ser reduccionista. Entender la complejidad es el objetivo de la ciencia, que por las razones anteriores no debería dividirse en compartimientos o especialidades: en los sistemas complejos adaptativos todo esta conectado. Nuestra supervivencia futura (sostenibilidad) dependerá de que entendamos esto.

Si van a empezar a leerlo el libro, les haría las siguientes recomendaciones:

1. Lean primero el postfacio. Tomen nota de los conceptos que no entienden, todos ellos son explicados en el texto y será mejor estar preparados para decir por ejemplo "¡ah! aquí explican lo que es la 'profundidad algorítmica' "

2. Lean la primera y la segunda parte como si fuera un texto académico: tomen notas, hagan diagramas, asegúrense de entender la mayoría de las explicaciones (obviamente no todo se va a entender).

3. La tercer parte es muuuuy interesante (posiblemente la más interesante de todo el libro) y si han leído bien la primera y la segunda la van a disfrutar.

4. La cuarta parte (excepto el postfacio) es esencialmente política. Los mensajes que contienen son claros, su lectura es importante para entender a qué nos enfrentamos en el futuro incierto que ha creado nuestra falta de comprensión de los sistemas complejos adaptativos de los que dependemos; pero, sinceramente, estos capítulos son prescindible.

5. Vuelvan a leer el postfacio.

Lo mejor de todo el libro: las anécdotas. Siendo el autor uno de los protagonistas de la física de los últimos 50 años de los 1900, sostuvo relaciones con muchos otros protagonistas de la ciencia de ese mismo período e historias que no se cuentan en los textos de estudio, emergen allí para alegrar de vez en cuando una lectura que puede ser difícil para la mayoría.

Lo peor del libro: no contiene una sola referencia bibliográfica. Entiendo que un personaje como Murray Gell-Mann no necesite "citar" a nadie, menos en un libro divulgativo como este, en el que pretende tal vez desarrollar ideas que domina; pero en la ciencia o en la academia en general estamos acostumbrados a que la historia de la ideas es una compleja telaraña de ocurrencias geniales, adivinanzas, caminos sin salida. Todas estas cosas están en libros y artículos de los autores que lo precedieron. Incluir así fuera una corta relación de los libros o los artículos de ciencia más importantes para el autor habría sido una deferencia mínima con todos los lectores futuros.

Con todo y como los buenos productos de la gente creativa e inteligente, el libro da de que hablar. ¡Léanlo!

[Jafar · Rating 4 out of 5]

Gell-Mann has a Nobel Prize in physics. He’s the co-discoverer of quarks, and the one who named them quarks. Quarks and jaguars represent simplicity and complexity, respectively. The book claims to be about the connection between the simplicity of the fundamental laws of physics and the complexity of the natural word – but I didn’t quite get the purported connection. The book, however, is full of interesting musings on a widely diverse set of subjects – from quantum physics to the preservation of cultural diversity.

I saw this poem by John Updike about neutrinos in the book. Neutrinos are elementary particles with no electric charge and almost no mass. They almost don’t interact with anything and thus pass through ordinary matter undetected. The thermonuclear reactions in the center of the sun produce neutrinos that rain down upon us during the day. During the night, with the sun behind our planet, these neutrinos pass straight through the earth and rain up upon us from below.

Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold shoulder steel and sounding brass,
Insult the stallion in his stall,
And, scorning barriers of class,
Infiltrate you and me. Like tall
And painless guillotines they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed — you call
It wonderful; I call it crass.

[Ty · Rating 2 out of 5]

i picked up this book by Murray Gell-Mann because i thought i would get some interesting discussions on particle physics...after all, Gell-Mann won the Nobel Prize in Physics in 1969...he named the "quark"...

and maybe the middle 3rd of the book did discuss this sort of thing, along with cosmology, astrophysics and such. the 1st third focused mainly on Gell-Mann's theories about complex adaptive systems and his attempts to show that self-organizing structures, like galaxies, stars, planets, etc. are really similar to cells, ants, mammals, societies and economies. an interesting thesis, but somewhat beat to death over the course of 100+ pages.

Gell-Mann uses the final 3rd of the book to muse on a wide variety of subjects, ranging from the debunking of paranormal activities, to environmentalism, to evoloution, to learning computing models, ad infinitum.

basically, this was a tough read...kind of like getting your fiber by eating the Cheerios...and the box. not recommended unless you are looking to improve your sleeping habits.

[Radha · Rating 5 out of 5]

This book was a hard one -- the prose and vocabulary are fairly advances, and I often had to read passages several times to parse exactly what was being communicated. However, it was an incredibly rewarding and thought-provoking read.

In the first half of the book, Gell-Mann makes a convincing parallel between unconscious and conscious systems, arguing that both are subject to a simple set of "evolutionary" rules that allow for the progression of simple to the complex. The second half of the book could be seen as an advertisement for interdisciplinary thinking (and for the Santa Fe Institute): Gell-Mann argues that the world's political, demographic, and social problems can only be solved with broad, sweeping analyses (as opposed to the compartmentalized approaches that characterize modern science.

This is much too dense to be a popular science book, but it was excellent.

Takeaways I really liked:

-- This book has the best interpretation of quantum mechanics for the layman I've ever read: the idea of the wavefunction collapse is replaced by the pruning of a "quantum tree"
-- Evolutionary adaptation can be seen like the 1st law of thermodynamics: information "flows" from the environment to organisms (and their genes), and the discrepancy between the two is reduced s the organisms adapt
-- How does the fact that complexity (both of the conscious and unconscious, i.e. galaxies) increases with time not contradict the second law of thermodynamics? The complexity of all objects is distributed like a bell curve. With time, the bell curve widens, so the most complex objects tend to become more complex. At the same time, the least complex objects become simpler.

[Jack Chaffin · Rating 4 out of 5]

This was a phenomenal book and helped open my eyes to a new interest of mine! The first and third sections I found particularly insightful, but I personally think that the explanations of probabilities during the second section were explained in a less than ideal way, at least for my brain. I dinged one star for the last chapter as well, because honestly he seemed to just be pontificating about things that are common sense now. I understand the book was written before I was alive so that may play a part in it, but I think that most people even in the late nineties were starting to understand the need for conservation. All in all a great book, I think if just lacked in clarity and conciseness in a couple key spots.

[Amanda Brooke · Rating 4 out of 5]

Bringing chemistry and physics to my level of understanding! I am reviewing this book after reading it 15 years ago - I can still remember what I read. I think that's remarkable.

[Haris Wahid · Rating 5 out of 5]

Some parts were a little too complex - even though the authour tries to remove as much mathematics and technicality as possible. But, even still, I was able to follow most of it except the really scientific and technical parts. And I loved it!!

[Random User · Rating 3 out of 5]

The Quest for Unity

Murray Gell-Mann stands as one of the titans of 20th-century physics. The 1969 Nobel laureate transformed the bewildering "particle zoo" of subatomic physics by introducing concepts such as "strangeness" and quarks, providing the fundamental framework for the Standard Model. This search for simplicity within chaos didn't end with quantum mechanics. In 1984, he co-founded the Santa Fe Institute, pioneering the interdisciplinary study of complex systems.

Published in 1994, *The Quark and the Jaguar: Adventures in the Simple and the Complex* represents the culmination of this intellectual trajectory. More than popular science, it's a manifesto for unified understanding—an attempt to build a philosophical bridge from fundamental physics (the "Quark") to the rich, adaptive tapestry of the observable world (the "Jaguar").

This review argues that while the book provides an unparalleled framework for understanding how complex systems operate, its mechanistic, information-centric approach ultimately fails to give a satisfying prescription for why they succeed or fail. Gell-Mann presents a brilliant descriptive framework for Complex Adaptive Systems (CAS), but reveals its limitations when addressing maladaptation and the subjective drivers of survival. His framework, a product of a physicist's search for universal laws, struggles to incorporate the contingent, historical, and often irrational nature of human agency.

The Architecture of Adaptation

The Complex Adaptive System as Learning Engine

Gell-Mann defines a CAS as a system that acquires information about its environment, identifies regularities, condenses those regularities into a "schema," and acts based on that schema. A CAS is a dynamic network of interacting agents—neurons in a brain, ants in a colony, traders in a market—that mutate and self-organise to increase survivability.

The central mechanism is the schema. A CAS processes environmental data, separating patterns from apparent noise. These regularities are compressed into an internal model—the schema—which describes the world, predicts future events, and prescribes behaviour. A child learning a language develops grammatical rules not by memorising sentences, but by identifying patterns in the speech they hear.

Crucially, this involves feedback. Actions based on a schema have real-world consequences that create selection pressures on competing schemata. Successful schemata (such as finding food and avoiding predators) are reinforced; failures are discarded. This iterative variation and selection allows the CAS to learn and co-evolve with its environment.

Randomnessing Complexity: Beyond Randomness

Gell-Mann approaches Complexity by first defining simplicity: the simplest description of an object is a concise summary of its function, ignoring finer details through "coarse-graining."

The initial candidate for measuring Complexity is Algorithmic Information Content (AIC)—the length of the shortest computer program that can generate a data string. A patterned string, such as "010101...", repeated a million times, has a low AIC because a short program can develop it. A random string has no discernible pattern and can only be generated by a program that essentially reproduces the string itself, thereby maximising randomness. This reveals why AIC measures randomness, not Complexity. Random gibberish has a higher AIC than a Shakespearean sonnet of equal length, because the sonnet contains regularities (grammar, meter, vocabulary) that make it compressible.

Gell-Mann's crucial refinement is Effective Complexity—not the AIC of the entire data stream, but the AIC of its identified regularities. A CAS separates incoming data into regular and random components. Effective Complexity is the length of the shortest description of that schema. This captures our intuitive sense of Complexity: perfectly ordered systems have low Effective Complexity (a simple description), and completely random systems also have low Effective Complexity (since there are no regularities to describe). Highly effective Complexity exists only in systems with rich, deep patterns—significant but compressible regularities.

The Edge of Chaos

Effective Complexity leads to the "edge of chaos"—the narrow regime of randomness and order where computation, life, and adaptation thrive. A crystal is too orderly and static to process information. High-temperature gas is too chaotic for stable patterns. Only at the edge of chaos can a system maintain both stability (cohesion) and flexibility (openness).

This corresponds to high Effective Complexity, and total randomness has near-zero Effective Complexity in the intermediate region, where intricate regularities emerge. Effective Complexity preaches its peak, and CAS must position itself in this fertile domain.

Evidence of Emergence: Zipf's Law

Gell-Mann points to statistical regularities, such as Zipf's Law, as evidence of this phenomenon. This states that word frequency in text is inversely proportional to its rank—the most frequent word occurs twice as often as the second most frequent, three times as often as the third, and so on. This power-law relationship appears in city populations, website visits, and earthquake magnitudes.

For Gell-Mann, Zipf's Law provides evidence of self-organisation. Large-scale, predictable patterns emerge spontaneously from local interactions without central planning. This demonstrates how systems can build predictive models of a world far from random.

The Limits of the Mechanistic Lens

Despite its descriptive brilliance, *The Quark and the Jaguar* falls short in providing a truly unified theory. The perspective, rooted in fundamental physics, creates blind spots when confronting the messy realities of philosophy, human agency, and maladaptation.

A Kantian Echo or Oversight?

Gell-Mann employs Kant's distinction between phenomenon (world as it appears to us) and noumenon (unknowable "thing-in-itself") to illustrate CAS-environment relationships. A CAS doesn't know fundamental laws directly, but builds a schema based on perceived regularities. A dog doesn't know Newtonian mechanics but develops an effective schema for thrown ball behaviour.

While clever, this reveals philosophical superficiality. Gell-Mann employs a profound framework, using it as a convenient illustration without delving into more profound implications. By treating knowledge as simple information processing, he sidesteps difficult questions about consciousness and subjective experience that Kant's distinction addresses.

The Gell-Mann Amnesia Effect Turned Inward

The book embodies the very effect named after its author. The Gell-Mann Amnesia Effect, coined by Michael Crichton, describes the phenomenon of reading an article on a known subject, identifying its errors, and then trusting the same publication on unfamiliar topics.

The Quark and the Jaguar*functions as brilliant, self-contained essays on quantum chromodynamics, linguistics, archaeology, evolution, and machine learning. Within each silo, Gell-Mann writes with unimpeachable authority. However, the central promise is unification, not just presentation. Here, the project falters. Connections between simple physics laws and complex human behaviour are asserted more than demonstrated. The reader, impressed by the mastery within sections, forgets to examine the connecting thread critically. They accept grand unification claims because individual parts are strong, overlooking that the book functions more as a curated collection of expert reports than a unified theory.

The Blind Spot of Maladaptation

The most significant limitation emerges with maladaptation. Gell-Mann acknowledges "maladaptive schemata" and "selfish schemes" where pattern-finding becomes detached from survival benefit. However, the mechanistic framework struggles to explain why systems persistently adopt a schema based on "incorrect basis of existence" when contradictory data is available.

The model frames maladaptation as information processing failure—algorithmic bugs. This inheritance from physics, which seeks universal and objective laws, is less equipped to handle the contingent, historical, and subjective elements that dominate biological and social systems. While biology depends on physics, it also depends on "vast additional information about how accidents turned out."

Gell-Mann attempts to treat culture, ideology, trauma, and belief as just more data to process into a schema. The critical flaw: this information isn't merely data—it constitutes the lens through which all other data is perceived, filtered, and valued. It defines the "actor's" identity, goals, and motivations. The CAS model lacks a robust theory of agency, describing the processor elegantly but saying little about its internal, subjective state—often the most critical behavioural variable.

This limitation is starkly evident in the final chapters, which advocate for a greater scientific role in governance to address global challenges such as environmental catastrophe. His plea for rational, data-driven, universal collaboration is logical within his mechanistic framework. Yet, it negates the observable reality he describes elsewhere: human actors and societies frequently operate on implicit, subjective, culturally ingrained survival beliefs, often defying objective data. The model cannot account for systems choosing to burn the world down because its schema defines "survival" in ways that make that action seem rational.

An Alternative Synthesis: John Boyd and Orientation

To address Gell-Mann's prescriptive shortcomings, consider the work of U.S. Air Force Colonel John Boyd. This military strategist developed a parallel but distinct adaptation theory that directly confronts agency and subjective sense-making problems.

From Shared Zeitgeist to Divergent Path

Boyd independently immersed himself in intellectual currents animating the Santa Fe Institute. His library contained works by Karl Popper, Thomas Kuhn, and Ilya Prigogine. He grappled with chaos theory, Complexity, and thermodynamics, understanding conflict as "non-linear clash of two Complex Adaptive Systems."

While influenced by the same scientific zeitgeist, their objectives differed. Gell-Mann sought a universal, objective description from an external viewpoint. Boyd sought practical survival methods within chaotic environments. This purpose difference led to a crucial theoretical divergence.

The OODA Loop Orientation Framework

Boyd's central contribution is the OODA Loop, which consists of the steps Observe, Orient, Decide, and Act. Standard interpretation as "act faster than the enemy" profoundly misunderstands its depth. The actual engine is Orientation—the complex, often implicit sense-making process that synthesises external observations with internal, subjective landscapes, including genetic heritage, cultural traditions, past experiences, and analytical capacity.

This is precisely the "actor network" missing from Gell-Mann's mechanistic model. Orientation formally incorporates subjective values, biases, and historical contingencies, determining how agents perceive the world and what they deem essential. It's the core of agency.

Answering the 'Ought'

Boyd's 1976 paper, "Destruction and Creation," provides a philosophical foundation that offers a meaningful response to maladaptation problems. Boyd argues that remaining adapted to a dynamic, uncertain reality requires continuous cognitive self-renewal—actively discarding old mental models that are no longer aligned with observed reality and creating new ones that are.

For Boyd, adaptation isn't a selection of competing schemata, but an active, often violent, psychologically demanding dismantling of a cherished worldview. This provides the prescriptive "ought" absent in *The Quark and the Jaguar*. One ought to relentlessly challenge and destroy orientation when it mismatches reality, because failure leads to stagnation and vulnerability. Systems become maladaptive when clinging to closed, rigid orientations, unable to perform creative destruction.

Conclusion: Description Without Prescription

The Quark and the Jaguar remains essential in the complexity science canon. Its intellectual scope is breathtaking, and Gell-Mann's ability to distil profound concepts into coherent vocabulary represents a monumental achievement. He provided language for new science, defining Complex Adaptive Systems, clarifying schema roles, and developing Effective Complexity as a rigorous tool for distinguishing meaningful patterns from noise.

Yet the book remains incomplete. Its central ambition—forging a unified theory linking complex and straightforward—remains unfulfilled, victim of the very Gell-Mann Amnesia Effect its author's name denotes. The mechanistic perspective limits engagement with subjective, historical, and cultural dimensions of adaptation. Its CAS model as an information processor is elegant but sterile, inadequately accounting for persistent irrationality or subjective belief primacy in human affairs. The book masterfully describes the Complexity of "how" and "what," but falters on the prescriptive "ought."

The full value is realised when read not as a final unified theory, but as the essential first half of a critical dialogue. Gell-Mann provides the indispensable map of a complex landscape where adaptive agents operate. However, for navigation compass—the theory of how to think, act, and survive under profound uncertainty—one must turn to strategists like Boyd, who understood that survival struggle is won or lost not in data processing, but in orientation forging. Gell-Mann described the world that the quark made. Boyd proposed a theory on how the jaguar, through the constant destruction and creation of its worldview, might endure within it.

[R Goose · Rating 5 out of 5]

“In 1963, when I assigned the name “quark” to the fundamental constituents of the nucleon, I had the sound first, without the spelling, which could have been “kwork”. Then in one of my occasional perusals of Finnegan’s Wake, by James Joyce, I came across the word “quark” in the phrase “Three quarks for Muster Mark.” Since “quark” (meaning, for one thing, the cry of a gull) was clearly intended to rhyme with “Mark,” as well as “bark” and other such words, I had to find an excuse to pronounce it as “kwork.” But the book represents the dream of a publican named Humphrey Chimpden Earwicker. Words in the text are typically drawn from several sources at once, like the “portmanteau words” in Through The Looking Glass. From time to time, phrases occur in the book that are partially determined by calls for drinks at the bar. I argued, therefore, that perhaps one of the multiple sources of the cry “Three quarks for Muster Mark” might be “Three quarts for Mister Mark,” in which case the pronunciation “kwork” would not be totally unjustified. In any case, the number three fitted perfectly the way quarks occur in nature.”

< —>< — >

Murray Gell-Mann was awarded the 1969 Nobel Prize in Physics for his work on the theory of elementary particles. As evidenced by the excerpt above, he discovered and named the quark, which is one of the subatomic particles that serve as building blocks for the protons and neutrons that form an atom’s nucleus. The Quark and the Jaguar was published in 1994.

In the afterword, the author describes the book as “comparatively nontechnical.” That it may be, but for someone with very little background in theoretical physics, there are great swaths in the middle of this book that are almost completely unintelligible. I struggled through it because there were enough little rewards along the path to make it worthwhile. In addition to the first-hand account of the faintly absurd process that led to the naming of the quark, there are many other delightful anecdotes from backstage at the science fair, such as the one in which Gell-Mann is tasked with facilitating someone else’s meeting with Einstein, or that time Robert Oppenheimer stormed out of a seminar muttering “Fire balls! Fire balls!” because someone changed the subject during the presentation of his final research effort.

The later part of the book is largely in the field of evolutionary biology and sustainability, which is slightly closer to my usual territory. A quarter-century has passed since ’94, but the discussions of biological mutations, selection pressures, and paths to better conservation practices are still very timely. The sections on machine learning and nascent AI provide an interesting peek into what it might have been like to stand consciously on the edge of the information explosion that has now grown into an uncontested reality.

The unrelenting specificity of the language used throughout the text was a real joy for me, and I picked up some delicious new vocabulary for complex adaptive systems that I expect will be widely applicable (if it hasn’t already gone out of style).

In The Quark and the Jaguar, Gell-Mann advocates more than once for the generalists who are willing and able to take a coarse look at the big picture, rather than developing a speciality. This wandering tour of his mind is a nice demonstration of how the brain of a polymath is positioned to make connections that might never become obvious to those with a narrower focus.

[Carol · Rating 4 out of 5]

I am re-reading this after about 10 years. Why hasn't anyone else checked it out of the library during that time. It is very provocative. Murray Gell-Mann is a theoretical physicist who won the Nobel Prize for predicting the quark. He also has a strong interest in biology, evolution, conservation, natural history, and anthropology. This book is linking all of these interests together. He centers on "complex adaptive systems", which can be bacteria developing immunity to antibiotics, a person learning from experience, cultures evolving, etc. How does life emerge from non-life? How do species differentiate? How does intellegence emerge when life evolves to a certain level of complexity? All these things are made of quarks, a few simple particles, yet look what variety and complexity comes out of this! It is OK to skim certain chapters if you find them too technical (for instance, he spends a lot of words formulating a technical definition of "complex"), but don't give up on the book: Just skip these parts and look for the main ideas. It is awesome!

[Steve · Rating 4 out of 5]

In the spirit of the Heisenberg Uncertainty Principle I'm not sure whether to give this book a 3 or a 5. Gell-Mann covers a lot of ground. He begins with adaptive complex systems veers to quantum theory QED and QCD and then to most other things in the universe language, creative thinking, rain forests and more.

In reading this book, it would be put to best use by trying to think in broad sweeps of the mind and see where Gell-Manns general concepts could be applied to your own discipline or complex problems you are working on. Your mind can not be a passive acquirer of factoids while reading this book, but needs to be an active participant in the creative thinking process.

[Two Readers in Love · Rating 5 out of 5]

This is the book that goes the farthest to disprove John Wheeler’s quote “if you are not completely confused by quantum mechanics, you do not understand it.” Accessible and yet profound, Mr. Gell-Mann takes the ‘mystic’ out of quan*t*u*m* ph*ysic*s.

[Thomas]

I liked the first few chapters, but will have to come back to this one later.

[Oscar G. Miranda · Rating 4 out of 5]

Leer "The quark and the jaguar" es como jugar al sudoku. Resolver las primeras líneas cuesta trabajo y requiere bastante atención, pero una vez que empiezan a llenarse los vacíos, el cuadro completo se llena por si solo.
Brilliantemente interdisciplinario. Una lectura emocionante sobre los sistemas adaptativos complejos. Como estudiante de biología, recomiendo este libro a aquél que quiera entender la relación estrecha entre la física cuántica, la segunda ley de la termodinámica y la evolución de las especies.
A pesar de ser un libro antiguo (en estándares científicos), los comentarios y vínculos que realiza Gell-Man siguen siendo tan vigentes como hace 25 años. Hubiera sido interesante esuchar los pensamiento de Gell-Mann sobre la inteligencia artificial, el resurgimiento de la derecha, la epigenética y los últimos descubrimientos del CERN.
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Reading "The quark and the jaguar" is like playing sudoku. Solving the first lines is hard at first, and requires lots of focus, but once the empty squares are filled, the complete board fills itselfs up.
Brilliantly interdisciplinary. A thrilling readinf about comex adaptative systems. As a biology student, I recommend this book to understand the strech relationship between quantum physics, the second law of thermodynamics and the evolution of species.
Despite being an old book (by scientific standards), Gell-Man's comments and links are as relevant as they were 25 years ago. It would have been interesting hearing his thoughts on artificial intelligence, the resurgence of the right, epigenetics, and the most recent discoveries at CERN.

[Kerry Pickens · Rating 4 out of 5]

The author Murray Gell-Mann (1929–2019) was awarded the 1969 Nobel Prize in Physics for his theoretical work on elementary particles. A graduate of Yale University and MIT, he taught at the California Institute of Technology from 1955 until his retirement in 1993. In 1984, he helped establish the Santa Fe Institute, whose goal was discuss policy solutions for improving the future through collaborative research efforts. A member of the research group you would recognize is the late author Cormac McCarthy. It’s interesting to note that convicted child sex offender Ghislane Maxwell’s father Robert Maxwell provided funding to the Santa Fe Institute as well as other research projects. There is a conspiracy rabbit hole you can go down there, but The British Foreign Office suspected Maxwell of being a secret agent of a foreign government, possibly a double agent or a triple agent, and "a thoroughly bad character and almost certainly financed by Russia". He had known links to the British Secret Intelligence Service (MI6), to the Soviet KGB, and to the Israeli intelligence service Mossad.

[Ricardo · Rating 2 out of 5]

Creí que iba a tener un carácter más explicativo.
En general no me ha gustado, aunque posee algunas partes que tratan sobre temas interesantes, suele hacerlo de una forma superficial y demasiado genérica y anecdótica, lo que hace que resulte difícil de seguir y entender lo que está diciendo o intentando exponer.
Ni siquiera, una vez terminado el libro, podría decir de qué trata exactamente, pues es una especie de popurrí extraño que mezcla comentarios anecdóticos sobre la vida del autor, con una variedad enorme de temas, desde computabilidad hasta ecología, pasando por la mecánica cuántica aunque, como he dicho, sin detenerse mucho en nada, aunque cierto es que todo parace girar en torno al concepto de sistema complejo adaptativo y complejidad física.
Me parece una obra redactada más para pasatiempo o proyecto personal del autor que para leer y beneficio del lector.
Personalmente, no creo que merezca la pena como lectura.

[Andrew · Rating 5 out of 5]

I loved this book!
The Quart & the Jaguar presents as a collection of philosophical views derived from a lifetime commitment to a chosen discipline, in this case Murray Gell-Mann presents his views & personal insights in the context of his personal commitment to quantum physics.
Fascinating man, brilliant insightful book.

This is my favourite 'book genre' if you will - that of an individual outlining their philosophical & metaphysical views in the context of a discipline of which they have committed to & made significant personal investment toward - I would greatly appreciate if anybody could recommend any other titles that may be appropriately identified within this 'genre', or means to locate books of like kind.
Additionally, I found the subject matter of quantum physics itself of great personal interest & would love to be directed to any literature that aids in the learning & understanding of the topic.

Thank you all in advance.

[Iancu S. · Rating 2 out of 5]

Many interesting individual chapters, but this particular jaguar has bitten off more than he can chew. An erudite author with far-reaching interests, but who does not fully tie them all together coherently in the book. Some of the technical discussions on quantum mechanics are too hard for a lay reader (and, I would venture a guess, too easy for the specialist). One example: we're being told that it's the *heterotic* variety of string theory that is a good candidate for a grand unified theory, before we're being told what string theory is. Similar for other presumably deep theoretical points (bootstrap principle, Hawking-Hartle no boundary condition etc) - one gets a sense that they do heavy lifting in certain theories, but I wasn't able to get easily behind the key intuitions, at least as explained here.

[Justin Harnish · Rating 4 out of 5]

Gell-Mann is one of the geniuses of our time and has been influential in shaping modern day complexity science and the Santa Fe Institute that is this fields chief research institute. His book "The Quark and the Jaguar" clearly outlines how these different domains are being researched and what the state of play was when it was written.

Chief amongst Gell-Mann's concerns is that the dynamism of human ideology, governance, and society is not great enough to tackle existential threats -- this is very poignant for the present day addition of the AI Safety threat as well.

Overall a good overview of the topics but dated as these sciences are racing forward, largely thanks to the shoulders of giants like Gell-Mann.

[Brian Block · Rating 2 out of 5]

This popular science book by Gell-Man, winner of the Nobel Prize in Physics, explores various branches of science and simple and complex systems. He makes a number of interesting connections between the laws of physics and how those translate to the natural world. This book felt more like a reminiscence of Gell-Man’s life and a history of science in the twentieth century. It touches a wide variety of topics from physics, chemistry, and biology to economics and culture. Honestly, this span of topics is to the book’s detriment. You can tell that Gell-Mann is a very intelligent man, but this book is more of the ramblings of an intelligent man than an organized, succinct dissertation.

[Diego F. Cantero · Rating 4 out of 5]

“Entiendo” que “físicos puros” en busca de sesudos trabajos sobre las partículas elementales, o graduados encapsulados en el reduccionismo universitario, se hubiesen sentido defraudados con esta obra de física teórica que contiene más política o sociología que ecuaciones.
Para los demás, que apreciamos la obra como una especie de “biblia” anti reduccionista, y que consideramos adquiere produndidad con el paso del tiempo, será una pequeña maravilla que leer y releer más allá (o acá) de que la teoría de supercuerdas ya no tenga fuerza.

[Robert Trull · Rating 5 out of 5]

Una obra maestra de Murray Gell-Mann, que versa sobre la aplicación de las ciencias de la complejidad en distintos aspectos, dede la vida cotidiana hasta la física de partículas.

Se nota que el escritor era un verdadero erudito y las páginas están repletas de datos interesantes y relacionados con el argumento que se está desarrollando.

Recomiendo releer este libro, pues una sola lectura quizás no sea suficiente para comprender la totalidad de los conceptos que se taran. Sin duda, uno de los mejores libros en ciencias de la complejidad jamás escritos.

[Liedzeit Liedzeit · Rating 3 out of 5]

Thema ist das Simple und das Komplexe. Sehr interessant, aber viel zu viel und dabei sehr oberflächlich.
Wunderbar, daß er direkt an der Barometer-Geschichte beteiligt war, als Richter: Ein Student soll in Prüfung mit Hilfe eines Barometers die Höhe eines Hauses bestimmen. Wunderbar. Am besten von allen Lösungen gefällt mir, das Hochsteigen und Einritzen bei jedem Stock, so daß die Höhe des Hauses nachher in Barometer units feststeht.

[Kristine · Rating 4 out of 5]

The author literally coined the term "quark" - clearly an expert modern physicist. As a physicist myself, I followed the discussions of particle physics, string theory, computational complexity, etc., and I understand the points the author is making about the nature of complexity. I appreciate the concepts from a fundamentals and mathematical philosophy point of view, but I would not recommend this book as a light read or for a casual scientist.