# The Emperor's New Mind *By Roger Penrose, with a foreword by Martin Gardner. Oxford University Press, 1989. ISBN 0-19-851973-7 / 978-0-19-851973-7. This is Penrose's first popular book. He argues that conscious understanding cannot be captured by any algorithm, so no computer running a program can have a mind. The book is also a long tour of the physics he thinks matters: computability, Gödel's theorem, classical and quantum mechanics, entropy and cosmology, and the brain. He ends by proposing that a not-yet-found theory joining quantum mechanics and gravity ("correct quantum gravity") is where the non-computable physics of mind must sit. It won the 1990 Science Book Prize. OUP still publishes it in the Oxford Landmark Science series.* > **What I actually read.** The book is in copyright (© Oxford University Press 1989; preface © Roger Penrose 1999, 2016) and I did not read all of it. I **read in full** the publisher's free sample of the current OUP edition, hosted by pageplace.de: [preview PDF](https://api.pageplace.de/preview/DT0400.9780192550064_A35506325/preview-9780192550064_A35506325.pdf). It contains the title and copyright pages, Gardner's foreword, Penrose's 1998 preface (with 2016 footnote updates), the **complete contents list with section headings and page numbers (1999/2016 pagination)**, the Prologue, and chapter 1 to p. 33. The **1989 first-edition page numbers** come from the contents page of the Internet Archive scans of the 1989 OUP printing ([`emperorsnewmindc00penr`](https://archive.org/details/emperorsnewmindc00penr), [`emperorsnewmindc0000penr`](https://archive.org/details/emperorsnewmindc0000penr)) and the 1991 Penguin reprint (same pagination). I read these through Open Library's public "search inside" snippets. Both sets of numbers are given below; they disagree because the 1999 paperback was reset. The **chapter list** also matches the contents note (MARC 505) in Harvard's library record. Quotations from the foreword, preface, Prologue and chapter 1 are from the preview. A few short phrases from later chapters are from search-inside snippets and are marked. Everything else in the chapter summaries (chapters 2–10 and the Epilogue) is my own paraphrase. It draws on the section headings, the snippets, Penrose's own preface, and the book's standard secondary literature. I did not see full text for those chapters. Related in this vault: the source video note [[Video Summaries/Curt Jaimungal/Roger Penrose My Crazy Idea That Explains the Universe]]. Penrose's *Fashion, Faith, and Fantasy in the New Physics of the Universe* (2016), named in the same video, is next in the [[Book Summaries/Queue|Queue]]. ## 1. Book facts | | | |---|---| | Title | *The Emperor's New Mind: Concerning Computers, Minds, and the Laws of Physics* (subtitle as on the 1989 title page and in the LC record; some Amazon listings misprint "the Law of Physics") | | Author | Sir Roger Penrose (born 8 August 1931, Colchester), mathematical physicist, Rouse Ball Professor of Mathematics at Oxford 1973–1998, now emeritus; Nobel Prize in Physics 2020 | | Foreword | Martin Gardner (pp. xi–xiv in the 1999/2016 printings) | | Edition used | **First edition**, Oxford and New York: Oxford University Press, 1989. xiii + 466 pages, illustrations, 24–25 cm; bibliography pp. [452]–460; index from p. 461. LCCN [89008548](https://lccn.loc.gov/89008548); LC class Q335 .P415 1989; Dewey 006.3; OCLC 19724273; US list price $30.00 (MARC 020). Open Library [OL2190164M](https://openlibrary.org/books/OL2190164M) / [OL18339648M](https://openlibrary.org/books/OL18339648M) | | Later printings | **1990**: OUP "Repr. (with corrections)", same pagination (Columbia record, OCLC 22165696); Vintage (UK) paperback, ISBN 0099771705. **1991**: Penguin Books (US) paperback, ISBN 0140145346, 466 pp. ([OL1884133M](https://openlibrary.org/books/OL1884133M)). **1999**: OUP paperback "with a new preface", ISBN 0192861980, about 602 pp., reset with new page numbers. **2016**: "Revised impression, as Oxford Landmark Science", paperback ISBN 9780198784920 (640 pp. per the publisher); ebook ISBNs 9780192550071 and 9780192550064 (copyright page of the preview) | | What changed in 1999/2016 | A new preface (dated September 1998). It restates the two-strand argument, gives Goodstein's theorem as an accessible Gödel-type example, drops the book's "one-graviton criterion" in favour of the scheme in *Shadows of the Mind*, and credits Stuart Hameroff with pointing him to microtubules. The 2016 footnotes add 2014 papers (Hameroff & Penrose, "Orch OR" review; Penrose, "On the gravitization of quantum mechanics 1"). The text of the ten chapters is otherwise unchanged ("the essential ideas … are the same as they were ten years ago", preface) | | Structure | Foreword; Preface (from 1999); Prologue; 10 chapters, 117 sections in all; Epilogue; References; Index | | Prize | Science Book Prize, 1990 (Open Library notes it as the Royal Society Winton Prize, the prize's later name; OUP calls it "Winner of the 1990 Science Book Prize") | | Audiobook | **Yes.** Unabridged, read by Julian Elfer, Tantor Media, 15 October 2019, 18 h 27 min ([Audible](https://www.audible.com/pd/The-Emperors-New-Mind-Audiobook/1515943836)). Older recordings: Audio Literature cassettes, 1990 and 1992 (ISBNs 1558002537, 1558004726), and New Millennium Audio, 2001 (ISBN 1931056781). I did not check whether those were abridged | | Open Library | Work [OL3474158W](https://openlibrary.org/works/OL3474158W) (the work record's display title is the German translation, *Computerdenken*); author [OL579149A](https://openlibrary.org/authors/OL579149A) | | Translations | Among others: German *Computerdenken* (Spektrum, 1991/2002), French *L'esprit, l'ordinateur et les lois de la physique* (Dunod, 1993), Spanish *La nueva mente del emperador* (Mondadori, 1991), Portuguese *A mente nova do imperador* (Unesp, 2023), Turkish *Kralın Yeni Aklı* (Koç University Press, 2015), Korean (Ewha Womans University Press, 1996) | | Cover | [Open Library cover 12978275](https://covers.openlibrary.org/b/id/12978275-L.jpg) | **Where it came up.** - Video: [Roger Penrose: "My Crazy Idea That Explains the Universe"](https://www.youtube.com/watch?v=iO03t21xhdk), *Curt Jaimungal* (Theories of Everything), published 2025-11-03, 1:56:13. Penrose names the book twice. At [28:38](https://www.youtube.com/watch?v=iO03t21xhdk&t=1718s) he says he wrote it to express the Gödel argument that understanding needs awareness and is not computation, and that he learned neurophysiology hoping to find a physical non-computational process. At [1:21:46](https://www.youtube.com/watch?v=iO03t21xhdk&t=4906s) he says he knew the Gödel thesis when he started but, after learning Hodgkin–Huxley nerve physiology, saw no way for quantum coherence to survive in neurons, so the book "ends weakly" (with quasicrystals) and without a solid brain site for collapse. Microtubules (with Stuart Hameroff) came later. - Requested by Video Summaries on 2026-11-06. The queue note asked for the subtitle, year and edition to be verified (done above). - Vault note: [[Video Summaries/Curt Jaimungal/Roger Penrose My Crazy Idea That Explains the Universe]]. ## 2. Book resources **Reference and catalog pages.** Publisher: [OUP (Oxford Landmark Science paperback, 9780198784920)](https://global.oup.com/academic/product/the-emperors-new-mind-9780198784920), with contents; [OUP Australia page](https://www.oup.com.au/books/higher-education/physics/9780198784920). Free publisher sample: [pageplace.de preview PDF](https://api.pageplace.de/preview/DT0400.9780192550064_A35506325/preview-9780192550064_A35506325.pdf) (foreword, preface, full contents, Prologue, chapter 1 to p. 33). Library of Congress: [89008548](https://lccn.loc.gov/89008548). Open Library: [OL3474158W](https://openlibrary.org/works/OL3474158W). Google Books: [2016 edition](https://books.google.com/books/about/The_Emperor_s_New_Mind.html?id=JF4vDwAAQBAJ). Wikipedia: [The Emperor's New Mind](https://en.wikipedia.org/wiki/The_Emperor%27s_New_Mind). **Free (legal).** - **No legal free full text.** The book is in copyright. Project Gutenberg: not applicable. - **Publisher's sample (free):** the [pageplace.de preview](https://api.pageplace.de/preview/DT0400.9780192550064_A35506325/preview-9780192550064_A35506325.pdf) covers about 60 pages, including the whole Prologue and the Turing test and Chinese room sections of chapter 1. - **Internet Archive / Open Library: borrowable.** Several scans of the 1989 OUP printing are in IA's `inlibrary` lending collection: [`emperorsnewmindc0000penr`](https://archive.org/details/emperorsnewmindc0000penr), [`emperorsnewmindc0000penr_f3m4`](https://archive.org/details/emperorsnewmindc0000penr_f3m4) and [`emperorsnewmindc0000penr_w3r3`](https://archive.org/details/emperorsnewmindc0000penr_w3r3). Borrow through [Open Library](https://openlibrary.org/works/OL3474158W) with a free account. A 1999 OUP paperback scan ([`emperorsnewmindc1999penr`](https://archive.org/details/emperorsnewmindc1999penr)) and the 1991 Penguin ([`emperorsnewmind00roge`](https://archive.org/details/emperorsnewmind00roge)) also exist; some scans are print-disabled access only. - **Not legal:** PDFs of the book circulate on file-sharing and course sites. I am not linking them. - **Libby/OverDrive: yes, ebook and audiobook.** [OverDrive ebook 4977008](https://www.overdrive.com/media/4977008/the-emperors-new-mind) (OUP, Oxford Landmark Science) and [OverDrive audiobook 4872864](https://www.overdrive.com/media/4872864/the-emperors-new-mind) (Tantor, read by Julian Elfer). Whether your library licenses them is a local question. - **Hoopla: yes, audiobook.** [Hoopla 12414375](https://www.hoopladigital.com/audiobook/the-emperors-new-mind-roger-penrose/12414375) (Tantor 2019, unabridged, 18 h 27 min). Hoopla also has *Fashion, Faith, and Fantasy*. - **Free companions (legal):** Penrose's 2020 [Nobel lecture](https://www.nobelprize.org/prizes/physics/2020/penrose/lecture/) (video); the long podcast interviews in section 4. **Paid.** - **Amazon print.** [Oxford Landmark Science paperback, ISBN 0198784929](https://www.amazon.com/dp/0198784929) (2016, with the 1998 preface; this is the one in print). [1989 OUP hardcover, ISBN 0198519737](https://www.amazon.com/dp/0198519737) and [1991 Penguin paperback, ISBN 0140145346](https://www.amazon.com/dp/0140145346), both used. - **Kindle.** Yes: Oxford Landmark Science edition, OUP, 28 April 2016, ISBN 9780192550071 ([Amazon UK listing, ASIN B074JCG4P9](https://www.amazon.co.uk/dp/B074JCG4P9); [search Amazon.com Kindle](https://www.amazon.com/s?k=9780192550071&i=digital-text)). Amazon UK notes it is only available on some devices because of its large file size (24.3 MB, many figures). - **Audible.** Yes: [The Emperor's New Mind, read by Julian Elfer](https://www.audible.com/pd/The-Emperors-New-Mind-Audiobook/1515943836), Tantor Audio, 2019, unabridged, 18 h 27 min. The book leans on figures and equations, so the audio works best alongside a print or ebook copy. - **Edition note.** Get the 2016 Oxford Landmark Science paperback, or the 1999 OUP paperback, because the 1998 preface is the best short statement of what Penrose still holds and what he dropped. The 1989 hardcover and 1991 Penguin have the original pagination (used for the 1989 numbers below), but no preface. ## 3. Author biography **Roger Penrose** was born in Colchester, Essex, on 8 August 1931. His father was the geneticist Lionel Penrose. His brothers are the physicist Oliver Penrose and the chess grandmaster Jonathan Penrose. He studied mathematics at University College London and took a PhD in algebraic geometry at Cambridge (1957), where lectures by Hermann Bondi and Paul Dirac and his friendship with Dennis Sciama drew him into relativity. With his father he devised the "impossible" tribar and staircase that M. C. Escher used in *Ascending and Descending* and *Waterfall* (Gardner's foreword). His main contributions: - **The singularity theorem (1965).** "Gravitational Collapse and Space-Time Singularities" (*Physical Review Letters* 14, 57) showed, using trapped surfaces, that collapse to a singularity is generic in general relativity, not an artefact of exact symmetry. He later extended this with Stephen Hawking (Hawking–Penrose theorems, 1970). It is the basis of his half of the **2020 Nobel Prize in Physics**, awarded "for the discovery that black hole formation is a robust prediction of the general theory of relativity" (the other half went to Reinhard Genzel and Andrea Ghez). - **Conformal methods and Penrose diagrams**, cosmic censorship (1969), and the Penrose process for extracting energy from rotating black holes. - **Twistor theory** (from 1967), which Gardner's foreword says Penrose himself classes as "tentative". - **Penrose tilings** (1974): two shapes that tile the plane only non-periodically. They later turned out to describe quasicrystals, discussed in chapter 10. - **The Weyl curvature hypothesis** (late 1970s), the claim that the Big Bang had zero Weyl curvature, as a source of the second law (chapters 7–8). It later led to **conformal cyclic cosmology** (*Cycles of Time*, 2010), the subject of the source video. - **Gravity-induced collapse of the wave function** ("objective reduction", 1990s) and, with Stuart Hameroff, the **Orch OR** theory of consciousness in microtubules, both direct sequels to this book. He was Rouse Ball Professor of Mathematics at Oxford from 1973 to 1998 and is now emeritus, at the Mathematical Institute. Honours include FRS (1972), the Wolf Prize in Physics with Hawking (1988), a knighthood (1994), the Copley Medal (2008) and the Nobel Prize (2020). His other popular books are *Shadows of the Mind* (1994), *The Large, the Small and the Human Mind* (1997), *The Road to Reality* (2004), *Cycles of Time* (2010) and *Fashion, Faith, and Fantasy in the New Physics of the Universe* (2016). ## 4. Author interviews and talks - **Curt Jaimungal, Theories of Everything (2025)**, the source video: [Roger Penrose: "My Crazy Idea That Explains the Universe"](https://www.youtube.com/watch?v=iO03t21xhdk) (1:56:13). It covers conformal cyclic cosmology, gravitational collapse of the wave function, the Gödel argument, his critique of modern AI ("artificial cleverness" without understanding), Libet's timing experiments and Hofstadter. A follow-up with Ivette Fuentes on a proposed collapse experiment aired 25 November 2025. - **Lex Fridman Podcast #85 (31 March 2020)**: [Physics of Consciousness and the Infinite Universe](https://lexfridman.com/roger-penrose/) (1 h 28 min). Chapters include "Consciousness and computation", "What does it mean to 'understand'" and "Whatever consciousness is, it's not a computation". It is the closest spoken summary of this book. - **Sean Carroll's Mindscape, episode 28 (7 January 2019)**: [Roger Penrose on Spacetime, Consciousness, and the Universe](https://preposterousuniverse.com/podcast/2019/01/07/episode-28-roger-penrose-on-spacetime-consciousness-and-the-universe/) (1 h 35 min). Mostly black holes and cosmology, with quantum mechanics and the brain at the end. - **Other podcasts**: The Joe Rogan Experience #1216 (December 2018); The Jordan B. Peterson Podcast #244 (April 2022); BBC Radio 4 *In Our Time* panels on Consciousness (1999), The Physics of Reality (2002) and The Measurement Problem (2009). - **Nobel lecture (8 December 2020)**: [nobelprize.org](https://www.nobelprize.org/prizes/physics/2020/penrose/lecture/). - **In print, with critics**: "Précis of *The Emperor's New Mind*" with open peer commentary and his reply, *Behavioral and Brain Sciences* 13(4), 1990, pp. 643–705, cited in his own preface. "Beyond the Doubting of a Shadow", his reply to critics of *Shadows of the Mind*, *Psyche* 2 (1996). ## 5. Summary **Thesis.** Penrose states it himself in the 1998 preface: "I argue that the phenomenon of consciousness cannot be accommodated within the framework of present-day physical theory." He rejects the view that "all aspects of mentality (including conscious awareness) are merely features of the computational activity of the brain". He does not look outside science: "it is not my contention that we should look outside science for an understanding of mentality, merely that existing science has not the richness to achieve what is required." The argument has "two main strands". The first uses Gödel and Turing to show "that mathematical thinking (and hence conscious thinking generally) is something that cannot be encapsulated within any purely computational model of thought". The second claims "an important gap in our physical picture of the world, at a level which ought to bridge the submicroscopic world of quantum physics to the macro-world of classical physics", and that the missing physics there must contain "something outside purely computational action" (all from the preface). Gardner's foreword sets out the target. "For decades now the proponents of 'strong AI' (Artificial Intelligence) have tried to persuade us that it is only a matter of a century or two (some have lowered the time to fifty years!) until electronic computers will be doing everything a human mind can do." He calls the book "the most powerful attack yet written on strong AI", and he explains the title: Penrose is the child in the third row "who dares to suggest that the emperors of strong AI have no clothes". **Outline.** Section titles are verbatim from the contents page. Page numbers are given as **1989 / 1999–2016**. The 1989 numbers come from the contents page of the 1989 OUP and 1991 Penguin scans (via search inside). The 1999–2016 numbers come from the OUP preview's contents page. *Front matter.* Foreword by Martin Gardner (1989: from p. vii, per the scan's index; 2016: pp. xi–xiv). Preface (1999 and 2016 only, pp. xv–xxiii). Acknowledgements and credits for figures, including Escher (Fig. 5.2). - **Prologue (p. 1 / 1).** The opening of the Ultronic computer: "THERE WAS A GREAT gathering in the Grand Auditorium, marking the initiation of the new 'Ultronic' computer." President Pollo wants it to take over "all those awkward decisions of State". The Chief Designer boasts that it "has over 10¹⁷ logical units. That's more than the number of neurons in the combined brains of everyone in the entire country!" When the audience is too awed to ask the first question, thirteen-year-old Adam, "the little lad in the third row", raises his hand. The Prologue breaks off before his question. The answer comes in the Epilogue. - **Ch. 1, Can a Computer Have a Mind? (pp. 3–29 / 3–39).** Introduction (3 / 3); The Turing test (5 / 6); Artificial intelligence (11 / 14); An AI approach to 'pleasure' and 'pain' (14 / 17); Strong AI and Searle's Chinese room (17 / 21); Hardware and software (23 / 30). Penrose sets out the questions ("What does it mean to think or to feel? What is a mind? … Are minds subject to the laws of physics? What, indeed, are the laws of physics?", p. 4, 2016) and promises to separate "speculation from hard scientific fact". He takes the Turing test seriously but as a rough guide. He defines strong AI: "mental qualities of a sort can be attributed to the logical functioning of any computational device, even the very simplest mechanical ones, such as a thermostat", and "all mental qualities … are to be regarded … merely as aspects of this complicated functioning" (pp. 21–22, 2016). He finds Searle's Chinese room "quite a powerful one": "the mere carying [*sic*] out of a successful algorithm does not in itself imply that any understanding has taken place" (p. 24, 2016). He then weighs objections, including the sheer complexity of any brain-scale program and Searle's "whole of India" version, where the individual symbol-shufflers look more like neurons than like a brain. Hardware and software covers the "teleportation" thought experiment and the claim that a person is the pattern, not the atoms. - **Ch. 2, Algorithms and Turing Machines (pp. 30–73 / 40–97).** Background to the algorithm concept (30 / 40); Turing's concept (35 / 46); Binary coding of numerical data (42 / 56); The Church–Turing Thesis (47 / 61); Numbers other than natural numbers (49 / 65); The universal Turing machine (51 / 67); The insolubility of Hilbert's problem (57 / 75); How to outdo an algorithm (64 / 83); Church's lambda calculus (66 / 86). A hands-on course: Euclid's algorithm, Turing machines written out as explicit instruction tables, a universal machine, then the halting problem by diagonal argument. "How to outdo an algorithm" is the seed of the book's argument: given any algorithm that correctly decides when computations never halt, we can construct a case it cannot settle but whose answer we can see. - **Ch. 3, Mathematics and Reality (pp. 74–98 / 98–128).** The land of Tor'Bled-Nam (74 / 98); Real numbers (80 / 105); How many real numbers are there? (82 / 108); 'Reality' of real numbers (86 / 112); Complex numbers (87 / 114); Construction of the Mandelbrot set (92 / 120); Platonic reality of mathematical concepts? (94 / 123). The chapter opens with a fable: "Let us imagine that we have been travelling to some far-off world. We shall call this world Tor'Bled-Nam" (snippet), a strange landscape that turns out to be the Mandelbrot set ("Tor'Bled-Nam" is "Mandelbrot" backwards). Cantor's diagonal argument, complex numbers and the iteration z → z² + c follow. The point is Platonism: the Mandelbrot set was discovered, not invented. Gardner: Penrose finds it "incomprehensible … that anyone could suppose that this exotic structure is not as much 'out there' as Mount Everest is". - **Ch. 4, Truth, Proof, and Insight (pp. 99–148 / 129–192).** Hilbert's programme for mathematics (99 / 129); Formal mathematical systems (102 / 133); Gödel's theorem (105 / 138); Mathematical insight (108 / 141); Platonism or intuitionism? (112 / 146); Gödel-type theorems from Turing's result (116 / 151); Recursively enumerable sets (118 / 155); Is the Mandelbrot set recursive? (124 / 161); Some examples of non-recursive mathematics (129 / 168); Is the Mandelbrot set like non-recursive mathematics? (138 / 177); Complexity theory (140 / 181); Complexity and computability in physical things (145 / 188). The core of the first strand. For any formal system we trust, Gödel's theorem gives a true sentence the system cannot prove, and we can see that it is true. So, for Penrose, "Mathematical truth is something that goes beyond mere formalism" (snippet), and mathematicians are not running a knowably sound algorithm. Non-recursive mathematics is shown to be concrete: Hilbert's tenth problem, the word problem for groups, and **tiling the plane with polyominoes**, where no algorithm decides whether a given set of tiles tiles the plane. Periodic and non-periodic tilings appear here (index: "periodic tilings 132–4") and return in chapter 10. The chapter ends with P vs NP and whether physical systems might compute things Turing machines cannot. - **Ch. 5, The Classical World (pp. 149–224 / 193–290).** The status of physical theory (149 / 193); Euclidean geometry (156 / 202); The dynamics of Galileo and Newton (162 / 209); The mechanistic world of Newtonian dynamics (167 / 217); Is life in the billiard-ball world computable? (170 / 220); Hamiltonian mechanics (174 / 225); Phase space (176 / 228); Maxwell's electromagnetic theory (184 / 238); Computability and the wave equation (187 / 243); The Lorentz equation of motion; runaway particles (188 / 244); The special relativity of Einstein and Poincaré (191 / 248); Einstein's general relativity (202 / 261); Relativistic causality and determinism (211 / 273); Computability in classical physics: where do we stand? (216 / 278); Mass, matter, and reality (217 / 280). Penrose sorts physical theories into **SUPERB, USEFUL and TENTATIVE** (with a joking fourth, MISGUIDED, snippet). Euclidean geometry, Newtonian mechanics, Maxwell's theory, special and general relativity, and quantum theory are SUPERB. He then asks whether each is computable. His answer is roughly yes in practice: classical physics is deterministic and, with a few odd mathematical exceptions (the Pour-El–Richards wave-equation result), contains no usable non-computability. Phase-space volume (Liouville's theorem) is set up here for the entropy argument of chapter 7. - **Ch. 6, Quantum Magic and Quantum Mystery (pp. 225–301 / 291–390).** Do philosophers need quantum theory? (225 / 291); Problems with classical theory (228 / 295); The beginnings of quantum theory (230 / 297); The two-slit experiment (231 / 299); Probability amplitudes (236 / 306); The quantum state of a particle (243 / 314); The uncertainty principle (248 / 321); The evolution procedures U and R (250 / 323); Particles in two places at once? (251 / 325); Hilbert space (257 / 332); Measurements (260 / 336); Spin and the Riemann sphere of states (264 / 341); Objectivity and measurability of quantum states (268 / 346); Copying a quantum state (269 / 348); Photon spin (270 / 349); Objects with large spin (273 / 353); Many-particle systems (275 / 355); The 'paradox' of Einstein, Podolsky, and Rosen (279 / 361); Experiments with photons: a problem for relativity? (286 / 369); Schrödinger's equation; Dirac's equation (286 / 372); Quantum field theory (288 / 374); Schrödinger's cat (289 / 375); Various attitudes in existing quantum theory (290 / 379); Where does all this leave us? (293 / 383). The longest chapter. It introduces the book's key distinction: **U**, the smooth, deterministic unitary evolution of the state (Schrödinger's equation), and **R**, the abrupt, probabilistic "reduction" when a measurement is made. U and R are inconsistent with each other, and R is added by hand. Spin states are pictured on the Riemann sphere, and EPR and Bell-type photon experiments are treated as real puzzles about non-locality. Penrose surveys Copenhagen, many-worlds and consciousness-causes-collapse views, and finds none satisfying. His conclusion is that R must be a real physical process from a theory we don't yet have. - **Ch. 7, Cosmology and the Arrow of Time (pp. 302–347 / 391–449).** The flow of time (302 / 391); The inexorable increase of entropy (304 / 394); What is entropy? (309 / 400); The second law in action (314 / 407); The origin of low entropy in the universe (317 / 411); Cosmology and the big bang (322 / 417); The primordial fireball (326 / 423); Does the big bang explain the second law? (328 / 426); Black holes (330 / 427); The structure of space-time singularities (335 / 435); How special was the big bang? (339 / 440). Entropy as coarse-grained phase-space volume. The second law needs a very low-entropy start. The cosmic microwave background is thermal, so the low entropy must lie in gravity: the early universe was extraordinarily smooth. Penrose contrasts the Big Bang (Weyl curvature zero, Ricci curvature only) with black-hole and big-crunch singularities (Weyl curvature diverges), the condition "I have termed The Weyl Curvature Hypothesis" (snippet). He estimates how special the initial state was, using the Bekenstein–Hawking entropy of a black hole the mass of the observable universe, and gets the famous odds of one in 10^(10^123), illustrated by a picture of the Creator aiming a pin at phase space. (This number is well documented in secondary sources and in Penrose's later books; I did not see the page in snippets.) - **Ch. 8, In Search of Quantum Gravity (pp. 348–373 / 450–482).** Why quantum gravity? (348 / 450); What lies behind the Weyl curvature hypothesis? (350 / 453); Time-asymmetry in state-vector reduction (354 / 458); Hawking's box: a link with the Weyl curvature hypothesis? (359 / 465); When does the state-vector reduce? (367 / 475). Penrose argues that the time-asymmetric Weyl curvature hypothesis and the time-asymmetric R process are two faces of one missing theory, "which I shall refer to as CQG ('correct quantum gravity'!)" (snippet), among whose "major implications" will be "WCH and R" (snippet). "Hawking's box", a thought experiment with a black hole in thermal equilibrium, suggests that information loss in black holes is balanced by R. The "one-graviton criterion" proposes that reduction occurs when the superposed alternatives differ by about one graviton's worth of space-time curvature ("The idea is that the 'one-graviton' level should lie comfortably between" the quantum and everyday levels, snippet). In the 1998 preface he abandons this criterion for the gravitational self-energy rule of *Shadows of the Mind*, the version now tested underground. - **Ch. 9, Real Brains and Model Brains (pp. 374–404 / 483–522).** What are brains actually like? (374 / 483); Where is the seat of consciousness? (381 / 492); Split-brain experiments (384 / 496); Blindsight (386 / 499); Information processing in the visual cortex (387 / 500); How do nerve signals work? (389 / 502); Computer models (392 / 507); Brain plasticity (396 / 512); Parallel computers and the 'oneness' of consciousness (398 / 514); Is there a role for quantum mechanics in brain activity? (400 / 516); Quantum computers (401 / 518); Beyond quantum theory? (402 / 520). Neuroanatomy for the general reader: the sensory and "motor homunculus" maps (Figs. 9.2–9.4), split-brain patients, blindsight, Hubel–Wiesel visual cortex, action potentials, and neural-network models. He notes the unity of consciousness against the brain's massive parallelism. He looks for where quantum effects could matter (single photons are detectable by the retina) and briefly discusses Deutsch's quantum computers. In the 2025 video he calls this the weak part: he had no mechanism for keeping quantum coherence in neurons. - **Ch. 10, Where Lies the Physics of Mind? (pp. 405–450 / 523–582).** What are minds for? (405 / 523); What does consciousness actually do? (409 / 529); Natural selection of algorithms? (414 / 534); The non-algorithmic nature of mathematical insight (416 / 538); Inspiration, insight, and originality (418 / 541); Non-verbality of thought (423 / 548); Animal consciousness? (425 / 550); Contact with Plato's world (426 / 552); A view of physical reality (429 / 555); Determinism and strong determinism (431 / 558); The anthropic principle (433 / 560); Tilings and quasicrystals (434 / 562); Possible relevance to brain plasticity (437 / 566); The time-delays of consciousness (439 / 568); The strange role of time in conscious perception (442 / 573); Conclusion: a child's view (447 / 578). Penrose proposes that consciousness is what lets us form judgements and "see" truths that no algorithm can reach. Natural selection could not have produced a knowably sound algorithm for mathematical truth. He gathers testimony from Poincaré, Hadamard and Mozart on sudden insight and non-verbal thought, and suggests that insight is contact with a Platonic world of mathematical truth. He floats "strong determinism", a universe that is exactly determined but not computable. He then speculates that quasicrystal growth, which seems to need non-local "choice", might be a model for non-computable action in the growth of synapses (the passage he now calls the book's weak ending). Libet's experiments on the half-second delays of awareness suggest that conscious time is not like physical time. "A child's view" ends with a plea to ask naive questions. - **Epilogue (p. 451 / 583).** Adam's question to Ultronic, picking up the Prologue. In the usual reading, the computer cannot answer a question about feeling, so the child is the one who sees the emperor has no clothes. I did not see the Epilogue text, so I am not quoting it. - **Back matter.** References (pp. 452–460 / 584–595); Index (461–466 / 596 onward). **Key ideas.** - **Understanding is not computation.** Gödel's theorem means that no knowably sound algorithm captures all the mathematical truths a mathematician can see. Penrose takes this to show that human understanding is not algorithmic (the "Lucas–Penrose" argument). - **Strong AI confuses performance with mind.** Passing the Turing test or running the right program does not guarantee understanding. Penrose sides with Searle's Chinese room while flagging its weak points. - **Mathematical objects are real.** The Mandelbrot set and Gödel truths are discovered, not invented. Insight is contact with that Platonic world. - **Known physics is computable.** Classical physics and the U part of quantum mechanics give no room for non-computable behaviour. Only the unexplained R process is a candidate. - **The gaps are linked.** The low entropy of the Big Bang (Weyl curvature hypothesis), the time asymmetry of R and black-hole information loss all point to one missing theory, "correct quantum gravity". - **Consciousness lives where that new physics acts.** The brain must somehow use objective reduction. The book did not know where; the later answer (with Hameroff) was microtubules. **Reception, in brief.** It became a bestseller and won the 1990 Science Book Prize. It was also among the most criticized popular-science books of its decade. In *Behavioral and Brain Sciences* (1990), dozens of commentators answered a précis of the book. Logicians and philosophers (Solomon Feferman, Hilary Putnam, George Boolos and others) argued that the Gödel argument fails: humans might run an algorithm that is not *knowably* sound, or might simply be inconsistent. AI researchers and philosophers of mind (Marvin Minsky, Hans Moravec, Daniel Dennett, whose *Darwin's Dangerous Idea* (1995) has a chapter titled "The Emperor's New Mind, and Other Fables") rejected the conclusion. Physicists largely respected the physics exposition but were sceptical of the brain proposal. Penrose answered in *Shadows of the Mind* (1994) and "Beyond the Doubting of a Shadow" (1996). He says in the preface that he had not anticipated "the vehemence that my thesis would evoke". ## 6. Fact-check Overall verdict: **mixed**. The bibliographic facts and the book's physics and mathematics exposition are solid. Its central conclusions (non-computable minds, gravity-induced collapse, a quantum role in the brain) are contested or unconfirmed, and Penrose has himself dropped some of the specific proposals. | Claim | Verdict | Evidence | |---|---|---| | OUP, Oxford and New York, 1989; xiii + 466 pp.; ISBN 0198519737; subtitle *Concerning Computers, Minds, and the Laws of Physics*; foreword by Martin Gardner | Supported | LC [89008548](https://lccn.loc.gov/89008548); Harvard MARC (245 $b and $c); Open Library [OL2190164M](https://openlibrary.org/books/OL2190164M) | | Ten chapters plus Prologue and Epilogue, titles and sections as in section 5 | Supported | Harvard MARC 505; OUP preview contents page; 1989 scan contents via search inside | | New preface 1999; reissued as Oxford Landmark Science 2016 | Supported | Copyright page of the OUP preview: "First published as an Oxford University Press paperback with a new preface 1999. Revised impression, as Oxford Landmark Science 2016" | | Won the 1990 Science Book Prize | Supported | OUP product page ("Winner of the 1990 Science Book Prize"); Open Library edition note | | Penrose wrote the book to argue that understanding needs awareness and is non-computational (video, 28:38) | Supported | Preface, "two main strands"; ch. 4 and ch. 10 section titles | | The book "ends weakly" with crystals and lacks a brain site for collapse (video, 1:21:46) | Supported (self-assessment) | Ch. 10 sections "Tilings and quasicrystals" and "Possible relevance to brain plasticity"; preface: "when I wrote it I knew of no place in the brain where it could be plausibly argued that the 'large-scale quantum coherence' could take place"; microtubules "came too late for inclusion in this book" | | Gödel's theorem shows human mathematical understanding is non-algorithmic | Disputed | Standard objections: a human could run an algorithm that is sound but not knowably so, or not sound at all (Feferman, "Penrose's Gödelian argument", *Psyche* 2, 1995; Putnam, review of *Shadows of the Mind*, *New York Times Book Review*, 20 Nov. 1994, and *Bulletin of the AMS* 32(3), 1995). Earlier form of the argument: J. R. Lucas, "Minds, Machines and Gödel", *Philosophy* 36 (1961) 112–127 | | Goodstein's theorem is true but not provable from Peano arithmetic (preface) | Supported | Kirby & Paris, "Accessible independence results for Peano arithmetic", *Bull. London Math. Soc.* 14 (1982) 285–293 | | Tiling the plane with polyominoes is algorithmically undecidable | Supported | Berger 1966 (Wang tiles); the polyomino case follows (Golomb 1970) | | Searle's Chinese room argument | Supported (as reported) | Searle, "Minds, brains, and programs", *Behavioral and Brain Sciences* 3(3), 1980, 417–457 | | Penrose's singularity theorem (1965) and Nobel Prize 2020 | Supported | *Phys. Rev. Lett.* 14, 57 (1965), [doi:10.1103/PhysRevLett.14.57](https://doi.org/10.1103/PhysRevLett.14.57); [Nobel Prize 2020 press release](https://www.nobelprize.org/prizes/physics/2020/press-release/) | | The Big Bang's special initial state: about one part in 10^(10^123) | Supported as Penrose's estimate | Follows from the Bekenstein–Hawking entropy of the observable universe's mass as a black hole; repeated in *The Road to Reality* (2004) ch. 27 and *Cycles of Time* (2010). It is an order-of-magnitude argument, not a measurement | | Quantum state reduction is a real, gravity-related physical process | Unconfirmed / partly constrained | Simplest Diósi–Penrose version strongly constrained by the Gran Sasso underground radiation test (Donadi et al., "Underground test of gravity-related wave function collapse", *Nature Physics* 17, 74–78, 2021). Penrose argues his scheme does not predict that heating (video, 40:01). Proposed tests continue (Fuentes, 2025) | | Quantum coherence relevant to consciousness can survive in the brain (later Orch OR) | Disputed | Tegmark, "Importance of quantum decoherence in brain processes", *Phys. Rev. E* 61, 4194 (2000), estimates decoherence times far too short; Hameroff and Penrose reply in *Physics of Life Reviews* 11 (2014) 39–78 | | Libet's experiments show delays in conscious awareness of about half a second | Supported (with caveats about interpretation) | Libet et al., *Brain* 102 (1979) 193–224 (backward referral of sensory timing); the interpretation remains debated | | The original 'one-graviton criterion' for reduction | Withdrawn by the author | Preface: "For some years, now, I have shifted my view away from this"; replaced by the self-energy rule in Penrose, *Gen. Rel. Grav.* 28 (1996) 581–600 | ## 7. Citations and references **What the book draws on.** The bibliography is on pp. [452]–460 (1989). Works it uses or discusses, going by the contents, the snippets and standard accounts of the book: Turing, "On computable numbers" (1936/7) and "Computing machinery and intelligence" (1950); Gödel's 1931 incompleteness paper; Church's lambda calculus; Searle (1980) and Schank's story-understanding program; Hofstadter and Dennett, *The Mind's I* (1981) on teleportation and strong AI; Mandelbrot's work on fractals; Pour-El & Richards on the wave equation; Bekenstein and Hawking on black-hole entropy; Hawking's box thought experiment; Hubel & Wiesel on the visual cortex; Hodgkin & Huxley on nerve signals; Sperry and Gazzaniga on split brains; Weiskrantz on blindsight; Libet on timing; Deutsch (1985) on quantum computers; Hadamard, *The Psychology of Invention in the Mathematical Field* (1945); and Jaynes (1980) on the origins of consciousness (snippet). I did not see the full reference list. **Related works.** Penrose, *Shadows of the Mind* (1994), the sequel and fuller defence; Penrose, *The Large, the Small and the Human Mind* (1997, with replies by Shimony, Cartwright and Hawking); Penrose, *The Road to Reality* (2004); Penrose, *Cycles of Time* (2010); Penrose, *Fashion, Faith, and Fantasy in the New Physics of the Universe* (2016), queued next. Opposing views: Hofstadter, *Gödel, Escher, Bach* (1979), already in this vault's queue; Dennett, *Consciousness Explained* (1991) and *Darwin's Dangerous Idea* (1995). Background: Hodges, *Alan Turing: The Enigma* (1983); Nagel & Newman, *Gödel's Proof* (1958). The source video also names Schrödinger's *What Is Life?* and Shan Gao (ed.), *Consciousness and Quantum Mechanics*, both queued. **Links this note used:** - Catalogs and text: [LC 89008548](https://lccn.loc.gov/89008548); [Open Library OL3474158W](https://openlibrary.org/works/OL3474158W); [OL2190164M](https://openlibrary.org/books/OL2190164M); [OL18339648M](https://openlibrary.org/books/OL18339648M); [OL1884133M](https://openlibrary.org/books/OL1884133M); [author OL579149A](https://openlibrary.org/authors/OL579149A); [cover 12978275](https://covers.openlibrary.org/b/id/12978275-L.jpg); IA scans [emperorsnewmindc00penr](https://archive.org/details/emperorsnewmindc00penr), [emperorsnewmindc0000penr](https://archive.org/details/emperorsnewmindc0000penr), [emperorsnewmind00roge](https://archive.org/details/emperorsnewmind00roge), [emperorsnewmindc1999penr](https://archive.org/details/emperorsnewmindc1999penr); [Open Library search inside](https://openlibrary.org/search/inside) (method); MARC records from the [Columbia](https://archive.org/details/marc_columbia) and [Harvard](https://archive.org/details/harvard_bibliographic_metadata) bulk sets on IA; [OUP preview PDF](https://api.pageplace.de/preview/DT0400.9780192550064_A35506325/preview-9780192550064_A35506325.pdf); [Google Books](https://books.google.com/books/about/The_Emperor_s_New_Mind.html?id=JF4vDwAAQBAJ); [Wikipedia](https://en.wikipedia.org/wiki/The_Emperor%27s_New_Mind). - Publisher and shops: [OUP](https://global.oup.com/academic/product/the-emperors-new-mind-9780198784920); [OUP Australia](https://www.oup.com.au/books/higher-education/physics/9780198784920); [Amazon paperback](https://www.amazon.com/dp/0198784929); [Amazon 1989 hardcover](https://www.amazon.com/dp/0198519737); [Amazon Penguin](https://www.amazon.com/dp/0140145346); [Kindle (UK) B074JCG4P9](https://www.amazon.co.uk/dp/B074JCG4P9); [Audible](https://www.audible.com/pd/The-Emperors-New-Mind-Audiobook/1515943836); [OverDrive ebook](https://www.overdrive.com/media/4977008/the-emperors-new-mind); [OverDrive audiobook](https://www.overdrive.com/media/4872864/the-emperors-new-mind); [Hoopla](https://www.hoopladigital.com/audiobook/the-emperors-new-mind-roger-penrose/12414375). - Author: [Nobel Prize 2020 press release](https://www.nobelprize.org/prizes/physics/2020/press-release/); [Nobel lecture](https://www.nobelprize.org/prizes/physics/2020/penrose/lecture/); [Wikipedia, Roger Penrose](https://en.wikipedia.org/wiki/Roger_Penrose); [Penrose 1965](https://doi.org/10.1103/PhysRevLett.14.57). - Interviews: [Lex Fridman #85](https://lexfridman.com/roger-penrose/); [Mindscape ep. 28](https://preposterousuniverse.com/podcast/2019/01/07/episode-28-roger-penrose-on-spacetime-consciousness-and-the-universe/). - Evidence and critique: [Tegmark 2000](https://doi.org/10.1103/PhysRevE.61.4194); [Donadi et al. 2021](https://doi.org/10.1038/s41567-020-1008-4); [Hameroff & Penrose 2014](https://doi.org/10.1016/j.plrev.2013.08.002); [Searle 1980](https://doi.org/10.1017/S0140525X00005756); [Kirby & Paris 1982](https://doi.org/10.1112/blms/14.4.285). - Source video: [Roger Penrose: "My Crazy Idea That Explains the Universe"](https://www.youtube.com/watch?v=iO03t21xhdk); [[Video Summaries/Curt Jaimungal/Roger Penrose My Crazy Idea That Explains the Universe]].