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Moda, fe y fantasía en la nueva física del universo
What can fashionable ideas, blind faith, or pure fantasy possibly have to do with the scientific quest to understand the universe? Surely, theoretical physicists are immune to mere trends, dogmatic beliefs, or flights of fancy? In fact, acclaimed physicist and bestselling author Roger Penrose argues that researchers working at the extreme frontiers of physics are just as susceptible to these forces as anyone else. In this provocative book, he argues that fashion, faith, and fantasy, while sometimes productive and even essential in physics, may be leading today's researchers astray in three of the field's most important areas string theory, quantum mechanics, and cosmology.
Arguing that string theory has veered away from physical reality by positing six extra hidden dimensions, Penrose cautions that the fashionable nature of a theory can cloud our judgments of its plausibility. In the case of quantum mechanics, its stunning success in explaining the atomic universe has led to an uncritical faith that it must also apply to reasonably massive objects, and Penrose responds by suggesting possible changes in quantum theory. Turning to cosmology, he argues that most of the current fantastical ideas about the origins of the universe cannot be true, but that an even wilder reality may lie behind them. Finally, Penrose describes how fashion, faith, and fantasy have ironically also shaped his own work, from twistor theory, a possible alternative to string theory that is beginning to acquire a fashionable status, to "conformal cyclic cosmology," an idea so fantastic that it could be called "conformal crazy cosmology."
The result is an important critique of some of the most significant developments in physics today from one of its most eminent figures."
Arguing that string theory has veered away from physical reality by positing six extra hidden dimensions, Penrose cautions that the fashionable nature of a theory can cloud our judgments of its plausibility. In the case of quantum mechanics, its stunning success in explaining the atomic universe has led to an uncritical faith that it must also apply to reasonably massive objects, and Penrose responds by suggesting possible changes in quantum theory. Turning to cosmology, he argues that most of the current fantastical ideas about the origins of the universe cannot be true, but that an even wilder reality may lie behind them. Finally, Penrose describes how fashion, faith, and fantasy have ironically also shaped his own work, from twistor theory, a possible alternative to string theory that is beginning to acquire a fashionable status, to "conformal cyclic cosmology," an idea so fantastic that it could be called "conformal crazy cosmology."
The result is an important critique of some of the most significant developments in physics today from one of its most eminent figures."
871 pages, Kindle Edition
First published February 22, 2016
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About the author
Roger Penrose
100 books1,316 followersSir Roger Penrose is a British mathematician, mathematical physicist, philosopher of science and Nobel Laureate in Physics. He is Emeritus Rouse Ball Professor of Mathematics in the University of Oxford, an emeritus fellow of Wadham College, Oxford, and an honorary fellow of St John's College, Cambridge, and University College London.
Penrose has contributed to the mathematical physics of general relativity and cosmology. He has received several prizes and awards, including the 1988 Wolf Prize in Physics, which he shared with Stephen Hawking for the Penrose–Hawking singularity theorems, and the 2020 Nobel Prize in Physics "for the discovery that black hole formation is a robust prediction of the general theory of relativity".
Penrose has contributed to the mathematical physics of general relativity and cosmology. He has received several prizes and awards, including the 1988 Wolf Prize in Physics, which he shared with Stephen Hawking for the Penrose–Hawking singularity theorems, and the 2020 Nobel Prize in Physics "for the discovery that black hole formation is a robust prediction of the general theory of relativity".
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April 3, 2017
Roger Penrose is 85, and a lot of the material in this book has previously appeared in The Road to Reality and Cycles of Time. By all rights it should be awful, but in fact it's pretty good; none of the standard rules ever seem to apply to him. Incredibly, he's still alert, still active, still working hard on his collection of wacky but fascinating ideas. He's made considerable progress over the last decade and eagerly tells you about it in his well-constructed sentences and trademark diagrams. He knows you were wondering about that odd connection he claimed existed between quantum mechanics and gravity; now he goes into detail, writes down new equations which, to your surprise, sort of make sense, tells you about an experiment he and his colleagues are planning with a beam-splitter and a tiny suspended mirror which just might be able to test whether the theory works.
He's improved his utterly bizarre cosmology, which not only has a universe before the Big Bang and one literally after the end of time, but connects them together. He scribbles down those cryptic conformal diagrams, with squiggly lines representing singularities and solid lines representing the infinite future, and explains the reasoning which led him to the conclusion that, even if this is obviously insane, the other alternatives are even more insane. When you start objecting, he presents sensible-sounding thermodynamic arguments to show just how much trouble inflation and the anthropic principle are in. You're trying to digest that, and he hits you with an afterthought from one of the final chapters of The Road to Reality. You know how he was trying to explain why holomorphic sheaf cohomology is really pretty obvious? Well, look at this picture! You see? You see? It is obvious! For a moment, you feel you agree with him.
He somehow manages to suck you into his world and show you his unique way of thinking. You can't categorise him. Sometimes he comes across as a traditional mathematician complaining about the lack of rigour in quantum field theory, sometimes as a visionary physicist with a startling new picture of the world, sometimes as the ultimate hard science-fiction writer, the sort of person Niven or Asimov would have liked to be if only they'd had the necessary technical skills. Every now and then you catch him shifting, but usually he's too quick for you.
At the end, he complains in a slightly surprised tone that he's never understood why people call him a maverick. In fact, he has very conservative views on physics. He almost makes it sound plausible. Then, on the final page, he tells you about his father's strong belief that Shakespeare's plays were written by Edward de Vere, the Earl of Oxford. As he says goodbye, he recommends in passing the original book on the subject, by (I looked it up, and it's correct), one J. Thomas Looney. Is he kidding you? He must be, but you glance at him and he's completely straight-faced.
There's only one Roger Penrose.
He's improved his utterly bizarre cosmology, which not only has a universe before the Big Bang and one literally after the end of time, but connects them together. He scribbles down those cryptic conformal diagrams, with squiggly lines representing singularities and solid lines representing the infinite future, and explains the reasoning which led him to the conclusion that, even if this is obviously insane, the other alternatives are even more insane. When you start objecting, he presents sensible-sounding thermodynamic arguments to show just how much trouble inflation and the anthropic principle are in. You're trying to digest that, and he hits you with an afterthought from one of the final chapters of The Road to Reality. You know how he was trying to explain why holomorphic sheaf cohomology is really pretty obvious? Well, look at this picture! You see? You see? It is obvious! For a moment, you feel you agree with him.
He somehow manages to suck you into his world and show you his unique way of thinking. You can't categorise him. Sometimes he comes across as a traditional mathematician complaining about the lack of rigour in quantum field theory, sometimes as a visionary physicist with a startling new picture of the world, sometimes as the ultimate hard science-fiction writer, the sort of person Niven or Asimov would have liked to be if only they'd had the necessary technical skills. Every now and then you catch him shifting, but usually he's too quick for you.
At the end, he complains in a slightly surprised tone that he's never understood why people call him a maverick. In fact, he has very conservative views on physics. He almost makes it sound plausible. Then, on the final page, he tells you about his father's strong belief that Shakespeare's plays were written by Edward de Vere, the Earl of Oxford. As he says goodbye, he recommends in passing the original book on the subject, by (I looked it up, and it's correct), one J. Thomas Looney. Is he kidding you? He must be, but you glance at him and he's completely straight-faced.
There's only one Roger Penrose.
March 6, 2017
Who did Roger Penrose think his audience was when he was writing this book? It comes across at first blush as a work of popular science, with topics (like the notion of quantum-mechanical spin) being carefully explained. But, while Penrose is usually careful about explaining the physics, he is completely cavalier with the math. I have a Ph.D. in physics and there were many places where I had trouble following what he was talking about. To fully digest Penrose's arguments, it is not enough for the non-expert to read the book; he must study it in some detail, including significant outside reading.
And those arguments—in the first three of the book's four chapters—are interesting. In each, he takes a significant modern physical theory (the "fashion" of string theory, the "faith" of quantum mechanics, and the "fantasy" of cosmological inflation) and both explains it and deconstructs why it may not be as believable as the broader community thinks it is. In all three chapters he gives a critical discussion, biased of course towards his own views but also clearly laying out why most people do subscribe to each of these theories. It is unfortunate that, in the fourth chapter when he presents his own theories, he drops this critical approach and gives a technical seminar without context.
The book can be read on at least three levels. The first (and the level from which I got the most out) is as a way for the person who has at least an undergraduate training in physics to go back and revisit many of the main ideas in modern physics. ("Ah, I remember what analytic continuation is!"). The second is as an introduction to these more modern theories, such as string theory. And the third is as a meaningful critique of those theories.
I suspect that only active practitioners in those fields in question will be able to understand the arguments at the third level. The second level should be accessible for those who have completed first-year graduate work in physics, and the first to those who studied it as an undergraduate. Let me stress that, in my opinion, the book is completely inaccessible to those without at least some training in physics. To drive this point home, allow me to quote a few random, representative passages, one from each of the three main chapters.
From Ch. 1, on string theory:
From Ch. 2, on quantum mechanics:
From Ch. 3, on inflation:
As an aside: it is clear that Penrose wrote his manuscript in the latex typesetting system, since he goes absolutely nuts with the cross-references, including, frequently, to sections you have not read yet.
And those arguments—in the first three of the book's four chapters—are interesting. In each, he takes a significant modern physical theory (the "fashion" of string theory, the "faith" of quantum mechanics, and the "fantasy" of cosmological inflation) and both explains it and deconstructs why it may not be as believable as the broader community thinks it is. In all three chapters he gives a critical discussion, biased of course towards his own views but also clearly laying out why most people do subscribe to each of these theories. It is unfortunate that, in the fourth chapter when he presents his own theories, he drops this critical approach and gives a technical seminar without context.
The book can be read on at least three levels. The first (and the level from which I got the most out) is as a way for the person who has at least an undergraduate training in physics to go back and revisit many of the main ideas in modern physics. ("Ah, I remember what analytic continuation is!"). The second is as an introduction to these more modern theories, such as string theory. And the third is as a meaningful critique of those theories.
I suspect that only active practitioners in those fields in question will be able to understand the arguments at the third level. The second level should be accessible for those who have completed first-year graduate work in physics, and the first to those who studied it as an undergraduate. Let me stress that, in my opinion, the book is completely inaccessible to those without at least some training in physics. To drive this point home, allow me to quote a few random, representative passages, one from each of the three main chapters.
From Ch. 1, on string theory:
"As mentioned above, dA^5xS^5 is certainly not a conformal boundary of A^5xS^5 because the "squashing down" of the infinite regions of A^5 in order to "reach" dA^5 does not apply to S^5, whereas for a conformal squashing this would have to apply to all dimensions equally."
From Ch. 2, on quantum mechanics:
"The Riemann sphere, being simply the space of ratios w:z of a pair of complex numbers (w,z), not both zero, is actually the projective Hilbert space PH^2, describing the array of possible physically distinct quantum states that arise from superpositions of any two independent quantum states of any kind."
From Ch. 3, on inflation:
"The notion of complexification if one that applies to real manifolds that are defined by smooth-enough equations (technically, analytic equations), and the complexification procedure simply involves replacing all the real-number coordinates by complex numbers (SS A.5 and A.9), while keeping the equations completely unchanged, so that we obtain a complex 4-manifold (which would be 8-real-dimensional, see S A.10)."
As an aside: it is clear that Penrose wrote his manuscript in the latex typesetting system, since he goes absolutely nuts with the cross-references, including, frequently, to sections you have not read yet.
February 9, 2017
Roger Penrose is 85
He is a giant. But Physics has moved away from him and in this book he’s kind of saying “this is where it sounds like I’m leaving things.”
Let me get a major gripe out of the way: The book comes with a Mathematical Appendix. I have in my life known a lot more math than there is in the appendix and can still read the appendix without feeling lost. So I thought I’d understand the book a bit. Warning: Climbing to the top of the Empire State Building gets you closer to the moon than understanding the Mathematical Appendix gets you to the stuff Roger Penrose discusses here. Zero exaggeration. Ten to the minus 124 exaggeration, if I’m allowed to use the author’s terms.
So I read this book the same way my 5-year-old sometimes listens to the news.
Which is to say it blew me away, of course. I’m not entitled to views here, but a true giant who lives, breathes and loves the history of the universe lays out the arguments he has made to his fellow physicists (not you and me!) regarding why:
1. Highly fashionable 26-dim string theory, while elegant and originally promising, is likely a dead end, for example because it leads to singularities
2. Supersymmetry between Fermions and Bosons cuts down the dimensions of string theory to a more manageable 10, but makes it necessary to believe in the existence of a whole lot of particles we will never observe
3. The holographic conjecture, while beautiful, relies on supersymmetry and requires that we radically revise what we believe about the cosmological constant, the gauge symmetry group and bulk space
4. Quantum entanglement is probably ultimately only a feature of the simplified, linear orthodoxy we cling to in Quantum Mechanics, which we will one day abandon for a nonlinear model. The Quantum Mechanics of the present is useful, but requires a leap of faith you should refuse to take.
5. Inflationary Cosmology poses even more problems than it answers questions and is a convenient untruth
Bits of the book here and there, on the other hand, are addressed to you and me, and it’s not just the gossipy bits. I did kind of take in how phenomenally precise the calculations are that we can perform surrounding the Big Bang and CMB, there is a tremendous lesson that explains how life on earth is due to the low entropy energy we get from the sun rather than its heat and I also got a feel for how our universe will end one day: electromagnetism will live forever, but anything with gravity will be gone. There is also repeated discussion regarding the manner today’s gravitation theory in combination with today’s quantum mechanics leads all sorts of quantities to infinity for no reason.
Significantly, Penrose repeatedly goes out of his way to say we must dream. All theories we now accept (but also plenty we have fully rejected) started as somebody’s fanciful dreams. Conversely, it is a bad idea to start with fun or elegant bits of math and hope it explains the universe.
So the last chapter is dedicated to theories closer to his heart regarding the creation of the universe, or rather its history and its future, and, as far as I can discern they largely are rather fantastical indeed, if not as fantastical as the currently fashionable theories.
He closes the book by tacking the other way, however, and admitting that personally he has a prejudice for theories that match our experience, such as his preference for four or five dimensions. Not that my angle matters, but I did rather enjoy (and partially understood the sketch of the math behind) the conformal cosmology idea, according to which the universe goes through continuous cycles of collapse and regeneration.
So the title of the book is incomplete.
It really ought to be “Fashion, Faith, Fantasy and Taste”
He is a giant. But Physics has moved away from him and in this book he’s kind of saying “this is where it sounds like I’m leaving things.”
Let me get a major gripe out of the way: The book comes with a Mathematical Appendix. I have in my life known a lot more math than there is in the appendix and can still read the appendix without feeling lost. So I thought I’d understand the book a bit. Warning: Climbing to the top of the Empire State Building gets you closer to the moon than understanding the Mathematical Appendix gets you to the stuff Roger Penrose discusses here. Zero exaggeration. Ten to the minus 124 exaggeration, if I’m allowed to use the author’s terms.
So I read this book the same way my 5-year-old sometimes listens to the news.
Which is to say it blew me away, of course. I’m not entitled to views here, but a true giant who lives, breathes and loves the history of the universe lays out the arguments he has made to his fellow physicists (not you and me!) regarding why:
1. Highly fashionable 26-dim string theory, while elegant and originally promising, is likely a dead end, for example because it leads to singularities
2. Supersymmetry between Fermions and Bosons cuts down the dimensions of string theory to a more manageable 10, but makes it necessary to believe in the existence of a whole lot of particles we will never observe
3. The holographic conjecture, while beautiful, relies on supersymmetry and requires that we radically revise what we believe about the cosmological constant, the gauge symmetry group and bulk space
4. Quantum entanglement is probably ultimately only a feature of the simplified, linear orthodoxy we cling to in Quantum Mechanics, which we will one day abandon for a nonlinear model. The Quantum Mechanics of the present is useful, but requires a leap of faith you should refuse to take.
5. Inflationary Cosmology poses even more problems than it answers questions and is a convenient untruth
Bits of the book here and there, on the other hand, are addressed to you and me, and it’s not just the gossipy bits. I did kind of take in how phenomenally precise the calculations are that we can perform surrounding the Big Bang and CMB, there is a tremendous lesson that explains how life on earth is due to the low entropy energy we get from the sun rather than its heat and I also got a feel for how our universe will end one day: electromagnetism will live forever, but anything with gravity will be gone. There is also repeated discussion regarding the manner today’s gravitation theory in combination with today’s quantum mechanics leads all sorts of quantities to infinity for no reason.
Significantly, Penrose repeatedly goes out of his way to say we must dream. All theories we now accept (but also plenty we have fully rejected) started as somebody’s fanciful dreams. Conversely, it is a bad idea to start with fun or elegant bits of math and hope it explains the universe.
So the last chapter is dedicated to theories closer to his heart regarding the creation of the universe, or rather its history and its future, and, as far as I can discern they largely are rather fantastical indeed, if not as fantastical as the currently fashionable theories.
He closes the book by tacking the other way, however, and admitting that personally he has a prejudice for theories that match our experience, such as his preference for four or five dimensions. Not that my angle matters, but I did rather enjoy (and partially understood the sketch of the math behind) the conformal cosmology idea, according to which the universe goes through continuous cycles of collapse and regeneration.
So the title of the book is incomplete.
It really ought to be “Fashion, Faith, Fantasy and Taste”
September 22, 2016
Excellent book about the current state of our understanding the Universe as seen by famed scientist Roger Penrose (of say the awesome Road to Reality fame); not an easy read especially if you are not a physicist (the math is glossed over more and the explanations are ok with physical sense of the stuff); for a better full review - which made me aware as well as made me get the book on the spot, check the one below by mathematical physicist P Woit (ot the Not Even Wrong fame)
http://www.math.columbia.edu/~woit/wo...
The book is worth reading just as an antidote to the current hyping of pseudo-scientific theories (multiverses and the like where anything goes as long as it makes a nice story) which may make for fun reading, but are quite dangerous in some ways (as P. Woit keeps reminding on his superb blog, and R. Penrose points out so well in this book in the Fashion part dealing with them - Faith is about Quantum theory and its main unsolved problem of the wave collapse ie the measurement problem, while Faith is about his specialty, relativity and the Universe at large scales)
http://www.math.columbia.edu/~woit/wo...
The book is worth reading just as an antidote to the current hyping of pseudo-scientific theories (multiverses and the like where anything goes as long as it makes a nice story) which may make for fun reading, but are quite dangerous in some ways (as P. Woit keeps reminding on his superb blog, and R. Penrose points out so well in this book in the Fashion part dealing with them - Faith is about Quantum theory and its main unsolved problem of the wave collapse ie the measurement problem, while Faith is about his specialty, relativity and the Universe at large scales)
June 3, 2017
Just a warning. I actually have a degree in physics and still found this book technically overwhelming. This is really for people deeply read in the field.
October 6, 2016
Road to Reality: New Perspectives
In this book, mathematician Roger Penrose provocatively suggest that the community of theoretical physics has engaged in promoting fashionable ideas, that have deep conceptual problems, as frontiers of new physics. The principles of quantum physics and string theory and predictions in cosmology are done recklessly. Penrose calls string theory a “fashion,” quantum mechanics “faith,” and cosmic inflation a “fantasy.”
Penrose observes that quantum physics has deep conceptual problems despite its success in predicting phenomenon in chemistry and physics. Quantum physics governs the behavior of matter and energy at the level of fundamental particles (quantum reality). In many-particle system such as biomolecules, living cells, planets, stars and galaxies, the quantum reality cease to exist; it can only be explained by the laws classical physics. Penrose thinks there is a threshold mass at which gravity (spacetime curvature) destroys the quantum phenomenon. In one of his interview, Penrose said that “you have to give up the idea of spacetime as we know it from Einstein.” The fact that an object can exist in many states at once contradicts the real world. The reason is that the mathematics of quantum physics has two parts. One is the evolution of a quantum system is described extremely precisely and accurately by the Schrödinger equation. In terms of physical reality, if you know what the state of the system is now, then you can calculate what it will be doing 10 minutes from now. However, there is the second part of quantum physics, which happens when you want to make a measurement. Instead of getting a single answer, you use the equation to work out the probabilities of many possibilities. The equation should describe the world in a completely deterministic way with certainty as we experience in real world, but it doesn’t. Penrose suggests that that the fundamental principles of quantum physics have not yet been found. Perhaps this is the reason that the full integration of classical gravity into quantum physics into a testable theory have not been successful. Penrose’s main concern is that the success of quantum physics have made physicists insensitive and treat that as the canonical gospel of physical reality. In an interview Penrose commented that his “own view is that quantum mechanics is not exactly right.”
Penrose expresses major concerns about string theory in particular which tries to present a unified picture of quantum gravity and sell it as the theory of everything. But this theory is without its usual problems, like the six hidden dimensions that has not been experimentally verified. The fact that strings are suggested to propagate in ten dimensions, and only four are large dimensions (including one time-dimension), and the rest are small, curled-up and decoupled with the larger dimensions intimidates Penrose. He would not compromise on decoupling these degrees of freedom with two sets and observes that causes instability; hence a stable ground state with four large spacetime dimensions would not be possible. Many predictions of the theory are not testable within the realm of available technology.
Penrose illustrates the inflationary cosmology as an example of fantasy since it does not explain what set the initial low entropy condition of the universe. Inflationary cosmology, which suggests that the universe inflated exponentially within a small fraction of a second after the Big Bang is a big fish observes Penrose. In fact it is sacrilegious to attack it, and even more sacrilegious is quantum physics which has become a faith. People don’t want to question it.
Penrose also discusses his “twistor” theory in which he explains how particles move and interact in spacetime, but spacetime themselves are secondary constructs that emerge out of a deeper level of reality. The conventional wisdom is that spacetime geometry fluctuate on quantum scales, altering how events relate to one another. Hence an event that was supposed to cause another may not happen creating paradoxes such as those found in time-travel. In twistor theory, causal sequences are primary and do not fluctuate. Instead the location and timing of events fluctuate. String theorists showed that an event of ambiguous location and time is nothing more or less than a string.
Many string theorists dismiss Penrose’s criticism. They claim that their theory has mathematical beauty and it has the ability to include the classical theory of gravity and it is the only theory of everything. Despite his criticism, he was invited by the Princeton University in 2003 where some of the most important proponents of string theory work. The ideas for this book was developed from these lectures.
Roger Penrose is a mathematician and firmly believes that understanding math is fundamental to the understanding of physics and physical reality. In his 2005 book, “The Road to Reality” math was extensively used as a concept learning tool even though that book was written for a general reader. This book also has math but less extensive than his 2005 book. Some sections are written for wider choice of readers but other parts require significant knowledge in mathematical physics. It will make it easier for a reader to know that Roger Penrose, in his 2009 interview with “Discover” magazine, admitted he was “bad” in math in school and in his own words he “was at least twice as slow as anybody else.” Eventually I would do very well. You see, if I could do it that way.” This is a great source encouragement for readers who did not have significant physics and math while they were in school. I recommend readers to skip the part of the book that is too intense but focus on main arguments of the book. One can still appreciate the efforts of Penrose’s masterful way of communicating his ideas.
In this book, mathematician Roger Penrose provocatively suggest that the community of theoretical physics has engaged in promoting fashionable ideas, that have deep conceptual problems, as frontiers of new physics. The principles of quantum physics and string theory and predictions in cosmology are done recklessly. Penrose calls string theory a “fashion,” quantum mechanics “faith,” and cosmic inflation a “fantasy.”
Penrose observes that quantum physics has deep conceptual problems despite its success in predicting phenomenon in chemistry and physics. Quantum physics governs the behavior of matter and energy at the level of fundamental particles (quantum reality). In many-particle system such as biomolecules, living cells, planets, stars and galaxies, the quantum reality cease to exist; it can only be explained by the laws classical physics. Penrose thinks there is a threshold mass at which gravity (spacetime curvature) destroys the quantum phenomenon. In one of his interview, Penrose said that “you have to give up the idea of spacetime as we know it from Einstein.” The fact that an object can exist in many states at once contradicts the real world. The reason is that the mathematics of quantum physics has two parts. One is the evolution of a quantum system is described extremely precisely and accurately by the Schrödinger equation. In terms of physical reality, if you know what the state of the system is now, then you can calculate what it will be doing 10 minutes from now. However, there is the second part of quantum physics, which happens when you want to make a measurement. Instead of getting a single answer, you use the equation to work out the probabilities of many possibilities. The equation should describe the world in a completely deterministic way with certainty as we experience in real world, but it doesn’t. Penrose suggests that that the fundamental principles of quantum physics have not yet been found. Perhaps this is the reason that the full integration of classical gravity into quantum physics into a testable theory have not been successful. Penrose’s main concern is that the success of quantum physics have made physicists insensitive and treat that as the canonical gospel of physical reality. In an interview Penrose commented that his “own view is that quantum mechanics is not exactly right.”
Penrose expresses major concerns about string theory in particular which tries to present a unified picture of quantum gravity and sell it as the theory of everything. But this theory is without its usual problems, like the six hidden dimensions that has not been experimentally verified. The fact that strings are suggested to propagate in ten dimensions, and only four are large dimensions (including one time-dimension), and the rest are small, curled-up and decoupled with the larger dimensions intimidates Penrose. He would not compromise on decoupling these degrees of freedom with two sets and observes that causes instability; hence a stable ground state with four large spacetime dimensions would not be possible. Many predictions of the theory are not testable within the realm of available technology.
Penrose illustrates the inflationary cosmology as an example of fantasy since it does not explain what set the initial low entropy condition of the universe. Inflationary cosmology, which suggests that the universe inflated exponentially within a small fraction of a second after the Big Bang is a big fish observes Penrose. In fact it is sacrilegious to attack it, and even more sacrilegious is quantum physics which has become a faith. People don’t want to question it.
Penrose also discusses his “twistor” theory in which he explains how particles move and interact in spacetime, but spacetime themselves are secondary constructs that emerge out of a deeper level of reality. The conventional wisdom is that spacetime geometry fluctuate on quantum scales, altering how events relate to one another. Hence an event that was supposed to cause another may not happen creating paradoxes such as those found in time-travel. In twistor theory, causal sequences are primary and do not fluctuate. Instead the location and timing of events fluctuate. String theorists showed that an event of ambiguous location and time is nothing more or less than a string.
Many string theorists dismiss Penrose’s criticism. They claim that their theory has mathematical beauty and it has the ability to include the classical theory of gravity and it is the only theory of everything. Despite his criticism, he was invited by the Princeton University in 2003 where some of the most important proponents of string theory work. The ideas for this book was developed from these lectures.
Roger Penrose is a mathematician and firmly believes that understanding math is fundamental to the understanding of physics and physical reality. In his 2005 book, “The Road to Reality” math was extensively used as a concept learning tool even though that book was written for a general reader. This book also has math but less extensive than his 2005 book. Some sections are written for wider choice of readers but other parts require significant knowledge in mathematical physics. It will make it easier for a reader to know that Roger Penrose, in his 2009 interview with “Discover” magazine, admitted he was “bad” in math in school and in his own words he “was at least twice as slow as anybody else.” Eventually I would do very well. You see, if I could do it that way.” This is a great source encouragement for readers who did not have significant physics and math while they were in school. I recommend readers to skip the part of the book that is too intense but focus on main arguments of the book. One can still appreciate the efforts of Penrose’s masterful way of communicating his ideas.
August 17, 2023
I would not be surprised if the editor had suggested a change of the title of this book into “Fashion, Faith, Fantasy and Frustration”. But I assume that Prof Penrose refuses any editorial changes and that is a real shame, because this book could certainly use some.
“Frustration” because, whilst Prof Penrose clearly is a distinguished mathematician, he is also a frustrated physicist. Prof Penrose has worked for 40 years on his twistor theory without getting any traction from the physics community to use it as a fundamental theory. Could this possibly be because after 40 years he has nothing serious to show for?
So one more book from Prof Penrose regurgitating his well-known frustrations. There is a famous quote about such prolific authors: “if he really had something interesting to write, he would already have written it.”
And the style, don’t let me even start on this.
I will now show this using past §3.1 and §2.1.1 (and A13.2 which refers to B2 and also Penrose[2004], Penrose[1979] and Penrose[1834] and the experimental confirmation of Zilovershatlovkomski[1964]) and as will be explained in the next chapter in §5.2 (which uses results of §1.11 and TRtR p 7,456). But before that I need to explain a complicated technical issue (see §B2 and the previous page and Fig 3.149(c.4), when turned upside-down) which is very important but not relevant at all, so I will do this in my next book. This clearly shows that 10^10^10^123^128 is a very large number and that the theory does not make sense.
This is not a quote from the book, but it could have come from it.
“Frustration” because, whilst Prof Penrose clearly is a distinguished mathematician, he is also a frustrated physicist. Prof Penrose has worked for 40 years on his twistor theory without getting any traction from the physics community to use it as a fundamental theory. Could this possibly be because after 40 years he has nothing serious to show for?
So one more book from Prof Penrose regurgitating his well-known frustrations. There is a famous quote about such prolific authors: “if he really had something interesting to write, he would already have written it.”
And the style, don’t let me even start on this.
I will now show this using past §3.1 and §2.1.1 (and A13.2 which refers to B2 and also Penrose[2004], Penrose[1979] and Penrose[1834] and the experimental confirmation of Zilovershatlovkomski[1964]) and as will be explained in the next chapter in §5.2 (which uses results of §1.11 and TRtR p 7,456). But before that I need to explain a complicated technical issue (see §B2 and the previous page and Fig 3.149(c.4), when turned upside-down) which is very important but not relevant at all, so I will do this in my next book. This clearly shows that 10^10^10^123^128 is a very large number and that the theory does not make sense.
This is not a quote from the book, but it could have come from it.
November 22, 2016
Ok, because it seems like a lot of people purchased this book without knowing what they were getting into, this is not for the casual, lay reader of science books. There is some very complicated math here and the language is written for those with an expertise in this area, if that is not you, you will likely get nothing from this. To those for whom this was written, this is an important challenge and moment of clarity for a lot of the ideas that are thrown around in modern physics, sometimes without the proper foundation. Penrose does a very thorough job explaining the improbability of several new and "fashionable" ideas in physics while at the same time in his final chapter laying out his own theories on a few key subjects. If you are looking for a stimulating challenge to some of the more difficult theories to swallow, this is a highly informative, though extremely dense read.
May 21, 2022
This has to qualify as the most difficult book that I have ever read. As Francis Bacon said...."Some books are to be read with the speed of summer lightning and some are to be chewed and digested". Well I think "Fashion, Faith etc" has pretty much given me indigestion. And it's taken me months to wade my way through....a few pages at a time. As a general rule, I try to read books before I read the preface or the critiques so I can make up my own mind about it and not be prejudiced by other writers. In this case, I read the Mathematical Appendices after I had read the book. I'm still not sure if this was a mistake......because I couldn't understand a high proportion of the appendices either.
As many of the reviewers have commented; you need a very high level of mathematics to be able to follow this book...and even some of the reviewers with a high level of maths admitted to being overwhelmed. Well. I guess, Penrose is a Nobel Prize winner. And he's co-authored books with Steven Hawking, And he's made major contributions to Maths and Cosmology across fields such as Black holes and tile tessellation. So not surprising that he's going to be using maths that is well out of my league.
In fact, I found myself reading through paragraphs of equations with infinity raised to the power of 2, in turn raised to the power of 3 where Penrose says something like ...."well we can ignore this because it's vanishingly small in comparison with some other similar looking expression". To all of this I have to simply say: "Well, OK if you say so!"....I just have to take it at face value.....I have no way really of knowing if he's right but he usually reduces it all to some prose summary such as:(p116) "To sum it up, it does seem clear that the AdS.CFT correspondence [the Holographic Principle] has opened a huge new area of research, which has related many active areas of theoretical research, making unexpected connections between such disparate fields as condensed matter physics, black holes, and particle physics. On the other hand, there is a strange contrast between this great versatility and wealth of ideas, and the unreality of the immediate picture of the world that it projects. It depends upon the wrong sign for the cosmological constant; it requires 4 generators of super symmetry, whereas none has been observed; it requires a gauge symmetry group acting on infinitely many parameters instead of the 3 that particle physics requires; and it's bulk space-time has 1 too many dimensions! it will be most fascinating to see where all of this leads". In other words; a fairly damning round-up of criticisms.
I write these reviews really for my own edification and as memory joggers not for any other readers (sorry) so I'm including an extract here from another reviewer on "Goodreads", Athan Tolis......he rather nicely summarises some of the main threads of Penrose's arguments, viz:
1. Highly fashionable 26-dimension string theory, while elegant and originally promising, is likely a dead end, for example because it leads to singularities
2. Supersymmetry between Fermions and Bosons cuts down the dimensions of string theory to a more manageable 10, but makes it necessary to believe in the existence of a whole lot of particles we will never observe
3. The holographic conjecture, while beautiful, relies on supersymmetry and requires that we radically revise what we believe about the cosmological constant, the gauge symmetry group and bulk space
4. Quantum entanglement is probably ultimately only a feature of the simplified, linear orthodoxy we cling to in Quantum Mechanics, which we will one day abandon for a nonlinear model. The Quantum Mechanics of the present is useful, but requires a leap of faith you should refuse to take.
5. Inflationary Cosmology poses even more problems than it answers questions and is a convenient untruth.
Basically, Penrose is saying that a lot of what physicists are saying about cosmology is based on fashion, faith and pure fantasy and the proponents are ignoring or glossing-over the very real mathematical problems in their quests.
I found myself wondering why Penrose himself was so against something like string theory; why he was opting for a simpler view of the universe? Was it because he was taking Occam's Razor seriously? Was it because he had his own Twistor theory that hadn't really caught on? Or was it because he agreed with Einstein, and many others, that the mathematics really was reflecting some sort of reality that we should, ultimately, be able to grasp?
I recall attending a lecture by Penrose at the Australian National University where he ran through some mathematics and showed some sort of matrix which he said "was intuitively obvious......that everyone would accept it". I was not quite convinced and my doubts were compounded when my Philosophy supervisor who was sitting alongside me commented that he was not sure that Penrose understood the psychology/philosophy of mathematics all that well. Not sure who was correct but it did sow the seed of doubt that even giant intellects sometimes get it wrong.
However, I thought that Penrose showed great intellectual honesty on p392 where he says that he has both a public reason and a private reason for objecting to higher-dimensional theories. The public reason would indeed be one based largely on the problems raised by the excessive functional freedom, but the private one was that from his undergraduate days he had been smitten by the power and the magic of complex analysis and geometry and had become convinced that this magic must also lie deep in the fundamental workings of the world. And he seemed to find this in with his twistor theory and the link between 3-dimensional geometry and quantum mechanical amplitudes but also a somewhat different link between the Lorenz group and the Riemann sphere. Both these relationships demanded the particulate space-time dimensionality that we see about us. So when he heard that string theory, to which he had initially been attracted .....had moved in the direction of requiring all these extra spatial dimensions...he was horrified ....and "found it impossible to believe that nature would have rejected all those beautiful connections with Lorenzian-4 space...and still do".
So it seems to me that Penrose is here confessing that he has his own brand of faith too.
But I come away from the book mildly depressed. I had believed that the great mathematicians of our time and the great cosmologists were actually getting close to the universal theory that would explain everything. But Penrose has me, more or less, convinced that, at best, we are a very long way from that universal equation and that many of the physicists didn't understand the underpinnings and the weaknesses in much of their mathematics.
And as for Penrose, I do have some sympathy that his twistor theory has never really become fashionable. After all.....it seems that to be successful in physics as in many other professions one has to be both fashionable and have faith in the latest fantasies.
If I gave this book 5 stars, I would be kidding myself because I probably only followed about 25% of it but to give it less than 4 stars would be churlish. Clearly it is a significant work. I just wish, more people (including myself) had the education to be able to understand all of it.
As many of the reviewers have commented; you need a very high level of mathematics to be able to follow this book...and even some of the reviewers with a high level of maths admitted to being overwhelmed. Well. I guess, Penrose is a Nobel Prize winner. And he's co-authored books with Steven Hawking, And he's made major contributions to Maths and Cosmology across fields such as Black holes and tile tessellation. So not surprising that he's going to be using maths that is well out of my league.
In fact, I found myself reading through paragraphs of equations with infinity raised to the power of 2, in turn raised to the power of 3 where Penrose says something like ...."well we can ignore this because it's vanishingly small in comparison with some other similar looking expression". To all of this I have to simply say: "Well, OK if you say so!"....I just have to take it at face value.....I have no way really of knowing if he's right but he usually reduces it all to some prose summary such as:(p116) "To sum it up, it does seem clear that the AdS.CFT correspondence [the Holographic Principle] has opened a huge new area of research, which has related many active areas of theoretical research, making unexpected connections between such disparate fields as condensed matter physics, black holes, and particle physics. On the other hand, there is a strange contrast between this great versatility and wealth of ideas, and the unreality of the immediate picture of the world that it projects. It depends upon the wrong sign for the cosmological constant; it requires 4 generators of super symmetry, whereas none has been observed; it requires a gauge symmetry group acting on infinitely many parameters instead of the 3 that particle physics requires; and it's bulk space-time has 1 too many dimensions! it will be most fascinating to see where all of this leads". In other words; a fairly damning round-up of criticisms.
I write these reviews really for my own edification and as memory joggers not for any other readers (sorry) so I'm including an extract here from another reviewer on "Goodreads", Athan Tolis......he rather nicely summarises some of the main threads of Penrose's arguments, viz:
1. Highly fashionable 26-dimension string theory, while elegant and originally promising, is likely a dead end, for example because it leads to singularities
2. Supersymmetry between Fermions and Bosons cuts down the dimensions of string theory to a more manageable 10, but makes it necessary to believe in the existence of a whole lot of particles we will never observe
3. The holographic conjecture, while beautiful, relies on supersymmetry and requires that we radically revise what we believe about the cosmological constant, the gauge symmetry group and bulk space
4. Quantum entanglement is probably ultimately only a feature of the simplified, linear orthodoxy we cling to in Quantum Mechanics, which we will one day abandon for a nonlinear model. The Quantum Mechanics of the present is useful, but requires a leap of faith you should refuse to take.
5. Inflationary Cosmology poses even more problems than it answers questions and is a convenient untruth.
Basically, Penrose is saying that a lot of what physicists are saying about cosmology is based on fashion, faith and pure fantasy and the proponents are ignoring or glossing-over the very real mathematical problems in their quests.
I found myself wondering why Penrose himself was so against something like string theory; why he was opting for a simpler view of the universe? Was it because he was taking Occam's Razor seriously? Was it because he had his own Twistor theory that hadn't really caught on? Or was it because he agreed with Einstein, and many others, that the mathematics really was reflecting some sort of reality that we should, ultimately, be able to grasp?
I recall attending a lecture by Penrose at the Australian National University where he ran through some mathematics and showed some sort of matrix which he said "was intuitively obvious......that everyone would accept it". I was not quite convinced and my doubts were compounded when my Philosophy supervisor who was sitting alongside me commented that he was not sure that Penrose understood the psychology/philosophy of mathematics all that well. Not sure who was correct but it did sow the seed of doubt that even giant intellects sometimes get it wrong.
However, I thought that Penrose showed great intellectual honesty on p392 where he says that he has both a public reason and a private reason for objecting to higher-dimensional theories. The public reason would indeed be one based largely on the problems raised by the excessive functional freedom, but the private one was that from his undergraduate days he had been smitten by the power and the magic of complex analysis and geometry and had become convinced that this magic must also lie deep in the fundamental workings of the world. And he seemed to find this in with his twistor theory and the link between 3-dimensional geometry and quantum mechanical amplitudes but also a somewhat different link between the Lorenz group and the Riemann sphere. Both these relationships demanded the particulate space-time dimensionality that we see about us. So when he heard that string theory, to which he had initially been attracted .....had moved in the direction of requiring all these extra spatial dimensions...he was horrified ....and "found it impossible to believe that nature would have rejected all those beautiful connections with Lorenzian-4 space...and still do".
So it seems to me that Penrose is here confessing that he has his own brand of faith too.
But I come away from the book mildly depressed. I had believed that the great mathematicians of our time and the great cosmologists were actually getting close to the universal theory that would explain everything. But Penrose has me, more or less, convinced that, at best, we are a very long way from that universal equation and that many of the physicists didn't understand the underpinnings and the weaknesses in much of their mathematics.
And as for Penrose, I do have some sympathy that his twistor theory has never really become fashionable. After all.....it seems that to be successful in physics as in many other professions one has to be both fashionable and have faith in the latest fantasies.
If I gave this book 5 stars, I would be kidding myself because I probably only followed about 25% of it but to give it less than 4 stars would be churlish. Clearly it is a significant work. I just wish, more people (including myself) had the education to be able to understand all of it.
December 3, 2016
***I won this book in a Goodreads Giveaway***
I love the premise of this book. Fashion, faith, and Fantasy in physics. Brilliant. The author is well known and knowledgeable...what could go wrong? two things.
1. No matter what it says in the description, this is not a book for lay people. You need a pretty strong background in math and physics to understand it. I have a PhD in physical chemistry and was lost in some sections. This is a minor issue, though, compared to...
2. AWFUL editing. Holy smokes...what editor let this through? The author is exceptionally wordy. In numerous places he wrote an entire paragraph to tell you what he was going to tell you in the next paragraph. The book would have been well served by having all that nonsense trimmed up.
I won't throw it totally under the bus, though. He did make compelling arguments in some sections (against the inflationary period of the big bang, for example).
I love the premise of this book. Fashion, faith, and Fantasy in physics. Brilliant. The author is well known and knowledgeable...what could go wrong? two things.
1. No matter what it says in the description, this is not a book for lay people. You need a pretty strong background in math and physics to understand it. I have a PhD in physical chemistry and was lost in some sections. This is a minor issue, though, compared to...
2. AWFUL editing. Holy smokes...what editor let this through? The author is exceptionally wordy. In numerous places he wrote an entire paragraph to tell you what he was going to tell you in the next paragraph. The book would have been well served by having all that nonsense trimmed up.
I won't throw it totally under the bus, though. He did make compelling arguments in some sections (against the inflationary period of the big bang, for example).
February 14, 2025
I need to reread this lol
A lot of the mathematical descriptions went over my head, and I probably should���ve read the appendix. I’ll reread this book as I improve my knowledge on math and physics, and I’ll probably start my reread by going through the appendix 💀
A lot of the mathematical descriptions went over my head, and I probably should���ve read the appendix. I’ll reread this book as I improve my knowledge on math and physics, and I’ll probably start my reread by going through the appendix 💀
November 18, 2024
This is a fascinating and educational book about three areas of modern physics: string theory, quantum mechanics and cosmic inflation.
The author points out severe mathematical problems with string theory that have not been addressed by its proponents. The use of extra dimensions causes problems. According to string theory, 6 additional dimensions could be wrapped in a Calabi-Yau manifold. However, the author's singularity theorem shows this would collapse in less than a second.
Quantum mechanics is well established with much experimental evidence. However, the author points out there are theoretical problems with the collapse of the wave function. QM does not say how, when, why or how often the wave function collapses. The author propses that at a certain mass and curvature of spacetime, it collapses under its own gravity.
Cosmic inflation says that the universe, in its early development, expanded exponentially. Many people, including Alan Guth, believe this explains the uniformity of the cosmic microwave background observed in the night sky. However, Penrose present an argument that it fails to do so.
Finally, and more constructively, Penrose presents his own alternative theories: twistor theory, objective reduction, and conformal cyclic cosmology.
It is absolutely fascinating to read about these ideas. It is up to the reader to decide whether to believe any of them to be true!
The author points out severe mathematical problems with string theory that have not been addressed by its proponents. The use of extra dimensions causes problems. According to string theory, 6 additional dimensions could be wrapped in a Calabi-Yau manifold. However, the author's singularity theorem shows this would collapse in less than a second.
Quantum mechanics is well established with much experimental evidence. However, the author points out there are theoretical problems with the collapse of the wave function. QM does not say how, when, why or how often the wave function collapses. The author propses that at a certain mass and curvature of spacetime, it collapses under its own gravity.
Cosmic inflation says that the universe, in its early development, expanded exponentially. Many people, including Alan Guth, believe this explains the uniformity of the cosmic microwave background observed in the night sky. However, Penrose present an argument that it fails to do so.
Finally, and more constructively, Penrose presents his own alternative theories: twistor theory, objective reduction, and conformal cyclic cosmology.
It is absolutely fascinating to read about these ideas. It is up to the reader to decide whether to believe any of them to be true!
November 7, 2017
Roger Penrose has a bit of a reputation for being pathologically optimistic about the ability of his target audience to comprehend the contents of his popular science books. From Emperor's New Mind, through its follow-up Shadows of the Mind; from his (arguably THE) opus magnus of popular science The Road to Reality, through Cycles of Time to this latest work Roger Penrose has given me endless hours of head-scratching, confusion, bewilderment and those odd indefinable moments of brilliant clarity when you realise you've understood a concept that he has been writing about; it is these latter, rare moments that bring me back to Penrose's works again and again.
This is a difficult book, no doubt about it, 20% of it is incomprehensible to me, the rest is difficult, and I consider my maths and physics background to be fairly good; and to be honest, if you want a similar critique of string theory then I would go to Lee Smolin's books on the subject first. This particular book covers some familiar ground for anyone who has read any of Penrose's other works, but it still stands alone as a book that integrates his criticism of modern theories of string theory, quantum mechanics and cosmology whilst arguing some optional view points from his own theories and those of others.
This book is divided into 4 sections: Fashion, Faith, Fantasy and a final section expounding Penrose's own suggestions for alternative routes to follow.
Fashion deals with the current, and fairly long-standing obsession with string theory; an area of physics research which has proliferated notions of multiple dimensions (26 or 10 depending on the particular formulation you choose). From Penrose's view the problem with this theory is that it has too many degrees of functional freedom: the problem from my point of view is that I couldn't for the life of me understand what impact this has even with the mathematical appendices and their infinity^infinity explanations. But I get that the unphysicality of those multiple dimensions and the poor predictive record of String Theory should at leat give pause to the Physics community.
Faith explores the underlying issues with quantum mechanics, in particular the difficulty surrounding the mechanism of QM in conjunction with gravity. In fact Penrose argues that linear QM models will eventually be superseded by a nonlinear model incorporating gravitational effects.
Fantasy casts a questioning eye over the very current, very fashionable inflationary theories. That these theories are cavalier about some obvious problems around entropy, and like string theory they are tweaked and special-cased to achieve closer matches to observation. Also similar to String theory is the fashionable aspect of Inflation, for example Brain Cox in his otherwise wonderful "Wonders of the Universe" TV series stated as irrefutable fact that, post-Big Bang, the universe has been involved in a process of "Eternal Inflation".
So what are Penrose's solutions? Well there is a long-standing theory of his (and my first wonderful encounter with his writings) regarding Twistor theory. Twistors are complex objects (in the mathematical sense) that provide a background space for 4 dimensional Minkowski space-time. They have proved successful in certain limited cases and have gained some small recent interest following an amalgamation with some aspects of string theory.
As regards cosmology, and particularly explanations for the the very low entropy of the early universe, Penrose has proposed a sort of cyclic universe model that naturally leads to a very low entropy and at the same time very smooth early universe. One of the many issues with the inflationary theories is that they fail to deal with the extraordinarily unlikely structure of the CMB [ 10^(-10^124) ]. This Conformal Cyclic Cosmology theory (it's the subject of his previous book Cycles of Time and is fascinating) has its own problems, requiring as it does that all matter has decayed to electromagnetic radiation in the unimaginably distant future, but if these can be demonstrated to be possible (e.g. proton decay) then this theory beautifully describes a mechanism for a very long, 10^100 years, life cycle for the universe, where a conformal hypersurface boundary, effectively at the end of one epoch, is indistinguishable from a Big Bang hypersurface at the start of the next epoch.
A really, really difficult book, but worthwhile.
This is a difficult book, no doubt about it, 20% of it is incomprehensible to me, the rest is difficult, and I consider my maths and physics background to be fairly good; and to be honest, if you want a similar critique of string theory then I would go to Lee Smolin's books on the subject first. This particular book covers some familiar ground for anyone who has read any of Penrose's other works, but it still stands alone as a book that integrates his criticism of modern theories of string theory, quantum mechanics and cosmology whilst arguing some optional view points from his own theories and those of others.
This book is divided into 4 sections: Fashion, Faith, Fantasy and a final section expounding Penrose's own suggestions for alternative routes to follow.
Fashion deals with the current, and fairly long-standing obsession with string theory; an area of physics research which has proliferated notions of multiple dimensions (26 or 10 depending on the particular formulation you choose). From Penrose's view the problem with this theory is that it has too many degrees of functional freedom: the problem from my point of view is that I couldn't for the life of me understand what impact this has even with the mathematical appendices and their infinity^infinity explanations. But I get that the unphysicality of those multiple dimensions and the poor predictive record of String Theory should at leat give pause to the Physics community.
Faith explores the underlying issues with quantum mechanics, in particular the difficulty surrounding the mechanism of QM in conjunction with gravity. In fact Penrose argues that linear QM models will eventually be superseded by a nonlinear model incorporating gravitational effects.
Fantasy casts a questioning eye over the very current, very fashionable inflationary theories. That these theories are cavalier about some obvious problems around entropy, and like string theory they are tweaked and special-cased to achieve closer matches to observation. Also similar to String theory is the fashionable aspect of Inflation, for example Brain Cox in his otherwise wonderful "Wonders of the Universe" TV series stated as irrefutable fact that, post-Big Bang, the universe has been involved in a process of "Eternal Inflation".
So what are Penrose's solutions? Well there is a long-standing theory of his (and my first wonderful encounter with his writings) regarding Twistor theory. Twistors are complex objects (in the mathematical sense) that provide a background space for 4 dimensional Minkowski space-time. They have proved successful in certain limited cases and have gained some small recent interest following an amalgamation with some aspects of string theory.
As regards cosmology, and particularly explanations for the the very low entropy of the early universe, Penrose has proposed a sort of cyclic universe model that naturally leads to a very low entropy and at the same time very smooth early universe. One of the many issues with the inflationary theories is that they fail to deal with the extraordinarily unlikely structure of the CMB [ 10^(-10^124) ]. This Conformal Cyclic Cosmology theory (it's the subject of his previous book Cycles of Time and is fascinating) has its own problems, requiring as it does that all matter has decayed to electromagnetic radiation in the unimaginably distant future, but if these can be demonstrated to be possible (e.g. proton decay) then this theory beautifully describes a mechanism for a very long, 10^100 years, life cycle for the universe, where a conformal hypersurface boundary, effectively at the end of one epoch, is indistinguishable from a Big Bang hypersurface at the start of the next epoch.
A really, really difficult book, but worthwhile.
December 20, 2018
Is he really a physicist?
As someone who studied physics and the calculus that we need for it, I would say this this book is overly complicated. For one thing when he tries to explain the difference between a domain and range of a function he uses insanely complicated terminology when you could just say it’s a variable of N inputs and M outputs and simply talk about the number of possible functions. And though he acknowledges that he’s not using Cantor style infinities, when he wants to say that it is over all the reels why Disney just use the symbol for all real’s instead of using the loaded term infinity to specify the degrees of freedom for a given set of functions or space times. All that said I don’t have too much problem with his arguments against string theory as I do see them as sound. And he has testable predictions for his counter theory to quantum physics so I’d say that’s reasonable let’s test it. I wasn’t totally clear on how Twistors work in terms of projecting onto a different surface though. I’m always eager for new interpretations of how the Wave Form Collapse so that was nice. I just wish the Kindle Edition could handle the power tower superscripts better. I’m really looking forward to see if any experiments can prove Twistor or Quantum Theory wrong! That’s exciting and bravo for a testable theory!
As someone who studied physics and the calculus that we need for it, I would say this this book is overly complicated. For one thing when he tries to explain the difference between a domain and range of a function he uses insanely complicated terminology when you could just say it’s a variable of N inputs and M outputs and simply talk about the number of possible functions. And though he acknowledges that he’s not using Cantor style infinities, when he wants to say that it is over all the reels why Disney just use the symbol for all real’s instead of using the loaded term infinity to specify the degrees of freedom for a given set of functions or space times. All that said I don’t have too much problem with his arguments against string theory as I do see them as sound. And he has testable predictions for his counter theory to quantum physics so I’d say that’s reasonable let’s test it. I wasn’t totally clear on how Twistors work in terms of projecting onto a different surface though. I’m always eager for new interpretations of how the Wave Form Collapse so that was nice. I just wish the Kindle Edition could handle the power tower superscripts better. I’m really looking forward to see if any experiments can prove Twistor or Quantum Theory wrong! That’s exciting and bravo for a testable theory!
October 15, 2018
This is a very difficult book to read and you need a college level math degree to get through it. I didn't understand it all, and I had to use several other resources besides Wikipedia to get through it, including Road to Reality by the same author.
So why 5 stars? This is a journey, and it opens your eyes, challenges your assumptions and compels you to dig deeper. His criticism of the current state of physics is understandable, and unlike his conclusions in the Emperor's New Mind, I agree with him.
Then comes chapter 4, and I was blown away by the insights. I am still stunned at the revelations after a good night sleep.
So why 5 stars? This is a journey, and it opens your eyes, challenges your assumptions and compels you to dig deeper. His criticism of the current state of physics is understandable, and unlike his conclusions in the Emperor's New Mind, I agree with him.
Then comes chapter 4, and I was blown away by the insights. I am still stunned at the revelations after a good night sleep.
February 10, 2021
Not for the mathematically feint of heart! Penrose does not shy away from math at all, most sections are almost incomprehensible, even to a math major (though it was long ago). The appendices are meant to clarify, but are short and assume lots of prior experience. I did like his take on quantum and he is into afraid to voice opinions that are not popular with most physicists.
October 12, 2016
This book is way more technical than I was expecting. I have a relatively strong math and abstract thinking background, but this was much closer to a textbook than I was expecting. Probably good for people in physics (or related fields). As a relative layman, this wasn't accessible.
Read
August 5, 2017Somewhat tedious, but he does show the weakness of current Big Bang theory, String theory and other tentative theories in physics.
December 25, 2020
This is an interesting but somewhat incoherent book. It reads as if he has collected previous material from various presentations and notes and then just slammed them together in one book. Even the titles of the chapters don't really make sense. Chapter 1 (entitled 'Fashion') rehashes his scientific and sociological criticisms of string theory which are already outlined in his previous book The Road to Reality. Chapter 2 ('Faith') is mostly revision of standard undergraduate quantum mechanics. Chapter 3 ('Fantasy') revises the usual cosmological models as well as conformal diagrams and the classical singularity theorems. Chapter 4 plugs twistor theory and conformal cyclic cosmology (most of the material on the latter is pulled from Cycles of Time, another pop science book by Penrose).
By the final paragraph, it does seem a little like he has lost the the plot in terms of trying to keep to a coherent narrative which the reader can follow and throws his hat into the ring on the Shakespeare authorship question, stating doubts that the works of Shakespeare were written by Shakespeare, for the following reasons: his father Lionel thought so too and Lionel was often right, ''Shakespeare didn't own any books'' and Shakespeare's signature ''looks illiterate'' (whatever that is supposed to mean). Probably not the best way to end a book where you are portraying yourself as a voice of reason in a landscape of confusion and should really have been cut out by the editors.
By the final paragraph, it does seem a little like he has lost the the plot in terms of trying to keep to a coherent narrative which the reader can follow and throws his hat into the ring on the Shakespeare authorship question, stating doubts that the works of Shakespeare were written by Shakespeare, for the following reasons: his father Lionel thought so too and Lionel was often right, ''Shakespeare didn't own any books'' and Shakespeare's signature ''looks illiterate'' (whatever that is supposed to mean). Probably not the best way to end a book where you are portraying yourself as a voice of reason in a landscape of confusion and should really have been cut out by the editors.
February 6, 2017
roger penrose is a little crotchety. i think talking to him would be a little dull, despite all the incredible knowledge in his head. that being said, i'm all for a little conservatism in physics. penrose wants to expose the paucity of actual experimental evidence for the supradimensional theories included in M He wants to show that while quantum superposition agrees with experiment, he wants to show that there are reasons to believe that there are deeper theories waiting to be worked out. also he thinks inflationary cosmology is a crock of shit. i've read 2 books on the subject and i've never been convinced. his own theories, presented in the last chapter, don't convince me either. it was just refreshing to see that at least some theoretical physicists are not rushing headlong into dead ends just because everyone else is.
a word on the math: it's hard. i had to leave many sections only partially understood. i don't think this is poor roger's fault. he treats us more like adults than other writers of this genre, presenting everything relevant. i think if you just push through the bewildering talk of tensors and phase space and freakin riemann 3surfaces, you'll arrive at a (very) basic understanding of the concept.
a word on the math: it's hard. i had to leave many sections only partially understood. i don't think this is poor roger's fault. he treats us more like adults than other writers of this genre, presenting everything relevant. i think if you just push through the bewildering talk of tensors and phase space and freakin riemann 3surfaces, you'll arrive at a (very) basic understanding of the concept.
December 24, 2022
Great topics. The unreasonable fashionability of String Theory, the unreasonable and unquestioned dogmas of quantum mechanics and the heady unproven and probably unprovable fantasies of modern theoretical cosmology. And although most critics would simply be dismissed out of hand Penrose has the depth and the stature to be at least listened to .... Maybe.
The problem with the book is the same problem that occurs with every Penrose book. He claims that this book is for the general reader - and it is marketed as such. But it isn't. He may be a great mathematical/theoretical physicist but he is a terrible writer. He has no sense of proportion. In one part he is ranting on about obscure points in string theory which only a fellow expert could possibly follow ( and this isn't me) but in another part he is defining what a sine is and explaining Fourier series ( yeah I know that already - but why is it in this book !! ). Most of it is highly technical gobbly gock only comprehensible to other niche specialists. And a waste of time for the rest of us. All long dreary six hundred pages of it !!
His brief actual discussions on fashion/faith/fantasy, politics/trends et al in modern physics are scanty at best and quite common place.
The problem with the book is the same problem that occurs with every Penrose book. He claims that this book is for the general reader - and it is marketed as such. But it isn't. He may be a great mathematical/theoretical physicist but he is a terrible writer. He has no sense of proportion. In one part he is ranting on about obscure points in string theory which only a fellow expert could possibly follow ( and this isn't me) but in another part he is defining what a sine is and explaining Fourier series ( yeah I know that already - but why is it in this book !! ). Most of it is highly technical gobbly gock only comprehensible to other niche specialists. And a waste of time for the rest of us. All long dreary six hundred pages of it !!
His brief actual discussions on fashion/faith/fantasy, politics/trends et al in modern physics are scanty at best and quite common place.
October 29, 2017
This may be a twilight book for Penrose, a chance to take a final stand on problems he has worked on during his long career. It has been written for educated lay people without much mathematical background. The book addresses three main topics: string theory, quantum mechanics, and general relativity, with their interrelationships. It was a long read, trying to pay attention to everything that was being said. Penrose sees many problems in all three main areas, but it is from his elevated experience with all the physics involved. His critique of string theory derives mainly from all the extra dimensions postulated for the various types of theories. Quantum mechanics fares better due to its grand precision in quantum field theory, but he still critiques its connection general relativity. Penrose expresses his greatest confidence in general relativity, although there remain many areas of almost pure speculation.
If you want a good overview of up-to-date modern physics and cosmology, this book presents it in a mostly readable form.
If you want a good overview of up-to-date modern physics and cosmology, this book presents it in a mostly readable form.
June 11, 2020
No le doy las 5 estrellas porque pienso que no cumple su objetivo, o por lo menos, el objetivo que yo creo tiene el libro. Según entendí es un libro divulgativo, pero me parece que para el neófito en física y en matemáticas le será muy difícil (por no decir imposible) de entender. Sin embargo es comprensible que esté escrito de forma que sea “poco entendible” pues, es lo que normalmente pasa cuando se desea dar a conocer los límites de una ciencia exacta a un publico no especializado.
Ahora, si lo lee alguien con formación científica o alguien que sea estudiante de ciencias exactas el libro es una obra de arte. Debido a que nos pone de manifiesto fronteras y herramientas para convertirnos en mejores investigadores. Para poner en un ejemplo, baste con citar alguno de los apéndices, están escritos con un grado de formalismo científico más alto de lo que el publico en general puede apreciar (por un momento me pareció estar leyendo uno de los libros de la carrera) pero que será maravilloso para los conocedores de la técnica.
Ahora, si lo lee alguien con formación científica o alguien que sea estudiante de ciencias exactas el libro es una obra de arte. Debido a que nos pone de manifiesto fronteras y herramientas para convertirnos en mejores investigadores. Para poner en un ejemplo, baste con citar alguno de los apéndices, están escritos con un grado de formalismo científico más alto de lo que el publico en general puede apreciar (por un momento me pareció estar leyendo uno de los libros de la carrera) pero que será maravilloso para los conocedores de la técnica.
December 28, 2016
An alert up front: this book is extremely heavy going, and the assignment of much of the mathematics to appendices is somewhat of a relief, with emphasis on "somewhat." I consider my maths to be relatively strong—I have a PhD, and (until this book) felt I was on stable ground in both the Relativistic and Quantum Mechanical worlds. But some of the concepts explored and, in the particular case of string theory, debunked were mind-bending at times. It will be interesting to see how this series of provocative essays is received by experts in the theoretical physics world, but if you can withstand the ride to the end the sheer breadth of argument and thought is stunning, and the formal writing style edging on poetic in places.
June 27, 2020
This is a book you want to read if you have questions about the many difficult and sometimes controversial aspects of modern physics by a man eminently qualified to write on the topics. Roger Penrose has had a storied career in physics and understands the strengths and weaknesses of each position. My only problem is that I don't understand the math, although he had shifted most of the difficult math to several appendixes. But I even have trouble understanding some of the "non-technical" math used in the text.
May 19, 2019
Overall, an intriguing read, if at times hard to follow. I expect I'll re-read the book, particularly the last chapter, at some point in the future in hopes of drilling some of the more esoteric concepts into my mind, but I was left with the nagging feeling that as well-made as Penrose's critiques of much of fashionable modern physics were, I'd love to see him comment on his own model with the same insight.
April 30, 2018
S tough but compelling read
What's exceptional about Penrose is the breadth of his expertise .. across qft, gr, cosmology and maths .. especially geometry. Not only can he challenger the completeness of ALL current theory .. he head some alternative solutions and argues well for their consideration. Many thanks Penrose :-)
What's exceptional about Penrose is the breadth of his expertise .. across qft, gr, cosmology and maths .. especially geometry. Not only can he challenger the completeness of ALL current theory .. he head some alternative solutions and argues well for their consideration. Many thanks Penrose :-)
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October 24, 2022More physics than in The Road to Reality, but still very heavy slogging unless you have a degree in physics, in which case it's a fairly quick read. One or two points I hadn't thought about, so it was worthwhile.
June 10, 2020
Realmente esto es mucho más que un libro de divulgación científica. Es un libro de estudio.
Plantea interesantes conceptos y da en cara muchos dogmas de la ciencia de forma ingeniosamente incómoda
Plantea interesantes conceptos y da en cara muchos dogmas de la ciencia de forma ingeniosamente incómoda
August 15, 2020
Should be required reading for aspirational theoretical physicists
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