Roger Penrose - beyond algorithms

Blogger Ref http://www.p2pfoundation.net/Multi-Dimensional_Science
Not knowably sound   Sir Roger Penrose is unique in offering something close to a proof in formal logic that minds are not merely computers. There is a kind of piquant appeal in an argument against the power of formal symbolic systems which is itself clothed largely in formal symbolic terms. Although it is this 'mathematical' argument, based on the famous proof by Gödel of the incompleteness of  arithmetic, which has attracted the greatest attention, an important part of Penrose's theory is provided by positive speculations about how consciousness might really work. He thinks that consciousness may depend on a new kind of quantum physics which we don't, as yet, have a theory for, and suggests that the microtubules within brain cells might be the place where the crucial events take place. I think it must be admitted that his negative case against computationalism  is much stronger than these positive theories.   Besides the direct arguments about consciousness, Penrose's two books on the subject feature excellent and highly readable passages on fractals, tiling the plane, and many other topics. At times, it must be admitted, the relevance of some of these digressions is not obvious - I'm still not convinced that the Mandelbrot Set has anything to do with consciousness, for example - but they are all fascinating and remarkably lucid pieces in their own right. 'The Emperor's New Mind'  is particularly wide-ranging, and would be well worth reading even if you weren't especially interested in consciousness, while a large part of 'Shadows of the Mind' is somewhat harder going, and focuses on a particular argument which purports to establish that "Human mathematicians are not using a knowably sound algorithm in order to ascertain mathematical truth".   I like the books myself, mostly, but I don't find them convincing. Of course, people find a lengthy formal argument intimidating, especially from someone of Penrose's acknowledged eminence. But does anyone seriously think this kind of highly abstract reasoning can tell us anything real about how things actually work?     You don't think maths tells us anything about the real world then? Well, let's start with the Gödelian argument, anyway. Gödel proved the incompleteness of arithmetic, that is, that there are true statements in arithmetic which can never be proved arithmetically. Actually, the proof goes much wider than that. He provides a way of generating a statement, in any formal algebraic system, which we can see is true, but which cannot be proved within the system. Penrose's point is that any mechanical, algorithmic, process is based on a formal system of some kind. So there will always be some truths that computers can't prove - but which human beings can see are true! So human thought can't be just the running of an algorithm.    These unprovable truths are completely uninteresting ones, of course: the sort of thing Gödel produces are arid self-referential statements of no wider relevance. But in any case, the doctrine that people can always see the truth of any such Gödel statement is a mere assertion. In the simple cases Penrose considers, of course human beings can see the truth of the statements, but there's no proof that the same goes for more complex ones. If we actually defined the formal system which brains are running on, I believe we might well find that the Gödel statement for that system really was beyond the power of brains to grasp.  I don't think that that could ever happen - it just doesn't work like that. The complexity of the system in question isn't really a factor. And in any case, brains are not 'running on' formal systems!   Oh, but they have to be! I'm not suggesting the 'program' for any given brain is simple, but I can see three ways we could in principle construct it. One. If we list all the sensory impressions and all the instructions to act that go into or out of a brain during a lifetime, we can treat them as inputs and outputs. Now there just must be some function, some algorithm, which produces exactly those outputs for those inputs. If nothing simpler is available (I'm sure it would be) there is always the algorithm which just lists the inputs to date and says 'given these inputs, give this output'. Two. If you don't like that approach, I reckon the way neurons work is sufficiently clear for us to construct a complete neuronal model of a brain (in principle - I'm not saying it's a practical proposition); and then that would clearly represent an implementation of a complex function for the person in question.  Three. As a last resort, we just model the whole brain in excruciating detail. It's a physical object, and obeys the normal laws of physics, so we can construct a mechanical description of how it works. Any of these will do. The algorithms we come up with might well be huge and unwieldy, but they exist, which is all that matters. So we must be able to apply Gödel to people, too.  Nonsense! For a start, I don't believe 'inputs' and 'outputs' to human beings can be defined in those terms - reality is not digital. But the whole notion of a person's own algorithm is absurd! The point about computers is that their algorithms are defined by a programmer and kept in a recognised place, clearly distinguished from data, inputs, and hardware, so it's easy to say what they are in advance. With a brain, there is nothing you can point to in advance as the 'brain algorithm'. If you insist on interpreting the brain as running an algorithm, you just have to wait and see which bits of the brain and which bits of the rest of the person and their environment turn out to be relevant to their 'outputs' in what ways and then construct the algorithm to suit. We can never know what the total algorithm is until all the inputs and outputs have been dealt with. In short, it turns out not to be surprising that a person can't see the truth of their own Gödel statement, because they have to dead before anyone can even decide what it is!  Alright, well look at it this way. We're only talking about things that can't be proved within a particular formal system. Humans can see the truth of these statements, and even prove them, because they go outside the formal system to do so. There's no real reason why a computer can't do the same. It may operate one algorithm to begin with, but it can learn and develop more comprehensive algorithms for itself as it goes. Why not?  That's the whole point! Human beings can always find a new way of looking at something, but an algorithm can't. You can't have an algorithm which generates new algorithms for itself, because if it did, the new bits would by definition be part of the original algorithm.   I think it must be clear to anyone by now that you're just playing with words. I still say that all this is simply too esoteric to have any bearing on what is essentially a practical computing problem. If I understand them correctly, both Dennett and your friend Searle agree with me (in their different ways). The algorithms in practical AI applications aren't about mathematical proof, they're about doing stuff. I was puzzled by Dennett's argument in 'Darwin's dangerous idea' in particular. He's quite dismissive about the whole thing, but what he seems to say is this. The narrow set of algorithms picked out by Penrose may not be able to provide an  arithmetical proof, but what about all the others which Penrose has excluded from consideration? This is strange, because the ones excluded from consideration, according to Dennett, are: algorithms which don't do anything at all; algorithms which aren't interesting; algorithms which aren't about arithmetic; algorithms which don't produce proofs; and algorithms which aren't consistent! Can we reasonably expect proofs from any of these? Maybe not, says Dennett, but some of them might play a good game of chess... This seems to miss the point to me. What I fear is that this kind of reasoning leads to what I call the Roboteer's argument (I've seen it put forward by people like Kevin Warwick and Rodney Brooks). The Roboteer says, OK, so computers will never work the way the human brain works. So what? That doesn't mean they can't be intelligent and it doesn't mean they can't be conscious. Planes don't fly the way birds do, but we don't say it isn't proper flight because of that...  Personally, I don't see anything wrong with that argument. What about this quantum malarkey? You're not going to tell me you go along with that? There is absolutely no reason to think quantum physics has anything to do with this. It may be hard to understand, but it's just as calculable and deterministic as any other kind of physics. All there really is to this is that both consciousness and quantum physics seem a bit spooky. It isn't conventional, established quantum physics we're talking about. Having established that human thought goes beyond the algorithmic, Penrose needs to find a non-computable process which can account for it; but he doesn't see anything in normal physics which fits the bill. He wants the explanation to be part of physics - you ought to sympathise with that - so it has to be in a new physical theory, and new quantum physics is the best candidate. Further strength is given to the case by the ideas Stuart Hameroff and he have come up with about how it might actually work, using the microtubules which are present in the structure of nerve cells.  They're present in most other kinds of cell, too, if I understand correctly. Microtubules have perfectly ordinary jobs to do within cells which have nothing to do with thinking. We don't understand the brain completely, but surely we know by now that neurons are the things that do the basic work.   It isn't quite as clear as that. There has been a tendency, right since the famous McCulloch and Pitts paper of 1947, to see neurons as simple switches, but the more we know about them the less plausible that seems. Actually there is some highly complex chemistry involved. Personally, I would also say that the way neurons are organised looks very much like the sort of thing you might construct if you wanted to catch and amplify the effects of very small-scale events. One molecule - in the eye, one quantum, as Penrose points out - can make a neuron fire, and that can lead to a whole chain of other firings.  At the end of the day, the problem is that quantum physics just doesn't help. It doesn't give us any explanatory resources we couldn't get from normal physics.   That's too sweeping. There are actually several reasons, in my view, to think that quantum physics might be relevant to consciousness (although these are not Penrose's reasons). One is that the way two different states of affairs can apparently be held in suspense resembles the way two different courses of action can be suspended in the mind during the act of choice. A related point is the possibility that exploiting this kind of suspension could give us spectacularly fast computing, which might explain some of the remarkable properties of the brain. Another is the special role of observation - becoming conscious of things - in causing the collapse of the wavefunction. A third is that quantum physics puts some limits on how precisely we can specify the details of the world, which seems to militate against the kind of argument you were making earlier, about modelling the brain in total detail. I know all of these are open to strong objections: the real reason, as I've already said, is just that quantum physics is the most likely place to find the kind of new science which Penrose thinks is needed.    I don't see it. It seems to me inevitable that any new physics that may come along is going to be amenable to simulation on a computer - if it wasn't, it hardly seems possible it could be clear enough to be a reasonable theory. In other words, your mind is closed to any possibility except computationalism. Consciousness seems to me to be such an important phenomenon that I simply cannot believe it is something just 'accidentally' conjured up by a complicated computation... Read: "The Emperor's New Mind"  An essential text on the consciousness question, and contains a great deal of fascinating stuff. The foreword is by the late great Martin Gardner, and fans of his will find a similar combination of deep thought with clear and entertaining exposition here. "Shadows of the Mind " Similar ground is covered here, although in this case the details of Penrose's argument about the non-algorithmic nature of mathematical thought is uppermost, and hence the going is just a little harder. Still a very readable treatment of subjects which inevitably require a degree of thought and concentration to assimilate.  Some Links: Biographical details  - from the University of St Andrews site Critical paper and response  - a critical paper by Patricia Churchland with a response from Penrose and Hameroff. Psyche  - Symposium on 'Shadows of the Mind' in the on-line journal.

Penrose's New Clothes

 

The Road to Reality: A Complete Guide to the Physical Universe by Roger Penrose Jonathan Cape, London, 2004, 1094 pages, £30 ISBN 0-224-04447-8

Blogger Ref http://www.p2pfoundation.net/Multi-Dimensional_Science



Bearing in mind the classic fairy tale by Hans Christian Andersen "The Emperor's New Clothes", I wouldn't be surprised if someone says, loud enough for the others to hear: "Look at the Penrose's new book. It's beautiful!" At first glance, the book does look stunning, and once we open it, we cannot miss the following statements printed on the inside flap of the paper sleeve: "The Road to Reality is the most important and ambitious work of science for a generation. It provides nothing less than a comprehensive account of the physical universe and the essentials of its underlying mathematical theory. (…) In a single work of colossal scope one of the world’s greatest scientists has given us a complete and unrivalled guide to the glories of the universe which we all inhabit."It is not known who is the author of these statements, however. This is the first shocking omission.It seems to me that Roger Penrose’s "The Road to Reality: A Complete Guide to the Laws of the Universe" is a very personal book, written by Penrose, and for Penrose. The first sixteen chapters are devoted to a galloping outline of the "underlying mathematical theory", but the author has failed to mention whether such an outlook has been helpful to any undergraduate or graduate student. I suspect that Penrose has not tested his mathematical outlook on anyone but himself. In my opinion, there are even more serious and alarming omissions. Penrose uses a well-known three-world diagram to present "the three forms of existence" (mental, physical, and Platonic mathematical worlds; cf. Fig. 1.3, pp. 17-18), but does not mention the proposition due to Leibniz (Monadology, 78) about ONE entity which emanates two complementary forms of existence, material and mental. Speaking about Leibniz, he discusses the notion of ‘dx’ as denoting an ‘infinitesimal quantity’ (p. 230), but fails to mention the paradoxes which we encounter by modeling ‘dx’ with a mathematical "point" (recall Zeno’s paradoxes and Thompson's lamp paradox of 1954, after James Thompson). Which brings us to the most important part of Penrose’s book, dealing with his insights and speculations in quantum physics and Einstein’s theory of gravity. Let’s recall some well-known facts. There is a profound mystery in our universe: 96 per cent of it is of some unknown nature, called ‘dark matter’ and ‘dark energy’. To quote from T. Reichhardt, Nature 421, 777 (20 February 2003): "The new data imply an age for the Universe of 13.7 billion years, and a distribution of mass and energy in which 4% of the Universe is normal matter (atoms), 23% is dark matter, and 73% is dark energy". The very first question regarding the so-called dark energy, which supposedly drives the expansion of the spacetime along the cosmological time arrow with constant acceleration, is about its physical substrate: energy of what? Let’s call it ‘energy of X’, and formulate the next, and perfectly obvious, questions: I look at my wristwatch and record an instant, t₁ . At some later time  t₂ , say, t₂ - t₁ = 8 min, the spacetime will be expanded by the dark energy of X. Where is the pool of X located at the first instant,  t₁ , and what kind of time would you attribute to it, relative to  t₁ ?It shouldn’t be surprising that we encounter immense difficulties. Penrose does acknowledge that "gravitational energy is a genuinely non-local quantity" (p. 467; see also Ch. 19.5), but provides only an example of mass-energy conservation law defined at ‘null infinity’, under the stipulations that (i) the spacetime is "asymptotically flat", and (ii) some hypothetical "gravitational waves" were emitted from some physically unrealistic "isolated system", "in the limit when the system becomes completely spatially isolated from everything else" (Fig. 19.10, p. 468). (This "isolated system" sounds like astrology to me, but maybe I’m wrong.) Also, Penrose does not make any effort to compare the two kinds of non-localities, from Einstein’s gravitational energy and the holistic nature of quantum entanglement (p. 407 and Ch. 23; see also pp. 667-668). He only explains the reason why he has been unable to provide the actual dynamics of the "reduction of state" (p. 855): there is a fundamental conflict with Einstein’s principle of general covariance (p. 850). Fair enough. However, in the discussion of Einstein’s cosmological constant [lambda], which is the first issue we address to clarify the puzzle of ‘dark energy of X’, Penrose writes the following (p. 777): "Thus, any non-constancy in [lambda] would have to be accompanied by a compensating non-conservation of the mass-energy of the matter. It is certainly much more theoretically comfortable to have [lambda] constant – as indeed consistent with observation".It is certainly "theoretically comfortable" to bypass the so-called coincidence problem (cf. N. Straumann, gr-qc/0208027), but only in a book reflecting the personal inclinations of the author. Had Roger Penrose chosen a different title for his book (say, "The Road to Reality: A Personal, Biased, and Incomplete Guide to the Laws of the Universe"), I wouldn’t have any objections to it. To sum up, I would recommend Penrose’s book mostly to graduate students in mathematical physics (a good exercise is suggested on p. 319), provided they have previously studied H. Weyl’s "Space-Time-Matter" (Fourth Edition, Dover Publications, New York, 1951, p. 270), as well as two fundamental papers, by T. Levi-Civita (Rendiconti della Reale Accademia dei Lincei, vol. 26, 381 (1917); English translation in A. Loinger, physics/9906004), and again by H. Weyl (Amer. J. Math. 66 (1944) 591; see Appendix in A. Loinger, physics/0407134). Then perhaps they will enjoy Claus Kiefer's "Quantum Gravity" (Oxford University Press, 2004, 320 pages; ISBN: 0-19-850687-2). It’s being written for graduate students, with great clarity and professional scrutiny. Perhaps the road to quantum gravity should include the physics of the human brain, particularly its amazing self-acting faculty: we think about the brain, with the brain. Perhaps this could be a hint to the nature of gravitational field: it is not only nonlinear in its own coupling, but also makes all matter fields self-interacting. Our mind is not material, and yet it can interact with its brain, just as the geometry of matter is not material but does interact with all physical fields: "Space acts on matter, telling it how to move. In turn, matter reacts back on space, telling it how to curve" (John Wheeler). However, the intrinsic "timing" of this bi-directional talk is missing, and I anticipate a "fundamental conflict with Einstein’s principle of general covariance" (p. 850), too. We can probably find comfort in the last lecture by Albert Einstein (Princeton University, April 14, 1954, according to notes taken by J. A. Wheeler): "The representation of matter by a tensor was only a fill-in to make it possible to do something temporarily, a wooden nose in a snowman." As Roger Penrose put it (p. 1045), "Perhaps what we mainly need is some subtle change in perspective – something that we all have missed…" Here I agree with Sir Roger. Only the change in perspective may not be subtle.
 
  D. Chakalov
August 10, 2004




Ref http://www.god-does-not-play-dice.net/Penrose.html#book

The Emperor's New Mind

From Wikipedia, the free encyclopedia

Jump to: navigation, search

The Emperor's New Mind: Concerning Computers, Minds and The Laws of Physics

Author	Roger Penrose
Country	England
Language	English
Genre	Artificial Intelligence
Publisher	Oxford University Press
Publication date	November 9, 1989
Pages	480
ISBN	ISBN 0-19-851973-7 (first edition, hardcover)
OCLC	19724273
Dewey Decimal	006.3 20
LC Class	Q335 .P415 1989

The Emperor's New Mind: Concerning Computers, Minds and The Laws of Physics is a 1989 book by mathematical physicist Sir Roger Penrose.
Penrose argues that human consciousness is non-algorithmic, and thus is not capable of being modeled by a conventional Turing machine-type of digital computer. Penrose hypothesizes that quantum mechanics plays an essential role in the understanding of human consciousness. The collapse of the quantum wavefunction is seen as playing an important role in brain function.
The majority of the book is spent reviewing, for the scientifically minded layreader, a plethora of interrelated subjects such as Newtonian physics, special and general relativity, the philosophy and limitations of mathematics, quantum physics, cosmology, and the nature of time. Penrose intermittently describes how each of these bears on his developing theme: that consciousness is not "algorithmic". Only the later portions of the book address the thesis directly.
Penrose states that his ideas on the nature of consciousness are speculative, and his thesis is considered erroneous by experts in the fields of philosophy, computer science, and robotics.^[1][2][3]
Following the publication of this book, Penrose began to collaborate with Stuart Hameroff on a biological analog to quantum computation involving microtubules, which became the foundation for his subsequent book, Shadows of the Mind: A Search for the Missing Science of Consciousness.
The Emperor's New Mind attacks the claims of artificial intelligence using the physics of computing: Penrose notes that the present home of computing lies more in the tangible world of classical mechanics than in the imponderable realm of quantum mechanics. The modern computer is a deterministic system that for the most part simply executes algorithms. Penrose shows that, by reconfiguring the boundaries of a billiard table, one might make a computer in which the billiard balls act as message carriers and their interactions act as logical decisions. The billiard-ball computer was first designed some years ago by Edward Fredkin and Tommaso Toffoli of the Massachusetts Institute of Technology.
Penrose won the Science Book Prize in 1990 for this book.^[4]

See also[edit]

• Church–Turing thesis
• The Emperor's New Clothes
• Orchestrated objective reduction
• Quantum mind
• Shadows of the Mind
• Raymond Smullyan
• Alan Turing
• Turing test

References[edit]

1. Jump up ^ L. J. Landau (1997), "Penrose's Philosophical Error", ISBN 3-540-76163-2 http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html
2. Jump up ^ Various critical reactions to be found in Behavioral and Brain Sciences vol. 13 #4 (1990), 643–705, and vol. 16 #3 (1993), 611–622, e.g. M. Davis "How subtle is Godel’s theorem? More on Roger Penrose"
3. Jump up ^ M. Davis (1995), "Is mathematical insight algorithmic", Behavioral and Brain Sciences, 13 (4), 659–60.
4. Jump up ^ Royal Society Winton Prize for Science Books: Previous winners. The Royal Society. Retrieved 12 March 2013.

[hide] v t e Works by Roger Penrose Books The Emperor's New Mind (1989) Shadows of the Mind (1994) The Road to Reality (2004) Cycles of Time (2010) Coauthored books The Nature of Space and Time (with Stephen Hawking) (1996) The Large, the Small and the Human Mind (with Abner Shimony, Nancy Cartwright and Stephen Hawking) (1997) White Mars or, The Mind Set Free (with Brian W. Aldiss) (1999) Academic works Techniques of Differential Topology in Relativity (1972) Spinors and Space-Time: Volume 1, Two-Spinor Calculus and Relativistic Fields (with Wolfgang Rindler) (1987) Spinors and Space-Time: Volume 2, Spinor and Twistor Methods in Space-Time Geometry (with Wolfgang Rindler) (1988)

Retrieved from "http://en.wikipedia.org/w/index.php?title=The_Emperor%27s_New_Mind&oldid=627102719"

Categories:

• 1989 books
• Physics books
• Science books
• Philosophy of mind literature
• Consciousness studies
• Philosophy of artificial intelligence
• Quantum mind
• Mathematics books
• Works by Roger Penrose

Shadows of the Mind

From Wikipedia, the free encyclopedia/ Blogger Ref http://www.p2pfoundation.net/Multi-Dimensional_Science

Jump to: navigation, search

Shadows of the Mind: A Search for the Missing Science of Consciousness

Author	Roger Penrose
Cover artist	Joel Nakamura
Country	USA
Language	English
Subject	Artificial intelligence, mathematics, & quantum mechanics
Publisher	Oxford University Press, 1st edition
Publication date	1994 (1st ed.)
Media type	Hardback
Pages	457 pages
ISBN	ISBN 0-19-853978-9 (1st ed.)
OCLC	30593111
Dewey Decimal	006.3 20
LC Class	Q335 .P416 1994
Preceded by	The Emperor's New Mind: Concerning Computers, Minds and The Laws of Physics

Shadows of the Mind: A Search for the Missing Science of Consciousness is a 1994 book by mathematical physicist Roger Penrose, and serves as a followup to his 1989 book The Emperor's New Mind: Concerning Computers, Minds and The Laws of Physics.
Penrose hypothesizes that:

• Human consciousness is non-algorithmic, and thus is not capable of being modelled by a conventional Turing machine-type of digital computer.
• Quantum mechanics plays an essential role in the understanding of human consciousness, specifically, he believes that microtubules within neurons support quantum superpositions.
• The objective collapse of the quantum wavefunction of the microtubules is critical for consciousness.
• The collapse in question is physical behaviour that is non-algorithmic and transcends the limits of computability.
• The human mind has abilities that no Turing machine could possess because of this mechanism of non-computable physics.

Contents

 [hide] 

• 1 Argument
  • 1.1 Mathematical thought
  • 1.2 Objective reduction
  • 1.3 Orchestrated objective reduction
• 2 Criticism
  • 2.1 Gödelian argument and nature of human thought
  • 2.2 Microtubule hypothesis
• 3 See also
• 4 Notes and references

Argument[edit]

Mathematical thought[edit]

Main article: Orch-OR § The Penrose–Lucas argument

In 1931, the mathematician and logician Kurt Gödel proved his incompleteness theorems, showing that any effectively generated theory capable of expressing elementary arithmetic cannot be both consistent and complete. Further to that, for any consistent formal theory that proves certain basic arithmetic truths, there is an arithmetical statement that is true, but not provable in the theory. The essence of Penrose's argument is that while a formal proof system cannot, because of the theorem, prove its own incompleteness, Gödel-type results are provable by human mathematicians. He takes this disparity to mean that human mathematicians are not describable as formal proof systems and are not running an algorithm, so that the computational theory of mind is false, and computational approaches to artificial general intelligence are unfounded. (The argument was first given by Penrose in The Emperor's New Mind (1989) and is developed further in Shadows of The Mind. An earlier version of the argument was given by J. R. Lucas in 1959.^[1] For this reason, the argument is sometimes called the Penrose-Lucas argument).

Objective reduction[edit]

Main article: Penrose interpretation

Penrose's theory of Objective Reduction is a prediction of Sir Roger Penrose about the relationship between quantum mechanics and general relativity. Penrose proposes that a quantum state remains in superposition until the difference in space-time curvature reaches a significant level.^[2] This idea is inspired by quantum gravity, because it uses both the physical constants and . It is an alternative to the Copenhagen interpretation, which posits that superposition fails under observation, and the many-worlds hypothesis, which states that each alternative outcome of a superposition becomes real in a separate world.^[3]
Penrose's idea is a type of objective collapse theory. In these theories the wavefunction is a physical wave, which undergoes wave function collapse as a physical process, with observers playing no special role. Penrose theorises that the wave function cannot be sustained in superposition beyond a certain energy difference between the quantum states. He gives an approximate value for this difference: a Planck mass worth of matter, which he calls the "'one-graviton' level".^[2] He then hypothesizes that this energy difference causes the wave function to collapse to a single state, with a probability based on its amplitude in the original wave function, a procedure taken from standard quantum mechanics.

Orchestrated objective reduction[edit]

Main article: Orch-OR

When he wrote his first consciousness book, The Emperor's New Mind in 1989, Penrose lacked a detailed proposal for how such quantum processes could be implemented in the brain. Subsequently, Hameroff read The Emperor's New Mind and suggested to Penrose that certain structures within brain cells (neurons) were suitable candidate sites for quantum processing and ultimately for consciousness.^[4][5] The Orch-OR theory arose from the co-operation of these two scientists and was developed in Penrose's second consciousness book Shadows of the Mind (1994).^[6]
Hameroff's contribution to the theory derived from studying brain cells (neurons). His interest centred on the cytoskeleton, which provides an internal supportive structure for neurons, and particularly on the microtubules,^[5] which are the important component of the cytoskeleton. As neuroscience has progressed, the role of the cytoskeleton and microtubules has assumed greater importance. In addition to providing a supportive structure for the cell, the known functions of the microtubules include transport of molecules, including neurotransmitter molecules bound for the synapses, and control of the cell's movement, growth and shape.^[5]

Criticism[edit]

Gödelian argument and nature of human thought[edit]

Penrose's views on the human thought process are not widely accepted in scientific circles (Drew McDermott,^[7] David Chalmers^[8] and others). According to Marvin Minsky, because people can construe false ideas to be factual, the process of thinking is not limited to formal logic. Further, AI programs can also conclude that false statements are true, so error is not unique to humans. Another dissenter, Charles Seife, has said: "Penrose, the Oxford mathematician famous for his work on tiling the plane with various shapes, is one of a handful of scientists who believe that the ephemeral nature of consciousness suggests a quantum process."
In May 1995, Stanford mathematician Solomon Feferman attacked Penrose's approach on multiple grounds, including the mathematical validity of his Gödelian argument and theoretical background.^[9] In 1996, Penrose offered a consolidated reply to many of the criticisms of "Shadows".^[10]
John Searle criticises Penrose's appeal to Gödel as resting on the fallacy that all computational algorithms must be capable of mathematical description. As a counter-example, Searle cites the assignment of license plate numbers to specific vehicle identification numbers, to register a vehicle. According to Searle, no mathematical function can be used to connect a known VIN with its LPN, but the process of assignment is quite simple—namely, "first come, first served"—and can be performed entirely by a computer.^[11]

Microtubule hypothesis[edit]

Penrose and Stuart Hameroff have constructed the Orch-OR theory in which human consciousness is the result of quantum gravity effects in microtubules. However, in 2000, Max Tegmark calculated in an article he published in Physical Review E^[12] that the time scale of neuron firing and excitations in microtubules is slower than the decoherence time by a factor of at least 10¹⁰. Tegmark's article has been widely cited by critics of the Penrose-Hameroff hypothesis. The reception of the article is summed up by this statement in his support: "Physicists outside the fray, such as IBM's John Smolin, say the calculations confirm what they had suspected all along. 'We're not working with a brain that's near absolute zero. It's reasonably unlikely that the brain evolved quantum behavior', he says."^[13]
However, in 2007, Gregory S. Engel claimed that all arguments concerning the brain being "too warm and wet" have been dispelled, as multiple "warm and wet" quantum processes have been discovered.^[14][15]

See also[edit]

• The Emperor's New Mind
• Computational theory of mind
• Quantum mind
• Alan Turing, creator of the Turing test
• Orch-OR

Notes and references[edit]

1. Jump up ^ Minds, Machines and Gödel
2. ^ Jump up to: ^{a b} Penrose, Roger (1999) [1989], The Emperor's New Mind (New Preface (1999) ed.), Oxford, England: Oxford University Press, pp. 475–481, ISBN 0-19-286198-0 
3. Jump up ^ 'Folger, Tim. "If an Electron Can Be in 2 Places at Once, Why Can't You?" Discover. Vol. 25 No. 6 (June 2005). pp33-35.
4. Jump up ^ Hameroff, S.R., and Watt, R.C. (1982). "Information processing in microtubules". Journal of Theoretical Biology 98 (4): 549–561. doi:10.1016/0022-5193(82)90137-0. PMID 6185798. 
5. ^ Jump up to: ^{a b c} Hameroff, S.R. (1987). Ultimate Computing. Elsevier. ISBN 0-444-70283-0. 
6. Jump up ^ Penrose, Roger (1989). Shadows of the Mind: A Search for the Missing Science of Consciousness. Oxford University Press. p. 457. ISBN 0-19-853978-9. 
7. Jump up ^ Penrose is Wrong Drew McDermott, PSYCHE, 2(17), October 1995
8. Jump up ^ Minds, Machines, And Mathematics – A Review of Shadows of the Mind by Roger Penrose David J. Chalmers, PSYCHE 2(9) June 1995
9. Jump up ^ Penrose's Gödelian argument (PDF) Feferman, PSYCHE 2(7) May 1995
10. Jump up ^ Beyond the Doubting of a Shadow – A Reply to Commentaries on Shadows of the Mind Roger Penrose, PSYCHE, 2(23), January 1996
11. Jump up ^ Searle, John R. The Mystery of Consciousness. 1997. ISBN 0-940322-06-4. pp 85–86.
12. Jump up ^ Tegmark, M. (2000). "Importance of quantum decoherence in brain processes". Phys. Rev. E 61 (4): 4194–4206. arXiv:quant-ph/9907009. Bibcode:2000PhRvE..61.4194T. doi:10.1103/PhysRevE.61.4194. 
13. Jump up ^ Tetlow, Philip (2007). The Web's Awake: An Introduction to the Field of Web Science and the Concept of Web Life. Hoboken, NJ: John Wiley & Sons. p. 166. ISBN 978-0-470-13794-9. 
14. Jump up ^ Engel, Gregory S.; Calhoun, Tessa R., Read, Elizabeth L., Ahn, Tae-Kyu, Mančal, Tomáš, Cheng, Yuan-Chung, Blankenship, Robert E., Fleming, Graham R. (12 April 2007). "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems". Nature 446 (7137): 782–786. Bibcode:2007Natur.446..782E. doi:10.1038/nature05678. PMID 17429397. Retrieved 7 December 2011.  Cite uses deprecated parameters (help)
15. Jump up ^ Panitchayangkoon, Gitt; Dugan Hayes; Kelly A. Fransted; Justin R. Caram; Elad Harel; Jianzhong Wen; Robert E. Blankenship; Gregory S. Engel (6 July 2010). "Long-lived quantum coherence in photosynthetic complexes at physiological temperature.". Proceedings of the National Academy of Sciences 107 (28). doi:10.1073/pnas.1005484107. PMC 2919932. PMID 20615985. 

• This article includes text originally by Philip Dorrell which is licensed under the GFDL

[hide] v t e Works by Roger Penrose Books The Emperor's New Mind (1989) Shadows of the Mind (1994) The Road to Reality (2004) Cycles of Time (2010) Coauthored books The Nature of Space and Time (with Stephen Hawking) (1996) The Large, the Small and the Human Mind (with Abner Shimony, Nancy Cartwright and Stephen Hawking) (1997) White Mars or, The Mind Set Free (with Brian W. Aldiss) (1999) Academic works Techniques of Differential Topology in Relativity (1972) Spinors and Space-Time: Volume 1, Two-Spinor Calculus and Relativistic Fields (with Wolfgang Rindler) (1987) Spinors and Space-Time: Volume 2, Spinor and Twistor Methods in Space-Time Geometry (with Wolfgang Rindler) (1988)

Retrieved from "http://en.wikipedia.org/w/index.php?title=Shadows_of_the_Mind&oldid=620087456"

Categories:

• 1994 books
• Physics books
• Science books
• Cognitive science literature
• Consciousness studies
• Quantum mind
• Works by Roger Penrose