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Roger Penrose Says Physics Is Wrong, From String Theory to Quantum Mechanics (discovermagazine.com)
129 points by ColinWright on May 4, 2012 | hide | past | web | favorite | 109 comments

Of course it's wrong; all scientific theories are provisional approximations, and the conflicts between quantum mechanics and general relativity are well known.

The hard part is proposing an alternative theory that fits all the known evidence. Quantum mechanics and general relativity both match a ton of observations; anything that is going to replace them will need to at least match the same set of evidence at least as well.

Put another way--when one theory replaces another, it must be fully contain the previous theory. General relativity, when applied to everyday human experience (i.e. not super fast, super big, super heavy), produces Newton's law of gravity.

Personally I think the next step in scientific understanding is in information theory. It has the possibility of unifying chaos theory, computer science, physics, and biology. I think this is how we'll develop an description of consciousness for example. We've already seen some preliminary reports that information theory can reproduce gravitation theory for instance.


Roger Penrose believes quantum mechanics will fail long before it conflicts with general relativity, which is a bold claim. In addition, the conflict between general relativity and quantum mechanics is popularly overstated. My understanding is that no one knows yet whether the non-renormalizability of gravity in QFT near the Planck scale is necessarily a sign that the theory breaks, rather than just a problem with perturbation theory. It's conceivable that non-perturbative effects will save the day.

"Put another way--when one theory replaces another, it must be fully contain the previous theory."

This is certainly our hope and desire, but I think you're taking it too far. For example, if we took what you're saying as some sort of prescriptive rule that is improper to violate, we wouldn't have found quantum theory in the first place!

So I think it's important to allow proliferation of theories that explain portions of the evidence, because that explores the space in which we might hope to find a unifying theory.

Can you recommend a good introduction to the theory of conciousness, especially one that relates it to physics and the Universe? I've seen the term "consciousness" in relation to these topics used before, but have a hard time getting information beyond "human conciousness" and how the brain works. Definitionally.

> Of course it's wrong; all scientific theories are provisional approximations

There's always a margin for experimental error, but I think scientific theories are much broader than just "provisional approximations". I think the key here is that they are conceptual models that we use to explain the phenomenon around us, which we then affirm by demonstrating their accuracy to within a certain margin. It's very much a reflection on us - the perceivers - as much as it is the phenomena themselves.

> The hard part is proposing an alternative theory that fits all the known evidence. ... Put another way--when one theory replaces another, it must be fully contain the previous theory.

Early astronomy didn't "fully contain" the astrology of the time. Same for chemistry vs alchemy.

I'm not saying that a replacement for quantum mechanics and general relativity will "contain less", just that it wouldn't be the first time if it did.

i agree on information. i see occasional references and try to keep track of them, but i have never found a good blog or similar to follow. do you know of anything?

various random links: http://www.scottaaronson.com/democritus/lec9.html http://perimeterinstitute.ca/personal/cfuchs/Oviedo.pdf http://carnap.umd.edu/philphysics/bub_courses.html

You seem to be engaging more with the headline writer than with Penrose. They're both, perhaps, wrong, but Penrose is wrong in a far more interesting way.

Penrose doesn't just think quantum mechanics is wrong in the sense that it can't quite be lined up with general relativity, he thinks that quantum mechanics and consciousness are the same problem and that we can't understand one without the other. Now, to me this smacks a bit of the old argument:

1. I don't understand baseball

2. I don't understand women

3. Therefore, women and baseball must be related somehow

but he has slightly better reasons than that for believing what he does.

Consciousness and quantum mechanics are both fascinating problems to understand; personally I don't think they're the same problem but I don't mind if some smart folks want to think carefully about the possibility that they are.

If consciousness is a property of quantum mechanics then this ought to be at least partially measurable. All you have to do is to construct an intelligent non-quantum computer and ask it "Hey, are you conscious?" Of course this doesn't really help you, because what if the computer just thinks it's conscious but doesn't have real consciousness the way we do? What would this even mean? What is it like to be an intelligent but non-conscious mind? In my own opinion the question is meaningless which is why I think consciousness is some kind of inevitable emergent property of intelligent systems; but of course there's thousands of philosophers out there tackling this very question so I won't pretend to have any original thoughts on it.

I don't understand why some researchers are so quick to blame our failure to understand consciousness on the fact that consciousness is a quantum phenomenon. I was under the impression that we're still nowhere near fully understanding the brain even from a classical perspective.

We understand parts of the brain classically. There are parts of the brain that operate like organic circuits of boolean operators.

There is no quantum level magic.

A large slab of Penrose's book The Emperor's New Mind is, if I recall correctly, devoted to describing how certain structures of the brain just might have some quantum mechanics involved. I don't recall the details and I don't know whether it's all been disproven as we understand the brain better.

I really have to read this book, since I've heard this sort of thing before and it never made sense to me why this matters. I mean, of course quantum mechanics is involved in the operations of the brain; it's involved in the operations of literally every single aspect of physical reality except gravity. People say things like "the brain uses quantum mechanics" and I think "yes, but so does Coca Cola, erosion, and rust."

I think part of it is conflating a few different views:

1.) The brain is some sort of quantum computer (almost certainly false)

2.) The brain as a physical system is somehow sensitive to quantum uncertainty, for example, in the probability of a neuron firing when stimulated. We might hypothesize that this explains our subjective experience of free will: we might be able to chose our world in the sense of the many worlds interpretation, but the worlds we're limited to are just different patterns of deterministic activity within the brain. This is very speculative, but appealing, and I think it deserves more consideration.

Quantum biology is making inroads in a few areas, such as in the mechanism of chlorophyll. I would not be surprised if it starts popping up in bits of neurology, even in the parts that we currently understand classically.

There's a huge difference between molecule-scale quantum chemical phenomena (as in photosynthesis) and quantum computation. Finding the former in the brain would be very cool, but it wouldn't be terribly surprising or revolutionize cognitive science the way the latter would.

It is thought that photosynthesis uses quantum computation to determine how to move energy internally within a cell. http://www.rsc.org/chemistryworld/Issues/2007/May/Photosynth...

Okay, so, let me try to enumerate these.

(1) The hardest part of quantum mechanics to understand is intimately tied to our nature as subjects. Quantum mechanics is an entirely deterministic theory about waves in superpositions which even explains how, why, and when it disappears and averages out into classical probabilities. Except it doesn't tell you why we don't see your television as 50% in your bedroom and 50% in your living room. For that we start to invent things like many universes, half of which have a TV in your bedroom and half of which have a TV in your living room -- or Penrose's idea that perhaps some magical interaction not yet observed forces something as large as a TV to "make up its mind" due to its gravitational warpings. It's just the fact that your subjective experience doesn't see this TV as half in one place, and half in another, where the wavefunction description fails. The rest is clean, deterministic, and precise.

(2) The second hardest part of consciousness to understand is something we basically take for granted in the hardest part of quantum mechanics. Compatibilist theories of free will make you feel warm and fuzzy but they don't really feel like they address the fundamental mystery: How can a deterministic system be said to "choose" something when that's a fuzzy airy-fairy notion and the actual outcome was written down in the book of history 13.7 billion years ago, full stop? Why do we feel like we've got a million options open when in fact this is false, false, utterly false, moronically-out-of-touch-with-reality crazy false? But in quantum mechanics, the idea that a quantum system has many options open, and can even "sniff around" over the whole space, and that it might make a difference if it does or not -- these things are very acceptable even if you take a deterministic approach to wavefunction collapse. You could maybe in principle go from "warm and fuzzy but I don't get it" to "weird and fuzzy but I think I get it," if the brain is intrinsically quantum.

(3) The hardest problem of consciousness -- how we reconcile our touchy-feely alive experience of red with a machine's cold unemotional ones and zeros -- is very easy to solve by saying "we aren't a machine; subjectivity is something more than a program." In fact, since programs can carry out programs, if consciousness is mechanical we might well ask, how do you know that your brain isn't a different conscious process which happens to be carrying out your own conscious process, and might someday soon get bored and kill you out of its own boredom and desire to live authentically? (This absurdity is also at the heart of Searle's Chinese Rooom argument.) The problem is that machines are such a good model that we have no idea what to replace them with. If quantum systems could really feel in a way that machines really can't, this would solve the problem neatly.

(4) One minor problem in consciousness is about how I'm able to hear things as I am seeing them -- multithreading would suggest that we have multiple consciousnesses doing the separate tasks separately; multitasking would suggest that we switch between these things so fast that it gives an illusion that they all come together, but I can't really do both at once. Quantum mechanics offers a tantalizing hint; for example, in a superconductor, two electrons of opposite momentum "get together" to form a larger particle called a Cooper pair. (You're advised not to think too hard about how they "stay together" with opposite momenta, because It's All Just An Excitation Anyways.) That larger particle can even do something which electrons never can -- it can form a Bose-Einstein condensate: it can conduct current without resistance.

(5) Everybody who watches Star Trek wonders what would happen if someone accidentally forgot to dematerialize you before re-materializing you down on the planet -- which one would be the right "you"? Quantum systems cannot be cloned in this way. The closest we can get is to identically prepare a system -- i.e. take another baby with the same genetic code and give it all of the same life experiences, and kill the ones who don't make the same choices in the same order. Without one of those, you can't clone an arbitrary unknown system into two copies without measuring it and thus forcing it into a classical state. If consciousness is quantum, then the classical state is dead. But if consciousness is just a program, then we're faced with a much scarier situation: in the transporter, you will actually die, but that's okay, because we'll create an impostor who will sleep with your wife for you -- in other words, it's okay because we'll never know the difference, and you'll be dead.

Just in case you are serious, or people believe you're serious:

1) Quantum mechanics operates on the quantum level. Macro objects, while composed of countless quantum systems, and thus are the result of the quantum systems of probabilistic particles and waves collapsing and such, are just that: the result of the quantum systems. This isn't subjective experience; it's an underlying behavior baring forth a different level of behavior. Just as it's possible, but doesn't make sense to describe Tetris in terms of electrons flowing through copper and semiconductors, one can describe the quantum behavior of what the TV is constructed of, but that wouldn't relate a bit to the meaningful object you watch shows on.

2) Probability on the quantum scale has nothing to do with the brain making choices; even if understanding quantum mechanics turns out to be essential to understanding consciousness, the brain can't change the laws of physics; it can't decide that certain waveforms will collapse in a way that appeals to it. By the same token, if you're a rational thinker, you'd understand that yes, if one develops an accurate enough model of the universe, the base stuff it's made of, you can predict the future. That's literally what science is; developing models which will predict how certain systems behave in a given condition. However going back to bullet 1, the concept of "free will" has nothing to do meaningfully with the base stuff of the universe. It's technically possible to be described in such terms, but that's not where decisions happen.

3) Again, going back to rationality; humans are part of the same deterministic system, operating under the same deterministic rules as everything else that exists. Sure subjectivity feels different than what we imagine a computer's (non)experience to be, but that's just a result of the conscious process (and the fact that most people don't empathize with machines).

4) I honestly don't even understand what you're trying to say here :\

5) This has nothing to do with anything at all but... you aren't the atoms that comprise you. You aren't even the -cells- that comprise you. "Seven years from now your body will be made of entirely different cells than it is now" and all that.

1) The problem that quantum mechanics has with consciousness is that you can connect macro objects (a cat) with the quantum effects on the quantum level (detector), so that we should actually observe quantum effects on macro objects. That's why Schrödinger's Cat is a paradox.

2) You can't really predict the future of a non-trivial closed system from within the closed system itself - no matter how you would "calculate" the future, you would never be able to include the state of your calculator/computer into the prediction (perfect compression does not exist). I.e., if I make a machine that predicts the future, I know the future, I can act to change it, so the future is different... and the machine does not predict the future, really.

In a way, the universe is the computer that is calculating its own future all the time.

> In a way, the universe is the computer that is calculating its own future all the time.

Reminds me of this book:


> Is the universe actually a giant quantum computer? According to Seth Lloyd—Professor of Quantum-Mechanical Engineering at MIT and originator of the first technologically feasible design for a working quantum computer—the answer is yes. This wonderfully accessible book illuminates the professional and personal paths that led him to this remarkable conclusion.

I agree with most of what you said except "Seven years from now your body will be made of entirely different cells than it is now". Some neurons in the brain are never replaced http://askanaturalist.com/do-we-replace-our-cells-every-7-or... (couldn't find a better reference)

Maybe, but still their atoms are always on the move...

(1) There is no firm distinction between the "quantum level" and the rest of our universe; a "Heisenberg cut" needs to be placed, but where it occurs doesn't matter. And quantum mechanics is multiparticle, so rather than "countless quantum systems," these "macro objects" are a quantum system -- just one. There is a wavefunction for the universe, in principle, if you allow the clean deterministic unitary part of QM to do its thing.

But the quantum behavior does really matter. The clean part of QM says that if there's an accumulation of events which would transfer my TV into my bedroom with probability 50%, my TV is described by the state matrix ½ |L><L| + ½ |B><B|, where |B> is its state in my bedroom and |L> is its state in my living room.

But we don't see that state. We see |L> or we see |B>. That is the "hardest part" of quantum mechanics, where one insists that the above superposition describes many worlds or that there is a nonunitary wavefunction collapse or whatever.

(2) I don't require that the brain change the laws of physics or decide that certain waveforms collapse in any particular way. However, for reference, quantum mechanics does work that way, so get used to it. A system "over here" can indeed "decide" how a system "over there" will collapse.

If I have photons over here in a fiber-optic cable, I can perform a measurement which will change the result of a double-slit experiment over there. I can choose whether the people over there will see an interference pattern or not. In fact, I can choose whether it will happen after their detectors have already measured their photons. We've done this experiment, it has been confirmed, and if it weren't confirmed, QM would just be flat out wrong. [Theory details: start with (|00> + |11>) ⊗ (|0> + |1>), apply a CNOT from qubit 3 to qubit 2, then choose to measure qubit 1 in either the |0>, |1> basis or the |0> + |1>, |0> − |1> basis to destroy or restore the interference pattern at qubit 3. It's called a "delayed-choice quantum eraser."]

We gave up that very sentence, "if one develops an accurate enough model of the universe, the base stuff it's made of, you can predict the future", with the advent of quantum mechanics -- at least, in the way I think you intend it. Hey, here's a nice quantum system, it's in the state |0> + |1>. You measure it in the computational basis. No matter how accurate your model is, you cannot predict which one comes out. If you could, you could do experiments to prove that nature was self-contradictory.

(3) The problem is precisely that the "results of the conscious process" don't appear to be mechanical, such that we can't empathize with machines. It's not just "we don't," but that machines are so precisely understood, and so simple, that you would have to invent a "ghost in the machine" and believe in weird supernatural crap to have them really feel anything. Hell, you probably think, for all your talk of rationality, that I really believe in ghosts -- and it's for precisely this reason. Machines seem to require a "ghost" inside them to feel.

What I want to say is different. If this supposition is correct, then applying it back to our own case poses a trilemma. Either (a) we don't really feel anything, or (b) we are not machines, or (c) we're stuck with weird supernatural crap. Of these three, (b) is the "easy way out;" abandon functionalism. It comes with its own problems about what we replace it with; functionalism is not easily replaced. There is an alternative (d) which is to not take the problem seriously, which many influential philosophers including Dan Dennett have made a reasonable option, but it seems unsatisfyingly to fall into the attitudes of (a) and (c) when actually practised.

(4) Quantum systems sometimes form higher-order excitations which escape the parallel and the serial. Electrons in parallel only flow with resistance. Electrons in series also only flow with resistance. A Cooper pair is a two-electron excitation which flows without resistance, even though its constituent electrons could only flow with resistance. It requires a higher-order description. That is very rare in mechanics.

(5) Take it one step further: classically, you aren't even the pattern of atoms that comprise you. That's what the Star Trek example proves. We could create two copies of this pattern classically, and there would suddenly be two distinct people in the universe. If someone pointed a gun at you and said, "hey, we've got to kill you, we created this identical doppelganger of you down on the planet, and now we're convinced that he's the real you," that would seem awfully disturbing to anyone. The only reason they go along with it in Star Trek is because we kill them before they can react.

But quantum mechanics offers something fundamentally different. You could be the quantum pattern. Or, at least, the Star Trek thought experiment wouldn't suffice to disprove it. That's why one might be hopeful that there is something quantum about mind.

> If quantum systems could really feel in a way that machines really can't, this would solve the problem neatly.

Late to the party, but pretty sure that's the situation we're in.

I'm not sure whether you're being satirical or whether you're explaining viewpoints other people or whether you're representing your own opinion. In response,

(1) It's deterministic w.r.t. the wave functions, but you can't really measure wave functions, you can only measure classical things like momentum or energy. (A measurement is actually an interaction, of course.) If you manage to give your TV a wave function 50% in the bedroom and 50% in the living room, then you decide to watch TV, you've just given yourself a wave function that is 50% in the bedroom and 50% in the living room, and 100% correlated with the TV's wave function. A wave function can't be measured because if you try to measure it, all you're really doing is correlating yourself with the wave function. So the real problem is that it's hard to reconcile our description of quantum mechanics with our experience of it. We describe QM as if we're outside Schroedinger's box, but we experience it from the inside. "Many worlds" describes it from the inside, but people don't like the many worlds interpretation exactly because it doesn't privilege one of the worlds as "real".

(2 & 3) Theories of free will were kind of worn out during the 17th century. Associating free will with quantum mechanics is kind of like shoving the Christian god into the cracks in evolutionary theory. There's little actual evidence that the brain takes advantage of QM decoherence on any scale worth appreciating. QM consciousness theories seem to have forgotten all of the progress during the age of enlightenment (David Hume, for example) wrt the definition of free will itself, and the phrasing of questions about free will in such a way that the discussion can be productive. The discussion about "qualia" in philosophical circles is equally unproductive. They call it "qualia" because they don't want to be called dualists, which is understandable.

(4) I'm not sure how this has anything to do with QM. The fact that our brain can do to things at once (which it demonstrably can) doesn't have anything to do with quantum mechanics. A car can do things that engines or wheels never can, but you'd never call it quantum.

(5) QM provides an "out" for objects which are cloned in the classical sense. In QM, there is no such thing as identity; two electrons (for example) are interchangeable. This means that if you prepare a classical clone of yourself but the two clones get mixed up, from a QM perspective the question of identity is meaningless. So if you say X is the clone and Y is the original and Y is dead, the labels "clone" and "original" are actually arbitrary and you could relabel X as the original and Y as the clone, so the clone is dead and the original is alive.

It's like you have a bucket of electrons, and you paint one of them orange so you can remember it later. Can't do that in QM. Even if you put one electron in a magnetic trap, there's no saying it doesn't swap places with one of the electrons still in your bucket. You can't paint one copy of yourself as "clone" and one as "original". Of course, two copies of a person (neither privileged over the other as "original") don't stay interchangeable for long.

Summary: Many philosophers and physicists alike have a warm and fuzzy conception of consciousness, but they're just being noisy and some folks are actually making progress. Warm and fuzzy is old news, and quantum is just the latest flavor of warm and fuzzy.

Daniel Dennett is an example of someone worth listening to about cognition, though I'm not saying he's right.

(1) I believe we just said the same thing. I agree. The hard part to understand is this "we describe it that way, we live it this way."

I should hasten to add that there is a slight problem with what you've said, called the "preferred basis problem," but for reasons which I don't want to get into here, I suspect that the unitary part of QM is also able to handle this to some extent.

(2/3) Even if theories of free will were worn out in the 17th century, the feeling of free will is pretty hard to ignore; it's just this feeling that there are many options open, that you have a meaningful choice between many possible futures. It's the same thing with qualia. Sure, you can get a lot out of red by saying "color is a 3-tuple of integers, the red predicate holds when, after subtracting out a background tuple, the first integer is larger than the other two by a substantial degree." We render all sorts of red images this way, we can build computers which identify red things in photographs, and so forth. But that's nothing like how we experience redness, and it's extraordinarily hard to express what we experience in that vocabulary.

(4) I guess I'm getting at the fact that the rules for composing quantum systems are much more important than the nondeterminism. To the extent that a car has multiple functions, like the ability to play music and the ability to drive somewhere, we generally either split it up into components acting in parallel, or split it up into components which act in sequence. Similarly, our conscious experience has many perceptual functions, but our core consciousness itself does not seem to be divisible in that way.

It's like the old crap about the "inner theater": seeing something ends up "displaying it on your inner screen". The big problem with the inner theater is that I still have to put a unified you inside of it; it isn't sufficient to separate your senses into different theaters. The composition rules for neurons just don't seem to create the unified whole that we experience.

(5) That sounds to me like a cop-out. Sure, we've got two electrons and we can't tell which is which. But you'd need a much more radical application of quantum mechanics to say "therefore, there is only one electron, really." You would still seem to be confronted with the fact that there are two consciousnesses which you can't distinguish -- you would just have the added problem that you can't tell which was the "original" who you are "supposed" to destroy, and which was the "copy" who is permitted to live, because that's an arbitrary distinction. But it would seem pretty radical to say that, even for their first moments of life, there is one consciousness spanning two bodies such that killing one of those bodies does not amount to murder. Even though you can't tell these two apart, it would seem straightforward on most functional theories of mind to say that there are indeed two of them.

I agree with your summary in general -- I especially like one comment by Searle on free will: "Now, I dread saying this because, Searle's Third Law is, whenever philosophers talk about quantum mechanics, what comes out is hot air at best. And by the way, that applies to a lot of the things physicists say about quantum mechanics too."

But I was specifically answering the question, "why are some researchers so quick to blame our failure to understand consciousness on quantum mechanics when we don't yet understand the classical parts of the brain?" I wasn't being satirical. Some of these points come from other people; some of them come from me, but the aggregate point is that it's not just a "latest" flavor of warm and fuzzy: it's a flavor of warm and fuzzy uniquely suited to the problem and disproportionately confirmed by experiment to be a key part of the universe's workings. I agree that it's so hard to reason about and understand quantum mechanics that mechanical models are not just "actually making progress", but are much easier to grapple with and prove or disprove.

It's like if you ask me why us physicists ever accepted string theory, with its difficult mathematics and huge multiplicity of dimensions and arbitrary geometries over those dimensions. We've been interested in it because gravity just falls out. In quantum mechanics, some of the building blocks of warm-and-fuzzy consciousness also just fall out. The problems with both string theory and quantum consciousness are that the rest of the model is considerably more difficult, even though the hard problems of today just seem to have a promising solution in those terms.

(3) My first problem is that most definitions for qualia I come across are back doors for dualism. The second problem is that I'm not sure there's any point to discussing purely subjective phenomena, since a discussion by its nature requires objective description.

(4) I don't have an inner theater, or if I do, I don't call it that. I have no idea what you are talking about. I don't know how this relates to a supposed indivisibility of consciousness (I mean... how are we supposed to know it's indivisible, since we lack the technology to cut a brain up and split it between bodies, not to mention the ethical issues? Am I supposed to trust you that it's indivisible? And what about the evidence from split-brain patients?)

If anything, I perceive a very disjointed self. For example, I feel like I have a distinctly single-threaded audio processor which can run independently of other functions. I can play the piano and talk, but not at the same time, and when I'm doing other things quietly I get free background music in my head without using an iPod. (I wouldn't call it inner theater.)

One reason we can't understand brains the way we understand cars is because the human brain is more complex by many orders of magnitude. So saying our "consciousness itself does not seem to be divisible in that way" is not very convincing. Microprocessors also don't seem to be divisible that way, but I've been assured that they are. And another important difference is the processes that designed cars, microprocessors, and brains. Part of the design criteria for cars and microprocessors is that they be easy to understand from understanding their parts. The car is designed to be understood.

A better comparison might be circuits designed using powerful optimization algorithms. A number of researchers have designed circuits using general purpose algorithms (such as genetic algorithms or swarm algorithms). For all but the most basic end goals, the circuits are practically incomprehensible. One researcher designed an analogue circuit to compute the cube of an input voltage, the resulting circuit defies understanding even though its components are clearly simple transistors. Another researcher made a signal analysis circuit using an FPGA, the resulting mess was a technological marvel but not something you could understand by sitting down and looking at the schematic. Given that the human brain is probably at least ten orders of magnitude more complicated, and created using an equally powerful optimization algorithm, there's no need to bring in quantum mechanics to explain why we don't understand the brain.

I think the major problem here is that too many people I meet have a narrow view of what it means to "understand" something. We're used to understanding (a) simple things, like thrown rocks and (b) complicated things for which there exists significant neural machinery to analyze, such as used car salesmen. As the things we try to understand become more and more complicated, the way we understand them becomes more and more like the Chinese room.

(5) Never said there was one electron. I said that the two electrons were interchangeable. I'm saying if you actually could clone someone to the extent necessary for Star Trek teleportation but forgot to dematerialize the original, then the label of "clone" and "original" is arbitrary. To me, it seems a cop out to assume that everyone agrees that one is the clone and one is the original.

Could you clarify what you mean by "confirmed by experiment" and "key part of the universe's workings"? The problem here is that the subject of the sentence is "it", so I'd like to know exactly what is confirmed by which experiment, please.

I'd also like to hear how consciousness just "falls out" of quantum mechanics, since my current understanding of Newtonian mechanics is sufficient to me. My theory is that I am a machine whose output is composed of deterministic parts and thermal noise, and I have yet to encounter experiences not explained by this theory.

As for string theory, its acceptance is hardly universal.

(3) To solve your first problem, remember that a definition is independent of its rhetorical purpose: that is, it tells you what we're talking about, but it does not force or "backdoor" any sort of metaphysics upon you. To solve your second problem, realize that you're committing a fallacy of equivocation: you're assuming that because something is ontologically subjective -- that is, it only makes sense in the context of a subject which experiences it -- that it is epistemically subjective -- that is, it can only be known, talked about, and reasoned about, by that subject who experiences it.

(4) Just look at the words you chose: "I perceive a very disjointed self." You chose the singular 'I' and the singular 'a self'. As a subject, you would like to be just one subject -- you would like all of the parallel efforts of your different neurons to identify one "me". But then suddenly you're astonished that all of your experiences must be described as unifying into a single whole, which can't simply be treated as separate senses, but come to you as part of one whole conscious experience. That in turn astonishes me.

If you believe Sperry's ideas on his split-brain patients, then yes, there is evidence that to divide the brain creates two conscious processes, simply by cutting off communication between parts of the brain. I guess you could add that to the list above, although it's not unique to quantum processes -- but if consciousness were caused by something quantum, then you would indeed expect that two systems which could no longer entangle could no longer form the same consciousness. But this is also true for certain classical systems, like computer networks, and might just as easily be described as a network effect -- which is why I didn't include it.

Re your discussion that cars are a bad example: I agree; I used them because (1) they were your example and (2) I never proposed that we "need to bring in quantum mechanics to explain why we don't understand the brain." Again, the question I was answering was, "why are some researchers so quick to blame our failure to understand consciousness on quantum mechanics when we don't yet understand the classical parts of the brain?" -- which presumes an agreement that yes, the brain is indeed something whose classical parts we don't yet understand. The question was "why might some people reasonably think that quantum mechanics will form an essential part of the theory?"

(5) It doesn't matter what people agree or disagree. What is pivotal about the Star Trek transporter case, what I am trying to articulate, is that it creates all sorts of difficult problems about identity. In particular, quantum consciousness theories, while often functionalist and materialist, see an opposition from much of what passes presently for materialist functionalism. This particular brand of materialist functionalism has certain philosophical problems, because they conceptualize consciousness as some sort of logical pattern or arrangement. So, for example, if a computer simulated a brain, even though we would say that there is no "brain" per se, presumably these people would say that there is nonetheless consciousness.

Now, the problems are diverse, and since I mentioned above the ontological/epistemic subjectivity distinction of Searle, I would like to raise that in the same articles Searle also mentions an observer-relative vs. observer-independent distinction: whether something is a computation depends on how you look at it, he points out -- but whether you are conscious should not depend on how I look at you.

That's not the Star Trek problem. The Star Trek problem comes instead, for me, from a book called Reasons and Persons by Derek Parfit -- it's relegated to part three of the book, but otherwise it's a good read, and you can skip to the chapter if you want without missing anything. There are an abundance of things which you might think "make you you," or more generally, make you the same person as you were five minutes ago, or even five years ago. But thinking about the Star Trek transporter, and one's visceral reactions to certain stories about imperfect transporters, tends to make many of these philosophically problematic. The problem is that even though there are two people who are qualitatively identical in the world, they are not "the same person" in the above sense. So the fact that you are "the same person" as someone five minutes ago would appear to not depend on any particular quality or aggregate of qualities. Qualities wouldn't make you who you are.

You've added, as I see it, that since the universe is quantum, even physical continuity can be made epistemically ill-defined if the replicas are sufficiently exact, but I don't think materialists would have a real problem with that.

But here's where a quantum approach could have a benefit: in a quantum theory of consciousness, qualities perhaps could make you who you are. The whole thought experiment crumbles if the device is not even in principle realizable, and that's precisely what quantum mechanics purports to offer.

(5b) The "it" is quantum mechanics.

(5c) First off that's not what I claimed -- I claimed that "some of the building-blocks of warm-and-fuzzy consciousness just fall out." Second, you're in luck: if Newtonian mechanics is sufficient to you, then Ehrenfest's theorem makes consciousness fall out of quantum mechanics, problem solved. Unfortunately, your "theory" requires modification because the "thermal noise" is quantum and the "deterministic parts" are not deterministic at bottom, but other than that, I invite you to use whatever your theory is, and apply your Hamiltonian with the Schrodinger equation rather than with Hamilton's equations of motion. On average, you'll get consciousness out again. QM does not take away; it adds.

Satire, right?

Useless comment, right? What part looks like satire to you? They are all pretty standard philosophical arguments, re Searl, Penrose et al.

It's confused bullshit. The rest doesn't matter.

Citation needed.

I don't see that as an accurate description of how Penrose is thinking about the problem (disclaimer: I've only read this interview, and not any of his books). I think he's saying that

1. Everything about QM other than its extremely accurate predictions is wrong

2. We don't have a theory that explains consciousness

And since he is looking for a unified theory, he wants his theory to encompass all of general relativity, the current domain of QM, and consciousness. He certainly understand current QM theory better than most of its detractors (AFAICT from this interview)

I've skimmed one or two of his books. There's no doubt that he knows his physics better than most physicists.

However I'm not sure what you're saying he's saying differs from what I'm saying he's saying. In both cases, the basic argument is that since we don't understand physics and we don't understand quantum mechanics then they might be related.

Now, that's not a conclusive proof that they're related but it might be true. If you look around the office and note that everybody is here except Alice and Bob, then you could hypothesize that maybe Alice and Bob are off somewhere together in a stationery cupboard smooching. On the other hand, maybe they're independently missing for totally different reasons. Personally I think Bob is at home with a cold and Alice is visiting her grandmother in Keokuk, but if Penrose wants to start flinging stationery cupboard doors open to look for them then that's fine with me.

(I may have overdone this analogy.)

I think we are saying similar things, but I'm getting the sense that you don't think there is a single unified theory to be found (not simply that humans are incapable of understanding it). Do you have a particular reason for thinking this?

I (and Penrose, I believe) like to think that there is a unified theory out there waiting to be found, because the alternative is that reality arbitrarily behaves in different ways in different situations. If that is the case, then fine, but we've made so much progress in science already by assuming that physical laws are universally applicable and not arbitrarily varying.

To put it another way, I reversed the premise and conclusion, Penrose think there is a unified theory, therefore there is a connection between consciousness and QM phenomenon that we don't understand. But you claim that Penrose doesn't understand A&B, therefore thinks there is a connecting universal theory.

Maybe it's a minor nitpick, but it caused me to question why I think there's a unified theory out there, which was good mental exercise.

Why do there need to be a unified theory?

That seems only the be necessary if you are looking for some sort of Truth which in itself is saying there must be a creator (i.e. someone must have defined the true way too look at this)

Science the way I understand it in its most postmodern interpretation isn't really about finding a unified theory but rather about finding the one thing that changes the paradigm and using that.

For instance beliving the world is flat might not be true, but it's true enough to get from one village to the next. The problem is when you want to travel further.

I think we are saying similar things, but I'm getting the sense that you don't think there is a single unified theory to be found (not simply that humans are incapable of understanding it). Do you have a particular reason for thinking this?

Well, a unified theory should "explain everything", but not necessarily on the right level. For instance, basic undergraduate-level physics and chemistry are sufficient to explain both "why is copper a conductor?" and "why do dogs like steak?" but this is not the correct level of explanation that you'd go to in order to understand both these phenomena. To explain the conductivity of copper, you'll want to go to crystal structures and electronic energy levels, whereas to explain why dogs like steak you'll want to bypass all the chemistry and go straight to the fact that dogs are omnivores, that fresh meat is a large portion of their ancestors' diets, that animals have nervous systems programmed to keep them alive, that eating is necessary to stay alive, and so forth. You could conceptually go all the way down to "this atom likes that atom" but these aren't the principles which you'd reach for.

Similarly, while everything should in theory be explicable by the fundamental physics of the universe, it may well be that consciousness can arise purely from classical physics.

A unified theory doesn’t have to explain consciousness. Far from it. Why should it? That’s absurd.

+1 for hilarious analogy

>In my own opinion the question is meaningless which is why I think consciousness is some kind of inevitable emergent property of intelligent systems;

Uh-oh...I was mostly with you up until that sentence. See http://lesswrong.com/lw/iv/the_futility_of_emergence/ (or the underlying http://lesswrong.com/lw/iu/mysterious_answers_to_mysterious_...).

Oh I definitely am just responding to this headline and article; I won't pretend to be any sort of expert on Penrose's views.

Personally I agree with you that consciousness is an emergent property of certain complex systems. I think some folks would like to rest free will on the probabilistic uncertainties we see in quantum equations. But IMO that is not necessary since we know through chaos theory that deterministic systems can still produce unpredictable results at high levels of complexity. And the brain is pretty damn complex.

It seems that consciousness is overvalued. There are more and more fields where conscious human brain losses against dumb silicon. E.g. chess, search.

"Is it true that you were bad at math as a kid?" "I was unbelievably slow... I always got lost... I was at least twice as slow as anybody else. Eventually I would do very well. You see, if I could do it that way, I would get very high marks."

Speaking as someone who still struggles with math, and was generally the dumbest kid in the most advanced classes, it's a huge relief to hear that someone as brilliant as Penrose experienced the same difficulties.

Grothendieck is one of the towering figures of 20th century math. He said:

"Since then I’ve had the chance in the world of mathematics that bid me welcome, to meet quite a number of people, both among my “elders” and among young people in my general age group who were more brilliant, much more ‘gifted’ than I was. I admired the facility with which they picked up, as if at play, new ideas, juggling them as if familiar with them from the cradle–while for myself I felt clumsy, even oafish, wandering painfully up an arduous track, like a dumb ox faced with an amorphous mountain of things I had to learn (so I was assured) things I felt incapable of understanding the essentials or following through to the end. Indeed, there was little about me that identified the kind of bright student who wins at prestigious competitions or assimilates almost by sleight of hand, the most forbidding subjects."

There are many other such mathematicians who aren't flashy. (I recall that Hilbert is a famous example.) So I wouldn't be discouraged by this. Environmental factors are probably far more important.

Of course, there is a top, though it's hard to tell who's furthest ahead when all options are above your own level. It's healthier for my mental sanity to recognize that great things can still be done by those not at the top than to try and suppose the top is nearer to me than I would like or suppose that the top doesn't exist. If you asked me who I thought was at the top of humans thus far, I'd respond with von Neumann. An excerpt from an interview linked at http://infoproc.blogspot.com/2012/03/differences-are-enormou...

Fermi and von Neumann overlapped. They collaborated on problems of Taylor instabilities and they wrote a report. When Fermi went back to Chicago after that work he called in his very close collaborator, namely Herbert Anderson, a young Ph.D. student at Columbia, a collaboration that began from Fermi's very first days at Columbia and lasted up until the very last moment. Herb was an experimental physicist. (If you want to know about Fermi in great detail, you would do well to interview Herbert Anderson.) But, at any rate, when Fermi got back he called in Herb Anderson to his office and he said, "You know, Herb, how much faster I am in thinking than you are. That is how much faster von Neumann is compared to me."

And there was this piercing comment made here a while back: http://news.ycombinator.com/item?id=1054201 An excerpt:

Look, I'm sorry to be the one to break this to you, but if you have difficulty with any programming concept, you must not be a supergenius. You're just an ordinary genius at best.

The sad truth is that there are some people for whom programming comes as naturally as thinking, with code formed as easily as thoughts; and if it takes an effort to understand any aspect of programming, you have just learned that you are not one of those people. Alas.

Interesting. How do we know that there is a top, and who is sitting on it?

I tried answering this question with the google search: "greatest 20th century mathematician". The top link was this (http://fabpedigree.com/james/mathmen.htm). Hilbert and Grothendieck were the highest 20th century mathematicians. (Mentions that Grothendieck is "widely considered the greatest mathematician of the 20th century".) von Neumann was a bit lower, #15.

But I personally don't understand the whole ranking thing. :) Math is in bad shape if you can order people this way. I know that in software, there are a few parts which deeply interest me; while I couldn't care less if the other parts happen to have some fancy virtuosos. (They're about as interesting to me as virtuosos of building houses out of toothpicks. Which no doubt requires great ingenuity, but it's not my interest.)

So if someone were to present me a list of top programmers... it's probably the case it's dominated by these toothpick-virtuoso analogues. And even if it magically weren't, the concept is weird, because the people active in my fields of interest all have their different, interesting perspectives. They're not clones of each other which differ only in a single rankable quality. It's more about actual ideas, rather than the managerial perspective which focuses on the human as carrying units of production.

(BTW, I can't tell how much Eliezer's joking in that quote, even though I've read his fiction. One can form code virtually "as easily as thoughts", but that's like forming verse as easily as thoughts. The question is, do you find their verse interesting?)

I don't know how old you are, but I'm pretty sure Penrose overtook you by the time he was your age.

Haha, that's an understatement, I'm sure he was light years ahead of me as early as 10. It's just inspiring to know that one can struggle with some of the basics and rebound to do great things.

I always felt I was slower than the other kids, but later I realised I was attempting to structure and understand the information whereas they were just regurgitating it. Once I did understand the information I could apply it far better than the others in class, and extend my understanding into new areas. That's just one reason someone may be "slower".

Please be charitable.

I thought I was. There's only a few dozen people on the planet who should be insulted by being told that they're not as good at mathematics as Roger Freaking Penrose.

A rather depressing interview. I enjoyed a lot of the explanations of Physics in *The Emperor's New Mind", but even there I could see big holes in his arguments about consciousness. For example, he talks about how its impossible to make an algorithm tile a grid in a certain way, but I had a screensaver which in fact did what he was saying was impossible. Here I just feel sort of sad and lost.

I think my least favorite line was probably this: "The trouble is, what can you do with it? Nothing. You want a physical theory that describes the world that we see around us." If you're going to use that to reject theories about the reality of the wave function, astronomers in the Renaissance would have been equally justified in rejecting the heliocentric system on account of it being at odds with what they saw around them, or Greek astronomers rejecting the notion that the world was round.

> astronomers in the Renaissance would have been equally justified in rejecting the heliocentric system on account of it being at odds with what they saw around them

False. Sights observed through a telescope were also part of "what they saw around them." A true theory accounts for all the evidence (and if it's not ultimately reducible to or based on something you can get from the five senses, it's not evidence).

Telescopes don't show you that (contrary to what your inner ear is telling you) its the Earth that moves rather than the sun. At best they tell you that Jupiter has things orbiting it.

Telescopes show that Venus displays phases like the moon while Mars and Jupiter don't, which is important evidence for heliocentrism and the order of the planets relative to Earth.

Telescopes also show that Jupiter's satellites experience eclipses, which isn't direct heliocentric evidence, but does tell you that Jupiter and its moons shine by reflected sunlight rather than intrinsic luminosity.

Telescopes also show sunspots, leading towards the discovery that the Sun is an active body, and to some notion of its size and mass. Telescopes can also show Venus transiting the Sun giving you a great idea of their sizes, which happened in 1639. http://en.wikipedia.org/wiki/Transit_of_Venus#First_scientif...

The switch to heliocentrism didn't happen overnight or as the result of a single observation or event, but telescopes brought in many different streams of evidence for it.

Telescopes also show that Mars does loops as it pans across our sky

That can be seen with the naked eye.

What did tell us that the Earth moves rather than the sun?

Nothing. Movement is relative, based on your chosen point of origin.

But, I guess your question was, how did we learn about the structure of the solar system, planets and orbits and all...

By observing the planets, you can map out their path, and you can see that they are not orbiting earth. The only sensible explanation is that all the planets, including Earth, must be orbiting the Sun.

Kepler then further observed that the orbits are elliptical, and then postulated Kepler's laws (that planets orbit the sun in an ellipse, with the sun in one of the focuses).

Also, astronomers in the Renaissance didn't have telescopes, so the moons of Jupiter weren't part of what they saw around them anyway.

I hate to point this out to someone with the username "planetguy", but Galileo certainly had telescopes, definitely lived in the Renaissance, and discovered four moons of Jupiter.

And as someone with the username "planetguy" I hate to be corrected, but you're right. My defense is that I am planetguy, not historyguy. :)

Historical brainfart.

> he talks about how its impossible to make an algorithm tile a grid in a certain way.

My guess, is that here he is talking about undecidability which appears quite often in mathematical problems, maybe something like this http://en.wikipedia.org/wiki/Wang_tile or http://www.nd.edu/~svandend/Tilings.pdf (pdf).

Uh. That's what evidence is for. If you have new evidence arguing for a different theory, then you present that evidence and have it tested. It gets added to the pool of "what we see around us".

That's why Penrose is unable to argue against QM the way he argues against string theory: there's experimental evidence and he can't gainsay that.

By the way, if you're looking for a good book to read on philosophy and the history of science, give David Harriman's book a shot. It's called "The Logical Leap: Induction in Physics."

If anyone is interested in the earlier Hacker News discussion of this article, it is here:


This quite an old article.

> From the September 2009 issue; published online October 6, 2009

Due to the inconsistency between quantum and relativity, I'm more inclined to believe that the problem is with relativity. The idea that physics is fundamentally non-deterministic satisfies me philosophically. If physics were deterministic, than I should be able to theoretically build a computer, input the state of the universe, and then be able to know what will happen in your life (assuming I don't tell anyone the computer output, because that would perturb the dynamics). I find that prospect far more unsettling than having to account for a superposition of states until I obtain more information in the future.

You would never be able to predict future states of the universe, simply because you cannot represent such states within the universe they represent. Without the ability to predict, the universe is effectively non-deterministic (literally, no one within it can determine its future states).

You make a good point. In my earlier post, replace "universe" with "solar system." Then, I can represent the states of the solar system in some subset of the universe, and I'll place this computer sufficiently far from the solar system so it doesn't interfere. Now I should be able to predict what happens on earth, unless you think that variables outside of our solar system significantly affect activities on earth, right?

1) Don't underestimate the butterfly effect. 2) We can already predict the future to a certain extent. 3) What you wish the universe was like is irrelevant. http://en.wikipedia.org/wiki/Wishful_thinking

Re 2: There should be an obvious qualitative difference between being able to predict where a ball will land if I throw it, and predicting who the passengers riding a particular train in 15 years will be.

Re 3: I was commenting on Roger Penrose's assumption that quantum must be "wrong" because it's "unintuitive" by expressing my opinion that I think quantum is more intuitive than deterministic theories. Indeed, Dr. Penrose and I are both using "wishful thinking," as did Einstein when he hypothesized that the speed of light is "constant in a vacuum." http://en.wikipedia.org/wiki/Speed_of_light#Special_relativi...

I don't think modern quantum theory holds that the universe is non-deterministic. I think it's still somewhat of an open question.

However, I also don't think a deterministic universe would be sufficient to allow you to predict it, because getting the state of the universe is still impossible following the uncertainty principle.

I'm not a physicist, but my understanding is that the debate about whether or not "quantum is deterministic" centers around what your interpretation is of the wave function. I think most physicists, who Penrose would probably criticize, believe the "Copenhagen Interpretation," which says that the wave function of a system is literally the function that, when you take the inner product with its conjugate, gives you the probability distribution of the state of the system, and hence, the state is non-deterministic.

The uncertainty principle arises from quantum. Specifically, it's a statement about the commutativity of operators that act on the wave function, which, going by the Copenhagen interpretation of physics, means it's a consequence of the non-determinism of the universe. I think this is a philosophically satisfying explanation for why getting the state of the universe is impossible.

But you can in fact build such a computer - you'll just have to solve the little problem of accounting for absolutely all the factors that directly and indirectly affect the result. Then predicting the future is easy peasy :-)...

Software execution is an entirely deterministic process (at least in theory), and even then, we cannot actually compute the result of that process on a sufficiently large computer.

Of course by this definition of wrong, Newtonian mechanics is wrong, which didn't stop me from taking a 400 level course on it.

Roger Penrose has fundamental thoughts about the physics and AI, not simply callling them wrong wrong in the sense of falsifibility..Read his books.

I don't think the aidenn0 is talking about falsifiability, but accuracy. As in, Newtonian mechanics is not 100% accurate, but it works well enough for macro-level calculations.

Like Asimov said, "when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together." - http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm

That is what aidenn0 seems to be talking about, but that's not what Penrose is talking about. Penrose is very clear that the predictions of QM are extremely accurate. His contention is that the implications of QM cannot be true (that there must be parallel worlds or "it doesn't matter what's really happening in a superposition of states, just that the predictions are accurate"), therefore QM as it is today cannot be a part of any single unified theory.

So basically equation helps you to make your measurement more accurate. (on some scales) what happens underneath is known but can't be accurately measured because it interferes with physical process. (wich comes to no suprise because the measurmenst are done from whitin the universe while it's "running", and that is why your measurment will have effect on future state of universe, )

Seems like Penrose is claiming that different interpretations of this measurement interference are not necessary. thats what i get from article. at least.

Not much content in this article. Read his books to get a feeling for the breadth and depth of his thought.

Are any of his book suitable as casual on-the-tram reading? Could you recommend one of his books? Thanks.

I wouldn't say any of his books are exactly casual reading. The Large the Small and the Human Mind is probably the most casual in that it merely requires thinking and even then some of that is done for you the responses from Abner Shimony, Nancy Cartwright, and Stephen Hawking (contributing authors). The others require active engagement to work through. Especially Road to Reality - there is nothing casual about that one.

I started reading Road to Reality very casually– bought the book one day, next day I was in a Starbucks enjoying it and my tea. 10 minutes later one of the employees takes a break and the only table open is next to mine near the back. After a few minutes of sighing, stretching, and looking at the door to see if any new customers were coming in he turned to ask what I was reading. The next 30 minutes was the first and only time I have ever had a discussion about particle physics with a barista.

Depends how strong you are - I have a copy of "The Road to Reality" on my desk at work, but not sure I'd want to carry it about!

All books are suitable for casually reading on trams, apart from really old and delicate or oversized ones.

I loved 'The Emperors's New Mind' and 'Shadows of the Mind', and did read some of those two while on train journeys, if that helps at all.

The Road to Reality, while certainly not a technical work in the traditional sense, is not light reading.

Note this: "I was unbelievably slow ... we had to do this mental arithmetic ... I was struggling away to do these tests ... I was at least twice as slow as anybody else."

Personally I like the article, and I agree with his concluding paragraph that there must be coherence preservation somewhere.

You need to look at one of the pillars of quantum mechanics he mentioned, where the observables of a system are only the probability, and this is due to 'decoherence' from a measurement. What he's trying to point out is that the coherence in the system must be preserved somehow, otherwise where could it go? It seems that this is very central to the difference between quantum mechanics and general relativity, and that the tiny connections to marry these two are yet to be found. His position is clearly 'it's in the details' not 'we must change everything' of string theory.

This argument reminds me very much of Thorne–Hawking–Preskill bet about information paradox.

PS: fascinating development in quantum weak measurement, where trading off measurement accuracy provides a window into coherence of a system.

We have so much more to understand about brain functioning in our current paradigm, and no pressing reason to try to build a new physics to help neuroscience. The theory of mind/experience of consciousness is an output of the brain, not part of its architecture.

Penrose's idea about the relationship between Consciousness and Quantum Mechanics was used by Neal Stephenson in his SciFi tome, Anathem. Very interesting concept, mediocre book.

I agree!

It's so sad to see old age claim a great mind.

I don't understand what you mean. His intellect certainly shines through in the interview, especially in the latter part where he talks about physics.

Really? I thought that the parts about physics were really disappointingly fuzzy. Especially: "physicists have to say, well, somehow your consciousness takes one route or the other route without your knowing it." I think that its sort of shocking that he could fail to understand the arguments of his opponents so badly as to end up saying something so ridiculous.

I have a generally negative opinion of Roger Penrose's ideas, but let's be fair: the fuzziness here was probably inevitable, given the popular nature of the magazine interviewing him. If you judged scientists harshly for sounding like handwavy simpletons in condensed interviews for reporters, you would end up drastically underestimating most scientists who have ever had such an interview.

It's sad to see judgmental certainty claim a young mind.

Care to elaborate?

> And yet the 78-year-old Penrose—now an emeritus professor at the Mathematical Institute, University of Oxford—seems to live the humble life of a researcher just getting started in his career. His small office is cramped with the belongings of the six other professors with whom he shares it, and at the end of the day you might find him rushing off to pick up his 9-year-old son from school.

Wonder if that's his kid? If I were feeling particularly sour today, I'd look up how much extra risk of birth defects etc using 69 year old sperm (rather than a more normal 30-40s) entails.

I guess that's none of your business.

You might want to start by looking up the way sperm is being produced. It will help you clear the confusion with the link between the mother's age and birth defects.

Age of the father does have an effect, actually. http://www.webmd.com/infertility-and-reproduction/news/20030...

edit: Also, as someone who's had to use sperm donation to conceive...

> Wonder if that's his kid?

is pretty offensive. It's his kid, whether he's the genetic father or not.

Although citation is needed, if I remember correctly, because of lacking healthy young Japanese men after WWII, ageing fathers' sperm contributed to at least as much to newborn malformations as the nuclear fallout.

But the thread also tells you about the euphemism under the guise of 'ego' in the article, and how society today is structured (ie. power of the old vs. youth in our times). At his age, he should clearly let go, by all standards, even if it so difficult. To quote a famous speech from another control freak who at least knew all about this, luckily Nature has provisions because it "clears out the old, to make room for the new. Right now the new is you. But you won't always be."

It's interesting that you mention the Japanese, because when I looked into it awhile ago, I could find no evidence of any increase in birth defects following the bombing. I could swear that we had pictures of deformed children in a textbook as a kid, so I started Googling it, but the only things I turned up said "no statistically significant increase".

It certainly does, especially for genetic (rather than developmental) defects. Wikipedia has a good summary


Still, the mother's age is a lot more important, all things considered.

Thought this was important enough to reply again. Wikipedia:

> In 1933, Lionel Penrose analyzed data for 727 children in 150 families and found no paternal age effect for the risk of Down syndrome after controlling for the maternal age effect. Largely based on a 2003 paper by Fisch et al. that found a paternal age effect only "in association with a maternal age of 35 years and older", a 2009 review of the literature subsequent to Penrose's paper concludes that "a paternal-age effect exists, but is very small in comparison to maternal-age effect in Down syndrome prevalence".

In principle, I suppose this is compatible with what your article stated:

> "Older fathers may contribute just as much as older mothers to the dramatic increase in Down syndrome risk faced by babies born to older couples. A new study found that older fathers were responsible for up to 50% of the rise in Down syndrome risk when the mother was also over 40.

I'm not sure how many conflicting studies are out there and factored into the 2009 review.

Down syndrome is only one possible birth defect. If you were to look up information on American sperm donation procedures, you'd find that there are estimates that use of donors leads to 1/5 the defects in part due to younger age and rigorous selection criteria - which strikes me as a powerful testimony to how much sperm quality can matter: http://en.wikipedia.org/wiki/Sperm_donation#Sperm_donation_a...

> in part due to younger age and rigorous selection criteria

How could you distinguish between those two effects in order to be confident that younger age is a significant contributing factor?

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