Sort-of guest post: Sean Carroll comments on whether quantum mechanics gives evidence for God

After a year of total dormancy, the Templeton Foundation has resurrected its Big Questions Online site, so we can expect it to disgorge gobs of fuzzy accommodationism until the End Times arrive.

One of the latest is a piece called “Does quantum physics make it easier to believe in God?”  It’s by Stephen M. Barr, a professor of physics at the University of Delaware who writes frequently on science and religion. His Wikipedia bio notes that “In 2007, he was awarded the Benemerenti Medal by Pope Benedict XVI. In 2010, he was elected a member of the Academy of Catholic Theology.” We can presume, then, that Barr is a Catholic.

So it’s not surprising that the answer to his question is “Yes, quantum physics does make it easier to believe in God.” (Would you expect any other answer on a Templeton site?) It boils down to the fact that, according to Barr, quantum mechanics (QM) shows that the human mind is independent of pure materialism, which he calls an “atheistic philosophy”:

Materialism is an atheistic philosophy that says that all of reality is reducible to matter and its interactions. It has gained ground because many people think that it’s supported by science. They think that physics has shown the material world to be a closed system of cause and effect, sealed off from the influence of any non-physical realities — if any there be. Since our minds and thoughts obviously do affect the physical world, it would follow that they are themselves merely physical phenomena. No room for a spiritual soul or free will: for materialists we are just “machines made of meat.”

Quantum mechanics, however, throws a monkey wrench into this simple mechanical view of things.  No less a figure than Eugene Wigner, a Nobel Prize winner in physics, claimed that materialism — at least with regard to the human mind — is not “logically consistent with present quantum mechanics.” And on the basis of quantum mechanics, Sir Rudolf Peierls, another great 20th-century physicist, said, “the premise that you can describe in terms of physics the whole function of a human being … including [his] knowledge, and [his] consciousness, is untenable. There is still something missing.”

Now bear with me since this isn’t my area of expertise, but the whole woo-ish conclusion of Barr’s piece rests on the “observer effect” in QM made famous by Schrödinger’s cat.  I had thought that this didn’t need to involve a human mind: that a machine could also be the observer that collapses a wave function, but Barr says that this ain’t so:

Thus, the traditional view is that the probabilities in quantum mechanics — and hence the “wavefunction” that encodes them — refer to the state of knowledge of some “observer”.  (In the words of the famous physicist Sir James Jeans, wavefunctions are “knowledge waves.”)  An observer’s knowledge — and hence the wavefunction that encodes it — makes a discontinuous jump when he/she comes to know the outcome of a measurement (the famous “quantum jump”, traditionally called the “collapse of the wave function”). But the Schrödinger equations that describe any physical process do not give such jumps!  So something must be involved when knowledge changes besides physical processes.

An obvious question is why one needs to talk about knowledge and minds at all. Couldn’t an inanimate physical device (say, a Geiger counter) carry out a “measurement”?  That would run into the very problem pointed out by von Neumann: If the “observer” were just a purely physical entity, such as a Geiger counter, one could in principle write down a bigger wavefunction that described not only the thing being measured but also the observer. And, when calculated with the Schrödinger equation, that bigger wave function would not jump! Again: as long as only purely physical entities are involved, they are governed by an equation that says that the probabilities don’t jump.

But what if one refuses to accept this conclusion, and maintains that only physical entities exist and that all observers and their minds are entirely describable by the equations of physics? Then the quantum probabilities remain in limbo, not 0 and 100% (in general) but hovering somewhere in between. They never get resolved into unique and definite outcomes, but somehow all possibilities remain always in play. One would thus be forced into what is called the “Many Worlds Interpretation” (MWI) of quantum mechanics.

Barr reaches a bold conclusion: unless you acccept the MWI (under which wave functions don’t collapse, so observers aren’t required, but every quantum event creates a new universe, yielding elebenty gazillion of them), you’re forced to the ineluctable conclusion that there is dualism: the mind is independent of matter and can influence matter.  Right up Templeton’s alley!:

The upshot is this: If the mathematics of quantum mechanics is right (as most fundamental physicists believe), and if materialism is right, one is forced to accept the Many Worlds Interpretation of quantum mechanics. And that is awfully heavy baggage for materialism to carry.

If, on the other hand, we accept the more traditional understanding of quantum mechanics that goes back to von Neumann, one is led by its logic (as Wigner and Peierls were) to the conclusion that not everything is just matter in motion, and that in particular there is something about the human mind that transcends matter and its laws.  It then becomes possible to take seriously certain questions that materialism had ruled out of court: If the human mind transcends matter to some extent, could there not exist minds that transcend the physical universe altogether? And might there not even exist an ultimate Mind?

Now I’m no physicist, but this sounded pretty strange to me. For one thing, dualism doesn’t imply an ultimate Mind, much less one that decrees that a cracker turns into Jesus on Sunday and that homosexual behavior is a “grave disorder.” So I wrote to Sean Carroll of Cosmic Variance fame—my go-to physicist on claims like this—and he gave me permission to reproduce his emailed answer.  As you might expect, he wasn’t wild about Barr’s piece:

I hadn’t heard this specific argument before, but it’s a natural one to make, in a God-of-the-gaps fashion: quantum mechanics is hard to make sense of, therefore maybe God. The only thing raising it above the level of that would be the specific suggestion that somehow conscious minds play an important role in QM. This is indeed something that some of the pioneers considered, but that has largely fallen out of favor since then (not that it was ever very favorable). Note that Barr is not quoting modern researchers in the foundations of QM, but a litany of dead physicists (Wigner, Peierls, von Neumann, Jeans). Great men all, but we know more now than we did then. In particular, we understand what makes wave functions seem to “collapse”—the process of decoherence, by which detailed information in the wave function is lost through interactions with a complex environment. A conscious mind would count as a complex environment, but so would the air in your room. As usual in this game, as we understand things better the apparent need for a divine assist disappears. That’s not to say we completely understand the measurement problem, but the “God interpretation” of QM is not a leading contender among modern thinkers.

As far as ontological commitments of the Many-Worlds Interpretation are concerned, I wrote about that mistake here. Shorter version: it’s not a proliferation of objects (including universes) that should count as uneconomical, but a proliferation of concepts, especially vague ones. Near the end of my post I used the example of theologian Richard Swinburne:

“The most egregious version of this mistake has to belong to Richard Swinburne, an Oxford theologian and leading figure in natural theology, who makes fun of the many-worlds interpretation but is happy to accept a completely separate, unobservable, ill-defined metaphysical category into his ontology.”

It would appear that Barr’s version is equally egregious.

Thanks to Sean for dissecting the piece.  As I suspected, it’s the usual Templetonian pablum about how science gives evidence for God.  Stay tuned for more of the same from Big Questions Online.

148 Comments

  1. Posted July 18, 2012 at 5:02 am | Permalink

    “the MWI (under which wave functions don’t collapse, so observers aren’t required, but every quantum event creates a new universe, yielding elebenty gazillion of them)” — IIRC, that is not the correct interpretation; rather, the elebenty gazillion universes always exist(ed), but just become increasingly differentiated from one another. See eg David Deutsch.

    /@

    PS. Surely the cat knows if it’s alive or dead?!

    • Posted July 18, 2012 at 5:12 am | Permalink

      Well, it would know if it is alive, anyway.

      • Posted July 18, 2012 at 6:44 am | Permalink

        Ah… got me.

        /@

    • Posted July 18, 2012 at 5:19 am | Permalink

      That’s just it. If you put a person inside the box instead, the people outside the box still don’t know the results of the experiment before they look inside. It’s a measurement issue, not a consciousness issue.

      Of course, this line of thought is where the idea comes from that we need God to collapse the universe’s wave function. Because, as usual, God is exempted from the restrictions that supposedly make him necessary, by fiat.

      • Torbjörn Larsson, OM
        Posted July 18, 2012 at 7:28 am | Permalink

        It is quantum gods all the way down.

    • gbjames
      Posted July 18, 2012 at 5:22 am | Permalink

      Not if it is in a coma.

      • Posted July 18, 2012 at 6:45 am | Permalink

        If the probabilities are even, is it in a semi-coma?

        /@

    • BillyJoe
      Posted July 18, 2012 at 2:03 pm | Permalink

      Incorrect about MWI:
      If those universes always existed but become increasingly differentiated, the MWI would explain nothing.

      Correct about the cat:
      That was the point. A cat cannot be both dead and alive, hence the any interpretation that suggests this should be the case must be wrong

      • Gregory Kusnick
        Posted July 18, 2012 at 2:58 pm | Permalink

        Watch the David Wallace video at #4. A cat can be both dead and alive (just as a single photon can take both paths through an interferometer). And a human brain can be simultaneously in the state of seeing a dead cat, and in the state of seeing a live cat, but never in the state of seeing a cat that’s both dead and alive.

        This is what quantum theory tells us if you think it all the way through. The historical reasons for not thinking it all the way through have to do with protecting human exceptionalism by setting consciousness apart from the natural world.

        • Posted July 19, 2012 at 5:40 am | Permalink

          A cat can be both dead and alive (just as a single photon can take both paths through an interferometer).

          Do we really know that something on the macroscopic scale of a cat can be both dead and alive? Quantum entanglement and coherence has not been demonstrated on that scale.

          The claim is simply an extrapolation from the micro scale, but we don’t understand quantum decoherence and/or wavefunction collapse well enough to extrapolate over the many orders of magnitude to a cat.

          • Gregory Kusnick
            Posted July 19, 2012 at 10:07 am | Permalink

            But we have no reasons, theoretical or observational, to think the extrapolation doesn’t work. It explains what we see just as well as collapse theory, without the extra postulate of collapse. So the only reason to cling to collapse is because we don’t like the philosophical implications of MWI.

        • BillyJoe
          Posted July 19, 2012 at 6:18 am | Permalink

          “A cat can be both dead and alive”

          Nope. As I said, that was the point of the thought experiment. In the double slit experiment you can create the interence pattern using photons and electrons, but as you increase the size of the projectile the interfernce pattern gradually disappears. It disapears completely with a molecule consisting of about 30 atoms. A cat is always either dead or alive.

          • Gregory Kusnick
            Posted July 19, 2012 at 10:13 am | Permalink

            All you’ve shown is that a cat is always observed to be either dead or alive, which is consistent with what I said. There’s nothing in the math that prevents a cat from being in a (non-interfering) superposition of dead and alive states.

            • BillyJoe
              Posted July 19, 2012 at 9:30 pm | Permalink

              To be clear, then, it is idiotic to think that a cat can be both alive and dead. THAT is the point of the Schroedinger’s cat thought experiment regarding macroscopic superposition.

              • Gregory Kusnick
                Posted July 19, 2012 at 9:51 pm | Permalink

                And the point of the EPR paradox was to show that entanglement is absurd, and that therefore something must be wrong with the theory.

                But as it turns out, Einstein was wrong, the theory is correct, Bell’s theorem holds, and we’ve had to accept that entanglement is a real (if counterintuitive) phenomenon.

                The fact that your intuition (or Schrödinger’s) balks at the idea of macroscopic superposition is not proof that it can’t happen. The theory says it can, and we have no evidence that the theory is wrong.

              • BillyJoe
                Posted July 20, 2012 at 5:20 am | Permalink

                Nope. If, in the double slit experiment, instead of photons, molecules of increasing size are used, the interference pattern gradually disappears. Using molecules greater than 30 atoms in size, th einterference pattern disappears altogether. In other words, quantum effects disappear at the macroscopic level of 30 atoms. In other words, cats are either alive or dead, never both alive and dead.

              • Gregory Kusnick
                Posted July 20, 2012 at 9:30 am | Permalink

                You’re repeating yourself, and the same answer still applies: all this shows is that quantum interference effects become unobservable when the wave function exceeds a certain level of complexity. This is exactly what’s predicted by decoherence theory, with no collapse necessary.

                The idea that the unobservable branch of the wave function ceases to exist is like claiming that galaxies poof out of existence when the Hubble expansion carries them beyond our observable horizon.

              • logicophilosophicus
                Posted July 20, 2012 at 9:30 am | Permalink

                Interference cannot stand proxy for all quantum effects. Mr Bose and Mr Einstein would certainly have an opinion.

                And, of course, in the Many Worlds interpretation there is one (infinitely branching) Universal Wave Function which can never collapse.

              • Posted July 21, 2012 at 9:41 am | Permalink

                @logicophilosophicus: And how did you deduce that the Bose-Einstein statistics have nothing to do with interference of the wave function? The Bose-Einstein statistics just impose a symmetry constraint on the wave function: that it should not remain the same on exchanging two bosons.

              • logicophilosophicus
                Posted July 23, 2012 at 9:17 am | Permalink

                @Ahannāsmi

                Gregory Kusnick wrote: “The fact that your [BillyJoe’s] intuition (or Schrödinger’s) balks at the idea of macroscopic superposition is not proof that it can’t happen. The theory says it can, and we have no evidence that the theory is wrong.”

                BillyJoe replied: “If, [1] in the double slit experiment, instead of photons, molecules of increasing size are used, the interference pattern gradually disappears. Using molecules greater than 30 atoms in size, the interference pattern disappears altogether. [2] In other words, quantum effects disappear at the macroscopic level of 30 atoms. In other words, cats are either alive or dead, never both alive and dead.”

                logicophilosophicus commented: “[1] Interference cannot stand proxy for all quantum effects. [2] Mr Bose and Mr Einstein would certainly have an opinion. [3] And, of course, in the Many Worlds interpretation there is one (infinitely branching) Universal Wave Function which can never collapse.”

                Ahannāsmi objected: “And how did you deduce that the Bose-Einstein statistics have nothing to do with interference of the wave function?”

                I didn’t. [1] and [2] are separate points. In [2] I was referring to Bose-Einstein condensates, which break BillyJoe’s personal rule of size, I suppose. ( [3] was a rather bigger example, against both of BillyJoe’s points.) Basically I am just agreeing with GK on this narrow point: that at the quantum mechanical level of description, there’s no size limit on superposition. (That doesn’t imply any judgment on my part about the ultimate nature of reality or the completeness of quantum theory.) You presumably agree:

                Ahannāsmi wrote: “…in the many worlds interpretation… there is a universal wave-function (corresponding to a quantum mechanical state of the whole universe)…”

      • Posted July 18, 2012 at 4:07 pm | Permalink

        Well, I’d have to let Deutsch rebut that. But it seemed to be a clear explanation at the time. ;-)

        /@

        • Posted July 18, 2012 at 11:48 pm | Permalink

          Leon Lederman in his The God Particle has a nice passage where he describes going to a talk by some theorists about the frontiers of current thought. It seemed perfectly clear to him as he left and he was looking forward to explaining it to his colleagues back in the lab, but he was decidedly nonplussed to realize that by the time he arrived there it had all more or less evaporated …

          I guess we lesser mortals shouldn’t feel so bad when similar things happen to us … :-)

    • Posted July 18, 2012 at 3:43 pm | Permalink

      Actually, the “may worlds” in the many worlds interpretation is just a literary device: the one and only axiom of the “may-worlds” interpretation can be stated as saying that there is a universal wave-function (corresponding to a quantum mechanical state of the whole universe), which undergoes a unitary evolution (that is, without any collapses). See for example Section II in Tegmark, M. The Interpretation of Quantum Mechanics: Many Worlds or Many Words? arXiv:quant-ph/9709032 (1997), at http://arxiv.org/abs/quant-ph/9709032

      • Posted July 18, 2012 at 3:44 pm | Permalink

        “may worlds” should be “many worlds”, of course. Sorry for the typo.

      • Posted July 18, 2012 at 4:12 pm | Permalink

        Ah! A many worlds interpretation interpretation! :-D

        Interesting. But too tired to digest now. Although I’m kind of reminded of a line from Doctor Who; something like: “Imagine a soap bubble with a smaller bubble on it. Well, it’s nothing like that.”

        /@

        • Posted July 19, 2012 at 3:41 pm | Permalink

          Technically, it is the “many worlds” part that is an interpretation of Everett’s postulate about the unitary evolution of the universal wave-function, rather than the other way around.

  2. Posted July 18, 2012 at 5:13 am | Permalink

    JAC: “I had thought that this didn’t need to involve a human mind: that a machine could also be the observer that collapses a wave function …”

    Well we can’t know for sure, since obviously it can not be the case that we know that a wavefunction has collapsed without involving our brains in establishing that.

    However, most physicists would say that a human brain is not necessary to collapse a wavefunction (though exactly how and what causes collapse is one of the most interesting areas of current research; it seems to occur at the level of a few particles interacting).

    “Barr says that this ain’t so: […] something must be involved when knowledge changes besides physical processes.”

    Barr cannot know that, it’s a mere assertion. He cannot prove that wavefunction collapse doesn’t occur in the absence of a human mind (even if we grant that minds are “non-physical”).

    It is pure hubris to say that human minds are intimately concerned in the detailed workings of physics. After all, the universe happily proceeded for over 10 billion years before there were any human minds around to collapse wave-functions, and no sensible interpretation of physics these days has them playing any role.

    • eric
      Posted July 18, 2012 at 6:23 am | Permalink

      Well we can’t know for sure, since obviously it can not be the case that we know that a wavefunction has collapsed without involving our brains in establishing that.

      Uh? We can know it collapsed the same way we can know all the air in that box is not sitting on the left side of it, with vacuum on the right. That is, its theoretically possible that all those atoms interacted in a way that left the cat’s wavefunction uncollapsed, but its highly satistically improbable that that’s the case. So improbable that we can basically ignore that outcome.

      • Posted July 18, 2012 at 7:13 am | Permalink

        We could calculate how likely the cat’s wavefunction was uncollapsed if we had a good theory of when wavefunctions collapse. Do we?

        • Torbjörn Larsson, OM
          Posted July 18, 2012 at 7:32 am | Permalink

          In decoherence theory there is no “collapse” but a gradual transition. I’ve seen experiments that can be interpreted as showing how one can observe going into and out of partial decoherence.

          I think that type of behavior is very difficult to predict out of a reliance on a mind observer, as the dial controlling decoherence is in the experiment.

          • Torbjörn Larsson, OM
            Posted July 18, 2012 at 8:32 am | Permalink

            Or more accurately perhaps, there is room for a gradual transition.

        • Torbjörn Larsson, OM
          Posted July 18, 2012 at 7:37 am | Permalink

          Here:

          “Most scientists have believed that the instant a quantum object was measured it would “collapse” from being in all the locations it could be, to just one location like a classical object. Jordan proposed that it would be possible to weakly measure the particle continuously, partially collapsing the quantum state, and then “unmeasure” it, causing the particle to revert back to its original quantum form, before it collapsed.

          Jordan’s hypothesis suggests that the line between the quantum and classical worlds is not as sharply defined as had been long thought, but that it is rather a gray area that takes time to cross.

          In the latest issue of Nature News, Postdoctoral Fellow Nadav Katz explains how his team put the idea to the test and found that, indeed, he is able to take a “weak” measurement of a quantum particle, which triggered a partial collapse. Katz then “undid the damage we’d done,” altering certain properties of the particle and performing the same weak measurement again. The particle was returned to its original quantum state just as if no measurement had ever been taken.”

          Presumably this gray area is as hard to explain as if a quantum mind would interact with the world, yet behave as if it didn’t need “collapse” itself. Who “collapses” the “collapser”?

      • RF
        Posted July 18, 2012 at 2:57 pm | Permalink

        You’re calculating the probability based on a particular theory, and the theory is what’s at issue, so you’re begging the question.

    • BillyJoe
      Posted July 18, 2012 at 2:12 pm | Permalink

      “we can’t know for sure [that a human mind is not required to ‘collapse the wavefunction'”

      Of course we can. The double slit experiment is carried out in a vacuum for the specific reason that molecules in the air would interact with the photons. If air is gradually introduced into the experimental setup, the interference pattern will gradually change to the scatter pattern.

      • logicophilosophicus
        Posted July 19, 2012 at 12:52 am | Permalink

        Preventing the experiment doesn’t invalidate any conclusions drawn from the “unprevented” experiment.

        • BillyJoe
          Posted July 19, 2012 at 6:22 am | Permalink

          You have misunderstood something. I was trying to show you that decoherence can be demonstrated to occur without the need for a mind/consciousness/observer.

          • logicophilosophicus
            Posted July 19, 2012 at 6:57 am | Permalink

            I knew what you were trying to do. I think, however, that the accepted QM view is that when a photon and (the electrons around) an air molecule interact, the result is a more complex wave function. This is a very old discussion. If such interaction was in fact “a measurement” and therefore led inevitably to immediate decoherence (or collapse, for that matter), then the electrons in atoms would be “measured” by the nuclei, and could no longer exist in quantum superposition.

            • BillyJoe
              Posted July 19, 2012 at 9:34 pm | Permalink

              How could there be a more complex wave function if the interference pattern gradually changes to the scatter pattern if air is gradually introduced into the experimental setup?

              • logicophilosophicus
                Posted July 20, 2012 at 1:52 am | Permalink

                If a photon is scattered, it changes direction and wavelength (Compton). It is still described by a (changed) wave function, but it can no longer interfere with the tuned photons in the directed beam. So what? Of course some of the scattered photons will eventually find their way through the slit(s), spoiling the fringes. So what?

                Mind, that would take an awful lot of air. I can’t remember seeing a Young’s Slit experiment done in a vacuum, but the interference fringes are clear enough. Thomas Young managed OK.

              • Posted July 21, 2012 at 11:36 am | Permalink

                If a photon is scattered, it changes direction and wavelength (Compton).

                Wrong. This would require the photon to loose energy, and this does not happen say, in cases like Rayleigh scattering (which is responsible for the blue color of the sky).

                The kind of scattering where it does happen is when highly energetic photons (X-rays typically) knock out electrons from atomic shells, just transferring part of the energy to the electron.

                On the other hand, it is also true that Young’s double slit experiment is typically not done in vacuum. The main reason it still works is that photons do not interact with air molecules much, and this has got nothing to do with MWI/ Copenhagen, or whatever notion one way have of the mind.

              • Posted July 21, 2012 at 11:36 am | Permalink

                *loose -> lose

              • logicophilosophicus
                Posted July 23, 2012 at 9:23 am | Permalink

                @ Ahannāsmi

                logicophilosophicus replied @ BillyJoe: “If a photon is scattered, it changes direction and wavelength (Compton). [I assumed the Compton effect – involving high energy photons – since diffraction isn’t much affected for visible light.] It is still described by a (changed) wave function, but it can no longer interfere with the tuned photons in the directed beam.” I also wrote: “I can’t remember seeing a Young’s Slit experiment [visible light] done in a vacuum, but the interference fringes are clear enough.”

                The Compton and Young references ought to make the distinction clear, but Ahannāsmi objected: ” ‘If a photon is scattered, it changes direction and wavelength (Compton).’ Wrong. This would require… highly energetic photons (X-rays typically)…” I thought I implied exactly that.

              • Posted July 23, 2012 at 6:12 pm | Permalink

                If a photon is scattered, it changes direction and wavelength (Compton).

                I read this as a claim that scattering implies necessary change in both wavelength and direction. That is clearly not the case Rayleigh scattering). If that is not what you meant, I apologize.

                Also I do not quute know what you mean by “since diffraction isn’t much affected for visible light.” Both diffraction and scattering can certainly be seen (rather easily) with visible light.

      • Posted July 19, 2012 at 4:53 am | Permalink

        You can also show it is unnecessary by axiomatizing a standard presentation of quantum mechanics and then seeing that there are no predicates necessary that correspond to minds, consciousness, etc. This was done by 1967, at least twice to boot: by both Popper and Bunge in a volume edited by the latter called _Quantum Theory and Reality.

        Or, heuristically, if QM required “minds” or something else of that sort, how would it even be applicable to where there *are* none; yes, there’s (to avoid begging the question) one near the two slit experiment, but there’s not one near the centers of stars, where nucleosynthesis takes place … and yet we know (to a high degree of truth, anyway) that one can use QM for such cases.

        • BillyJoe
          Posted July 19, 2012 at 6:20 am | Permalink

          Yes, good point.

        • logicophilosophicus
          Posted July 20, 2012 at 2:37 am | Permalink

          1) Circular argument. You believe consciousness is (a property of) brain (and, clearly, there are no brains in stellar cores). But that is not known. The Hard Problem is unsolved. Bohm suggested that the complex mind we have is made of the organisation of a primitive consciousness which is a property of every electron. (At least that explains qualia…)

          2) There’s no distance limit on measurement/collapse. If the cat-in-the-box is transported to some distant, sterile portion of the universe, it is alive+dead until mission control reads the monitors. “Near” doesn’t crop up in the analysis – I think it’s just your insertion.

        • logicophilosophicus
          Posted July 20, 2012 at 2:43 am | Permalink

          Popper’ philosophy is dualist. He can afford to insist on material realism without observation because the mind already exists, for him, on different basis. I’m no expert on Popper, but I think it is ironic to use him as an argument against the necessity for mind.

          • Posted July 20, 2012 at 5:00 am | Permalink

            Yes, Popper was a dualist. So? It happens to be that his axiomatization of quantum mechanics is “ghost free”, regardless.

            In any case, Bunge is certainly not, and I mentioned his presentation of the same idea in the same place, so …

            • logicophilosophicus
              Posted July 20, 2012 at 9:21 am | Permalink

              Well, I only criticised your use of Popper. But since you ask…

              Popper 1967, Bunge 1967. Two great philosophers (NOT physicists). That’s a long time ago – you’d think that everyone would have caught on by now if their work was definitive. Not so. Modal interpretations have never been mainstream, and are much criticised. For instance read

              http://arxiv.org/abs/quant-ph/9709032

              which I chose in fairness because it is an attempt to rescue modal interpretations from a variety of disproofs.

              On the other hand, if you know better, that will save a lot of discussion here since it will demolish both the Copenhagen and Many Worlds interpretations – the two most popular views among physicists.

  3. Chris
    Posted July 18, 2012 at 5:31 am | Permalink

    Is this guy in any way related to Deepak Chopra?

    • Posted July 18, 2012 at 6:14 am | Permalink

      I’m sure their consciousnesses are linked by non-local quantum phenomena, making them all part of a single quantum-spiritual plane.

      • Posted July 18, 2012 at 6:47 am | Permalink

        Is there such a thing as quantum incoherence as well as quantum decoherence?

        If so, it seems to be catching…

        /@

  4. Posted July 18, 2012 at 5:35 am | Permalink

    Here’s a wonderfully concise presentation of MWI by David Wallace.

  5. Posted July 18, 2012 at 5:48 am | Permalink

    If you’re up for it, here’s an excellent and fairly accessible summary of the overwhelming case for MWI.

    http://lesswrong.com/lw/r8/and_the_winner_is_manyworlds/

    In it you’ll find this quote:

    “Early physicists simply didn’t think of the possibility of more than one world – it just didn’t occur to them, even though it’s the straightforward result of applying the quantum laws at all levels. So they accidentally invented a completely and strictly unnecessary part of quantum theory to ensure there was only one world – a law of physics that says that parts of the wavefunction mysteriously and spontaneously disappear when decoherence prevents us from seeing them any more. If such a law really existed, it would be the only non-linear, non-unitary, non-differentiable, non-local, non-CPT-symmetric, acausal, faster-than-light phenomenon in all of physics.”

    Now that’s a violation of Occam’s razor.

    • Torbjörn Larsson, OM
      Posted July 18, 2012 at 8:00 am | Permalink

      I don’t think MWT (as I call it) is overwhelming, or it would already be testable.

      [I like it, but currently I prefer the decoherence Copenhagen because of its dynamism in cosmology. (See my longish comment below.)]

      I don’t think decoherence theory claims that parts of the wavefunction “disappear”. It preserves unitarity, or it wouldn’t be suggested:

      “A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue.”

      Rather I believe it is claimed in the simplest interpretations that the unitarity preserving states are impressed onto the environment analogous to how entropy is ‘moved’ there. “Since the system’s dynamics are represented by irreversible representations, then any information present in the quantum system can be lost to the environment or heat bath.” [Ibid]

      Maybe another prediction for why the cosmology must end up in expansion, and why, if some universes collapses because of their parameters, there must be an expanding multiverse? Both entropy and decoherence need an environment that can soak up increasing amounts of “slop”.

      Also, there is no faster-than-light physics involved. The effects of decoherence is transmitted by the light cone, it has been explained to me.

      The non-locality of spacetime appears with Penrose twistor theory as he marries relativity mechanics with quantum mechanics. A local event in twistor space can map to two points in spacetime AFAIU. So you can equally well say that the deeper physics of spacetime is local (twistor space) as non-local (spacetime). It is inherently no more mysterious than that there is no aether but a vacuum – it is a case of how to properly map observations onto physics.

      • Posted July 18, 2012 at 9:44 am | Permalink

        I may misunderstand you, but it seems like you’re conflating decoherence theory with collapse theory.

        AFAIU it’s not decoherence theory that posits the magical disappearance of parts of the wavefunction with non-local, FTL physics. It’s the collapse theory that does that.

        May I ask what “simplest interpretations” you refer to, and how they are simpler than MWI? TIA.

    • Torbjörn Larsson, OM
      Posted July 18, 2012 at 8:38 am | Permalink

      “Also, there is no faster-than-light physics involved. The effects of decoherence is transmitted by the light cone, it has been explained to me.”

      I should add that decoherence looks to be gradual in (arguable) experiments, see my response to coelsblog. No need for local collapses to be ftl.

      • Torbjörn Larsson, OM
        Posted July 18, 2012 at 8:40 am | Permalink

        D’oh, “local collapses” – local decoherence.

  6. Posted July 18, 2012 at 5:57 am | Permalink

    and again, no examples of how this supports the idiot Christian god. Everyone claims that only their god is supported and of course none are.

    • elainetherave
      Posted July 18, 2012 at 7:01 am | Permalink

      I pray to many gods but get no answer to Syria murders of men,women and children.
      I need kkproof that their god out of say 2,000 gods is the true god.

    • JonLynnHarvey
      Posted July 18, 2012 at 8:16 am | Permalink

      I have never understood how apologists for theism then made the “quantum leap” (sorry on this page I cannot resist that) from a generic God to a Judeo-Christian God.

      At least a theist like Immanuel Kant remains just a generic theist, rather than a especially traditional Christian. (Kant’s notions on causality have been overturned by quantum physics BTW.)

      • Posted July 18, 2012 at 9:19 am | Permalink

        Whether Kant was a theist is somewhat open to doubt see for instance AC Grayling on the subject: http://newhumanist.org.uk/996/reasonable-bounds.

      • Posted July 19, 2012 at 4:56 am | Permalink

        This is true of many of the figures from ~100-200 years earlier in the scientific revolution. Many folks keep claiming these folks as “one of them”, but a slight bit of reading of standard (contemporary!) biographies makes this seen to be clearly wrong.

  7. peter
    Posted July 18, 2012 at 6:36 am | Permalink

    Just a tiny example on the low quality of writing (thinking?) that went into Barr’s essay:

    “…If the mathematics of quantum mechanics is right (as most fundamental physicists believe)…”

    Well, if the mathematics were not right, I could easily prove that 3=7, and any other mathematical assertion plus its negation.

    He perhaps meant to say something like ‘If the mathematics of quantum mechanics gives a theory which agrees exactly with physical reality (as most fundamental physicists believe)..’. But I am not sure he has ever even thought about the distinction.

    It seems a great shame that Hugh Everett was basically lost to physics, it seems because of the initially poor reception of his many-worlds interpretation. Apparently the Copenhagen interpretation was much more accepted by physicists from soon after 1925 till at least the 1970’s. So some of the more confident assertions here about the interpretation of quantum theory seem premature to me. I guess I’d be inclined to
    go with “The Strangest Man” (see the recent biography–I refer to Dirac), and stick to Tegmark’s bird’s eye of the world, ignoring the turtle.

    • Torbjörn Larsson, OM
      Posted July 18, 2012 at 8:07 am | Permalink

      I always found the Everett interpretation refreshing, as soon as I understood it was acceptable.

      I can’t say I understand all its ramifications, especially in Deutsch’s hands. His theory of time should be rather at odds with Carroll’s, I suspect. =D

  8. logicophilosophicus
    Posted July 18, 2012 at 6:37 am | Permalink

    a) Quantum mechanics makes it easier to believe in God. The Measurement Problem is an explanatory gap… If there were no gaps, it would be harder; so it makes it easier for now. If all the gaps are eventually closed, it will be impossible to believe in any kind of God who interacts with the universe. (More seductively, for theists, it is a gap just where consciousness – “spirit” in Godspeak – is lurking…)

    b) But decoherence as currently hypothesised only accounts for the appearance of wave function collapse. There is no actual collapse. The dead and living versions of the cat remain in a state of superposition at some level.

    • Posted July 18, 2012 at 7:11 am | Permalink

      There is no actual collapse. The dead and living versions of the cat remain in a state of superposition at some level.

      How do you know that?

      • logicophilosophicus
        Posted July 18, 2012 at 10:53 am | Permalink

        It’s part of the theory, nothing to do with my knowledge.

        Personally I’m happier believing in the phenomenal cat than the explanatory wave function.

        • Gregory Kusnick
          Posted July 18, 2012 at 12:02 pm | Permalink

          Each version of the phenomenal you is welcome to believe in its respective version of the phenomenal cat. And the wave function explains that too.

          • logicophilosophicus
            Posted July 18, 2012 at 12:34 pm | Permalink

            You need to talk to Coelsblog: how do YOU know wave functions don’t collapse?

            I think they do uniquely collapse…

            Or maybe there really is a multiverse of all possible collapses. If so, Max Tegmark calculates that there are an infinite number of universes identical to this one, with the first identical copy of me 10^10^29 metres away. Closer than that are vast numbers of analogs of me, in worlds where “I” am hailed as a Messiah (“you” too – in other universes), universes where “I” never lose at roulette (the analogs of James Randi in those worlds must have had a hard time of it)… Profoundly unsatisfying. A theory that explains everyhing explains nothing, they say. But it is the favoured view these days.

            • Gregory Kusnick
              Posted July 18, 2012 at 12:53 pm | Permalink

              Decoherence doesn’t explain “everything” (by which I think you mean “anything”); it explains the same observations that wave function collapse does, but more parsimoniously, by eliminating the need for the extra postulate of collapse.

              Also, you seem to be conflating Many Worlds with the multiverse of inflationary cosmology, which is a separate idea.

              • logicophilosophicus
                Posted July 19, 2012 at 1:14 am | Permalink

                1) I mean that everything possible happens an infinite number of times somewhere.

                2) Correct but irrelevant. This isn’t my theory, so I’m not asserting its validity, but…

                Tegmark points out that the set of 10^10^118 distinct universes demanded by some interpretations of cosmic inflation is identical to the set generated in the Many Worlds interpretation. Of course it is the former set that gives rise to his 10^10^29m distance to the nearest perfect “clone”. The distance is an average, of course, and could never be measured/travelled even in principle, since that would mean the two zones were parts of he same universe.

                But the interesting cosmological issue is that there is no way to distinguish two identical universes. Bousso and Susskind conjectured that the two sets are one and the same, and that in fact non-local sharing of information between near-identical “clones” could actually *explain* decoherence…

                Or something like that.

              • Posted July 19, 2012 at 6:58 am | Permalink

                I mean that everything possible happens an infinite number of times somewhere.

                This is my biggest problem with many-worlds: it inescapably, utterly, and completely demolishes statistics.

                There are an infinite number of universes with each possible sequence of events, including all the ones where something is so statistically unlikely that it’s not going to happen in the lifetime of the universe (such as all the gas molecules in the room randomly migrating to the ceiling, thereby suffocating you).

                And since all these infinities are the same size (regardless of what type of infinity they are), that means that you have the exact same odds of finding yourself in any one of these infinities.

                Worse, there are more ways for the universe to spontaneously devolve into unrecoverable chaos than there are for it not to — say, for example, by radioactive particles decaying instead of not — so the logical result is that we’d find ourselves not in one of the nice, orderly, predictable universes but rather one of the incoherent chaotic ones.

                By way of comparison, consider a truly random string of numbers, such as what π is hypothesized to be. In it, yes, you’ll eventually find all of Shakespeare, and you’ll even find it an infinite number of times, as well as an infinite number of variations on it (such as the exact complete works but with the first instance and only the first instance of Hamlet’s name changed to “Iamlet”). But do you have any idea how long you’d have to search before you found anything other than static?

                I don’t care that the many-worlds interpretation arises naturally from the math. It doesn’t fit the observations, and it doesn’t fit the observations in a way even more spectacularly than the god hypothesis doesn’t fit the observations.

                Many-worlds is worng, hopelessly flawed, spectacularly so, and I’m amazed physicists are still clinging to it. Maybe it’s because their experiences of math are all decidedly finite and they never actually do any work with infinite and trans-infinite math and thus, as is common with innumerate people in general, insist on thinking of infinities as incomprehensibly big but still finite numbers. They’re not, and the whole ballgame changes as soon as something that’s not countable is involved — and those changes are radical in ways that are even less intuitive than quantum mechanics.

                Cheers,

                b&

              • logicophilosophicus
                Posted July 19, 2012 at 7:11 am | Permalink

                @ Ben Goren

                Agreed.

              • Posted July 19, 2012 at 10:08 am | Permalink

                And then there are infinitely many worlds in which Ben and “lp” actually understand MWI and are wholeheartedly in agreement with it… :-D

                /@

              • josh
                Posted July 20, 2012 at 2:01 pm | Permalink

                @Ben Goren
                “And since all these infinities are the same size (regardless of what type of infinity they are), that means that you have the exact same odds of finding yourself in any one of these infinities.”

                ?? You seem to be implying that if I randomly select a digit from pi, my odds of picking an even number are the same as my odds of picking the digit ‘3’ since there are an infinite number of both kinds in the sequence of pi. Obviously, that’s wrong so why don’t you think a MWI would depend on probability densities/ on the proportion of one probability to another, the same way any QM theory does when dealing with infinitely many quantum states, like the position or momentum states of a free particle.

                What observations don’t you think MW fits?

            • Gregory Kusnick
              Posted July 19, 2012 at 10:30 am | Permalink

              Ben, physicists aren’t “clinging” to MWI; they’re converting to it, in ever-larger numbers.

              And wave-function amplitudes aren’t infinities; they’re complex numbers with magnitudes between zero and one, and not all the same size. It’s perfectly possible to compare them and conclude that one is, say, twice as likely as another. Trust me, guys who do QM for a living are not innumerate; they understand the math much better than you or I do.

              • Posted July 19, 2012 at 11:32 am | Permalink

                And they convert reluctantly.

                The reason for their reluctance, IMO, is that collapse postulate allows for the possibility that minds are immaterial, whereas MWI treats minds like any other material object, arising out of the wave function.

              • logicophilosophicus
                Posted July 20, 2012 at 2:54 am | Permalink

                Actually MWI has no answer (yet – I’m betting on never) to the Hard Problem. But if you are right, and physicists believe in MWI BECAUSE it holds out a better chance of confirming mind=brain, then their reasoning begs the question, and is invalid (though if it is just a preference, rather than an inference, they are entitled of course). It proves nothing.

              • josh
                Posted July 20, 2012 at 12:50 pm | Permalink

                logicophilosophicus-
                You’ll have to state the ‘Hard Problem’ coherently before I worry too much about whether MWI explains it. IMO, MWI is the best interpretation because it is parsimonious. It doesn’t have anything directly to do with confirming mind=brain, it just doesn’t make the ad hoc assumption that human observers aren’t subject to the laws of QM, it doesn’t invoke an undefined point of measurement where collapse occurs and it doesn’t require a fundamental indeterminacy (as opposed to a familiar epistemological one.)

              • Posted July 21, 2012 at 12:39 am | Permalink

                Precisely. I am appalled at the invective leveled by commentors at MWI, just based on the understanding that MWI says that there are infinitely many universes, and premature bold conclusions that MWI is “flawed”.

                All that MWI mathematically says, is that the universe is a “closed” system, in that it has a quantum wave function, which evolves in time according to the Schrodinger’s equation. That’s it. No less, no more. All the talk about “infinitely many” universes is just wordplay: an attempt to describe the mathematics. If you have examples demonstrating that this postulate is false, please write them up and publish them on the arXiv.

                I am sorry to say this, but critiquing MWI on the basis that it involves “infinitely many” universes is not much different from a creationist who criticizes evolution based on the “fact” that the probability of a human arising “by chance” is too small.

                By the way, Ben, I have worked in a department where we had to deal a lot with QM (and at some point, I was working on that stuff too, but I do more probabilistic stuff now). I expect that given the last paragraph of that comment of yours, you would be surprised to know that most of these “innumerate” physicists and computer scientists who work with QM are not in any way innocent of measure theory.

              • logicophilosophicus
                Posted July 21, 2012 at 4:53 am | Permalink

                My mind=brain comment was directed at what (I think) leg9ball was saying – that a prior commitment against the involvement of consciousness (as opposed to evidence) led to endorsement of MWI (or any other theory). That would be unscientific/illogical.

                Josh/Ahannāsmi
                MWI doesn’t actually posit Many Worlds? That’s nonsense. It may well be true that working physicists “shut up and calculate”, but from Everett to Tegmark the published accounts are quite clear. We only see one of the superimposed states because we live at the instant of measurement in only one of many universes. Since this description aims to account for the world we experience, it doesn’t do away with experience/mind and is no more parsimonious than the Copenhagen interpretation.

                On “fundamental indeterminacy” I think that’s unavoidable unless you believe in either hidden variables or infinitely Many (real) Worlds. Otherwise you live in a statistical quantum universe.

              • Posted July 21, 2012 at 8:32 am | Permalink

                @logicophilosophicus: “MWI doesn’t actually posit Many Worlds? That’s nonsense.”

                Well, it doesn’t, and your arguments seem to be veering, as I said earlier, to arguments from incredulity. I gave you the Everett postulate. The only difference between that and any other interpretation is that it applies what they use on small systems (such as Hydrogen atom) to the whole universe. I have yet to hear one argument that the other interpretations are flawed because they posit “infinitely many” Hydrogen atoms. Notice that the difference here is just of scale: the Hydrogen atom has an infinite dimensional state space too.

                Secondly, I don’t know where you get the idea that MWI (or more accurately, Everett’s postulate) is popular because of having anything to do with the mind-body problem. Even in the Copenhagen interpretation, the mind plays no role, as has been states in other comments. You are probably confusing the Copenhagen interpretation with the unsupported, discredited and “giant-leap-of-faith” consciousness causes the collapse interpretation. All the arguments I have heard for is are logical descendents of “von Neumann has told you it is good, and von Neumann is an intelligent man.” Not the best argument, as I am sure you wold agree.

              • Posted July 21, 2012 at 8:38 am | Permalink

                @logicophilosophicus: Also, as I said earlier, if you are so certain you have made a startling discovery that all that the innumerate physicists have been saying is clearly wrong, why don’t you just write a paper and put it up on the arXiv? (I say this because I am yet to hear an argument except those from incredulity). It does not have to be long: many important papers on the foundations of QM and quantum computation have been less than 2 pages.

                You will have a shot at immortality at least in the theoretical physics and theoretical computer science communities, and perhaps, if your arguments are good, you would have changed the world.

              • Posted July 21, 2012 at 12:18 pm | Permalink

                @logicophilosophicus:

                It may well be true that working physicists “shut up and calculate”, but from Everett to Tegmark the published accounts are quite clear.

                Yes, Tegmark is quite clear. However, he is quite clear in saying what I said in my comment above. He is also quite clear in dismissing the canard that Everett somehow postulated multiple non-interacting universes. If you don’t believe me have a look at Section II of the Tegmark paper I have already linked twice on this thread, but which I would link to again: http://arxiv.org/abs/quant-ph/9709032

              • logicophilosophicus
                Posted July 23, 2012 at 9:49 am | Permalink

                @Ahannāsmi

                Well, there is also the fact that Everett titled his 139 page paper “The Many-worlds Interpretation of Quantum Mechanics”. On page 98 he explains why: the act of measurement/observation (the observer can be inanimate in MWIQM) splits the observer into a presumably infinite number of elements each of which perceives its own element of the superposition, and such observer elements are forever separated. Each perceives a different world. On page 116 you will find that Everett justified his interpretation *precisely* because it avoided the objectionable distinction between conscious observers and inanimate measurers. Also note that Everett regards interpretation of QM as largely aesthetic – my only objection above was aesthetic.

              • Posted July 23, 2012 at 6:18 pm | Permalink

                “Also note that Everett regards interpretation of QM as largely aesthetic – my only objection above was aesthetic.”

                I will take you on your word for that, but would like to remind you posted an “agreed” to Ben’s comment which was trying to claim that MWI was somehow flawed on mathematical/statistical grounds.

                On the other hand I am not sure why you still cling to the belief that MWI is the only interpretation in which consciousness does not matter. It does not matter in any but (as I alluded to earlier) von Neumann/Wigner “consciousness causes collapse” model, for which you would be hard pressed to find supporters. In particular, consciousness does into come into the picture in the Copenhagen interpretation.

              • Posted July 23, 2012 at 11:46 pm | Permalink

                the last line in my comment should be “In particular, consciousness does not come into the picture in the Copenhagen interpretation.”

            • Posted July 21, 2012 at 11:47 am | Permalink

              @logicophilosophicus: I highly doubt your attribution to Tegmark of the claim that “there are an infinite number of universes identical to this one, with the first identical copy of me 10^10^29 metres away.” Here is a quote from one of his papers, (available here for free download, emphasis from the original):

              What Everett does NOT postulate:
              At certain magic instances, the the world undergoes some sort of metaphysical “split” into two branches that subsequently never interact.

              Further evidence in support of my skepticism it is a rather meaningless claim to make anyway (even granting the existence of multiverses, how do you compute distance between them in metres? That’ll either have to mean that the two copies are in the same metric space, which contradicts the original multiverse assumption, or that failing, it’s rather like converting liters into metres, if you ask me. The mathematical reason is that there is no canonical way to measure distance between two points in two different metric spaces).

              • logicophilosophicus
                Posted July 24, 2012 at 5:37 am | Permalink

                @ Ahannāsmi

                Rather than respond separately to three or four posts I’ve written one long one – apologies in advance.

                You wrote: “…if you are so certain you have made a startling discovery that all that the innumerate physicists have been saying is clearly wrong, why don’t you just write a paper and put it up on the arXiv? (…I am yet to hear an argument except those from incredulity).”

                That’s a bit confrontational. My position is that I assume always that the physicists are excellent mathematicians who get their maths right. (Not “innumerate” – you invented that.) I carefully read the abstract and discussion sections of their papers (skimming the rest with appropriate humility), and draw conclusions. The main conclusion here – not original, and hardly worth a paper, would you say? – is that there is serious disagreement – and therefore room for disagreement – over what the mathematics of wave mechanics imply about reality. In the you persistently cite, Tegmark says: “The reader must choose between two tenable but diametrically opposite paradigms… 1: The… mathematical structure… is physically real… 2: The subjectively perceived… view is physically real…” Personally I think that if denying the reality of either is “tenable” then denying the reality of both is tenable – we may not be even close to ultimate reality, and it is untrue that we “must choose between…” That is an argument from logic, not incredulity.

                You also wrote: “Tegmark is quite clear… in dismissing the canard [a bit confrontational?] that Everett somehow postulated multiple non-interacting universes. If you don’t believe me have a look at Section II of the Tegmark paper (“…Many Worlds or Many Words”). I’ve read it. Basically it offers the choice above, preferring paradigm 1, the Platonic reality of the (universal) Schrödinger equation. That’s Tegmark’s MUH in embryo. This is how he spelled out the consequences of the view in 2005: “…the simplest and most elegant theory involves parallel universes by default.” That’s in http://arxiv.org/pdf/0905.1283.pdf

                You also wrote: “I highly doubt your attribution to Tegmark of the claim that ,there are an infinite number of universes identical to this one, with the first identical copy of me 10^10^29 metres away.’ ” A bit confrontational again? Well, it was straight out of the same paper (Tegmark 2005).

                You also wrote: “…it is a rather meaningless claim to make anyway (even granting the existence of multiverses…) …there is no… way to measure distance between two points in two different metric spaces…” No measurement is involved, just a statistical analysis of what Vilenkin calls the “Universe Beyond the Horizon”. The distances are averages (I already said that in my posts) and are not measurable (I already said that too.)

                You also quoted Tegmark: “What Everett does NOT postulate: At certain magic instances, the the world undergoes some sort of metaphysical ‘split’ into two branches that subsequently never interact.” True, but not in the way you think. Everett objected to what Tegmark calls “magic instances” (instants?) in the sense that he wouldn’t accept the input of a conscious observer as having any non-physical effect on the wavefunction (i.e. Heisenberg’s view of reduction). That doesn’t mean Everett did not posit Many Worlds right from the start. In a footnote added to the published version of his PhD thesis (“Relative State” Formulation of Quantum Mechanics) he wrote: “From the viewpoint of the theory ALL elements of a superposition (all ‘branches’) are ‘actual’ [the one any of us experiences at any moment, for example] “…The theory itself predicts that our experience will be what it in fact is.” (A bit of a stretch in my view – experience involves more than a mathematical function.)

                Back on thread, we might say, you also wrote: “In particular, consciousness does not come into the picture in the Copenhagen interpretation.” As Professor Joad might have said, “it all depends what you mean by ‘the’.” There was (no doubt still is) a lot of disagreement in CI. This is Heisenberg: “The act of recording… which leads to reduction of the state, is not a physical, but rather, so to say, a mathematical process. The vector is devoid of any physical reality but rather is a mathematical representation of the knowledge of the observer…” from a letter to Renninger in 1960. If you can define knowledge to my satisfaction without invoking consciousness, you’ll have persuaded me.

                I think you have rather strenuously denied what I wrote, but I have done you the courtesy of carefully searching out all my sources and clarifying my position. The sources, at least, should be useful.

              • Posted July 24, 2012 at 9:53 am | Permalink

                “(Not “innumerate” – you invented that.) ” As I said earlier, you posted an “agreed” to Ben Goren’s post which made all the arguments against MWI that you now seem to eschew: including (verbatim) the accusation of “innumeracy” against the physicists. Of course, I’ll take you on your word, and assume that you “agreed” with Ben by mistake.

                “there is serious disagreement ….. over what the mathematics of wave mechanics imply about reality.” The very point is that there is not. Any realistically observable phenomenon gives the same results no matter what interpretation you use. There is only one proposed experiment paradigm, that of quantum suicide, which might be able to distinguish between Coenhagen and MWI interpretations, but it is unclear if it really can. That is precisely why the debate about interpretations has to go into aesthetics. To repeat, there is no mathematical or statistical reason (as Ben Goren asserted, and as you seemed to agree then, but not now) that would lead one to prefer MWI over Copenhagen. Even aesthetic reasons are suspect: as I said the difference is one of scale. The Copehagen interpretation applied to a Hydrogen atom the same formalism that Everett applies to the Universe. The same remark applies to your repeated claims about the “actuality” of the different branches of the wavefunction: why don’t you argue about at length whether we have to perceive the “two” states of an electron which goes via a unitary operation from |0> to |0> + |1> (modulo normalization) has having “subjective reality” or not.

                As for your several claims of my alleged “confrontational” remarks, I would like you to refer to your comment where you replied “That’s nonsense” to a description of the MWI with which you now seem to agree. For what it is worth, I do not think my remarks are confrontational at all, given that I was reponding to a completely false charge of talking “nonsense”.

              • Posted July 24, 2012 at 10:06 am | Permalink

                ““The act of recording… which leads to reduction of the state, is not a physical, but rather, so to say, a mathematical process. The vector is devoid of any physical reality but rather is a mathematical representation of the knowledge of the observer…” ” I am not an authority on what Heisenberg thought or believed, but nowhere here is the observer seems to be postulated to have consciousness. At least for me (and most other people who do Quantum) it seems rather clear that “knowledge” in the sense of Copenhagen interpretation does not require consciousness at all. An electron interference pattern is formed on the screen no matter whether a (conscious) observer is looking or not. You can put a video camera to catch the glow, and the CI (at least the currently accepted version) would make the right prediction of the intensity of the fringes recorded on the film.

              • Posted July 24, 2012 at 10:10 am | Permalink

                Also, about your 10^10^29 copies statement, you seem to be confusing (as a commnetor above already pointed out) the multiverses of inflationary cosmology (quite a different matter) with the “multiple branches of the wavefunction” multiple worlds of MWI. Here is the quote in its entirety:

                “A generic prediction of cosmological inflation is an infinite “ergodic” space, which contains Hubble volumes realizing all initial conditions — including an identical copy of you about 10^10^29m away.”

                Tegmark, in the same section from which you took the quote, distinguishes between this (his Level I) and MWI (his Level IV).

              • logicophilosophicus
                Posted July 28, 2012 at 2:53 am | Permalink

                @ Ahannāsmi

                I have not had the chance to go online this week. I hope you don’t find the tardiness of this reply uncivil.

                i) Re “innumerate”/“agreed”: My apologies. I wrongly thought you interpreted my comments as rubbishing the numeracy of physicists, but I see you were quoting Ben Goren. My terse “agreed” was not meant to imply anything more than that my own discomfort with MWI, in particular with the infinite proliferation of universes, tallied with his. I had already stated earlier that MWI may be true (but incomplete): my agreement with BG is obviously therefore limited. I see I was wrong to suggest you “invented” anything.

                Re my assertion that interpretations disagree about what constitutes “reality”, you wrote: “Any realistically observable phenomenon gives the same results no matter what interpretation you use.” You have a blind spot there. Everyone agrees that the calculations work, but Heisenberg thinks reality is what is observed, Everett thinks that the infinitely many branches unobserved by (say) me have equal but secondary reality (to do so he RE-defined “observation” and “memory” i.e. Heisenberg’s “knowledge”), Bohm thinks there are hidden variables which are part of the ultimate reality (Einstein, too, believes wave mechanics is “incomplete”), Bohr believes (and reiterates for decades) that neither the wave equation nor the observer has independent reality (reality is the fact of observation), Tegmark believes that the maths (including alternative maths describing universes with different laws) is the fundamental (Platonic) entity (in agreement with Everett re the Universal Schrödinger Equation, but he believes there are infinitely many alternative equations/universes), Penrose believes that both the phenomenal world and the maths are ontologically real, and his (and Hameroff’s) theory is only one of a whole bunch of theories which generally equate phenomenal reality with objective reduction or decoherence, Ghirardi thinks reduction/decoherence is an added property of quantum-scale entities, Cramer resuscitates the advanced-waves solutions of Maxwell’s equations and… “Serious disagreement” goes all the way back to Solvay 1927 and beyond. You are saying that the formalism (the maths) is the same and therein lies the reality. But then where are the matter, the energy, the fields, never mind the qualia, the morality, the urge to understand? Whence the vast range of disagreement?

                You dismiss the dependence of Heisenberg’s account on “the knowledge of the observer…” thus: “At least for me (and most other people who do Quantum) it seems rather clear that ‘knowledge’ in the sense of Copenhagen interpretation does not require consciousness at all. An electron interference pattern is formed on the screen no matter whether a (conscious) observer is looking or not. You can put a video camera to catch the glow, and the CI (at least the currently accepted version) would make the right prediction of the intensity of the fringes recorded on the film.” That’s the von Neumann chain – where and why does it break? That’s the question. Failing to consider this is exactly parallel to ignoring all those incompatible theories by cutting off discussion at the knees, that is, between calculation and interpretation. A generation of physicists either studied under the great theorists or under the great calculators, and learned their attitudes there. This is Feynman, from his UCLA lectures on QED about 30 years ago: “…this framework of amplitudes has NO EXPERIMENTAL DOUBT about it: you can have all the philosophical worries you want as to what the amplitudes mean (if, indeed, they mean anything at all), but because physics is an experimental science and the framework agrees with experiment, it’s good enough for us…”

                You wrote: “Also, about your 10^10^29 copies statement, you seem to be confusing (as a commnetor above already pointed out) the multiverses of inflationary cosmology (quite a different matter) with the… multiple worlds of MWI… Tegmark, in the same section from which you took the quote, distinguishes between this (his Level I) and MWI (his Level IV).” (Actually Levels I and III, but never mind.) It was Bousso and Susskind who identified (not “confused”) the two multiverses, as I already pointed out – Tegmark’s reason for regarding I+III as “irreducible” was obviously unconvincing for them: “…there are mathematically defined relations between points in causally separated Hubble volumes (generated by relations between topologically neighbouring points)…”

                I see your “confrontational” stance was retalliation for my writing “That’s nonsense” to your claim re MWI: “All the talk about ‘infinitely many’ universes is just wordplay…” Sorry, not so. This post is too long already, so although I have many sources making the same point, I’ll go straight to the source. I already gave you Everett’s “branches” quote which should be enough, but why (between 1957 and 1967) did he adopt the name “Many-worlds” for his theory? It was because of the enthusiastic support of Bryce Dewitt: “I still [in 1970] recall vividly the shock I experienced on first encountering this multiworld concept. The idea of 10^100+ slightly imperfect copies of oneself all costantly splitting into further copies…” The assertion that “Many-worlds” doesn’t mean what it says is nonsense, traceable no doubt to the “shut-up-and-calculate” school of quantum physicists.

                Personally I only assert that there are deep divisions concerning the nature of reality, and I have produced ample evidence. In fact I have just re-read the Debate (1996) and Afterword (2010) chapters of Hawking and Penrose’s “The Nature of Space and Time”. The disagreements are fundamental, and the two don’t even seem to understand each other! “…despite… increased knowledge, our two point of view appear to have diverged even further… indicative of the fact that… there remains a very healthy debate concerning… the fundamental nature of physical reality.” That from two theorists with the same background.

  9. Posted July 18, 2012 at 6:53 am | Permalink

    I take it that the good Catholic has never consumed enough sacramental wine at one go to get drunk?

    Or does he posit that alcohol has some particularly powerful quantum woo in it that messes with the conscious quantum observation bits?

    Really, the notion that there’s something more to consciousness than what goes on inside the skull should have died with the invention of beer. I can only conclude that those who still hold onto such an incoherent concept must be partaking too much for their brains to function properly.

    Cheers,

    b&

  10. elainetherave
    Posted July 18, 2012 at 6:59 am | Permalink

    What a great god to have created just a perfect world. Child abuse, child soldiers, 20,0000 children dying a day yet he seems to have time to watch American and english football. So is Brian COx lying, are all the scientists that believe in evolution wrong. Evil is man made ‘In the beginning man created god’.To excuse all their cruelty,like praying for a childs recovery and god does not answer. Too busy playing ‘war games’.

    • Torbjörn Larsson, OM
      Posted July 18, 2012 at 8:16 am | Permalink

      Man can behave cruelly, needlessly so, but so can all mammals. The sight of baboons that have learned to kidnap feral dog puppies and grow for watch dogs is heart-rending. [Youtube] Even if it isn’t fact, and it is still arguable I think, the film snippets are enough “evil”.

      As apes goes, humans are a rather peaceful lot, it is chimps that nearly always fight and go on war parties. Sure, we could be more like bonobos too.

    • JonLynnHarvey
      Posted July 18, 2012 at 8:19 am | Permalink

      The Holocaust and cancer are for me the two best arguments against God. Apologists occasionally fall back on a verbal sleight of hand called the onTological argument. I call the argument against God from cancer the onCological argument.

      • logicophilosophicus
        Posted July 19, 2012 at 2:02 am | Permalink

        Strictly speaking, all you have done is to argue that the kind of god *you* expect gods to be is inconsistent with reality. However unsatisfying it may seem, you can’t argue along the lines that Christians, say, have to believe in *your* by-definition-unbelievable god.

        Personally I find the notion of Original Sin repulsive, but it’s an integral part of the Roman Catholic world view, and accounts for all the evils of the world in that view. And, of course, death is only unacceptable to the materialist. To Chistians it is the door to everlasting “life” – I think most of them imagine some new (or reconstituted) body as well as a “soul”.

        • BillyJoe
          Posted July 19, 2012 at 6:33 am | Permalink

          “I find the notion of Original Sin repulsive”

          Don’t worry about it. It’s been proven false. Genetic studies (mitochondrial Eve and y chromosome Adam) have conclusively shown that Adam and Eve must have lived at least 40,000 years apart. There was no original sin and therefore no need for redemption. The whole basis of christianity has collapsed.

          • logicophilosophicus
            Posted July 19, 2012 at 7:08 am | Permalink

            I don’t worry about Original Sin, since I don’t believe in it. I am just repelled by the concept.

            I think you are mistaken if you think educated Catholics depend on literal acceptance of the Eden myth for their belief in Original Sin.

            (Btw – Y-chromosome “Adam” only proves that we all descended from the same guy at that date. He doesn’t prove that all humans before him were not similarly descended from a single male [they pretty certainly were, though he may have been pre-human] who – for all we know – was a contemporary of Mitochondrial Eve… No doubt some ingenious Christian has already reidentifed Y-chromosome “Adam” as Noah.)

            • elainetherave
              Posted July 19, 2012 at 9:37 am | Permalink

              Please read The Bible according to Mark Twain, get your facts from there.We could go on for ev er discussing this but lets face it,No God,-no Gods,

              • logicophilosophicus
                Posted July 19, 2012 at 10:30 am | Permalink

                I don’t understand your point.

            • BillyJoe
              Posted July 19, 2012 at 9:42 pm | Permalink

              You don’t understand. No Adam and Eve, no original sin. No original sin, no need for redemption (the son of god dying oin the cross). No redemption and Christianity is bankrupt.
              Also if you ask christians, the vast majority do believe in a literal Adam and Eve. There has to be, otherwise their religion is bankrupt.
              And the point about mitochondrial Eve and y-chromosome Adam is that people alive today can not have been descended from a single couple at any time in the past (ie Adam and Eve could not have existed).

              • logicophilosophicus
                Posted July 20, 2012 at 7:41 am | Permalink

                “I think you are mistaken if you think educated Catholics depend on literal acceptance of he Eden myth for their belief in original sin.” Belief in evolution doesn’t prevent belief that humanity was onle blameless or free from sin and somewhere along the line gained the capacity for evil and for the responsibility for evil. What do you reckon? Is a modern child killer responsible in a way that a chimp child killer isn’t? See for example

                http://www.jirrs.org/jirrs_nr_1/08-brannan.pdf

                Personally I find that view repulsive, because it makes us immoral and our distant ancestors moral. I think they were amoral and we are a mixture of moral and immoral.

                “…people alive today can not have been descended from a single couple at any time in the past…” Sure they can. Mitochondrial Eve could have had a mate who was the ancestor of all subsequent human beings. Unlikely, but possible. And she (and everyone alive now) could have been descended from a more remote couple… In fact its not that unlikely. Human chromosome 2 is reckoned to be the result of a major unique macromutation, the fusion of two ape chromosomes. It is presumably the case that – whether or not the mutant and ancestral stock were interfertile – we are all descended from the same single family. I doubt whether that has much to say about religion, your “single couple” statement is a false conclusion and almost certainly false.

  11. Dave
    Posted July 18, 2012 at 7:06 am | Permalink

    Quoting scientists isn’t the same as citing real science.

    And there’s a parallel between the emergence of conscious complexity from material reality and the emergence of snowflake complexity from the raw elemental material composing water, for instance.

    • Andy Dufresne
      Posted July 18, 2012 at 7:42 am | Permalink

      Quoting scientists isn’t the same as citing real science.

      This ought to be one of the basic ground rules for engaging the religious and Templeton types in these discussions: if someone refuses to acknowledge this difference, then there’s nothing to discuss.

      But it’s always a treat to watch a smart physicist like Sean or Vic Stegner take down these “quantum gods” arguments. Is there anyone who became a god believer because of quantum mechanics?

      • eric
        Posted July 18, 2012 at 8:03 am | Permalink

        Is there anyone who became a god believer because of quantum mechanics?

        If Einstein’s reaction is any indicator, the reverse seems to be more common; people see QM as so absurd that they see it as being in a sort of opposition to the idea of a rational, anthropomorphic, caring God.

        • peter
          Posted July 18, 2012 at 2:29 pm | Permalink

          For Einstein, maybe rational, though doubtful; certainly not anthropomorphic or caring.

  12. MKray
    Posted July 18, 2012 at 7:24 am | Permalink

    Wigner subsequently recanted his view concerning the role of consciousness in quantum measurement.
    I met Peierls and I really can’t imagine him wishing to give support to theistic beliefs.. we deserve a citation, at least.

    Finally, I deplore all arguments of the form `just a … (lump of meat…)’. It appears to deny all the wonderful things that humans are… you can’t take them away from us! If they all come from a lump of meat, so be it: that just gives something wonderful for generations of scientists to explain.

    • logicophilosophicus
      Posted July 18, 2012 at 11:07 am | Permalink

      I think it’s more accurate to say that Wigner changed his view about the specific idea that the conscious act of observation caused the wave function to collapse.

      Your “recanted” makes it appear that Wigner cam back into a less mystical orthodoxy. Actually he went the other way, I understand, concluding that consciousness was all-pervasive and fundamentally mysterious. I could be mistaken.

      • peter
        Posted July 18, 2012 at 3:31 pm | Permalink

        I think so too. At his height, Wigner’s work, such as relating Lorentz group representations to quantum theory, was wonderful, and needed in quantum field theory and the Standard Model.

        But this stuff we are now referring to was mostly when in his 80’s and 90’s. Some think a kind of senility is evidenced by his association with the Moonies; certainly his sister, Dirac’s widow, was not a fan of that.

    • Occam
      Posted July 18, 2012 at 11:11 am | Permalink

      Do you happen to know whether the Wigner consciousness quote belongs to his later years, when he dabbed in Eastern philosophy? Was it just a philosophical rumbling, or backed up by anything more substantial?

      One of my physics profs, a student of Fritz Houtermans (and, earlier, I believe, of Pauli), hence a repository of wry comments about the founder generation of QM, would very occasionally spice up a lecture by quoting some oracular utterance by a respected luminary: seemingly profound, of import beyond the boundaries of physics, and utterly disproved by later research.
      A discreet and mild-mannered man, he did not press the point. Only once did he offer a homily to match: “The operative word for para-scientific ruminations of physicists is just that: ruminations. No matter how nutritious for the principals, and however fertile when appropriately seeded in an adequate soil, the product at the end of the process is, prima facie, a pile of dung.”

      • logicophilosophicus
        Posted July 18, 2012 at 11:55 am | Permalink

        I think Wigner would have disagreed – there’s a famous remark of his about scientific intuition being more enlightening than spadework. I can’t recall the wording.

        Anyway, here’s a link re your question:

        http://www.newworldencyclopedia.org/entry/Eugene_P._Wigner

        • logicophilosophicus
          Posted July 18, 2012 at 12:03 pm | Permalink

          Mind you, that New World Encyclopedia has its own agenda.

  13. Torbjörn Larsson, OM
    Posted July 18, 2012 at 7:27 am | Permalink

    Carroll’s reply and the LOLCatPhysics image makes me happee. Not being a quantum physicist even I have come to understand that decoherence makes away with the classical Copenhagen to at the very least replace it with its decoherence form.

    Decoherence is to my knowledge not yet tested but very much implied by experiments that shows it is a gradual process, not instant. I.e. you can go into and out of partial decoherence.

    Another Barr-stopper is the proposal that the wavefunction is real, and proposals how to test that. Then there is no “knowledge” interpretation of constrained statistical outcomes to put gods into, just the usual observability on statistical outcomes of systems doing the constraining.

    In the middle ground, I think the practice of labeling different theories of quantum mechanics as “interpretations” is giving too much. The mechanism of decoherence, if it exists, shows that we can still pare the set of theories down even if they were originally constructed to predict the same physics. It is too early to give up on the elimination of alternatives.

    On the other end, while Many-World Theory (as I like to call it) is the most parsimonious quantum theory as it combines a few basic concepts, I am no longer a hopeful supporter. (But I can’t reject it either.) The reason is that as I understand it decoherence puts a very good physics dynamics onto the light cone and cosmology both.

    Decoherence would resolve entanglement by signaling the result at light speed, I am told. Seems intuitive and no need for MWT world splits for a physics as we know it.

    The universal expansion ‘clock’ would be locally delayed by absence of interaction with a complex environment where entanglement briefly appears. After decoherence the light cone from the parts of the entangled system would catch up with the universal expansion. Again, a small modification of what we already see.

    Obviously local delays don’t happen often or we would notice it more, but that is consistent with the fragility of entangled systems. I imagine (no cosmological expert) that there is no cosmological horizon problem for entanglement and decoherence, since the inability of light cones to catch up with expansion happens when redshift weakens signals and observation of expansion into invisibility.

    MWT looks exciting, but so does a dynamical quantum-relativistic cosmology as it has been described to me.

    Finally, I didn’t know that “The Unreasonable Effectiveness of Mathematics in the Natural Sciences” Wigner was also a quantum mind dualist. But I guess one gods-of-the-gaps woo is as good as another.

    • Torbjörn Larsson, OM
      Posted July 18, 2012 at 8:21 am | Permalink

      But see MKray above on Wigner too.

      • logicophilosophicus
        Posted July 18, 2012 at 11:08 am | Permalink

        …and my reply.

    • Gregory Kusnick
      Posted July 18, 2012 at 11:56 am | Permalink

      Torbjörn, you’re talking as if Many Worlds and decoherence were two competing theories. As I understand it (perhaps incorrectly), Many Worlds arises from decoherence theory. When two branches of the universal wave function decohere to the point where they can no longer interfere with each other, they effectively behave as separate universes, and that’s where the many worlds come from.

      Personally I think Many Worlds is a misleading name for it. Stars and galaxies don’t actually get cloned wholesale. It’s all one world (or universe), but with many superposed histories.

  14. Posted July 18, 2012 at 7:58 am | Permalink

    If the “observer” were just a purely physical entity, such as a Geiger counter, one could in principle write down a bigger wavefunction that described not only the thing being measured but also the observer.

    Wait, if other people observe the mechanical observing machine that’s observing the collapsing wave function, I could just make an even bigger wave function that collapses when that other person tells me.

    I’m the only true conscious person that exists!

    Carry on all you meat automata, you amuse me.

  15. JonLynnHarvey
    Posted July 18, 2012 at 8:23 am | Permalink

    Hardly anyone here has mentioned Victor Stenger’s full-length book “The Unconscious Quantum” which is a rebuttal to much of this.

  16. squinky101
    Posted July 18, 2012 at 8:39 am | Permalink

    I would add that even if one could defend a quantum mechanical basis that the mind is separate from brain matter then why don’t animals that have neurons and prefrontal cortexes (and the same quantum mechanical effects) have minds like ours? Further, our mind and consciousness can easily be altered by damage to its brain matter. Does a person in a vegetative state have a mind? A newborn child? A newborn with anencephaly? An ant? A petri dish of neurons? Dead neurons?

    • Posted July 18, 2012 at 8:43 am | Permalink

      …a drunk?

      b&

      • squinky101
        Posted July 18, 2012 at 8:51 am | Permalink

        a drunk Christian?

        • gbjames
          Posted July 18, 2012 at 9:22 am | Permalink

          a drunk Muslim?

    • Torbjörn Larsson, OM
      Posted July 18, 2012 at 8:47 am | Permalink

      Such questions that the apologist should consider, I don’t mind at all.

    • RFW
      Posted July 18, 2012 at 9:19 am | Permalink

      Or someone with simple dementia, like a long-time friend, now well into his eighties, who doesn’t remember a thing about the house he and his wife have lived in for over fifty years. [Vascular dementia – brain intact but not enough oxygen getting to it.]

      Or someone with advanced Alzheimer’s. Another elderly friend’s wife came down with a fast moving form, and it wasn’t long before the answer to “How’s Ruth?” was “Like an empty house with no one home.” By the time she died there’d been no trace left of her personality for a good year or so.

      • squinky101
        Posted July 18, 2012 at 11:12 am | Permalink

        You are your brain. QED.

        Anyone who says otherwise has a lot of explaining to do.

    • Scott near Berkeley
      Posted July 18, 2012 at 12:58 pm | Permalink

      I was going to make the same argument, based simply on memory. What difference does QM-based-consciousness “eternal life” make if you “can’t take it (i.e…”YOU!!”) with you..”? That “YOU!!” is the physical particles, enzymes, ions, nerve channels, that make up our ability to have memory, cannot magically travel outside your skull when you die. Just like your nose, teeth, arms, eyeballs, ears, they stay right ‘here’ when one dies.

      This whole quantum mechanics argument/ consciousness is the very definition of superfluous.

      It’s like arriving at dockside, ready to depart on a round-the-world cruise, only to find that a hole (the physical memory stays) in the hull has developed, and one’s prized vessel is now under twelve feet of water. The size of the engine, the number of crew, the naval architect who designed her, the provisioning, size of the deck, navigational instruments…these are absurd to even mention… the damn boat’s on the bottom, and none of that (and, the uncertainty of the position of the atoms that make up the vessel…thank you QM) makes not one scintilla of difference!!!!!!!!!!

      • logicophilosophicus
        Posted July 19, 2012 at 2:13 am | Permalink

        I think Penrose and Hameroff consider the point that even when the neural correlates of memory are dispersed after death, their quantum entanglements remain, indestructible.

  17. Thanny
    Posted July 18, 2012 at 9:43 am | Permalink

    This confusion about what counts as “observation” is pretty pervasive among quantum woo advocates.

    An “observation” is nothing more than something measurable happening, whether or not a big meat computer is around to measure it. It has nothing whatsoever to do with consciousness.

    It’s also worth pointing out that the notion of a wave function is part of a mathematical model of reality, not reality itself.

    • BillyJoe
      Posted July 19, 2012 at 6:50 am | Permalink

      Yes, and what a misunderstanding: in the double slit experiments, the observer is actually the sensors at the slits! If the sensors are turned off, there is no “observer” and an interference pattern results. If the sensors are turned on, ther is an “observer” and a scatter pattern results. The experimenter can drop dead as he presses go for all it matters the the result.

  18. Posted July 18, 2012 at 11:37 am | Permalink

    If a mind is what’s needed to collapse a wavefunction, and if God is (has) a mind, and if God sees/knows all, then quantum mechanics is impossible, because all wave functions will immediately collapse.

    Quantum mechanics disproves God’s existence. In your face, Barr!

    • BillyJoe
      Posted July 19, 2012 at 6:51 am | Permalink

      Unfortunately, your premise is wrong.

  19. Lawrence B. Crowell
    Posted July 18, 2012 at 2:15 pm | Permalink

    The role of consciousness in quantum physics is not known, but it is not necessary to invoke consciousness to analyze what happens in a measurement. A measurement is a form of entanglement. A quantum system in a superposition of states may become entangled with other states, where in the case of the environment this can be a large reservoir of states. The superposition of the quantum system is removed and converted into entanglements with these other states. The density matrix is reduced to diagonal elements ρ_{ii} = |ψ_i|^2 and off diagonal terms like ρ_{ij} = ψ*_iψ_j are replaced with entanglements of the states ψ_i — >ψ_iχ_i with the auxiliary states χ_i. If these auxiliarly states are orthogonal this removes the off diagonal matrix elements corresponding to a superposition. This is the basis for decoherence theory.

    The human observer is then reduced to looking at outcomes which are really a form of classical collapse. In other words it is not different from looking at a hand of cards dealt to you. The two observers in the EPR measurement observe spin up or down in much the same way if there is one ball under one of two cups, I observe it under cup A and the other observer look under cup B somewhere else I know there will be no ball there — instantly. The rub though is quantum physics and decoherence gives no predictive theory for what actually materializes in a measurement.

    There is then an unknown relationship between the dynamical theory of quantum wave equations and randomness. Randomness is not axiomatically provable; there is no axiomatic method for determining if something is completely random. Algorithms which produce random numbers are really in fact pseudo-random. So there is a deep question here concerning the foundations of physics.

    It is to convenient to shove a God into some place where current knowledge is incomplete. If that had been done in the past and taken as the :final answer we would still think angels pushed the planets around.

    LC

  20. Kevin
    Posted July 18, 2012 at 2:27 pm | Permalink

    As usual, not an answer to a big question, but conjecture, wild guessing, and wishful thinking.

    Along with some quote mining of dead people, and ignoring any evidence that comes from people who are around to actually defend themselves.

    Ghouls.

    Stay classy, Templeton.

    • BillyJoe
      Posted July 19, 2012 at 6:53 am | Permalink

      Stay classy? Since when?

  21. Posted July 18, 2012 at 7:24 pm | Permalink

    With as much disrepsect as we can muster — quantum = some god is just stupid.

  22. MNb
    Posted July 19, 2012 at 2:58 am | Permalink

    Sure QM gives evidence for some god or another – one playing dice. So I expect Barr to convert either to the gods of the Greek Olympus or to the Flying Spaghetti Monster.

  23. Alex SL
    Posted July 19, 2012 at 3:42 am | Permalink

    Meh. My take is this: We know for completely unrelated reasons (biology & medicine) that dualism is false, so his interpretation of quantum must be false.

    This idea is just ludicrous, and – correct me if I am wrong – I thought the point of Schroedinger’s cat was to show its absurdity instead of giving a convincing example?

    • BillyJoe
      Posted July 19, 2012 at 6:54 am | Permalink

      You are absolutely correct.
      It’s amazing how many do not understand that simple fact.

  24. Bruce Gorton
    Posted July 19, 2012 at 4:42 am | Permalink

    The thing with Schroedinger’s cat is that it more illustrates knowability than it does any truism of the universe.

    Whether the cat is dead or alive is a fact quite separate to our knowledge of whether it actually is dead or alive, we just cannot know which it is without checking.

    The answer thus isn’t “both” it is “we don’t know.”

    • BillyJoe
      Posted July 19, 2012 at 6:56 am | Permalink

      Unfortunely, you missed the point.
      See post #23

    • akismet-40ce12ddb2623e473d03ba906b3f75cb
      Posted July 21, 2012 at 8:32 am | Permalink

      That’s not true. The answer really is both. Well, for a real quantum system, because a real cat would observe itself.

  25. akismet-40ce12ddb2623e473d03ba906b3f75cb
    Posted July 21, 2012 at 8:30 am | Permalink

    We now know that there is no “quantum jump”. We now know how to catch a quantum system in the middle of decoherence. There is nothing instantaneous or discontinuous about it, and we have every reason to believe now that everything is a quantum system, even what looks to be classical to a very good approximation.

  26. Posted December 2, 2013 at 4:14 pm | Permalink

    sub

  27. J. P. Ziller
    Posted May 12, 2014 at 8:12 pm | Permalink

    Sean Carroll doesn’t handle Barr’s point well. Decoherence explains why the wave function *seems* to collapse, but it doesn’t claim to provide a mechanism for the *actual* wave function collapse – it doesn’t claim to solve the Measurement Problem. See any good discussion of the subject — e.g. the Wikipedia article on Quantum Decoherence. Barr’s point concerns the Measurement Problem that decoherence doesn’t claim to solve.


2 Trackbacks/Pingbacks

  1. […] Sort-of guest post: Sean Carroll comments on whether quantum mechanics gives evidence for God […]

  2. […] It’s not just cranks who have an interpretation of quantum mechanics that suggests the answer is “consciousness!” and “God!”. But I was particularly sad to see this peddled by a professor of physics to defend his faith. Details and a smackdown by Sean Carroll here. […]

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