Monday, June 25, 2012

Professor Ratzinger on Modern Physics

WARNING: I about fell out of my chair when I read this. Please be seated with seat belts fastened before reading.

This is the final post in a series paying tribute to Pope B16 seven years on. Below sums-up several pages of Introduction to Christianity, Part I, Chapter V, Belief in the Triune God.

Faith consists of a series of contradictions held together by grace. This expresses, in the realm of theology, a discovery that relates to the law of complementarities in physics. Here we meet the play between faith and modern thought.

The physicist is becoming increasingly aware that we cannot embrace given realities – like the structure of light or matter – in one form. From different sides we glimpse different aspects which cannot be traced back to each other. Only by circling round, by looking from different, apparently contrary angles can we allude to the truth, which is never visible to us in its totality.

E.Schrodinger promoted the structure of matter as "wave alone", thereby hitting on the idea of being that has no substance, but is purely actual, whose apparent “substantiality” is only from the pattern of movement from superimposed waves. This is an exciting allegory for God subsisting in a multitude of relations, which are not substances, but “waves” which form a perfect unity and fullness of being. This is already formulated for all intents and purposes in St. Augustine, when he develops the idea of the pure act–existence (particle–wave).


We know today that in a physical experiment, the observer enters into the experiment. Only by doing so can he arrive at a physical experience. This means that there is no pure objectivity in physics, and that even here, the result of the experiment (natures answer) depends on the question put to it.

He who tries to be a mere observer experiences nothing. Even the reality of God can only impinge on the vision of him who enters the faith experiment with God. Only by entering does one experience; only by cooperating in the experiment does one ask at all; …..and only he who asks shall receive.


“The scientist has scaled the mountains of ignorance; he is about to conquer the highest peak; as he pulls himself over the final rock, he is greeted by a band of theologians who have been sitting there for centuries.”

Robert Jastrow- Former leading NASA scientist.



It's a little slow, but science
finally seems to be catching-up to Catholicism.


46 comments:

  1. Oh dear, where do I start?

    It's not that we can't express the concept of matter in one form (particle or wave), it's that the macroscopic concepts that we encounter in this macroscopic world so not have a atomic corollary. It's like asking what colour are electrons? Colour exists in our world, not in the atomic world and neither do waves or particles as we understand them.

    Fortunately we have a mathematical model of the atomic realm, quantum mechanics, that is remarkably correct at both explaining existing phenomena and predicting future measurements. Quantum Electro-Dynamics (QED) is accurate to 10 decimal places as compared with experiment.

    Theology, however one might try to graft it on to modern physics, has never explained anything about the atomic world, let alone made a prediction.

    ReplyDelete
    Replies
    1. Atomic theory, quantum mechanics and mathmatics wonderfully help us understand material things. And okay, theology does not explain the atomic world, just as physics does not explain altruism, hope, and love, let alone the placebo effect, the law of non-contradiction, or why existence exists. Faith and reason are two wings which lift us to the full truth of reality. Why should we try to graft theology on to physics and graft one wing onto another? Why not accept the complementarity of both and fly higher?

      Delete
    2. "physics does not explain altruism, hope, and love, let alone the placebo effect, the law of non-contradiction, or why existence exists." And neither does it try. Those are explained by other areas of human inquiry. But the claim was not that physics can explain everything, but that theology in some way predicted modern physics. I just finished reading Lucretius De Rerum Natura (Copely's translation) and while I found it fascinating that Lucretuis described atoms and their motion (the swerve) it was just a lucky guess on his part was was in no way predictive of modern physics.

      Delete
  2. "We know today that in a physical experiment, the observer enters into the experiment." But we've always know that. The observer enters into any experiment by deciding what one is going to measure. If you have a container of gas, you can decide to measure the temperature, the pressure, the chemical composition. What you choose to measure determines the outcome.

    Quantum theory puts it more precisely as it says if you choose to measure the position of a particle, you loose information about momentum, if you choose to measure energy, you lose information about the time of a transition. Nature has an inherent graininess.

    It's not that there's no objectivity, it's that the accuracy of measurements are determined by the uncertainly relationships, which are typically well below the accuracy of our measuring devices.

    ReplyDelete
    Replies
    1. Hi R1,

      No, we did NOT always know that. At one time we did not believe nature had any inherent graininess. Only as we learn more do we find this out empirically and interestingly, it fits surprisingly and unexpectedly well with theological statements (I'll stop short of calling them predictions).

      That is the point of Ben's post. His example is that, as we learn more, the duality, if you will, of light in its wave and particle aspects is different from other phenomena. Light somehow is more general, can inhere more than other "things". It is somehow of a higher order. It accommodates both the wave-ness and particle-ness of matter.

      One conclusion is that this is evidence that, as you get nearer to the roots of being (beingness itself), that thing, whatever it is, must be able to ground all modes of being. For example particle and wave, which once didn't seem to be able to coexist in a single thing is found in light. We discover that there is perhaps a hierarchy of being.

      God has been understood and described as the "ground of being" and transcendental. If he is, then he must accommodate both wave and particle and, in fact, all possible modes of being.

      Ben's mention of Heisenberg is appropriate because God is the observer who does NOT enter into the observation. We ourselves cannot know both velocity and position, but God can, IFF (if and only if) he his transcendent of the physical universe.

      Delete
    2. I fail to see how Heisenberg's uncertainly principle conforms with theological statements. Light is not of a higher order than particles or waves, it is just different than either. There is no hierarchy of order or being in physics.

      How is wave and particle a mode of being. They are just properties, like colour, charge, spin, etc.

      Delete
    3. I am sorry, I jumped tracks. What I heard
      "We know today that in a physical experiment, the observer enters into the experiment. Only by doing so can he arrive at a physical experience. This means that there is no pure objectivity in physics, and that even here, the result of the experiment (natures answer) depends on the question put to it."

      I thought of how the observer of an event affects the event. That is to me the essence of Heisenberg.

      Delete
    4. No, the Heisenberg uncertainty principle only sets a lower limit on how precisely you can measure two complementary variable (i.e. position and momentum, energy and tine, etc.)

      In a classical (non quantum sense) this always occurred. Let's say you want to measure the temperature of a glass of water. You put a thermometer into it but since the thermometer is either at a higher or lower temperature than the glass of water you change the measurement. All Heisenberg did was reveal the absolute lower limit to that uncertainty.

      Delete
    5. I don't know how that is different from what I said. It had been thought that there was NO theoretical lower limit on that knowledge. That, with increasingly sensitive equipment, we could determine the velocity and position of every particle of matter and then predict any future state from the present state.

      That is forever unknowable.

      Delete
    6. But Joe, where does theology make any sort of prediction/revelation that foreshadows Heisenberg's Uncertainty Principle?

      This is the problem I have with religious people trying to graft on their theology onto modern science. It's forced and doesn't appreciate the science. You talk about the dual nature of matter, particle and wave. But one could equally say matter encompasses particle, wave, and energy in a triune oneness, distinct, yet the same, one preceding from the other in a central unifying mystery that religion anticipated and science is only now beginning to realize. See it's easy to transform science into bogus theology

      Delete
    7. R!,

      The point I was trying to make is this. While it is impossible for us to know all of this, it is reasonable to say that a transcendent being can. That's all. I didn't take it very far because I realized that it wasn't relevant to the point Ben was making. I'll have to revisit this in a separate post.

      Ben was talking about the duality of matter into waves and particles and that light seems to encompass both. In fact as far as we know light is the only thing that has properties of both. Where I wanted to go was to say that light demonstrates how some things can have properties from two things that were heretofore thought incompatible. "How can something be both particle AND wave?"

      Here's a better direction. This aspect of light corresponds to how, in the argument from contingency, the ultimate ground of being must actively and continually make compatible ALL possible modes of being. That is, both particle and wave are possible because the first uncaused cause has particle-ness and wave-ness in it. In fact, that first uncaused cause must have all possible modes of being in it.

      Light itself shows a compatibility with two modes that were thought incompatible which can be thought to demonstrate a step toward this idea of the ground of being making compatible two modes that were once-thought incompatible.

      Is this a proof? No but it is a piece of the puzzle that fits. The New Science fits in the Old Theology. Quite reasonably too.

      Delete
    8. The question "How can something be both particle AND wave?" is not quite right. It should be "How can something have the properties of a particle and a wave?" And the answer is because it does. We don't have a macroscopic substance that exhibits both properties but there is no requirement that the atomic realm must have macroscopic counterpoint. Note : Both light and particles exhibit both wavelike and particle like properties.

      "the first uncaused cause has particle-ness and wave-ness in it."
      Does the first ""the first uncaused cause" have charge, mass, spin, parity, lepton number, etc.

      "The New Science fits in the Old Theology." But light has polarization, momentum, wavelength, etc. Does that fit the old theology as well?

      Delete
    9. Additionally, the creation has some “imprint” of the creator in it, so it make sense that the universe, light, matter, etc., would have some aspects of infinity and mystery. The more questions we answer, the more questions are raised. We are always asking, “What caused the cause?”

      Delete
    10. I agree with your restatement. My question "How can something...?" was meant to be rhetorical in that nothing else we know of acts in both modes. Since it's a first, science will work hard to place it in one or the other category. Now we know that it fits some kind of super-category where both wave and particle properties/behavior are applicable.

      Yes the ground of being will have be compatible with ALL modes of being. It makes possible quarks to have spin, parity, etc.

      Delete
    11. Joe - Science does not seek to fit it into one or the other catgory. It will seek to model it, with mathematics, and make predictions that test the model. If it works, great, if no refine or redo. That's a process that has no analogy in theology.

      Ben - Just because science is mysterious and religion say God is mysterious does not mean they are one in the same. (What happened to Jimmy Hoffa is a mystery but it has nothing to do with religion) Science sees a mystery as something to be solved, religion sees it as something to be revelled in. Completely different.

      Delete
    12. R1,

      I disagree strongly.

      Science seeks to understand, in part, through similarity. Categories help us group by properties or behaviors so that we can understand something new by its similarity to something old.

      It is a completely reasonable approach when a new phenomenon occurs, old categories are first tried and fail conclusively, then and only then, a new category is created. That is how you model something. It would be a poor model indeed to create a new category for each phenomenon.

      Delete
    13. Of course they are not the same. The artist is not the painting and the painting is not the artist, BUT we may learn or understand some things about the artist just by studying the artwork.

      Delete
    14. Joe - My point was only that the "categories" we encounter at the atomic level often have no macroscopic equivalent. We say and electron has "spin" but it doesn't mean it spins like a top or that a quark has up, down, charm, strange, truth or beauty (or top and bottom is you're American).

      Ben - One may learn to differing degrees about the artist from the painting but that's a far cry from saying all the properties of the painting must be found in the artist, or vice-versa.

      Delete
  3. Lastly, all science is contingent. All scientists will admit that theories, even ones as firming established as quantum mechanics can be overturned. (There's a chance the Einstein and Bohem hidden variables theory may one day be proven correct). To hitch your theology to a specific scientific theory is to risk repeating Christianity's mistake of adopting the Aristotelian view of the Cosmos and basing its theology on that worldview.

    ReplyDelete
    Replies
    1. Hello R1, I see this post got your attention. Catholicism certainly does not “hitch” theology to any specific scientific theory. The post merely expresses some thoughts of a younger Joseph Ratzinger back in the 1960’s that I found intriguing to say the least. I personally feel that scientific progress will lead more and more scientist to conclude that there must be a non-contingent intelligence working behind the scenes of the universe.

      Delete
    2. When Pope Pius XII endorsed the Big Bang theory of the as a validation of the Catholic faith Fr. Lemaitre, one of the originators of the Big Bang theory was alarmed. He knew science was contingent and saying that the Big Bang validates Catholic teaching raises the question of what happens if the Big Bang theory is overturned. Is Catholic theology of the origin of the cosmos then invalidated.

      As to a non-contingent intelligence, modern experience yields many scientists to see the cosmos is exactly what it would be if it evolved under natural laws. The gaps where God existed before are diminishing and although science has not answered all the questions, it's going in the direction where there are fewer and fewer mysteries.

      Delete
    3. I’m not sure why Fr. Lemaitre would be “alarmed”. Perhaps he was worried about confusion among portions of the laity not well formed in the faith. If his Big-Bang is found to be wrong by future scientist, it will not change Church teaching. JP2 called evolution a plausible theory. If evolution is found to be wrong by future scientist, it also will not change Church teaching.

      As far as mystery, do not think of it as something we just have not figured out yet. Think of it more as an invitation to the mind. It means that there is an inexhaustible well of Truth from which the mind can drink and drink again in the certainty that the well will never run dry.

      Delete
    4. I think he was alarmed because the then Pope embraced the Big Bang before many scientists had. I assume the Pope was anxious to embrace a theory that posited a creation moment as opposed to Hoyle's steady state theory. But of course if the Big Bang gets disproved, the Church will just embrace another theory and say it conforms with Catholic teaching.

      As to evolution, even though my training is in physics, I find evolution one of the best supported theories in science.

      Delete
    5. Mistake? The Church got 300 + years out of Aristotle! That rising tide, sir, lifted a great number of boats. Let's see you pick from our cultural patrimony a useful strain of thought that will be mined for a similar or better length of time. I said "pick" as in choose one that initiates a significant program, not "elect" to participate in one already underway.

      Is the contingency of science itself contingent? What? Mere word games? So much so with infinity. It is a learned figment of the imagination; a logical entailment of basic assumptions of the somatic experience of manipulating mathematical objects; axiomatic not physical.

      Delete
  4. "The physicist is becoming increasingly aware that we cannot embrace given realities – like the structure of light or matter – in one form."

    Sure we can, mathematically. Unfortunately the mathematical equations don't lend themselves to analogies in our world. Also they take years of study so they are inaccessible to all but the practicing scientist, but they are remarkably accurate, remarkably predictive and quantum mechanics is responsible for a substantial portion of the world's economy as anything with an integrated circuit in it would be impossible without it.

    ReplyDelete
    Replies
    1. I did not study math in great detail, so I have a question I hope you can answer.

      If you take a segment of space and give it a beginning and end, we may call it a line, and if you break it into further chunks we may call those chunks fractions, such as one-half or one-quarter of the line. Each fraction signifying a smaller and smaller segment of space on the line.

      Consider the fraction (one divided by one trillion to the trillionth power). Does that fraction exist logically in our line segment? What about the fraction (one divided by infinity)? Is there an infinite amount of space in the smallest of fractions in our line segment?

      OR is there a mathematical leap, not yet known to us, that allows us to “jump” that smallest of spaces in our line segment (as defined by our fractional analysis) to the edge of the segment, where fractions do not exist?

      But if fractions do not exist, how can there be any space at all to begin with?

      I imagine there are a hundred ways to answer my questions, and another hundred questions that could be asked. Where does it all lead?

      Delete
    2. As soon as you bring infinity into the mix, all intuition is off. For instance there are an infinite number of fractions between and two counting numbers, therefore it would seem there must be more fractions that counting numbers. Alas it's not so, the number of counting numbers (0, 1,2,3...) are the same as the number of fractions (1/2, 1/3, 1/4,...)

      http://duartes.org/gustavo/blog/post/counting-infinity

      Delete
    3. This is in reply to Rationalist1 (R1) (and I hope it won't seem too snarky :>) ). Judging from his comments, I'm not clear how deep his/her understanding of quantum mechanics (QM) and its interpretation(s) might be. Speaking as a physicist with 57 years in the field (including published papers on QM), I find it remarkable that R1 does not take into account the ideas of two of the great minds--Von Neumann and Wigner--who developed the theoretical foundations of QM, and postulated as the last step in the measurement process a conscious mind. And even later (199x?), the great American physicist John Wheeler proposed the Participatory Anthropic Universe, created by observation, and as a physical test of that notion a "delayed choice" double slit experiment.
      If R1 would like to broaden his horizons he might read "Quantum Mechanics", Volume 5 in the series "Scientific Perspectives on Divine Action", papers on conferences called by Pope John Paul II. In particular, he might want to read the paper by Raymond Chiao on the results of his delayed choice experiment, which lend themselves nicely to a Berkeleyan interpretation, "esse est percipe" (to be is to be perceived). Or also,"Mathematical Undecidability, Quantum Nonlocality and the Question of the Existence of God" (Driessen and Suarez) or "On Physics and Philosophy" (d'Espagnat). If these works are too hairy, then maybe "Quantum Enigma" (Rosen and Kuttner) would be a good book to explore alternative interpretations of QM (written for a class of non-scientists).

      Delete
    4. anselm,
      Thanks for participating! I’ll be sure to check out your website. Have you read Fr. Spitzer’s Book, New Proofs for the Existence of God? If yes, what are your thoughts?

      Delete
    5. Thank you Ben for your comments. You have a fine blog, and I'm glad I came across it (via National Catholic Register). I've read Fr. Spitzer's book (I am involved with the Magis group and was one of the Magis Facebook moderators until I got disgusted with trolls, snarky comments and people who knew neither science nor philosophy and didn't want to learn). Fr. Spitzer is a remarkable man, a polymath who knows more about more topics than anyone I've ever met. Nevertheless I'm not entirely happy with the book for the following reasons. I myself don't believe you can "prove" the existence of God unless you agree with the assumptions for those proofs (which is why there are so many intelligent--as well as stupid--atheists). Some of the cosmological proofs he cites--e.g. the Guth-Vilenkin theorem--are not science, since there is no way they can be empirically tested, i.e. falsified by observation; the proof from the Second Law can be evaded (with difficulty) as Roger Penrose has tried to do by a very fancy cosmology and space/time transformation theory, using the entropy of black holes. There is indeed empirical evidence for a creation moment, a Big Bang--the red shift, the COBE background radiation--but unfortunately due to the opacity of the early universe (before photons came out of hiding, so to speak)--we can't go observationally past the 300,000 year limit, so we have to infer what happened before that time. What I'm trying to say is that there is much about cosmology--multiverses, inflationary theory, etc.--that is beautiful mathematics, but is not science. I'd call it mathematical metaphysics, and to rely on that as evidence for the existence of God is, I believe, a mistake. Fr. Spitzer's other proofs, the variation on Lonergan's proof and the variation on Anselm's ontological proof are very impressive, but you have to agree with the assumptions for them to make you a believer. I'll try go on at greater lengths about all this in my blog as the Spirit moves me :>) .

      Delete
    6. Thanks. Speaking of fine blogs, I’ll need to join yours or at least put it on the favorites bar! Take care.

      Delete
  5. Anslem - My Quantum mechanics training came from more conventional sources, Albert Messiah's Quantum Mechanics and Landau and Lifschift Course in Theoretical Physics when I studied at U of T. I am slightly familiar with the minority view that "consciousness cause collapse" interpretation but I thought Wigner retracted his view later in life. Beside bordering on solipsim, it places an inordinate amount of emphasis on minds and raises the issue to a universal mind close to pantheism to facilitate the collapse of quantum wave functions on the moons of Pluto (for instance).

    If you want to go down the Bishop Berkeley idealism route where to exist is to be perceived you might as well take one more step to either Christian Science or some schools of Buddhism.

    ReplyDelete
    Replies
    1. R1: my quantum mechanics training was from Schwinger's QM and advanced QM courses (ca 1951/52), Dirac, Edmonds, Wigner, Weyl, Griffith, Abragam; I have also read those parts in Messiah's text dealing with angular momentum. I'll agree that your training in the mathematical apparatus of QM is well founded. Nevertheless, I find your comments on the interpretation of QM to be perhaps facile.
      Not all physicists adhere to the standard Copenhagen interpretation (or lack of interpretation) of QM. Indeed (and I forget whether it was Feynmann, Pauli or Heisenberg who said it) "anybody who says he understands quantum mechanics doesn't." There are many physicists more eminent than I who reject the Copenhagen interpretation. I should add that I myself am not entirely comfortable with the mind/consciousness/measurement trilogy, although it seems better to me than any of the other current QM interpretations. But, maybe, as, Bernard d'Espagnat says there is a "hidden veil" that will forever hide a complete interpretation.

      Granted in brief comments there is a limit on explanation, nevertheless I find your comments on "solipsim"(sic) and idealism leading to Christian Science/Buddhism to be clever, but philosophically incoherent.

      I would still recommend, if you'd like to broaden your horizons on QM and philosophy, the previously recommended references. There are also various articles and books by Michael Redhead and collaborators on the philosophical implications of QM non-locality that should interest you.

      Delete
    2. Certainly not all scientists accept the Copenhagen interpretation but the vast majority do. It's partially for pragmatic reasons, it works so why worry, but also the other interpretations, for

      The quote "If you think you understand quantum mechanics, you don't understand quantum mechanics." is generally attributed to Feymann, but may have been Neils Bohr.

      My comment on the solipsism of many of the more "adventuresome" treatments of QM is that they border on requiring the universe to be an all pervading consciousness, without which nothing can happen or exist. To bring up Bishop Berkely's idealism interpretation of reality can lead to philosophical pantheism of which Christian and some schools of Buddhism embrace ("All is God").

      Science is conservative, it embraces new theories only when sufficient evidence is proferred to substantiate the change. One should be cautious when embracing somewhat exotic theories of QM and ask if one is accepting them because of the evidence to support that interpretation or embracing them because they support one philosophical or religious viewpoint.

      Delete
    3. As you said, most physicists don't worry about the interpretation--but that's very much like accepting that a car starts up when you turn the key, but not knowing why that won't work occasionally. Interpretations of QM (or any physical theory) are constructed to fit the theory and empirical data so in general they can't be falsified (but see below), so the choice between models is to some extent a matter of philosophical taste, as your comments suggest. So interpretations lie in a ambiguous borderland between science and philosophy. To my knowledge there 7 or 8 extant interpretations of QM, and only the Bohm hidden variable interpretation has been disproved (by the Aspect experiments disproving Bell's Theorem). There is a report that one interpretation--the Transactional Model--was confirmed by the Afsha experiment, but that has been disputed (see http://philsci-archive.pitt.edu/2199/ ). I'm not sure whether the Many Worlds interpretation could be tested empirically even though it seems to solve the measurement problem.

      I still don't find your comments about solipsism and Berkeleyean idealism convincing. Solipsism as commonly understood does not have to do with a universal mind/consciousness but rather the brain-in-a-vat model (the only thing real is what is in my mind and all my sensations and thoughts could be impressed from outside a la Matrix). And I don't see that you've provided the deductive or inductive trail from "esse est percipe" to Christian Science / Buddhism.

      I do concur, as a very right-wing (in all senses) person, that science is conservative. But there is a difference between theories (confirmed or falsified empirically) and interpretations of those theories. Lord Kelvin would interpret electromagnetic waves and the ether mechanically (until the Michelson-Morley experiments eliminated ether drift). I think the point of B16's comments on science and religion is that there is nothing in science that contradicts the dogma/doctrines of the Church,notwithstanding claims of evangelical atheists: what we know from science and from faith are not inconsistent ( the double negative is not equivalent to "consistent").

      Delete
    4. Anslem - Stephen Barr, a Cathotic blogger, makes an almost identical comment to my line of reasoning on this interpretation of QM leading to solipsism. (see the comments section)
      ( http://bigquestionsonline.com/content/does-quantum-physics-make-it-easier-believe-god )

      Delete
  6. By the way, speaking of infinity, Adam Drozdek has a fine article on this (which also touches on the existence of God):
    "Beyond Infinity: Augustine and Cantor"
    See: http://www.erudit.org/revue/ltp/1995/v51/n1/400897ar.pdf
    I'll quote from the abstract
    "SUMMARY : It is argued in this paper that for Augustine 1. infinity is an inborn concept which is
    a prerequisite of any knowledge ; 2. mathematics - because it relies on the concept of infinity
    - is the best tool of acquiring knowledge about God, and 3. God is neither finite nor infinite
    and his greatness is beyond infinity. Augustine is original in combining these three aspects in
    his philosophy, and all three aspects can again be found in Cantor."

    ReplyDelete
  7. It's not often I'm the 3rd most knowledgeable on a topic that I deign to comment on so correct me if I wander into unsubstantiated nonsense...

    There are stupid reasons for believing and stupid reasons for not believing (in a higher power) but the only sensible reasons for believing require some a priori assumptions that are not, in a rational view, justified. Doesn't mean they are not correct, simply that there is a leap of faith where you accept certain things, emotionally, and then the rest follows.

    My view is that the mind is not special in any sense and therefore is not particularly important in collapsing quantum wave functions. I would like to know on what basis minds are considered to be in any way special configurations of matter such that they can impact quantum uncertainty in a way that other measuring devices cannot. And if that is considered the case, is there a certain 'amount' of mind, is the cat's too limited to collapse the Schroedinger's Cat wave function? Is a child's too small to have a gender hence the child is both male and female until it's either born or tested? Is there a level of IQ that is required? (Almost reductio ad absurdum, but I'd be interested in anyone following up).

    Rationalist1 - electrons do have a colour, technically, since they have a wavelength they are the colour of that wavelength, which happens to be electron coloured.

    A general QM question - what happens in the twin slit if we have a measuring device over one of the slits storing information on which one a given photon/electron/bucky ball went through (but don't look just yet) and then we observe the pattern on the wall/plate? Is it an interference pattern (because we don't know which slit it went through)? Is it a straight up double line where each one went through either/or (because we measured which one it actually went through)? Does it matter if we then delete the file and no mind ever actually knows which one it went through?

    Sorry if that's really simple, it's been a while since I did any QM, but I find it really interesting because it's so counter-intuitive to my mid-sized ape brain.

    ReplyDelete
    Replies
    1. March Hare - Colour is ascribed to substances that reflect photons in the 4000 to 7000 angstrom range (roughly the range of visible light). Electrons have a wavelength (not in that range) but are not photons. Electron play a role in colour in that it's the electron shells in a substance that determine what colours are absorbed or reflected, but electrons, like protons, neutrons do not have colour as such.

      Delete
    2. Pah, my ultraviolet-viewing bee would disagree with your homo sapien-centric range of wavelengths.

      On a more technical note, electrons could also be considered (virtually) all, and no, colours since they both absorb and emit the whole colour spectrum. But I digress, my pet bee still disagrees with your range and says you are a species-ist.

      Delete
    3. Every starting assumption is, in a sense, non-rational, that is to say it is reinforced by external data or by inner data (as Lonergan would have it), i.e. by feelings. Your question about the double slit experiment would be encompassed by the "delayed choice experiment". Google "delayed choice experiment" and you'll see lots of articles. I think this will also answer your question about storing the data, and that also has to do with the gedanken "Wigner's Friend" experiment. (Again, do a Google search)

      Delete
    4. March Hare - I stand convicted. What's interesting is to see pictures of flowers in UV to see what insects see.

      As to colour it manisfests itself at a larger scale than the electron, it's the electron in an atom, (possibly bonded in a substance - Compare the colour of carbon in coal and a diamond) that determines the colour.

      Delete
    5. March Hare, the latest thoughts on the delayed choice experiment that I've encountered are in http://arxiv.org/pdf/1007.3977v1.pdf
      There's also good preliminary stuff in the Wikipedia article.

      Delete
    6. March hare, with respect to color you may be interested in a discussion of the problem of qualia ("what's it like to see red") as posed by the problem of "Mary's Room"; http://lesswrong.com/lw/5n9/seeing_red_dissolving_marys_room_and_qualia/
      It also has to do with what is consciousness, and the physicalist/anti-physicalist views of consciousness.

      Delete
  8. anselm, thanks - lots of good stuff there. hard on my brain, as it should be!

    Duhem, I like much of what LW does, but I was there beforehand and, on this one, i'm not convinced.

    ReplyDelete
    Replies
    1. March Hare, as I understand the Belgian's paper (cited above), there is no time element involved for quantum entanglement. So there is no "before" or "after" for the delayed choice experiment. Which would mean for your thought experiment, that if you saw a single slit, on the record (for two measuring devices at each slit), the computer data would show it had gone through one slit and if you saw a diffraction pattern, the devices would show it had gone through both slits. Now the Belgian's derivation assumes no energy differences, so there is no time evolution in the solution of the state vector Schrodinger equation--I assume that's ok, but wonder about a more general case...anyhow, after reading the paper I think I understand it better.

      Delete