Monday, October 26, 2015

Does Quantum Mechanics Speak to Catholic Teaching?

Schrodinger's Cat Images from light
 that never saw the object.  
Gabriela Lemos Nature article
"God is a mathematician of very high order and He used advanced mathematics in constructing the Universe. "  Paul A. M. Dirac, Nobel Prize Winner for his pioneering work in quantum theory. 
"Anyone who tells you they understand quantum mechanics is a liar." attributed to Richard Feynman (in one form or another), Nobel Prize winner for work in quantum electrodynamics.
"The one thing worse than a theology that attempts to draw connections between physics and God is a theology that believes it has no need of such connections, a theology that believes it can concoct the divine out of metaphysical whole cloth."  Philip Clayton, "Tracing the Lines" in Quantum Mechanics--Scientific Perspectives on Divine Action.*


On the right-hand column you'll see that of the five posts most visited on this blog, three deal with quantum mechanics and religion.  If, then, the relation between quantum mechanics and Catholic doctrine is intriguing, why not explore a general question:  does quantum mechanics inform theology, and if so, how?

What I will try to do is to put forth some general considerations.  Particular intersections of quantum mechanics with teachings of the Church are discussed in several posts on my blog (see the right hand column and References**).   Those who want to plunge into the deep end of the swimming pool,  might go to two volumes published by the Center for Theology and Natural Science (in collaboration with Vatican Observatory Publications).    The books are collections of papers presented at conferences called by Pope St. John Paul II to explore "Scientific Perspectives on Divine Action":   Quantum Mechanics,  Quantum Cosmology *.

I'll not try to give even a horsies and duckies sketch of the basics of quantum theory, except insofar as it is relevant to the theology discussed.    Also, I'm not going to discuss all intersections of quantum mechanics  and theology that might be of interest--some have already been covered in previous posts referenced below.


Quantum mechanics is peculiar (in more ways than one)!   The theory yields extremely accurate predictions and has not been proven incorrect in any experiments thus far.     Nevertheless (as per Feynman's quote) it is not intelligible in terms of every-day experience.    The mathematical formalism is elegant, and there is not a problem at the next stage:  letting physical quantities stand in for the mathematical variables.    The difficulty is at a higher level:  the interpretation of measurements in terms of qualitative models that correspond to our intuitive view of what the world is like.

If you go to the Wikipedia article on Interpretation of Quantum Mechanics you'll find 15 different interpretations (and there are subdivisions amongst many of these).   Some of these interpretations bear directly on matters of theology; others, not so much.      

Related to interpretation are general positions scientists and theologians take on just how quantum mechanics might be relevant to matters of faith.   Philip Clayton (Tracing the Lines*) has laid out five such positions:
  1. No reasons can be given, other than purely subjective ones, for any theological position (Cushing)
  2. Serious theological positions can be given in some cases, but quantum physics is too give rise to helpful theological conjectures (Polkinghorne).
  3. Some constructive theology can be written...even if our conjectures remain highly speculative (Chiao, Clayton, Russell, Stoeger, Tracy).
  4. ...Strong theological conclusions can be reached on the basis of modern physics (Dombs)... Intelligent Design theorists (Behe, Dembski) argue that evolution requires a prior intention and an in-built design on God's part.
  5. The convergence between the conclusions [of quantum physics] and the teachings of [Eastern] religious traditions is so great that they should no longer be regarded as separate realms...but as one integrated whole [Bohm, Capra].      
The names added in parentheses are those of physicists/philosophers/theologians who, according to Clayton, have taken the position in question.   My own position is between 3 and 4.    I'll consider below how three aspects of quantum theory--Superposition, Entanglement/Non-locality, the Measurement Problem--might bear on theological matters.

But before doing that, let me bring up one very general question about quantum physics that bears on theology.    Bernard d'Espagnat has suggested that quantum physics manifests a "veiled reality" .   If that is so, can this theory then tell us  what God is like, or would that also be "veiled", hidden?   Or, if God is not totally comprehensible to us--only partially intelligible--does that mean God and quantum mechanics are parallel mysteries?  Read the linked article and decide; but whichever way you decide, it is clear that quantum mechanics does inform theology in this matter.


In an early post  I speculated on whether the superposition principle of quantum mechanics might offer an analog of the Holy Trinity.    The general notion is that a state in quantum mechanics can be represents as the superposition of several component states;  one of the component states may be that which is detected by a measurement.    The notation used is conventional:  | "something", property> is a state that represents a "something" that has a "property".    So we write for God, the Trinity

        |God, the Trinity> = |God, the Father> + |God, the Son>  + |God, the Holy Spirit>

In that post, I explained how the act of measurement--picking out either God, the  Father,  God, the Son, or God, the Holy Spirit as the measured component state--might be envisioned:    for example, seeking God the Father in the prayer "Our Father";  seeking the God the Holy Spirit in looking within ourselves to be better, as in the Examen of the Night Prayer (Liturgy of the Hours).

In terms of the theological implications, this is but an analog, a way of trying to understand a deeper mystery,  much as the oft-used example of a triangle with God the Father, God the Son, and God the Holy Spirit at the corners of the triangle.  


Perhaps the most non-intuitive aspect involves the entanglement of two things, such that they seem to interact (instantaneously) even when physically separated at far distances from one another (the non-locality aspect).    There are many experiments that verify this.   The picture at the top of the column is one such:   photons (light particles) are experimentally prepared to be "entangled" and then physically separated by half-reflecting mirrors such that one passes through an object and another not.    Nevertheless there is an image from the photons that do not pass through or near the imaged object (the cat).

Here's a highly non-real example that illustrates entanglement.  I'm going to use the  conventional notation described above,  | something, property >   where the line and bracket indicate that "something" has some "property".    Let's consider a man, who votes Republican, state  |M,R>, and a woman, who votes Democratic, state |F,D>.     They get married and in the marriage vows promise to vote the same way.    So there results

|M,R> |F,D> (single)--->Marriage ---> |M,F,married> =|M,R>|F,R> + |M,D> |F,D>

Voting Republican or voting Democratic is entangled between husband and wife:
if the husband is away from home on election day and casts his absentee ballot as a Republican, his wife--even though she does not know how he has voted--will always vote Republican;   similarly, if the wife is away and casts an absentee ballot Democratic, the husband--without knowledge of his wife's vote--will always vote Democratic.    This is entanglement, action-at-a-distance.

The principle of special relativity, requiring that no information can be carried at a speed faster than light, is not violated (in real physics, if not the example), because no information is transmitted by the joint behavior of separated particles.

In the Divine Intervention Series on Quantum Mechanics*  Michael Redhead gives an exhaustive treatment of the assumptions--determinism, non-locality, etc--required for entanglement to hold.    In the linked article Redhead argues that entanglement and non-locality yield an "indeterministic", a "holistic non-separability" interpretation of quantum mechanics, such that
"[this interpretation] allows 'room' for divine action on particular occasions...Holism is an anti-reductionist thesis that shows how every element of the universe has for its ground of being the  totality of the whole, which pantheists would want to identify with God."
What are the theological implications of entanglement?   Eastern mystics hold that such entanglement shows that we are non-separable parts of a universe that is one entity and that the desired state is to immerse ourselves into that entity.

As a Catholic, I don't believe that claim.  In the Judaeo-Christian theology, God treats each of us as individuals, and when (or if) we attain heaven, we go as individuals.    Indeed, if one examines the entangled state function, each "something" remains as an individual, even though there is a necessary connection between its properties and the properties of the "something else" with which it is entangled.

The vision of entanglement is not a new one;  Dante foresaw it in the 14th century in The Divine Comedy:
"In its depths I saw in-gathered, and bound by Love into one volume, all things that are scattered through the universe, substance and accident and their relations, as if joined in such a manner that what I speak of is One simplicity of Light. I think I saw the universal form, of that bond, because, in saying it, I feel my heart leap, in greater intensity of joy."  Dante, Il Paradiso, Canto XXXIII, "The Final Vision""
One can also argue that entanglement justifies the relation between Jesus and us, as in the Parable of the King and the Final Judgment in Matthew:
 "Then shall the righteous answer him, saying, Lord, when saw we thee an hungred, and fed thee? or thirsty, and gave thee drink?
When saw we thee a stranger, and took thee in? or naked, and clothed thee?
Or when saw we thee sick, or in prison, and came unto thee?
And the King shall answer and say unto them, Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me. [emphasis added]  Matthew 25:37-40 KJV


Quantum Mechanics is a beautiful theory, mathematically elegant, but there is a major flaw in its connection with the real world.   When the system has a state that is considered as a superposition of states, then a measurement will collapse that total state into one of the components.    To take our example above, the married state is a superposition of the state: man votes Republican, woman votes Republican,   and the other state: man votes Democratic, woman votes Democratic:
          |Married >   =  |M, R> |F,R>  +  |M,D> |F,D>   
The measurement (voting in an election) gives
        |Married> =  |M,R> |F,R>    or   |Married > =|M,D> |F,D> 
so the act of measurement (voting in an election) has "collapsed" the prior superposition to just one of the components.

The difficulty is that this "collapse" is not intrinsic to the basic equation used in quantum mechanics, the Schrodinger equation.   It can be added to the theory by use of a "Projection Operator" that represents measurement, but that is an ad hoc addition to the theory;  the ad hoc nature of this essential operator distresses many philosophers of science,  and some (not all) physicists. 

Two of the ways proposed to bypass the  Measurement Problem have theological implications.

Von Neumann proposed early in the development of quantum mechanics that the act of observation is a necessary (if implied) aspect of quantum theory, and, therefore it is this act of observation that induces the collapse of the state function;  since the choice to observe is controlled by a mind, it is the mind that executes the collapse and registers the final measured state.    The essential role of the observer' is confirmed in  experiments such as the delayed choice experiment.   This reasoning can be used to support a Berkeleyan view of reality, that reality is that which is perceived, "esse est percipi" (to be is to be perceived).   I've discussed this in a post, Quantum Divine Action via God, the Berkeleyan Observer, so please visit that post for an extended discussion.

In another answer to the Measurement Problem, the collapse of the  state function upon measurement is eliminated.   Instead of one state existing after measurement, all states continue to exist, either in alternate universes, or in alternate brain states.   This interpretation--the Many Worlds or Many Minds--is advocated by some physicists and philosophers, but rejected by others because of its "ontological extravagance".    There is a significant theological consequence for this interpretation that has to do with the Molinist view of God's Foreknowledge and Free Will.   For an extended discussion of this, I refer the reader to my post, "Free Will and God's Providence, Part IV".


Here, in brief, are the main ways in which quantum theory impinges on Catholic teaching and theology:
  • The "veiled reality" underlaying quantum mechanics strongly suggests that science, per se, can not reveal all that can be known of God.   
  • Entanglement makes a deterministic view of the world unlikely and allows freedom for Divine Action.  
  • The "Measurement Problem" yields two significant implications for Catholic theology:  one, a justification for a Berkeleyan view of reality, with God the "ultimate observer" maintaining the universe;   the other, a many worlds/many minds interpretation of quantum mechanics that fits in with a Molinist account of God's foreknowledge and free will.


*The linked reference to CTNS publications will show five icons for the books summarizing the Conference publications.   Click on the upper left (pink) "Quantum Mechanics" icon and a column will appear on the right hand listing each author's paper;   click on the author's name and a summary of his/her paper will appear.    Do similarly with the "Quantum Cosmology" icon.

**Listed below, in addition to those given in the post and in the right-hand column, are posts on quantum mechanics.  Links to web sites explaining quantum mechanics are given in the posts.    Enjoy!!
Philosophic Issues in Cosmology 3: Mathematical Metaphysics--Quantum mechanical models for early stages of the universe.
God, Symmetry and Beauty I:
 The Standard Model and the Higgs Boson.
God, Symmetry and Beauty in Science II: A Personal Perspective

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