Quantum Physics as a Natural Avenue for Divine Intervention
About a century ago, a series of ideas and experiments developed into the theory of quantum physics and overturned many of the principles established centuries earlier by Isaac Newton. The new science also overturned prior difficulties posed by the clash between natural law and Jewish theories of divine intervention. Under classical physics, a break in nature is needed to account for even non-miraculous intervention, like God giving rain when Israel observes His commandments. Quantum physics, on the other hand, describes a world in which divine intervention need not contradict any physical laws.
The current theories of quantum physics derive from the discovery that many physical attributes of nature are quantized, meaning that they come in indivisible packets. In 1900, Max Planck conjectured that energy is quantized – a theory which resolved an outstanding problem related to blackbody radiation.[ii], [iii] In 1905, Albert Einstein theorized the same for light; if a beam of light were imagined to be a series of discrete particles (called photons), the well-known problem of the photoelectric effect suddenly became explainable.[iv] However, earlier experiments had already demonstrated that light is a continuous wave; evidently, light can be experimentally portrayed as either a wave or a stream of distinct particles, depending on what the experimenter chooses to show.
The bizarre dualism that light is both a wave and a particle was soon extended. In 1924, Louis de Broglie theorized that all matter has wave-like characteristics. It was previously accepted that all matter consists only of discrete particles – atoms and their subatomic components, including protons, neutrons, and electrons. However, in 1927, wave-like properties were demonstrated for electrons, using the same experiment that originally led physicists to believe that light is a wave.
The classic method for coaxing light to behave like a wave is the two-slit interference experiment: A beam of light is sent through an opaque surface containing two thin parallel slits. As the light arrives at a screen behind the slits, an interference pattern is formed, consisting of regions alternating between high and low brightness. This is explained by the wave model of light: As the wave passes through each of the slits, it spreads radially outwards from the other side of the slit, just as a wave in the ocean behaves when it hits a wall with a small opening. The two outwardly expanding ripples that emerge from the slits can constructively combine (when two crests intersect) or deconstructively cancel each other out (when a high point on one ripple meets a low point on the other ripple), depending on the geometrical point in which they meet. These equidistant high and low points of intersection create the telltale interference pattern on the screen. In this way, a stream of electrons exhibits wave-like characteristics.
To add to the strangeness of the wave-particle duality, which has by now been confirmed for both light and matter, wavelike properties have been demonstrated not just for continuous streams of particles, but even for individual particles. In a variation of the two-slit experiment, the intensity of the light beam is reduced until one photon is fired every few seconds. Still, the interference pattern emerges as if a normal light wave went through both slits and caused interference. This troubled physicists; with what can a lone photon interfere, if it only passes through one of the slits? Quantum physics’ resolution is to loosen the definition of a particle’s location. As long as a particle is not being directly observed, its location is not absolute, but rather probabilistic, related to a distribution known as its wavefunction.[v] For example, in the case of the two-slit experiment, the wavefunction of the single photon records a 50% probability that the photon will travel through the right slit, and a 50% probability that it will travel through the left slit. These probability “waves” are what interfere with each other on the back side of the slits, causing the interference pattern.
If unobserved particles follow wavefunctions, but every time we look at a particle we see it in one specific location, then the observation must “collapse” the wavefunction. Effectively, the probability distribution of where the particle is likely to be found – a distribution which, in theory, assigns some chance to every point in space – changes upon observation to a 100% probability that the particle will be located exactly where it is observed.
But what does this say about the nature of the wavefunction in the first place? It was appealing to many physicists, including Einstein, to refer to wavefunctions as representing our imperfect knowledge of the particle’s position, though the particle was, in reality, in a single determinate location at all times.[vi] On the other hand, some developers of quantum theory, such as Niels Bohr, insisted that the wavefunction results not from our lack of knowledge of the system, but of the system’s innate indeterminateness. We are not overlooking some so-called “hidden variables” which would indicate precisely where the particle will be found; rather, no such hidden variables exist, and the unseen particle lacks a specific address.
For decades, this debate was believed to be impossible to settle, since it relates to the nature of unobserved particles. Remarkably, in 1964, John Stewart Bell discovered a complex experimental method to determine whether these hidden variables exist. A decade later, the results were in: Bohr was right that a particle does not have a specific location at any instant it is not being observed. Probabilistic wavefunctions are thus objective. An unobserved particle might be imagined (though not seen, of course) as a broad smear, more concentrated in areas where an observation is likely to find it, and less concentrated where it is less likely to be found.
When we actually observe a particle, its wavefunction immediately “collapses” to 100% probability of appearing exactly where it is found, and no chance of appearing anywhere else in space. Obviously, the point to which the wavefunction will collapse is impossible for physicists to foresee, but it corresponds to the probability distribution of the wavefunction. In this way, the collapse follows the mathematics of random variables. As an example, the wavefunction of a photon in the two-slit experiment represents a 50% probability that it will pass through the right slit and a 50% probability that it will pass through the left slit. If one thousand photons are used for this experiment, and a special sensor collapses the wavefunction by recording through which slit each photon passes, we expect to find 50% passing through the right slit and 50% passing through the left slit.[vii] Within statistical tolerances, we will find that about half of the photons go either way, even though it is impossible to accurately predict through which slit any individual photon will go. There is no information that indicates the behavior of a given particle, so, as far as science is concerned, it is totally random.[viii]
* * *
Needless to say, this quantum description of reality, which affirms that the elements underlying the universe behave on a purely random basis, is unsettling. Moreover, it seems to align with the godless worldview of the Greek philosopher Epicurus. In Moreh Nevukhim, Rambam records five ancient theories of divine providence; the first is that of Epicurus. “First Theory: There is no Providence at all for anything in the Universe; all parts of the Universe, the heavens and what they contain, owe their origin to accident and chance; there exists no being that rules and governs them or provides for them. This is the theory of Epicurus, who assumes also that the Universe consists of atoms, that these have combined by chance, and have received their various forms by mere accident. There have been atheists among the Israelites who have expressed the same view; it is reported of them: ‘They have denied the Lord, and said He is not.’”[ix], [x], [xi]
This need not spell disaster for religious Jews who also subscribe to modern physics. Even if the objective randomness of wavefunction collapse is not blindly accepted, the theory of quantum physics still works. Physicists have only demonstrated that there is no physical reason why particles appear in one place instead of another. A religious person is free to believe that the process of wavefunction collapse is not totally random and baseless, but rather directed by God. This does not create any problems with the physics or statistics behind the theorem, as the randomness of any string of data is fundamentally impossible to prove. Statistical tests of randomness look for specific patterns in seemingly random data sets; any test can only suggest that a string is unlikely to be random, but it cannot directly prove its randomness.[xii] Ultimately, randomness is random – anything can happen.[xiii] Therein lies the escape hatch from Epicurean philosophy: God has the ability to fidget with quantum physics without anybody’s knowledge, so the process is not necessarily random.[xiv]
Although quantum physics allows for a theory of divine intervention, it does not promote it. The notion of God’s involvement in nature through seemingly random quantum processes is a fundamentally nonscientific concept, in that it is experimentally impossible to prove or disprove.[xv] Yet, this avenue to divine intervention in the world is historically unique, since, unlike earlier theological theories, it does not necessitate a break in nature. Newtonian physics, the predecessor to quantum mechanics, was totally deterministic. All future events were precisely determined by initial conditions; if scientists had exact data on all the matter in the universe at one moment, they would be able to calculate forces and interactions to perfectly predict all future states of the universe. Such a view precludes God’s active and continuing involvement in the natural order, in apparent contradiction to many biblical verses which promise that God will reward Jews for observing His commandments and will punish them for their transgressions.[xvi] When one’s religious doctrines of divine intervention clash with deterministic science, he or she must create exceptions to reconcile them, by allowing discreet loopholes in nature or the occasional violation of physical law.[xvii]
In quantum theory, though, determinism is displaced by intrinsic indeterminism. We only know what we cannot know – it is impossible to scientifically ascertain how subatomic particles will behave when we try to observe them. Whether the patterns forecasted by a wavefunction emerge randomly or with divine direction is a philosophical question, not a scientific one. This accommodates God’s involvement in the world through a verified gap in science, without need for an interruption of nature.
But does any of this matter? If God naturally shapes the subatomic world, where the odd and unfamiliar landscape of quantum physics has been experimentally demonstrated, what of the macro scale, the world in which we live? Is there any real difference to us if some miniscule particles appear in a different location than chance alone might determine? Can that possibly add up to a fulfillment of God’s promise to provide rain when His nation observes the Torah and to withhold it when they stray?[xviii] If not, this naturalistic approach to divine involvement might be inadequate for a religious philosophy of real divine intervention in the world.
Unfortunately, it is usually impossible to point to quantum events and track their implications in the jumbo-sized world with which we are familiar. Some direction might be found in a modern field of science called chaos theory. Certain enormously complex systems are highly dependent on their precise initial conditions, and it is virtually impossible to predict how they will develop. A famous example is the Butterfly Effect in weather. In 1972, Edward Lorenz addressed a group of meteorologists about the impossibility of knowing whether a butterfly flapping its wings in Brazil may cause a tornado in Texas some time later.[xix] As far as we can tell, it is just as likely that the tornado was linked to a butterfly in Peru, or the butterfly in Brazil actually averted a tornado in Kansas; not enough is known about the initial conditions to prefer one conjecture over another. In chaotic systems like weather, scientists cannot encapsulate the full results of a minor event or trace back a catastrophic event to its root causes, not because the systems are inherently indeterministic, as in quantum physics, but because of the enormous amount of information needed to make such assessments.
A similar ambiguity exists regarding the effects of God’s hypothetical involvement in quantum mechanics. One cannot say with any sort of scientific certainty that a handful of changes on the quantum scale will amount to anything noticeable, like a rainstorm or a drought. But, simultaneously, neither can one rule that out on scientific grounds; though man may not know everything about the initial conditions necessary to model chaotic systems, God does. If God were really interacting through quantum randomness, He – the Temim De’im, One of Perfect Knowledge[xx] – could certainly make it count by starting a process that culminates with great significance on the macro scale.
The theories of quantum physics, along with those of chaos theory, surely do not necessitate a religious outlook on God’s ongoing involvement in the universe. Nevertheless, the possibilities they create for coexistence between natural law and divine intervention should not be underappreciated. As human comprehension of nature grew immeasurably starting in the seventeenth century, it seemed to contradict popular religious doctrine. It is remarkable that further development of the scientific theories in more recent times has reversed the trend from conflict to confluence.
Gilad Barach is a third-year YC student majoring in Physics and Mathematics, and is a staff writer for Kol Hamevaser.
[i] The science content of this article has been reviewed by Dr. Amish Khalfan, instructional assistant professor of Physics at Yeshiva College.
[ii] Blackbody radiation refers to how objects such as metals glow when they are heated. In what was known as “the ultraviolet catastrophe,” the existing models failed to explain the radiation in the ultraviolet spectrum.
[iii] The theorems and experiments discussed in the next three paragraphs are described in: Paul Tipler and Ralph Llewellyn, Modern Physics (New York: W.H. Freeman, 2008).
[iv] The photoelectric effect is the name for the phenomenon that light shining on a metal excites electrons as a function of the light’s frequency, not its intensity. This could not be explained under classical physics.
[v] This follows Max Born’s interpretation that a particle’s wavefunction represents its probability of being found at different points in space. (Jim Baggott, The Quantum Story (New York: Oxford University Press, 2011), 74.) For reasons discussed below, Born’s interpretation is now agreed upon by most physicists.
[vi] Various theories attempt to explain the interference pattern observed in the two-slit experiment in light of Einstein’s insistence that a particle is always at a definite location. For one recent explanation, see Alexey A. Kryukov, “The double-slit and the EPR experiments: A paradox-free kinematic description” (2007), Cornell University Library, available at: www.arxiv.org.
[vii] In statistics, the Law of Large Numbers states that, if many trials are conducted, the overall proportion of “successes” converges to the probability of “success” from a single trial. For our purposes, a success can be considered passage through the right slit. As more and more photons are fired at the screen, the proportion of overall photons that pass through the right slit will tend to 50%, because that is the probability for any given photon. (Jim Pitman, Probability (New York: Springer-Verlag, 1993), 101.)
[viii] Objective randomness is very rare in science. For example, when a computer programmer needs to generate a random number, he or she will often use what is called a “pseudorandom number generator” which yields a very unpredictable number. Still, the inherent process of generating this number involves some algorithm which pre-determines the result. According to quantum theory, though, quantum events may be used to create a truly random number generator.
[ix] Jeremiah 5:12.
[x] Moreh Nevukhim 3:17. Excerpt from Moses Maimonides, Guide for the Perplexed, transl. by M. Friedländer (New York: Dover Publications, 1956), 282.
[xi] At first blush, it would seem that the halakhic category apikores is related to Epicurus’ name, but the established definition of an apikores does not correspond to the Epicurean philosophy about which Rambam writes. The Talmud provides two possible definitions of an apikores: one who disgraces Torah scholars, and one who disgraces his friend in the presence of a Torah scholar (Sanhedrin 99b). R. Shimon ben Tsemah Duran (Rashbats) explains that the title apikores is indeed named after Epicurus, who denied God, but Hazal expanded it to include other intolerable religious transgressions (Magen Avot to Avot 2:14).
[xii] Donald E. Knuth, The Art of Computer Programming, Vol. 2, Third Edition (Reading, MA: Addison-Wesley, 1998), chapter 3.3.
[xiii] If, for example, a person were to maliciously change one digit in the “random digits table” found in the back of statistics textbooks, it would be absolutely unperceivable.
[xiv] It is possible to say that none of the apparent randomness in wavefunction collapses happens “naturally,” but, rather, it is all designed and manipulated by God. Strictly speaking, this extent of intervention is not needed; Epicurus’ statement that all of nature is governed by random processes can be contradicted with the minimalist admission that some of nature is governed by God.
[xv] In Popper’s terms, the theory is not falsifiable. (Karl Popper, The Logic of Scientific Discovery (New York: Harper and Row, 1968), chapter 6.)
[xvi] For example, see the lengthy passages of reward and punishment: Lev. 26:3-46 and Deut. 28:1-69. Based on these and other verses, Ramban famously denies the very existence of a natural order (commentary to Ex. 13:16). Rambam, while strongly subscribing to the notion of nature, still reads in these verses God’s involvement in national prosperity and disaster (Mishneh Torah, Hilkhot Ta’anit 1:1-3).
[xvii] Both of these options are proposed by Rambam when he discusses the intersection of miracles and nature. One of his proposals is that all miracles were pre-programmed into nature during the world’s creation (see Avot 5:6 and Rambam’s commentary (to 5:5 in his counting)). His second idea allows for the occasional and temporary interruption of nature (Moreh Nevukhim 2:27).
[xviii] Deut. 28:12, 23-24.
[xix] “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?” (Edward Lorenz, The Essence of Chaos (Seattle, WA: University of Washington Press, 1995), Appendix 1.)
[xx] Job 37:16, my translation.
