In several fields of contemporary science -- in particular, in cosmology and cosmogony -- the boundary between science and philosophy has become radically blurred. Scientific discussion in these areas is permeated with philosophy and metaphysics. As the philosopher of science George Gale writes, "it seems clear...that we are entering a phase of scientific activity during which the physicist has out-run his philosophical base-camp, and, finding himself cut off from conceptual supplies, he is ready and waiting for some relief from his philosophical comrades-in-arms."1 Since metaphysics has entered scientific debate, the theistic scientist can, without apology (though, perhaps, not without explanation), introduce theistic explanations which are as plausible as, if not superior to, naturalistic explanations.
This is a controversial thesis. But those who dispute it in the name of methodological naturalism need to explain why naturalistic hypotheses, which are no less metaphysical than theism, are to count as legitimate explanations whereas theistic hypotheses are not. In what follows, I examine three areas of current scientific debate (the Big Bang origin of the universe, the "fine-tuning" of fundamental physical quantities for intelligent life, and quantum physics and cosmology) where theism can contribute positively to the discussion.
In 1922, the Russian mathematician Alexander Friedman predicted the expansion of the universe. Seven years later Edwin Hubble verified this prediction by observing that galactic light is red-shifted. When the expansion is coupled with the 1968 Hawking-Penrose singularity theorems, it leads, via a time-reversed extrapolation, to a universe which began at a point in the finite past, before which it literally did not exist.
That initial event has come to be known as the "Big Bang." This cosmological singularity, from which the universe sprang, marked the beginning, not only of all matter and energy in the universe, but of physical space and time themselves. The Big Bang model thus dramatically and unexpectedly supported the biblical doctrine of creatio ex nihilo.
Indeed, given the truth of the maxim ex nihilo nihil fit (out of nothing comes nothing), the Big Bang requires a supernatural cause. Since the initial cosmological singularity represents the terminus of all space-time trajectories, there cannot be any physical cause of the Big Bang. Rather, the cause must transcend physical space and time: it must be independent of the universe, and unimaginably powerful.
Moreover, this cause must be a personal being, endowed with free will.2 An impersonal, timeless, deterministic cause would either bring about the effect eternally or not at all. A temporal effect could originate from a timeless cause only if that cause were a personal agent, who could freely bring about the temporal effect without any change in antecedent determining conditions. The cause of the origin of the universe must therefore be a personal Creator, who a finite time ago brought the universe into existence by his free agency. In the words of Thomas Aquinas: "And this is what everybody means by God."
Of course, the Big Bang model has its detractors, motivated in some cases by frankly anti-theological animus. As physicist Hubert Reeves remarks, the Big Bang "involves a certain metaphysical aspect which may be either appealing or revolting."3 Only slightly tongue-in-cheek, Christopher Isham observes:
Perhaps the best argument in favor of the thesis that the Big Bang supports theism is the obvious unease with which it is greeted by some atheist physicists. At times this has led to scientific ideas, such as continuous creation [steady state] or an oscillating universe, being advanced with a tenacity which so exceeds their intrinsic worth that one can only suspect the operation of psychological forces lying very much deeper than the usual academic desire of a theorist to support his/her theory.4
A good example of such deep-seated anti-theological sentiment is Nature editor John Maddox's editorial, "Down with the Big Bang," where he hoped for the downfall of the Big Bang model, because in it, he believes, theological creationists find "ample justification" for their creationist creed.5 The sub-head to Maddox's article reads,
"Apart from being philosophically unacceptable, the Big-Bang is an over-simple view of how the Universe began, and it is unlikely to survive the decade ahead." (Nature, v.340, August 10, 1989)
Maddox, correctly apprehending the theological bearing of the Big Bang, calls for alternative models, and several have been proposed.
Yet two of the leading alternatives -- the steady state model and the oscillating model -- are now generally recognized as failures. The steady state model never secured a single piece of empirical verification, could not account for the existence of more radio galaxies in the past than today, and was finally laid to rest in 1965 by the discovery of the microwave background radiation, a vestige of an earlier, very hot, and very dense state of the universe.6
For its part, the eternally oscillating model contradicts observational cosmology, which indicates that the universe would have to be ten times denser than it is to allow the universe to re-contract after reaching a maximum distension. Even if the universe did re-contract, however, no known physics could reverse such a Big Crunch and cause the universe to bounce back to a new expansion. Finally, if the universe oscillated, thermodynamics mandates that entropy accumulates from cycle to cycle. Each successive cycle expands more slowly, with a larger radius. Thus, as one traces the cycles back in time, they become progressively smaller, terminating in a first cycle and an absolute beginning. Thus, neither model provides a plausible alternative to the Big Bang.7
There is a third alternative, however. The marriage of the General Theory of Relativity to Quantum Theory has given birth to quantum models of the universe. One should say "would-be marriage": these two great theories of modern physics are mutually inconsistent, and nobody knows how to reconcile them.
Quantum models attempt a reconciliation. Prior to 10-43 second after the Big Bang, quantum physics must be employed to describe the universe. Relativity and Quantum Theory must be united to describe this brief moment.
One class of models, called vacuum fluctuation models, appeals to quantum vacuum effects to explain the origin of the universe. These theories hold that just as sub-atomic particles can emerge spontaneously from the vacuum, so the material universe could have emerged from empty space, as a fluctuation of that vacuum.
These models are closely tied to so-called Inflationary Theories of the early universe. Such theories adjust the standard Big Bang model by stipulating that around 10-35 second after the Big Bang, the universe expanded faster than the speed of light, in an "inflationary" epoch, after which it settled down to its present rate of expansion. Before the inflationary epoch, the universe was just empty space -- a vacuum. The material universe began when the energy in the vacuum converted into matter by a quantum physical process.
As one regresses prior to the inflationary epoch, the universe collapses to infinite density. But vacuum fluctuation models hold that before inflation, the Universe-as-a-whole was not expanding. What appears to be the expansion of the whole universe is really only the expansion of part of it. Our observable universe is part of a wider Universe-as-a-whole -- itself a vacuum in a steady state. Throughout this vacuum, sub-atomic energy fluctuations create material particles out of the energy in the vacuum. These then grow into separate mini-universes within the whole. We observe only our own mini-universe exanding, but know nothing about other, similar mini-universes.8
Our universe thus did not begin in an initial singularity, but emerged by an uncaused fluctuation from the vacuum of a wider background space. As this view is often expressed, the universe is a "free lunch" -- something for nothing.
The congenial "free lunch" language is, however, misleading. A quantum mechanical vacuum spawning material particles is far from the ordinary idea of a "vacuum" (meaning nothing). Rather, a quantum vacuum is a sea of continually forming and dissolving particles, which borrow energy from the vacuum for their brief existence. This is not "nothing," and hence, material particles do not come into being out of nothing. Popular presentations of these models often do not explain that they require a specially fine-tuned, background space-time on the analogy of a quantum mechanical vacuum. The origin of the observable universe from this wider space-time is not a free lunch at all. It requires an elaborately set table, which must be paid for.
And here an obvious question arises. Why should we suppose that only our part of the universe (and parts like it) is expanding, rather than the whole universe?
This violates the Copernican Principle, which underlies all of modern astronomy and astrophysics. According to that principle, we occupy no special place in the universe, but see what any other observer elsewhere would see. Without the Copernican Principle, we could say that we exist at the center of the universe, or even that distant galaxies obey different laws of nature. Without compelling evidence to the contrary, we should assume that our observations are typical and that the universe we observe does not differ fundamentally from the whole. And no evidence indicates that the whole universe (beyond what we observe) is not expanding or that this wider universe has the special properties needed to spawn local universes via vacuum fluctuations.
Indeed, since we are confined to the observable universe, one wonders how we could ever have such evidence. Postulating a different, wider universe is akin to postulating God -- except that, unlike God, we have no independent reason to think that a wider universe exists. As the Dutch physicist Van der Weele muses, "We will never be able to determine which of these possibilities is actually true (if any), so all our ideas about the outer universe are doomed to remain metaphysical speculations."9 There is nothing wrong with metaphysics. But naturalistic explanations which posit realms beyond the reach of evidence are no more science, and no less metaphysics, than supernaturalistic explanations.
In any case, vacuum fluctuation models conflict with observational cosmology.10 Such models cannot specify when and where primordial vacuum fluctuations will grow into universes. Within any finite time interval, fluctuations may occur at any point in space. Given infinite past time, universes will spring into being at every point in the vacuum. As they expand, these universes will collide and coalesce -- and this contradicts observation.
One theorist avoids the difficulty by stipulating where fluctuations may occur in the wider space.11 Fluctuations which grow into universes must occur infinitely far apart in the background space, giving each universe an infinite "growing" space. But even this scenario does not avoid the difficulty. With infinite past background time, each infinite region of background space will spawn an open universe, filling the volume of that region completely. By now, all individual universes will have coalesced.
According to C. J. Isham, this difficulty is "fairly lethal" to vacuum fluctuation models, thus, they "have not found wide acceptance."12 Colliding universes can be avoided by postulating that the background vacuum space is itself expanding -- but then we must posit an origin of the wider universe itself, and we are back where we started.
Vacuum fluctuation models have now been abandoned even by some of their original expositors. Brout and Spindel contend that an explanation of the origin of the universe "must await the yet-to-come quantum theory of gravity."13 That brings us to the second class of quantum models.
In recent years, the particular quantum gravity model which has drawn the most attention is the Hartle-Hawking model, popularized by Stephen Hawking of Cambridge University. Hawking's popularization of his views, the best-seller A Brief History of Time, is remarkable for its overtly theological orientation. Hawking admits that if the universe began to exist, then one could identify the Big Bang as the instant of divine creation.14 In fact, some attempts to avoid the Big Bang, he acknowledges, were probably motivated by the feeling that a beginning of time "smacks of divine intervention."15 Whether Hawking shares this motivation or not, he touts his model as preferable to the Big Bang because no edge of space-time exists at which "one would have to appeal to God."16
Hawking hopes that by introducing quantum physics at the universe's earliest stage, prior to 10-43 second, he can eliminate the singularity. To do this, Hawking introduces imaginary numbers -- like the square root of -1 -- for the time variable in his equations. He proposes that prior to 10-43 second time becomes imaginary, thus rounding off the singularity. Space- time in this early region is geometrically the four-dimensional analogue of the two-dimensional surface of a sphere. Any point on a sphere arbitrarily designated as the "initial" or "beginning" point is just like any other point. (In particular, it does not mark an edge or boundary to that surface.)
Thus, on Hawking's model, the past is finite, but boundless. Since imaginary time cannot be distinguished from space, no point on this sphere-like surface is actually earlier than any other point, just as no point on the surface of a ball is "earlier" than any other point. As Hawking explains:
...There would be no singularities at which the laws of science broke down and no edge of space-time at which one would have to appeal to God or some new law to set the boundary conditions for space-time.... The universe would be completely self-contained and not affected by anything outside itself. It would be neither created nor destroyed. It would just BE.17
Hawking is not reluctant to draw theological conclusions from his model:
The idea that space and time may form a closed surface without a boundary...has profound implications for the role of God in the affairs of the universe.... So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end. What place, then, for a creator?18
One could criticize Hawking's model on physical grounds alone.19 But I shall look much deeper, at the philosophical or metaphysical foundations of his theory. Lawrence Sklar reminds us that such concerns are entirely appropriate:
The adoption of one scientific theory rather than another, sometimes and in very crucial cases indeed, rests as much upon the philosophical presuppositions of the scientists as it does upon the hard data of the laboratory. You can't do very good philosophy unless you get your science right. But you can't do science in full self-conscious understanding, unless you realize how much it depends upon philosophical modes of reasoning as well.20
Hawking's quantum cosmology provides a good case in point. His model is rife with unexamined philosophical assumptions which are, at best, unproven and, at worst, false.
Hawking does not take his theory to be merely a mathematical model which does not really describe the world. Such a non-realist or instrumentalist interpretation is compatible with the claim that the universe actually began to exist in real time and was created. Hawking would then only be re-describing the origin of the universe using the mathematical formalism of quantum mechanics. That there is no beginning of the universe in his model would not eliminate the beginning of the universe in reality. Hawking claims to have eliminated a real beginning and any need for a creator. Thus, he must -- and does -- take his model really to describe the early universe. But this is precisely where problems begin.
Take just one example: Hawking's use of so-called "imaginary time." Here two problems arise. First, "imaginary time" is physically unintelligible. An imaginary interval of time makes no more sense than, say, the imaginary volume of a glass, or the imaginary number of people in a room. Hawking insists that imaginary time is "a well-defined mathematical concept."21 But does that mathematical concept correspond to any physical reality? As Sir Herbert Dingle cautioned,
In the language of mathematics we can tell lies as well as truths, and within the scope of mathematics itself there is no possible way of telling one from the other. We can distinguish them only by experience or by reasoning outside the mathematics, applied to the possible relation between the mathematical solution and its supposed physical correlate.22
From both experience and philosophy it is, I think, obvious that the use of imaginary numbers for the time variable is a mere mathematical artifice. Imaginary numbers are useful when computing certain equations, but one always converts back to real numbers to yield a physically meaningful result.
Yet Hawking declines to reconvert to real numbers because then the singularity suddenly reappears. Hawking states,
Only if we could picture the universe in terms of imaginary time would there be no singularities.... When one goes back to the real time in which we live, however, there will still appear to be singularities.23
Thus, Hawking does not really eliminate the singularity. He conceals it behind the physically unintelligible artifice of imaginary time.
Secondly, using imaginary numbers for the time variable makes time a spatial dimension, which is just bad metaphysics. Space and time are essentially different. Space is ordered by a relation of betweeness: for three successive points x, y, and z on a spatial line, y is between x and z. But time is ordered in addition by a unique relation of earlier/later than: for two successive moments t1 and t2 in time, t1 is earlier than t2, and t2 is later than t1. As the philosopher George Schlesinger points out: "The relations 'before' and 'after' have generally been acknowledged as being the most fundamental temporal relations, which means that time deprived of these relations would cease to be time."24 Thus, time cannot be a dimension of space. Moreover, time is also ordered by the relations past/future with respect to the present. For example, my eating breakfast this morning was once present; now it is past. There is nothing even remotely similar to this relation among things in space.
But perhaps Hawking can be interpreted as holding, not that time in the earliest stage of the universe is a dimension of space, but that as one goes back in time, one arrives at a point where time is replaced by a spatial dimension. The early history of the universe would thus be timeless.
Postulating a "timeless" era before time began, however, is to climb inside a contradiction. Before and after are temporal relations. Saying that this timeless segment existed before time presupposes a time before time, which is self-contradictory. Hawking seems to realize the impossibility of having two successive stages of the universe, one timeless and the other temporal, and so he adopts the bizarre position that real time is just an illusion. He asserts,
This might suggest that the so-called imaginary time is really the real time, and that what we call real time is just a figment of our imaginations. In real time, the universe has a beginning and an end at singularities that form a boundary to spacetime and at which the laws of science break down. But in imaginary time, there are no singularities or boundaries. So maybe what we call imaginary time is really more basic, and what we call real is just an idea that we invent to help us describe what we think the universe is like.25
As the philosopher Quentin Smith points out, this intepretation is "preposterous...at least observationally, since it is perfectly obvious that the universe in which we exist lapses in real rather than imaginary time."26 If Hawking were right, we could not say (for example) that Churchill died after his birth, since this describes a temporal relation between these two events.
Significantly, this philosophical critique applies not only to the Hartle-Hawking model, but to all quantum gravitational models. All derive space-time from a quantum mechanical region which is a four-dimensional space involving imaginary time. Such scenarios cannot be repaired by scientific advances, because their shortcomings are metaphysical, not physical.
If these models are interpreted non-realistically, of course, no metaphysical objection arises. But then, the models say nothing about reality. The universe really did begin to exist; and if it began to exist, it requires a supernatural cause.
Cosmology also furnishes our second example where theology contributes positively to our understanding of the world. In recent years, the scientific community has discovered that a nexus of complex and sensitive initial conditions must be given in the Big Bang to permit the origin and evolution of intelligent life on Earth. The universe appears to have been incredibly "fine-tuned" for our existence. In the various fields of physics and astrophysics, classical cosmology, quantum mechanics, and biochemistry, discoveries have repeatedly disclosed that intelligent carbon-based life on Earth requires a delicate balance of physical and cosmological quantities. If any one of these quantities were slightly altered, the balance would be destroyed, and life would not exist.27
Changes in the gravitational or electromagnetic forces, for example, by only one part in 1040 would preclude the existence of stars like our sun, making life impossible. Changes in the speed of the expansion by only one part in a million million when the temperature of the universe was 1010 degrees would have either resulted in the universe's recollapse long ago, or precluded galaxies' condensing, in both cases making life impossible. The present temperature of the universe is so isotropic [uniform] that Roger Penrose of Oxford calculates that "the accuracy of the Creator's aim," when he selected this world from the set of physically possible ones, must have been on the order of one part in 1010(124).28
Contemporary cosmologists have attempted to eliminate some of this fine- tuning via inflationary models of the early universe. On these models, around 10-35 second after the Big Bang, the universe inflated exponentially, pushing certain poorly-tuned features of the universe out beyond our event horizon.
Yet inflationary models are extremely speculative. They rest on so-called Grand Unification Theories (GUTs), themselves speculative. No positive observational evidence establishes that the universe underwent an inflationary phase. In fact, inflationary models predict a universe possessing critical density, whereas observation supports a value ten times lower than that (see above). And no inflationary model has yet succeeded in starting and stopping inflation so as to allow for galaxy formation. Most importantly, inflationary models require the same fine-tuning which some theorists had hoped to eliminate via such models.
Universes not permitting intelligent life are thus inconceivably more probable than life-permitting universes. Many scientists conclude that such a delicate balance cannot be dismissed as coincidence, but requires explanation. Traditionally, that explanation would have been divine design.
Loath to admit design, however, some thinkers appeal to the so-called Anthropic Principle. First proposed by Brandon Carter in 1974, the Anthropic Principle takes different forms, generating confusion about what precisely the principle asserts. In The Anthropic Cosmological Principle, Barrow and Tipler state various versions of the principle, the most fundamental being the Weak Anthropic Principle (WAP). According to this principle, the astonishingly improbable properties of the universe are not surprising once we realize that we could not have observed anything else. Barrow and Tipler state:
The basic features of the Universe, including such properties as its shape, size, age, and laws of change must be observed to be of a type that allows the evolution of the observers, for if intelligent life did not evolve in an otherwise possible universe, it is obvious that no one would be asking the reason for the observed shape, size, age, and so forth of the universe.29
Thus, our own existence acts as a selection effect in assessing the various properties of the universe.
Notice the word "observed." This is crucial, because if we omit it, the resulting statement -- "the basic features of the universe must be of a type that allows the evolution of observers" -- is clearly false. The universe need not contain intelligent life. To be sure, the following statement is necessarily true:
If the universe is observed by observers within it, then its basic features must allow the existence of those observers. This is trivial, however, and does not explain why the universe has, in fact, the basic features it does.
But Barrow and Tipler contend that while the weak anthropic principle appears to be true, but trivial, it has "far-reaching implications."30 In particular, we need not explain the basic features of the universe, because there is nothing to be surprised at. The weak anthropic principle implies that we ought not to be surprised at observing the universe to be as it is -- for if the universe were not as it is, we could not observe it. No surprise is warranted. We should expect the universe to look delicately balanced. No explanation is needed, and a divine designer is gratuitous.
Does this follow from the Anthropic Principle, as Barrow and Tipler claim? Certainly we should not be surprised that we do not observe a universe incompatible with our own existence. But we still should be surprised that we do in fact observe a universe compatible with our existence, in view of the fine-tuning required.
Consider an illustration.31 Suppose you are to be executed by a firing squad of 100 trained marksmen, all of them aiming rifles at your heart. You are blindfolded; the command is given; you hear the deafening roar of the rifles. And you observe that you are still alive. The 100 marksmen missed!
Taking off the blindfold, you do not observe that you are dead. No surprise there: you could not observe that you are dead. Nonetheless, you should be astonished to observe that you are alive. The entire firing squad missed you altogether! Surprise at that extremely improbable fact is wholly justified -- and the fact calls for explanation. You would immediately suspect that they missed you on purpose, by design.
Similarly, we should not be surprised that we do not observe features of the universe incompatible with our existence. (We cannot observe that we do not exist.) Yet we should be surprised that we do observe features of the universe compatible with our existence -- in view of the enormous improbability that the universe should possess such features.32 Therefore, the weak anthropic principle fails entirely to remove our justified surprise at the basic features of the universe.
Proponents of the weak anthropic principle will contend that I have missed the whole point of the principle. Our surprise is justified, they would say, only if the basic features of the observable universe are co- extensive with the basic features of the Universe-as-a-Whole. Yet our observable universe, they would add, is but one member of a collection of diverse universes, within the Universe-as-a-Whole. All possible universes, including our observable universe, exist within this wider Universe. Some universes, like ours, contain life: the vast majority do not. We exist in one of the few lucky universes -- and no one should be surprised at, or try to explain, dumb luck.
This is the so-called World Ensemble hypothesis, which is typically conjoined with the weak anthropic principle. Various theories have been offered for generating a World Ensemble. Wheeler proposes an oscillating universe in which each cycle emerges with a new set of physical laws and constants.33 Linde suggests that our observable universe is but one of many different mini-universes which inflated from the original larger Universe.34 In Everett's widely discussed "Many Worlds Interpretation" of quantum physics, all possible states of a quantum measurement situation are actualized, and the observer himself splits off into each of these different worlds.35
No evidence exists for any of these theories apart from the fact of intelligent life itself. And each of the theories faces formidable scientific and philosophical objections.36 Wheeler's theory, for example, not only succumbs to the problems generic to oscillating models, but posits singularities at the termini of each cycle. It is not a model of an oscillating universe at all, but only a series of unrelated worlds. Inflationary models require extraordinary fine-tuning before inflation, so the appearance of design is not eluded. The Many Worlds Interpretation of quantum physics is so fantastic that philosopher of physics John Earman calls its splitting of space-time a "miracle." "Not only is there no hint as to what causal mechanism would produce such a splitting," he complains, "there is not even a characterization of where and when it takes place."37
Even if a multiple universe model were unobjectionable, would that rescue us from a divine Designer? The Anthropic philosopher argues that if the Universe-as-a-Whole contains an exhaustively random and infinite number of universes, then anything that can occur will occur somewhere. But why should we think that the number of universes is actually infinite, or that the multiple universes are exhaustively random? Neither postulate is necessary. To avoid intelligent design, we must assume much more than the existence of multiple universes.
"Some anthropic theorizers seem all too eager," Earman notes, "to embrace any form of world making that gives purchase to their modus operandi."38 Why this eagerness? The philosopher of science John Leslie explains that, although the idea of a World Ensemble is sketchy and faces powerful objections, still people think that it must be correct. How else could life originate?39 Yet divine design, Leslie argues, is no more obscure than the World Ensemble, nor less scientific.40 With the World Ensemble, we have already launched our bark out onto the metaphysical deep; if the God hypothesis provides us a surer passage, why not avail ourselves of it? As Leslie reminds us, those who think that "science proper" has boundaries which are easy to fix are becoming increasingly rare.41
In his book The Mystery of the Quantum World, Euan Squires writes, "In an effort to understand the quantum world, we are led beyond physics, certainly into philosophy and maybe even into...theology."42 The notorious "measurement problem" is a case in point.
According to the received interpretation of quantum physics, quantum systems possess dynamic properties like position, momentum, and spin orientation only when these are measured by some classical apparatus. But any physical measuring device can itself be given a quantum physical description. Thus, the problem arises that finally nothing outside quantum physics remains to make the measurment which is a necessary condition of the reality of the relevant properties.
Sometimes the measurement problem is stated in terms of the collapse of the wave function associated with a quantum system. In writing the laws of quantum mechanics, Schrodinger treated quantum entities as waves. Associated with every quantum system is a particular wave, called its wave function, symbolized by µ. The square of µ at any location gives the probability of the associated entity's being located there if it were measured. Before the measurement, the entity literally has no precise position, but a range of positions, varying in probability. Once a measurement has been carried out and the entity's position detected, however, then the probability of the entity being at that location is 1: the wave function is said to have collapsed. The measurement carried out on the quantum system brought about the collapse. This led Niels Bohr, the father of the orthodox understanding of quantum theory, to conclude that dynamic properties are not intrinsic properties of the quantum system itself, but relational properties with respect to the entire measurement situation.43
Since the classical measuring device is also describable by the equations of quantum mechanics, it, too, has an associated wave function. The measuring device itself, therefore, also lacks any intrinsic dynamic properties (such as precise location or velocity). But if the measuring device itself is not a classical system -- if it is itself indeterminate -- then it cannot collapse the wave function of the quantum system being measured. So how does the wave function collapse?
Bohr never answered this problem. He took for granted the existence of the classical measuring apparatus. Bohr's Copenhagen Interpretation of quantum physics dealt only with the interrelation between the quantum and classical realms without shedding light on either realm in itself.
What solution is there? If we say that the wave function of the measuring apparatus is collapsed by a third device, then we are off and running along an infinite regress. Where or when along this regress do we find a non-arbitrary stopping point at which reality becomes determinate?
One might argue that quantum indeterminacy does not really matter to us, here at the macroscopic level. If we measure the position of even a paper clip to an accuracy of 1/100 cm, for instance, the complementary uncertainty in its velocity is only 10-20 m per year.
Yet quantum indeterminacy can be amplified through various devices to yield an intolerable macroscopic indeterminacy. Consider Schrodinger's infamous cat, a hapless animal imprisoned in a chamber along with a bit of radioactive substance. If, within an hour's time, atomic decay is detected, a relay causes a hammer to break a flask of hydrocyanic acid, thereby killing the cat. But if no decay is detected, the cat remains unharmed.
So -- after an hour's time -- is the cat dead or alive? Quantum theory requires us to say that because atomic decay is intrinsically indeterminate, so, too, is the state of the cat. Its state is a super-position of the two states of being alive and being dead. (It does no good to say that the cat or the measuring device collapses the wave function of the atomic particle. The entire cat cum measuring device cum atomic particle is itself describable in quantum mechanical terms, and so is indeterminate.)
Von Neumann cuts the infinite regress where human consciousness observes the quantum system. Reality thus depends (at least with respect to dynamic properties) on human observers. But this implies that Schrodinger's cat is neither dead nor alive until I open the box and look in, which seems incredible. In any case, my consciousness is linked to a human brain. What collapses the wave function of the physical system, "me observing the cat?" Human observers only perpetuate the regress.
The theist may offer a way of escape. Why must the observer be human? Could God act as a Cosmic Observer, who collapses the wave-function in any measurement, or who would collapse any wave-functions in the universe with respect to any possible measurement? God is unembodied Mind, self-consciousness not linked to any material substratum. He cannot be described by the equations of quantum mechanics and so is unaffected by quantum physical indeterminancy. Hence, there is no regress in His case.
I am not suggesting, with Barrow and Tipler44, that we posit some Ultimate Observer in the chronological future, who stands at the close of all the temporal series of observers in the history of the universe. That implies backwards causation, past and present reality being determined by something that does not yet exist. Rather, I suggest that God now knows, and has always known, the outcome of any possible measurement in the universe, so that the wave function in any actual measurement is collapsed by Him.
Some theorists have actually entertained this solution, but it has met with little sympathy. Alastair Rae, for example, alleges that:
this point of view...does little to solve the problem, but merely restates it. If...God's consciousness is determining which state a quantum system will occupy, then we are still left with the question of at which point in the measuring chain this choice is exercised. Presumably God doesn't look at the photon passing through the polarizer at least until the detector state has changed. Why not?...We are simply back where we started, not knowing at what point the measuring chain ends and why.45
But the measurement problem is not our ignorance of why and where the measuring chain ends. Rather, in wave function reduction, quantum physics throws us into a vicious infinite regress that cannot be broken. A Cosmic Observer (outside the laws of quantum physics) solves this conceptual problem by non-arbitrarily interrupting the regress of measurements and so collapsing the wave function. Where and why he interrupts it is irrelevant to the solution of the problem.
Secondly, Rae conflates God's determining the state of a quantum system with God's observing it. If He does the first, then quantum indeterminacy is not ontic -- built into the way the universe really is -- but epistemic: we may not know why a particle strikes a screen at certain coordinates, but nonetheless, it is determined by God. By contrast, God's role as Cosmic Observer is compatible with genuine indeterminacy. God does not choose which of the possible states of a quantum system will be actual, but He actualizes whichever one happens to result from a measurement by His observing that measurement.
Thirdly, when we speak of God's observation, we must not construe this anthropomorphically, as though God must look at the photon passing through the measuring device. In quantum measurement, although the measuring device may disturb the system being measured, this is not necessary. The observer need not influence the final state of the system measured. The observer merely objectifies or actualizes the outcome, "fixing" reality in the relevant respect. God need only be aware of the outcome of any measurement, that is, have a true belief about the result. As a Cosmic Observer, God knows the outcome of every measurement immediately. Thus, to answer Rae's question, God's observation of a quantum measurement involves no intermediate links in the measurement chain, and the reason for this immediacy is His omniscience.
Polkinghorne has other misgivings about God as Cosmic Observer. "Divine reduction of wave packets would be overkill," he complains, "since it would operate everywhere and always."46 For example, every electron fired in the famous two-slit experiment, measured or not, would be forced through a definite slit on its way to the target. Similarly, Squires advises, "God must be selective -- he must not reduce all wave functions automatically." Otherwise He might collapse the wave function to yield a determinate position for a particle, when we wanted instead to measure its velocity! "It is therefore necessary that the God who reduces wave functions," Squires argues, "should know about these other observers and should know what they intend to measure."47
But, as Cosmic Observer, God does not automatically collapse all wave functions everywhere and always. If we take the orthodox Copenhagen Interpretation seriously, then nothing corresponds to the dynamic properties of quantum entities apart from measurement. Dynamic properties are relational, involving the entire measurement situation. Quantum entities have no intrinsic (that is, unmeasured) position, momentum, or spin.
Hence, God need not collapse the wave functions of unmeasured quantum systems. Rather, He knows the outcome of every quantum measurement actually made, or the outcome of any measurement that could be made. He could have known this from the beginning of time,48 and certainly He could know (presently) every quantum measurement as it occurs.
Thus, theism offers a plausible solution to the measurement problem within the received interpretation of quantum physics. If this solution looks too metaphysical, consider the alternatives. Take, for example, the Many Worlds Interpretation of quantum physics. On this view, the wave function of a quantum system never collapses. Rather, all possible values of a measurement are equally real. We observe only one value because, in every measurement, the quantum system being measured and the measuring device somehow split into parallel worlds. We observe one value; but in the parallel worlds we (or our counterparts there) observe different values. The measurement problem never arises. Of course, no evidence exists for this extraordinary ontology, but it is part of the discussion about how to understand quantum physics. Polkinghorne is right when he says, "one must recognize this suggestion for what it is. It is a speculation of metaphysics...."49 But if naturalistic metaphysics have a place at the table when quantum theory is under discussion, then the theist must be given his place too.
All this assumes that the Copenhagen Interpretation is correct. Perhaps it is not. Perhaps a neo-realist interpretation (with non-local, hidden variables), as envisioned by de Broglie and Bohm, will carry the day. Or perhaps quantum physics describes only ensembles of identical systems, for which its predictions are precise and deterministic. Our conclusion, therefore, must be conditional: if one accepts that the wave function is real and that there are no hidden variables, then theism is the most plausible solution to the measurement problem.
Finally, quantum physics supports a theistic metaphysic in another area: quantum cosmology. As noted above, cosmologists have tried to marry Quantum Theory to Relativity Theory to describe the origin of the universe. Prior to the Planck Time, the curvature of space-time becomes so severe that the entire universe becomes a quantum entity. So why would there not be a wave function of the universe? Quantum cosmology assumes that at the start the universe does have such a wave function. For our universe to exist, this wave function must collapse.
But then the inevitable question arises: who or what collapses the wave function of the universe? Since all ordinary spatio-temporal observers are within the universe itself, the answer, on the orthodox Copenhagen Interpretation of quantum physics, can only be: an Observer who transcends space and time.
Secular quantum cosmologists cannot abide this answer. Thus, they embrace the Many Worlds Interpretation of quantum physics instead. As Oxford physicist John Barrow muses,
It is no coincidence that all the main supporters of the Many Worlds Interpretation of quantum reality are involved in quantum cosmology....This interpretation of quantum reality is adopted by quantum cosmologists because it does not require the universe to be observed.50
Yet, apart from anti-theistic bias, there is no reason to adopt the bloated ontology of the Many Worlds Interpretation, rather than theism, which, as Barrow admits, supplies a mathematically consistent picture of creation. Theism is simpler and is independently supported by other sources. By contrast, the Many Worlds Interpretation may not even be coherent because it cannot make sense of the numerical predictions of quantum theory.51
Again, our conclusion is conditional. If there is a wave function of the universe, then a supernatural Cosmic Observer and Creator plausibly explains the collapse of the wave function and the existence of the universe. Even Quentin Smith, no friend of argumentative theism, has called this "the best scientific argument for God that is present in twentieth-century science."52
I hope that my limited examples -- the Big Bang, fine-tuning, and quantum physics and cosmology -- have shown the power of theism to illuminate the world revealed to us by modern science. In the renewed dialogue between science and theology, theology must not be a mute listener. She has too much to offer to be silent.
Copyright © 1996 William Lane Craig. All
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File Date: 11.14.96
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