Updated: Oct 5, 2020
The Many Worlds Interpretation is a desperate attempt to salvage a materialistic dismissal of the mind.
Since ancient Greece, atheists have denied that the human mind has any immaterial existence. But this denial has always raised a thorny question for atheists: If the mind does not transcend the brain, what accounts for our conscious experience—the fact that I experience the world as an “I”? Why aren’t human beings unconscious automatons, acting in the world without any first-person perspective?
To answer this question, the biologist Thomas Huxley argued that consciousness is a kind of accidental waste-product of the brain. On Huxley’s view, the brain determines what it will do all on its own, without any need for conscious experience. Consciousness, for unknown reasons, simply happens to bubble up out of the gears of the machine. To make Huxley’s materialist view clearer, imagine an organism that looks and reacts like a human being but lacks all conscious experience. This organism behaves as a human would, but has no first-person perspective observing the world—no “I.” Now imagine that a helpless ghost is also attached to this automaton, doomed to observe the world but never to cause anything. To Huxley, this ghost is human consciousness.
On Huxley’s view, your consciousness—that is, you—are like a passenger in the driver’s seat of the body. In Huxley’s words, consciousness is as useless to the brain as “the steam-whistle which accompanies the work of a locomotive engine.”
Huxley’s view also means that you do not continue to exist from one moment to the next. As your brain creates a series of experiences, there is no fixed “person” that is having each of the experiences in the series. Rather, the person created by your brain a moment ago has ceased to exist. A new, fleeting blip of consciousness follows it, only to pass away forever. Your basic identity, as a being that exists through time, is as illusory as your experience of having effects in the world.
With the advent of quantum mechanics, however, a peculiar puzzle began to put pressure on classical atheism and its materialist view of the mind. At the center of this puzzle is the overwhelming impression that, in quantum mechanics, the mind plays some special role—a role that could not be played by a material thing.
This impression is not confined to the realm of New Age mystics. The physicist Fritz Wolfgang London, whose views are taught in physics textbooks, held that the mind of an observer plays a special role in measurement. Eugene Wigner, an influential physicist and winner of the Nobel Prize in Physics, once stated that, while many philosophical ideas “may be logically consistent with present quantum mechanics… materialism is not." Rudolf Peierls, a Manhattan Project physicist, likewise believed that something about the human minds transcends matter.
Even physicists who are professing atheists, of whom there are many, seem to find it impossible to avoid giving the impression that minds have some special causal role. In the words of atheist physicist Jim Al-Khalili, measured particles seem “to have been aware” of the behavior of experimenters. Jonathan Allday, co-author of the Oxford textbook Advanced Physics, is also an atheist—one of the sneering variety, even. In his book Quantum Reality, Allday similarly writes that “each electron, from the very first onward, seems to have ‘knowledge’ of the final interference pattern.”
Of course, neither Al-Khalili nor Allday believes that physics contradicts classical materialism. Their language, however, illustrates the gravity of the problem. It seems as if there is no way to explain physics without subtly undercutting classical materialism.
Into this fray stepped the late physicist Hugh Everett III. A dyed-in the-wool nihilist, Everett is known for ordering that his ashes be dumped into a trashcan when he died—a practice that Everett’s daughter later copied upon committing suicide. Everett brought this same dedication to bear in his scientific career. Today, Everett’s disciples praise him for bringing an atheistic scorn of the immaterial back to quantum mechanics.
As a graduate student in the 1950s, Everett was alarmed to discover that traditional quantum mechanics did not line up with his materialist commitments. He was repulsed by the fact that the human mind seemed to be given a special role—a conclusion that Everett thought smacked of the supernatural. There seemed to be “a magic process in which something quite drastic occurred, while in all other times systems were assumed to obey perfectly natural continuous laws.” In Jonathan Allday’s words, Everett firmly believed that such a “‘magic process’… should not be considered in quantum physics.”
Everett therefore devised the Many Worlds Interpretation of quantum mechanics—perhaps the most widely-known interpretation in contemporary popular culture. The purpose of the interpretation was, in essence, to create a consistent model of quantum mechanics that would preserve Thomas Huxley’s materialistic dismissal of the mind. Everett's model continues to be extremely influential.
David Deutsch, a militantly atheistic contemporary physicist, regards himself as a sort of apostle of Hugh Everett. “Everett was before his time,” says Deutsch. Before Everett, “things were regarded as progress which are not explanatory, and the vacuum was filled by mysticism and religion and every kind of rubbish. Everett is important because he stood out against it.” Deutsch’s words of praise are important: Everett's greatest achievement is not the elegance of his mathematical model, but that the fact that his model pushed back against "religion," which is of course false.
The physicist Stephen M. Barr—a rare theist among physicists—admits that the Many Worlds Interpretation successfully reconciles the math of quantum mechanics with materialism. Yet the interpretation, Barr says, is “awfully heavy baggage for materialism to carry.” In the words of Bryce DeWitt, a proponent of the interpretation, Many Worlds means that there are literally “10^100 slightly imperfect copies of oneself all constantly splitting into further copies, which ultimately become unrecognizable.” This, Dewitt concedes, “is not easy to reconcile with common sense. Here is schizophrenia with a vengeance.”
Why do materialist physicists feel compelled to accept the “heavy baggage” of innumerable branching realities? The answer is that the puzzle of quantum mechanics appears to poke materialism in the eye.
The Observer Effect
The origin of the puzzle is the famous double-slit experiment. This experiment has been performed with a variety of small particles, including molecules composed of as many as 100 atoms. Visualizing the experiment is simple. Suppose a board, containing a single slit, is positioned in front of a screen. When particles are fired, one at a time, through the slit, they arrange themselves in a fairly predictable band, as shown in Figure 1.
Now imagine that we instead use a board containing two slits. Again, we begin firing the particles one at a time. We would expect the particles to arrange themselves in two bands. Instead, they arrange themselves on the screen in a wave-like “interference pattern,” as shown in Figure 2. But why should the particles behave differently when there are two slits rather than one? This question gives rise to the name “double-slit experiment.”
When we look at the interference pattern on the screen, it looks as if a large wave of particles has splashed through both slits at once, bouncing off one another. But, of course, the particles did not splash through the slits at once: they were fired through one at a time. Why, then, do the particles arrange themselves in a wave? As Jim Al-Khalili noted, each particle seems “to have been aware of their being two slits.”
This is only the surface of the puzzle. Next, we naturally want to find out how this is happening. As the particles are fired, how are they arranging themselves in this pattern? Are some swerving to the left, some to the right, and so on, until a pattern emerges?
To answer this question, we now place a detector on only the right-hand slit. The detector will tell us each time a particle passes through this slit. Note that, no matter which slit the particle goes through, this detector should enable us to know the paths of all of the particles. If a particle strikes the screen without going through the right-hand slit, then it must have gone through the left-hand slit.
When we run the experiment with a detector on one slit, the wave-like pattern now disappears entirely. The particles now arrange themselves in two simple bands on the screen, as shown in Figure 3. Put differently, all of the particles now behave as we expected them to when we first tried the experiment. It looks as if the particles “know” they are being observed and change their behavior accordingly.
Physicist Seth Lloyd’s popular-level book Programming the Universe contains the clearest description of the double-slit experiment that I have encountered. “Observation (or measurement, as it is conventionally called) destroys interference,” writes Lloyd. “When you ask the particle where it is, it is forced to confess that it is in one place or the other and no longer in both places at once.”
Why might some atheists, like David Deutsch, see this result as tending towards “religion” and as a threat to their atheistic worldview? To answer this question, think back to Thomas Huxley’s view of consciousness. To reject the existence of a soul, Huxley needed some other explanation for the phenomenon of first-person conscious experience. Huxley’s answer was that our consciousness is a mere waste product generated by the brain, like vapor rising from a machine.
But on Huxley’s view, the results of the double-slit experiment are completely unexpected. If mental states are powerless byproducts, then consciousness should have no more influence upon the movements of particles than would the presence of a nearby brick. Why should particles “care” whether they are being consciously observed or not?
A few common objections will now have to be dealt with. Many members of the Internet atheist community are confused about this experiment, and it is common to see lay atheists assert that the experiment does not even superficially challenge materialism. The particles do not behave differently because they are being “observed,” many say, but because the use of a measuring device somehow physically pushes the particles, causing them to behave differently. Physicists, however, do not accept this explanation. Seth Lloyd, for example, diffuses it unambiguously:
It is interesting to note, in the above experiment, that the measurement disturbs the particle’s wave whether or not the detector clicks. The detector clicks only if the particle goes through the right-hand slit, where the detector is located. But when the detector fails to click, meaning that the particle has gone through the left-hand slit, the interference pattern is still destroyed—that is, the measurement still disturbs the particle’s wave. The particle need not ever come close to the detector.
Why should a particle going through the left-hand slit behave differently on account of their being a detector on the right-hand slit? Evidently because, by going through the only slit without a detector, it is therefore revealing its location to an observer. Lloyd is certainly not carrying water for an immaterial view of the mind. Like most other physicists, Lloyd is an atheist.
Similarly, in online discussions among laypeople, another explanation some atheists offer is that the particles respond to the creation of memories in our brains simply because our brains are objects. To create a memory in our brains is to interact with an object. Perhaps the particles do not “care” that our brains produce consciousness: instead, all objects influence the particles through interaction, and the category “all objects” simply happens to include our brains.
But so-called “delayed choice” variations of the experiment defeat this objection. The gist of these experiments is that devices still interact with the particle, but do so in such a way that we can never know which path the particle took. When we look at the final result recorded on the screen, we see that the particles have now gone back to the wave-like “interference pattern.” In the words of Stephen Barr, if a camera takes a picture of a particle, “the camera and film become part of the… evolution of a wavefunction.” The thing that makes the difference is apparently not measurement in a mechanical device, but a conscious observer.
A famous thought experiment by Eugene Wigner—known as “Wigner’s friend”— makes the same point. Wigner asked us to imagine that he is performing the double-slit experiment alone in a lab. If Wigner cannot obtain results from the detector, the screen will show an interference pattern. If, instead, Wigner is able to learn results from the detector, then the screen will show two bands. The detector and the screen, like Barr's camera and film, are therefore said to be in an “entangled state” that is collapsed by Wigner’s observation.
Now, says Wigner, suppose that Wigner and his friend are performing the double-slit experiment together, and that Wigner goes to lunch while the experiment is being performed. While Wigner is at lunch, is the friend in an “entangled state” until Wigner talks to him to find out the results? Wigner says that the answer is no—the lab assistant already knows what the result is. “It follows that the being with a consciousness must have a different role in quantum mechanics than the inanimate measuring device,” Wigner concluded.
Physics and Philosophical Premises
How do physicists themselves interpret this data? Although there are many competing interpretations of quantum mechanics, the largest group holds to the “traditional interpretation,” which is that the act of “measurement” collapses the “wavefunction,” or a superposition of possible states, into one outcome or the other.
To be clear, most of these traditional physicists would balk at the suggestion that they believe “consciousness” plays any special causal role. If you asked them why it does not, however, Physicist Euan Squires states that “their reasons would be based more on prejudice than on sound argument, and the proportion of those who reject [a causal role for consciousness] would be much smaller if we considered only those who had actually thought carefully about quantum theory.”
This is, after all, a question of what philosophical conclusions should be drawn from the scientific data. Wigner himself said that there was a “perennial question, whether we physicists do not go beyond our competence when searching for philosophical truth. I believe that we probably do.”
According to Barr, the conclusion that consciousness plays a distinct role “seems to follow logically from the traditional interpretation of quantum theory.” If “measurement” has a distinct role—and delayed-choice experiments consistently show that mere interaction with a physical device is insufficient to constitute measurement—then Barr's conclusion follows logically from the premises supplied by science.
Of the many interpretations of quantum mechanics, Barr says that only the Many Worlds Interpretation succeeds in reconciling science and materialism by eliminating any apparent special role for consciousness. How does it do this? In Allday’s words, the Many Worlds Interpretation holds that “relative states are equally valid ontologically. All of them are true at the same time, which raises an obvious problem in relating that idea to our experience.” Everett addressed this problem by positing that reality is infinitely subdivided, and that each human being exist in an infinite number of copies. Hence Bryce DeWitt’s description of the interpretation as “schizophrenia with a vengeance."
Why should we be compelled to adopt a view of reality as bizarre as Many Worlds? Barr summarizes the argument:
One argument that is sometimes made in favor of the many-worlds interpretation is that it is forced upon one by any attempt to describe the entire universe by the laws of physics. If the ‘system’ one is studying is the whole universe, then there cannot be any observer to collapse the wavefunction, since by definition the observer has to stand outside the system and make measurements of it. But no observer can stand outside the entire universe and make measurements of it... Consequently, the wavefunction that describes the entire universe must be interpreted in a many-worlds way.
In other words, one argument for the Many Worlds Interpretation explicitly presupposes atheism. Allday makes more or less this exact case. In a section of his book Quantum Reality entitled “The Deep End…,” Allday raises two arguments against a unique causal role for consciousness. First, he says, “it closes science off in an unsatisfactory manner. If mind lies beyond the reach of physics, then it seems that the crucial role of measurement has been put out of play as far as further research is concerned." Secondly, he says, it seems to suggest the existence of an omnipresent mind: something which might be called “God.” Allday dismisses this idea almost out of hand.
Hilary Greaves, an Oxford philosopher of physics, offers a similar defense of Many Worlds. Writes Greaves:
To the charge of ontological extravagance it can be countered that, first, such ‘extravagance’ is preferable to the theoretical extravagance and inelegance required to eliminate other branches when our best formalism predicts their existence; secondly, this ontological extravagance is anyway not too damaging when the extra entities are of the same kind as those already admitted to existence.
You may by now be sensing a theme. Everett did not believe “magic” should be a result of quantum physics. Deutsch affirms that progress in science cannot lead to non-materialist answers. Allday says that positing something beyond material explanation closes off science; this is "unsatisfactory," in other words, by virtue of being non-materialist. Greaves claims that imagining an infinite number of unseen worlds is less extravagant than introducing any entities of a new kind: that is, non-materialist entities. Proponents of Many Worlds expressly derive their interpretation from a prior philosophical commitment: that anything which sounds like the "the soul" or "God" is always less plausible than any alternative explanation, no matter how extravagant.
If this rule does not explicitly presuppose atheism, it at least makes it impossible to ever prove that dualism or theism is true, no matter how much evidence we have for them. Imagine that tomorrow, Jesus Christ appeared bodily before a crowd of thousands and, in the presence of news cameras, walked on water and raised the dead. If we are to take Many Worlds proponents at their word, they would remain utterly unconvinced of Christianity. Hilary Greaves could watch the footage, speak to the witnesses, examine the death certificate, and still conclude that the entire thing must have been an elaborate conspiracy. While this conspiracy theory might require "extravagance,” we can hear her intone, this "is anyway not too damaging when the extra entities are of the same kind as those already admitted to existence.”
The history and philosophy of Many Worlds is a lesson in the sociology of science. The sociologist Elaine Ecklund has found that scientists who are atheists generally became atheists as teenagers and before becoming scientists, creating the misleading impression that a scientific education produces atheism. Ecklund’s pattern holds true of Everett himself, who came to physics already a convinced materialist.
Yet the Many Worlds Interpretation shows that this prior commitment to atheism also has theoretical, and not just sociological, effects on the scientific world. Both secular and religious laypeople often imagine that scientists create their models in a spirit of impartiality, and that these models sometimes happen to come into conflict with religion. In realty, as we can see from David Deutsch’s own words, the arrow sometimes goes in the other direction. Sometimes a model is created based on the philosophical premise—assumed before the evidence is actually gathered—that the claims of theistic religion are false. The model might even be admittedly ridiculous without that premise to support it.
The Many Worlds Interpretation's own defenders cannot help but admit that their theory has something of the "extravagant" and even the "schizophrenic," but see that extravagance as worthwhile precisely because it serves the overriding goal of combating the immaterial. We know exactly what kind of immaterial things these theorists are seeking to avoid. This kind of intellectual contortionism could only be produced by what Os Guinness has called “the anatomy of an unbelieving mind in its denial of God.” “Claiming to be wise, they became fools.”
Christian apologists have rightly exalted Christianity’s role as a driving force behind the advancement of science. We must continue, now more than ever, to portray scientific research as an act of worship, and the exploration of the universe as a divine calling. At the same time, we must remember that scientists are not floating brains detached from everyday human influences. Scientists, too, are humans, and human beings are agenda-driven.
Atheist quantum physicists are capable of imagining endless invisible realities in order to defend philosophical materialism. This should sound familiar to anyone familiar with the cosmology debate—for atheist cosmologists have similarly insisted upon infinite invisible multiverses in order to explain away the appearance of design. Both Many Worlds and the multiverse endure, despite their transparent extravagance, because each model follows from the philosophical premises of its materialist proponents. Christians should question these philosophical assumptions and, in doing so, raise up scientists who will not have to shoulder their unwieldy weight. The secrets of the universe do not belong to materialism—and they need not wait while materialists drag their heavy baggage across the world stage.
 Allday, Jonathan. Quantum Reality: Theory and Philosophy. Boca Raton, FL: CRC, 2009. 429.  Barr, Stephen M. Modern Physics and Ancient Faith. Notre Dame, IN: U of Notre Dame, 2003 (hereinafter "Barr"). 228.  Barr, Stephen M. "Does Quantum Physics Make It Easier to Believe in God?" BQO. 10 July 2012.  Allday at 440.
 Byrne, Peter. "The Many Worlds of Hugh Everett." Scientific American. Oct. 2008.  Allday at 455.
 Lloyd, Seth. Programming the Universe: A Quantum Computer Scientist Takes on the Cosmos. New York: Knopf, 2006. 108.
 See Allday at 20-21. It's also been brought to my attention that the Christian apologist Michael Jones of Inspiring Philosophy has an excellent video series on quantum mechanics, including on delayed choice experiments.
 Allday at 430. Notably, later in life, Wigner renounced the conclusion of the thought experiment. Yet his reasoning was basically philosophical rather than scientific. “If we want to avoid the solipsistic attitude,” he wrote, “…we should not consider an observation to be the basic concept [in wavefunction collapse].” Wigner, Eugene Paul, Review of the Quantum-Mechanical Measurement Problem, 1984. 68. Why did Wigner decide Wigner’s Friend led to solipsism? His argument was as follows: if we conclude that the observer collapses the wavefunction, we then must ask the question “what is an observer?”. Wigner said that the only coherent answer to this question is “only I am an observer.” Since this answer precludes other people from being observers, it follows that other people are in a superposition of states, which means “we are led to a solipsistic philosophy.” See generally Wigner, Eugene Paul, Physics and Its Relation to Human Knowledge, 1977. Wigner found this objectionable because “it is not reasonable to assume that another person’s observations are not equally correlated by the laws of quantum mechanics.” Review at 68. Interestingly, this objection is also the key premise of Wigner’s Friend. Wigner continued to explicitly reaffirm this premise, writing “If the result of the measurement enters into the consciousness of some person, the measurement is then surely completed—it is not possible to accept the idea that a person is in a superposition of two states.” Id. at 71.
 Barr at 242.
 Barr at 250.
 Allday at 431.
 Id. at 465.