Many modern Christian apologists such as William Lane Craig or John Lennox present the origin of the universe in the finite past as evidence that God exists. In response, many modern atheists have sought to undermine such arguments by claiming that the existence of God is not required to account for the universe’s origin, usually by appealing to various scientific models of the universe’s origin. Because my expertise is in theoretical chemistry and quantum physics rather than in cosmology, I don’t have the background to evaluate the scientific plausibility of these cosmological models as alternatives to traditional Big Bang cosmology (nor -I expect- do most atheists!) However, I am qualified to address a claim that I frequently see advanced on the internet as a purportedly knock-down response to the claims of theists: the idea that ‘quantum fluctuations’ in some vague and unspecified sense explain the universe’s origin. In this essay, I’ll briefly explain what quantum fluctuations are and why they should not be invoked to explain the origin of the material universe out of nothing.
My argument is straighforward:
- P1. If a ‘quantum fluctuation’ occurs, then it can be described by a wavefunction
- P2. Wavefunctions describe ‘something’, not ‘nothing’
- C. Therefore, if a ‘quantum fluctuation’ occurs, then it is ‘something’ not ‘nothing’
If this argument is correct, then atheists should not argue that ‘quantum fluctuations’ show that ‘something’ can come from ‘nothing’ because quantum fluctuations assume the existence of ‘something’ not ‘nothing’. Are there reasons to believe that this argument is sound? Read on!
The common objection
The Kalam cosmological argument is the most common argument for the existence of God on the basis of the origin of the universe in the finite past. It runs as follows:
P1. Everything that begins to exist has a cause for its existence.
P2. The universe began to exist.
C. the universe has a cause for its existence
In defending premise 1 of the Kalam, Christian apologists often observe that “ex nihilo, nihil fit” (“out of nothing, nothing comes”) is a basic principle of metaphysics. In response to this claim, I have seen many atheists insist that quantum mechanics invalidates this principle via ‘quantum fluctuations.’ The idea often presented is that ‘nothing’ is unstable and that a ‘quantum fluctuation’ causes ‘nothing’ to become ‘something.’ Is there anything wrong with this claim?
What is a quantum fluctuation?
The term ‘quantum fluctuation’ is used to describe a number of phenomena in quantum mechanics: the correlation of electrons in atoms and molecules, the zero-point energy of harmonic oscillators, the effects of tunneling, the spontaneous appearance of matter-antimatter particle pairs, etc… What all of these phenomena have in common is the existence of what is known as a ‘superposition state.’ In quantum mechanics, particles and fields can exist in two or more different states at the same time. When one of the states predominates, the remaining state is often referred to as a ‘quantum fluctuation.’ For example, if we imagine a quantum mechanical coin that can exist in the single state ‘heads’ or the single state ‘tails’, a superposition might consist of the state 99% ‘heads’ and 1% ‘tails’, where the small 1% contribution of the tails state could be seen as a quantum fluctuation. A ‘quantum fluctuation’ can be either dynamic or static. A dynamic (or time-dependent) ‘quantum fluctuation’ refers to the emergence of a superposition state as time progresses. A static (or time-independent) ‘quantum fluctuation’ refers to the fact that the wavefunction exists in a superposition state at some particular instant of time.
Why don’t ‘quantum fluctuations’ show that something can come from nothing?
Having defined ‘quantum fluctuations’, let’s now return to our argument:
P1. If a ‘quantum fluctuation’ occurs, then it can be described by a wavefunction.
P2. Wavefunctions describe ‘something’, not ‘nothing.’
C. if a ‘quantum fluctuation’ occurs, then it is ‘something’ not ‘nothing.’
P1 is seemingly unavoidable. The wavefunction is the basic unit (or at least, one of the basic units) of reality in quantum mechanics. There is no quantum mechanics without a wavefunction; most textbooks will even refer to the existence of wavefunctions as one of the fundamental postulates of quantum mechanics. Theoretical-physicist-turned-Columbia-philosophy-professor David Albert begins his book The Wave Function with the remark that “Wave functions, or some mathematical equivalent of wavefunctions, come up in every quantum theory and in every proposal for making explicit conceptual sense of the quantum theories that we presently have” (p. ix). Hence, it seems impossible for someone to appeal to a ‘quantum fluctuation’ and then to deny that this event or entity can be described by a wavefunction. If it cannot, then it makes little sense to even use the term ‘quantum’.
Yet P2 also seems quite strong. Regardless of how we view the ontological status of wavefunctions, there is little question that they somehow describe something that actually exists. To say it another way, it seems extremely strange to insist that this particular wavefunction describes something which does not exist! When we make use of wavefunctions in experimental physics, they never refer to ‘nothing’; they always refer to ‘something.’ Even the ‘quantum vacuum’, which people sometimes confuse with ‘nothing’, actually refers to an entity with real properties, the most obvious of which is a zero-point energy that has measurable effects on experiments. To posit a wavefunction which describes ‘nothing’ is therefore to posit a wavefunction which is unlike any wavefunction we’ve ever encountered. Even ignoring philosophical considerations, it seems dubious to insist that at the beginning of the universe, there was a wavefunction that described a non-entity with no properties.
But if we accept both of these premises, it follows that we cannot simply appeal to ‘quantum fluctuations’ to refute the claim that “ex nihilo, nihil fit (out of nothing, nothing comes).” If a ‘quantum fluctuation’ necessitates the existence of a wavefunction which describes ‘something’, then it cannot provide an instance of ‘something’ emerging from ‘nothing.’
To be very clear, I am not arguing that all of those who appeal to ‘quantum fluctuations’ are engaged in hand-waving. As I’ve already said, I am not a cosmologist and I’m quite certain that many cosmologists and theoretical physicsts who employ such a term have a specific, mathematical definition in mind. Perhaps they are using the term to refer to chaotic inflationary models. Perhaps they are using the term to refer to Hawking’s No Boundary Proposal. But I am urging laypeople not to use ‘quantum fluctuations’ as a kind of magical incantation which wards off the attacks of philosophers and apologists.
Relevance for cosmological arguments
So what of the Kalam Comsological Argument, or cosmological arguments more broadly? I think that a conservative assessment of the current science would conclude that physics does not and potentially cannot offer a refutation of these kinds of arguments. For example, even Neoatheist Sam Harris seemed skeptical of astrophysicist Lawrence Krauss’ claims in his book A Universe from Nothing, asking repeatedly for clarification on how Krauss is using the word ‘nothing.’ Theoretical physicist turned philsopher David Albert was far less sparing in his review of the book in the NYTimes. When Krauss laments that “some philosophers and many theologians define and redefine ‘nothing’ as not being any of the versions of nothing that scientists currently describe,” and that “[he is] told by religious critics that [he] cannot refer to empty space as ‘nothing,’ but rather as a ‘quantum vacuum,’ to distinguish it from the philosopher’s or theologian’s idealized ‘nothing,'” Albert responds: “all there is to say about this, as far as I can see, is that Krauss is dead wrong and his religious and philosophical critics are absolutely right.”
Perhaps an even more humorous exchange occurred in a debate between renowned chemist Dr. Peter Atkins and Christian philosopher Dr. William Lane Craig. In response to Craig’s insistence that ‘something’ cannot come from ‘nothing’, Dr. Atkins at one point avers that “There is nothing here; I will concede that. But it’s an extremely interesting form of nothing. There was nothing originally. There is nothing here now. But [through] whatever event happened at the inception of the universe, it became an interesting form of nothing, which seems to be something” (see 1:02:22-1:02:46 here). It’s possible that Dr. Atkins is being mildly facetious here, although context suggests that he means to be taken seriously. Regardless, if our scientific beliefs really do require us to maintain that the entire universe is actually ‘nothing,’ we have good reason to suspect that our scientific beliefs are mistaken.
In my estimation, then, a purely scientific attack on cosmological arguments is a dubious enterprise. Although I believe the argument(s) to be sound, if I were an atheist, I would instead take issue with the A-theory of time implicit in the Kalam or with the very notion of causality in a quantum mechanical universe (see agnostic philosopher Peter Millican’s cautious response to the Kalam in his debate with Dr. Craig). To see an example of how scientific arguments against the Kalam should be combined with careful philosophical analysis, see atheist Graham Oppy’s article here.
That being said, in the spirit of the inquiry, I welcome critique of the argument presented above. If cosmologists, theoretical physicists, or even non-scientists are unconvinced by my argument, I would be happy to correspond with you. For readers curious about the nature of quantum mechanics and its non-cosmological philosophical implications, see this video. For readers curious about scientific evidence for God’s existence, see here.