Alexander Vilenkin is the Director of the Institute of Cosmology at Tufts University in Massachusetts. In his essay, “The Beginning of The Universe,” Vilenkin argues from modern science that the universe has an absolute space-time boundary (beginning). Additionally, Vilenkin philosophizes about the implications of his evidence for a beginning and draws some conclusions about how the universe could begin to exist a finite time ago without the need for some external cause. Vilenkin is an expert in his field (cosmology) and presents a very persuasive case for the finitude of the past based on the current scientific evidence. When Vilenkin begins to speak philosophically, however, he seems to make some critical errors that make his philosophical conclusions much less convincing than his scientific ones. Overall, Vilenkin’s main arguments seem a scientific success, but a philosophical failure—his scientific claims being thoroughly persuasive, while his metaphysical points, misguided and implausible.
Vilenkin’s approach is informative and mostly neutral. He spends a significant portion of his essay laying the groundwork for the modern scientific evidence of a universe that is not past-eternal. What Vilenkin presents at the front of his essay is not a matter of much controversy in physics. His presentation of the Penrose singularity theorem and inflationary theory is mostly a historical survey of physics’ journey towards modern cosmology.
Vilenkin does not begin to argue for a unique position until he draws out the implications of the Borde-Guth-Vilenkin (BGV) theorem, which he helped to develop in 2003. The theorem suggests that any model of the universe that includes a universe that is (on average) expanding must terminate at a finite time in the past. Vilenkin does not expect a physical loophole; he states, “The BGV theorem is sweeping in its generality. It makes no assumptions about gravity or matter.” He is clear—the theorem’s equations imply that there must be a past, space-time boundary. If the BGV theorem is correct, then this seems to be compelling evidence that cosmological models pointing to a space-time origin are, in fact, accurate. Vilenkin includes an appendix with the mathematical account of this theorem at the end of his essay.
According to Vilenkin, physicists don’t take issue with the BGV theorem. Instead, they try and construct models of the universe that will avoid it altogether and, therefore, its implications. Vilenkin looks at two such cosmological models that physicists attempt to build. The first is an eternally closed, static universe that “burst into inflationary expansion” at some spontaneous time. According to the theory, the universe would not be in an on-average state of expansion because—having existed for an infinite amount of time—expansion would be just an infinitesimally small part of the universe’s lifespan. Vilenkin shows that such a universe would be susceptible to unstable quantum phenomena. Given an infinite amount of time, no matter how unlikely, a quantum collapse would occur. Vilenkin’s argument from the quantum instability of this model seems almost philosophical. If the universe had existed for infinite time and then burst into expansion, why hadn’t it already done so at some previous point, given the existent probability of quantum collapse and an infinite amount of time?
A second model that Vilenkin assesses is one suggesting a universe that has been cycling through an infinite number of expansions and contractions. According to Vilenkin, these models have typically been unable to avoid a beginning, given the conservation of entropy between each of its cycles (as described by the second law of thermodynamics). Some physicists have tried to avoid this by suggesting the expansion period be longer than the contraction period. Vilenkin points out that if expansion is longer than contraction, then this puts the universe in an on-average state of expansion throughout its lifetime. This implies its subjection to the BGV theorem. It seems that Vilenkin accurately shows that both static and cyclical models of the universe cannot avoid a beginning, given the boundary described by the BGV theorem.
Vilenkin’s treatment of these alternative cosmological models seems open-handed and fair. He appears to see no reason to try and avoid a beginning by devising alternative models; instead, Vilenkin opts to go with what the current evidence suggests. He assesses past-eternal models of the universe both fairly and unbiasedly. The BGV theorem, quantum instability, and the second law of thermodynamics make it very convincing that cosmological models conforming to the current scientific evidence, must have a beginning.
Vilenkin shifts, albeit unknowingly, from a scientific evaluation of the evidence to a philosophical one. He laments how both theologians and atheists use his theorem in support of arguments for or against theologically significant conclusions (such as God is [is not] the cause of the beginning). Vilenkin is not convinced that the scientific evidence has anything meaningful to say about the “God” question. He does, however, give an assessment which he considers to show the “emergence of the universe as a physical process that does not require a cause.”
Vilenkin acknowledges a philosophical principle affirming that “nothing can be created from nothing.” This metaphysical principle seems to hold for everything in reality, whether physical or not—something cannot come from “not anything.” But Vilenkin seems to assess this principle in terms of physical law. When considering the idea, Vilenkin says, “there is a loophole in this reasoning, energy of the gravitational field is negative; it is conceivable that this negative energy could compensate for the positive energy, making the total energy of the cosmos equal to zero.” Vilenkin is suggesting that, on balance, the total amount of energy in the universe is really zero, and so allows for a spontaneous creation out of “nothing.”
This claim seems to slip from science to philosophy and back again. “Nothing” (in the metaphysical sense) is a term of universal negation—meaning “not anything.” If the zero-balance energy of the universe has any sort of potentiality at all, then it is not “nothing” in that sense. Vilenkin maintains that this spontaneous “creation” would be an uncaused, quantum event and that it’s possible that “universes are popping out of nothing like bubbles in a glass of champagne.”
It seems as though the “nothing” that Vilenkin is referring to is actually some sort of quantum state that obeys the laws of quantum mechanics. Vilenkin thus seems guilty of equivocating on the term “nothing” in his assessment. That “nothing can come from nothing” is a metaphysical principle, not a physical law, and some quantum fluctuation would not avoid it. Indeed, it seems the very reason that theologians and philosophers would find the scientific findings of Vilenkin so attractive is that this is so.
The physical stratum that Vilenkin calls “zero-energy” also seems to be infinite in the past. But it appears that while, on the one hand, Vilenkin argues for a spontaneous quantum universe tunneling into existence from “nothing,” his own works in physics and cosmology make that theory improbable. Any kind of zero-energy state that has the potential to tunnel into a different type of state at any given time would be subject to the same critiques that Vilenkin gives for an eternal, static universe. Given infinite time, why wouldn’t this zero-energy universe have tunneled into existence at some previous time? Vilenkin seems to slip into some form of eternally existent quantum universe—of the very type he himself disproves. He admits, in the end, that this “quantum creation” event is highly speculative and leaves many unanswered questions. Vilenkin’s claim that the beginning of the universe does not require a cause seems philosophically misguided and (by his own argument) scientifically unpersuasive.
Given the duality of science and philosophy present in his paper, some of Vilenkin’s arguments are persuasive and some seem uninformed. Scientifically, Vilenkin’s work in cosmology is highly impactful, and his work on the BGV theorem has become a lens through which to view any physical model of the universe. His willingness to accept an absolute beginning of the universe leaves him unbiased and open to assessing the evidence fairly. When Vilenkin steps out of the scientific arena, his thinking becomes less clear and, so, less impactful. He seems to sneak in a bias against anything supernatural (beyond the physical world) when considering the philosophical implications of his physics. Generally, Vilenkin demonstrates that his thesis is persuasive when it comes in the form of his unbiased expertise, but not so as a philosophical layman.
 Alexander Vilenkin, “The Beginning of The Universe,” In The Kalām Cosmological Argument, vol. 2, ed. Paul Copan and William Lane Craig (New York: Bloomsbury Academic, 2018) 152.
 Vilenkin, 153.
 Vilenkin, 154.
 Vilenkin, 154.
 Vilenkin, 154.
 Vilenkin, 155.