Claims by prominent and not-so-prominent physicists that the universe can create itself from nothing are not exactly new. Indeed, such claims have been made since the discovery of quantum mechanics, or at the very least since Bohr and Heisenberg formulated their interpretation of quantum mechanics, which is sometimes referred to as the Copenhagen Interpretation . A similar theory was invoked by Fred Hoyle in his support for a steady state condition of the universe (which amounted to a rejection of the Big Bang theory, whose name he coined). This condition he held as a means of rejecting the beginning of the universe in time, a rejection which Hoyle made for explicitly metaphysical and theological reasons: namely, as a rejection of theism .
Unfortunately for the steady-state theorists and big-bang deniers, the weight of empirical evidence points to the universe’s having a beginning, thus vindicating Fr Lemaitre’s “Big Bang” theory. They are therefore forced to try a different approach to “proving” that there is no Creator, an endeavor which is more metaphysics than physics, even if that former word is considered a “dirty” word among most physicists today . The result involves far more philosophical speculation than physical science, albeit speculation dressed in the language of mathematics and presented as the latest of theoretical science. And while one or two of these competing theories may ultimately prove to be true—none is really testable at this time, and some cannot be testable at any time —too often the theory leads to philosophically (and especially metaphysically) shabby conclusions, which conclusions are rarely warranted by the actual empirical science in which physicists are principally trained.
One such conclusion—perhaps the most important and certainly the most frequent of late—is that the universe can still create itself out of nothing. “Nothing” is then conveniently redefined as something, which is very obviously not nothing. That something might be the theory of gravity, or it might be virtual particles, or a quantum wave function, or spacetime, or (most recently) relativistic quantum fields. In the latest case of this redefinition of “nothing,” the physicist in question was so brazen as to complain that theists who didn’t accept his argument had merely “moved the goalposts” concerning the meaning of “nothing!”
In his now decades-old book “The Philosophy of Thomas Aquinas,” the well-known Thomistic philosopher Etienne Gilson sets out rather explicitly just what is meant by “nothing.” In doing so, he is setting forth a definition which St Thomas Aquinas used (emphases mine):
“We speak of creation whenever something which was not, begins to be. In other words, there is creation wherever a transition occurs from non-being to being, in other words from nothingness to being. Applying this notion to all existing things, we may say that creation, which is the emanation of all being, consists in the act whereby all things pass from non-being or nothingness to being [Summa Theologica I.44.1]. This is the meaning of the expression that God has created the world from nothing. But it is important to note that in this assertion the preposition “from” signifies in no way the material cause; it means simply a sequence. God has not created the world from nothing in the sense that He caused it to issue from nothing as from a sort of matter, but in the sense that, after the nothing, being appeared. ‘Creating from nothing,’ in short, means ‘not creating from something.’ This expression, far from putting any matter at the beginning of things, systematically excludes all conceivable matter, in the same way as when we say that someone is sad about nothing, we mean that his sadness has no cause.”
Note that this definition cites Saint Thomas Aquinas, who lived and died in the 13th century, and who is considered not only a doctor of the Church, but arguably the doctor of the Church . If theists have moved the goalposts, we did it at least 800 years ago , which ought to be quite ample time for the apologists of a Creator-less creation to reformulate their arguments. The renowned physicist and Anglican clergyman Rev. John Polkinghorne says this much more succinctly when he writes that
“The thought of the Creator’s sustaining the world in being has traditionally been expressed in Christian theology by the phrase creatio ex nihilo, creation out of nothing. It does not mean that God used some peculiar stuff called nihil from which to make the universe, but that the universe is at all times held in being, rescued from the abyss of nothingness by the divine will alone” (Science and Theology: An Introduction).
Indeed, arguments that the universe creates itself out of nothing without a Creator because of “gravity,” or “quantum fluctuations,” or what have you, are not so much arguments for the creation of a universe out of nothing as they are arguments that the universe was formed from a sort of “prime matter” , which might be anything from the vacuum state’s fluctuations to string theory’s strings and branes to wave functions. Concerning that prime matter, Saint Thomas Aquinas writes that
“God brought things into being from no preexisting subject, as from matter…
Now, the order that obtains between act and potentiality is this: although in one and the same thing which is sometimes in potentiality and sometimes in act, the potentiality is prior to the act, which however is prior in nature to the potentiality. Nevertheless, absolutely speaking, act is necessarily prior to potentiality. This is evident from the fact that a potentiality is not actualized except by a being actually existing. But matter is only potentially existent. Therefore, God who is pure act, must be absolutely prior to matter, and consequently the cause of it. Matter, then, is not necessarily presupposed for His action.
Also, Prime matter in some way is, for it is potentially a being. But God is the cause of everything that is…Hence, God is the cause of prime matter—in respect to which nothing [else] preexists. The divine action, therefore, requires no preexisting matter” (Summa Contra Gentiles, Book 2, Chapter 16).
Thus, what is so often described by the modern physicist as “creation” is only what St Thomas would have called “change.” There is no passing from nonbeing to being, but only a change from one condition to another, as when (for example) the quantum wave state describing the universe collapses and brings forth photons and “matter” and eventually stars and planets and the rest. However, this change presupposes something which might be changed, that is it presupposes some “prime matter” with which everything began, prime matter whose existence must also be explained.
Even that prime matter must be given its existence by a Creator—as St Thomas notes above—and cannot merely come into existence because for the laws of physics (which are themselves not even “nothing”). If so many prominent physicists fail to recognize this it is, in the words of Fr Stanley Jaki,
“partly because of [their] notorious scoffing at philosophical considerations. [They have] no sensitivity to the fact that the ontological difference between being and non-being is infinite, even if the entity in question is a mere fraction the mass of the alpha particle. But unless there is sensitivity to that non-quantitative infinite distance, there will be no adequate concern for the equally infinite distance between being and boing when it involves the total mass of the universe” (Cosmology: An Empirical Science?).
As for the doctrine that God created the universe from nothing, modern science has hardly made a dent in this. As the late Professor Ralph McInenry notes, St Thomas Aquinas himself sought to show that there is no contradiction between a thing’s being created by God and its being eternal in duration . Aquinas rather famously noted that the doctrine which the universe has a beginning in time is a matter of faith—he didn’t believe that it could be actually proved—but that even an eternal universe might be created.”This analogy occurs to Thomas: the sun might always illumine an object, but left to itself [the object] would not be illuminated. So its being in darkness is naturally prior to its being illumined, whether or not there ever was a time when it was not illuminated” (A First Glance at Thomas Aquinas: A Handbook for Peeping Thomists). In much the same way, non-being is prior to being for the universe and any “prime matter” from which it came, whether or not there was a time when this prime matter did not exist. Thus, there is an ontological gap which must be crossed between being and non-being for the universe to exist. This ontological gap is infinite, and thus may only be crossed by an infinite cause, God. It is only His existence which prevents the universe from being sucked over the abyss into nothing-ness, that is, into non-existence. The latest scientific theory can do nothing to either prove or disprove this point.
 For more discussion (and critiquing) of this, see Fr Stanley Jaki’s collection of essays, “The Limits of a Limitless Science and Other Essays.” In the essay Beyond Science he writes,
“Even worse proved to be the [intellectual] disease sparked by Heisenberg and Bohr as they claimed that the uncertainty principle definitely discredited the principle of causality. The ultimate form of that disease is the claim that the physicist can literally create matter, indeed entire universes out of nothing….Yet even the most elementary form of causality is not within the competence of physics. No physicist has ever observed causality. Physicists merely observe a succession of events, as all non-physicists do. Only by taking recourse to metaphysics, tacitly or not, can physicists and non-physicists alike take this or that succession of events for causal interaction.”
 In his “Theology and Modern Science,” theology professor Fr James Wiseman writes (citing Fred Hoyle’s “The nature of the Universe“):
“Hoyle’s alternative theory was that of a steady-state universe, no doubt advocated by him not simply on scientific grounds but also because he sensed that the big bang theory implied a Creator, an implication unacceptable to someone who had once written that ‘religion is but a desperate attempt to find an escape from the truly dreadful situation in which we find ourselves.'”
 So remarked Professor Gennady Shvets in a departmental colloquium a the University of Texas a few years ago. The remark was met mostly with winks and smiles.
 For example, the theory of multiple universes which is sometimes drudged up as a refutation of the fine-tuning of physical constants to support life in the universe. Such a theory is put forth by no less eminent a physicist that Professor Stephen Weinberg, who cites this theory specifically as a refutation of the fine-tuning in the essay A Designer Universe? (Science and Religion: Are They Compatible?, edited by Paul Kurtz). That there cannot be any scientific verification of “other universes” is a fact which is conveniently and even studiously ignored by the defenders of these theories, since if any information can flow from one universe to the other, then the two are not really separate universes
 In his Aeterni Patris, Pope Leo XII—who reigned near the end of the 19th century—more-or-less declared that Saint Thomas Aquinas would be the Church’s more-or-less official philosopher. Again, this declaration was made well over 100 years ago, so it shouldn’t come as a surprise when at least the Catholic subset of theists insist on this definition of creation out of nothing. At with over a billion adherents worldwide, the Catholic Church is hardly a minor and unheard-of sect of Christianity, or indeed of theists in general.
 And, in fact, this concept of creation can be traced to earlier Christian sources. Professor Edward Feser suggests that Saints Anselm (12th century), Augustine (4th-5th centuries), and Athanasius (2nd-3rd centuries)–“to stick with just the A’s”– would have had no problem with this definition of creatio ex nihilo. For his part, Fr James Wiseman notes that the Hebrew verb bara’ meaning “to create” is only used when the subject is God, but the verb ‘asah “to make” is used of both God and men. “‘Making’ is thus analogous to human ‘manufacture,’ by which an object is fashioned so as to receive its particular character, whereas ‘creating’ is not comparable to what humans do. God alone could ‘create’ heaven and earth, whatever this activity might mean more exactly” (Theology and Modern Science). So this supposedly modern “goal-post moving” concept of creation from nothing looks to have its roots in Genesis, the first and oldest book of the Scriptures.
 This is somewhat debatable, of course. Could the quantum foam for the vacuum state be considered “prime matter?” I am not here claiming unequivocally that this is the case, but rather by analogy.
 Thus, if the universe does come into existence due to, for example, a fluctuation in a quantum vacuum state which was “always there,” it does not prove that the universe was causeless, or even that the quantum vacuum state itself is uncreated.
Update: Welcome to New Advent readers!