Physics may eventually be able to tell us “how the universe began,” in the sense of describing the physical events that happened in the first moments of its history, though physics is not quite there yet. However, even when physics gets to that point, it will not be able to say anything about the creation of the universe.
The reason is that “Creation” is not fundamentally about the first events in the history of the universe, but about why there is a universe at all. The distinction can be made clear with some analogies. A novel has some first words, but those first words do not explain why there is a novel. The reason there is a novel is that an author decided to create it. The “beginning of the novel” is just a set of words that come first in its internal sequence. The “origin of the novel,” in the sense of the ultimate cause of its existence, is the mind of the author who thought it up. Similarly, the “beginning of a symphony” is just a set of notes that come first in its internal sequence, whereas the “origin of the symphony” is the mind of its composer.
Physics can tell us about the “beginning of the universe” — the first events in its sequence — but not about “the origin of the universe” — the ultimate cause of its existence as something real. That, according to Catholics and other theists, is God.
In recent times, some atheists have suggested that the laws of physics actually might be able to explain why there is a universe. In particular, the physicist Stephen Hawking, towards the end of his life, proposed that the laws of gravity and quantum mechanics taken together (i.e. “quantum gravity”) may be able to do this. However, Hawking saw things more clearly in 1988, in his best-selling book A Brief History of Time. There he reminded his readers that any theory of physics is “just a set of rules and equations,” and then asked,
“What is it that breathes fire into the equations and makes a universe for them to describe? The usual approach of science of constructing a mathematical model cannot answer the question of why there should be a universe for the model to describe.” 1
This point can be explained by another analogy. Any game (say, chess or football) has a “set of rules.” Those rules tell you how any game described by them would begin and end, what kinds of events could occur in it, and under what conditions and in what manner they could occur. But they cannot tell you whether any actual game described by those rules is being played, has ever been played, or ever will be played. Nor would the mere set of rules have the power to make such a game take place. Similarly, the laws of physics are a set of rules that describe the kinds of things that can happen in a certain type of universe. (Different laws of physics would describe different types of universes.) But no laws of physics have the power to make there be an actual universe of that type. This was Hawking’s point in 1988, and it remains true today. Quantum gravitational laws are no different in that respect than any other.
Why is there an actual universe for the laws of physics to describe? One can say that this question has no answer, as atheists do. One can say that God is the answer, as Catholics and other theists do. (And both of these answers are compatible with doing good science.) What makes no sense at all, however, as Hawking correctly observed in 1988, is to say that the laws of physics are the answer.
1.. Stephen Hawking, A Brief History of Time (Toronto: Bantam Books Toronto, 1988), 174.
Resources for further study
Faith, Science, and Reason: Theology on the Cutting Edge (2nd edition), Christopher T. Baglow (Midwest Theological Forum, 2019), Chapter 3.
The Believing Scientist: Essays on Science and Religion, Stephen M. Barr (Eerdmans, 2016), Chapter 16 (“Modern Physics, the Beginning, and Creation”).