Did the universe begin to exist or has it always existed? RTB argues that strong biblical and scientific evidence point to a beginning. We would say the Bible claims that the universe began to exist and that science can address the assertion. This notion of a beginning represents a significant, testable claim of Christianity, and the standard model of cosmology—an inflationary big bang—definitely points to a beginning.
However, scientists occasionally publish articles claiming that new research disproves the big bang or, more pointedly, indicates that the universe has existed forever. I expect to see more of these types of articles in the future. Thus, I want to articulate some key points related to the question of a beginning and to think through the issues to help you understand the nature of the problem and the proposed answers.
Theological and Scientific Background
From a biblical perspective, the doctrine of creation ex nihilo states that there was nothing but God and, by means of his incalculable wisdom and infinite power alone, God brought the universe (all matter, energy, time, and space) into existence from nothing. That the early church fathers placed this doctrine alongside Jesus’ incarnation, death, and resurrection illustrates its importance. One reasonable inference of creation ex nihilo is that the universe began to exist.
Big bang cosmology provides strong scientific support for the idea of a beginning. Albert Einstein’s development of the theory of general relativity (GR), Edwin Hubble’s discovery of the expansion of the universe, and Stephen Hawking and Roger Penrose’s space-time theorems all point strongly to a beginning for the universe.
Originally formulated in the 1960s and 1970s, the space-time theorems show that as a star collapses to form a black hole, GR leads to an end of time inside the black hole. Then, given the expansion of the universe, these theorems demonstrate that enough mass exists to force a similar conclusion for the entire universe when time is run backwards. Consequently, the theorems prove that a singularity (a point at which the density becomes infinite) marks the beginning of the universe’s existence.
An Important Caveat
In order for the theorems to genuinely prove a beginning for the universe, all the necessary conditions must be met. Specifically, GR must govern the dynamics of the universe. In the moments leading up to the singularity (when running time backwards) the energy conditions and scale of the universe demand a quantum mechanical description. However, GR is fundamentally a classical theory that includes no quantum mechanical aspects. Stated another way, the precise moment when the space-time theorems say a singularity exists corresponds to the moment when our confidence that GR describes the dynamics of the universe stops. In order to truly answer the question (scientifically speaking) of whether the universe began to exist, scientists need a quantum theory of gravity—something they currently lack.
Does Quantum Gravity Negate the Big Bang?
An important question to consider is: Will the true quantum theory of gravity show that the universe has existed forever? At this time, the quick answer is that scientists don’t know, because all attempts to formulate such a theory are speculative and no experiments discriminate between them and the standard cosmology.
One point worthy of note is that none of these quantum gravity approaches negate inflationary big bang cosmology. They agree with the standard measurements: the abundance of elements in the universe, the cosmic background radiation, the expansion history, structure formation (such as galaxies, stars, and planets), and so forth. In fact, the latest results from Planck confirm that “the standard model of cosmology remains an excellent description of the universe.” The existence of the singularity is the only place where the two approaches depart, and each approach differs in the details.
Several research articles argue for a beginning-less universe based on attempts to formulate a quantum theory of gravity. In almost all of those articles the researchers acknowledge that scientists still have not found the quantum theory of gravity but they are trying to find useful approximations.
In one, a recent article in Physics Letters B, the classical trajectories of general relativity were replaced with quantum Bohmian trajectories. By definition, Bohmian trajectories cannot cross, and this nature removes the singularity in the earliest moments of the universe, meaning that time extends to the infinite past.1 In a second research paper, string theory, one prominent approach to a quantum theory of gravity, imposes symmetries on the universe and these symmetries effectively eliminate any of the infinities required by a singularity.2 A third proposal invokes loop quantum gravity, which implies a maximum “compressibility” to the universe such that a previous contracting phase bounces, giving rise to our big bang universe.3 Other approaches use endless cycling, black holes, colliding branes, extra dimensions, and endless static states.
The main point to keep in mind at this time is that scientists currently have no way to know which (if any) of these quantum gravity possibilities is correct, or even if a quantum theory of gravity exists. This uncertainty means two things. First, we need not fear that scientists have discovered that the universe was eternal in the past. Second, we should express appropriate caution regarding any claims that science has established a beginning to the universe.
History Points to a Beginning
In the midst of this uncertainty, looking to the past provides a helpful guide. At the beginning of the twentieth century, based on ideas originally developed by Isaac Newton, scientists thought the universe had existed forever. Einstein’s development of GR and Hubble’s measurement of expansion moved scientific thought toward a beginning. However, the proposal of a steady-state cosmology and an oscillating cosmology mid-century both seemed to remove the need for a beginning, only to be invalidated by further observations. By late-century the space-time theorems strongly affirmed the need for a beginning. At about the start of this century, the multiverse seemed to tip the balance back toward an eternal universe until further research demonstrated that inflationary multiverses still seem to require a beginning. For a more in-depth discussion of these issues, listen to my interview with Phil Harper on Premier Radio’s Unbelievable? (hosted by Justin Brierley).
What Does It All Mean?
In the last 125 years of cosmology history there have been many attempts to prove an eternal physical realm. Thus far, all those endeavors ended with the conclusion pointing to a universe with a beginning in the finite past. My bet is that all these quantum gravity approaches will ultimately reveal evidence for a universe with a genuine beginning.
So let’s keep searching.