Did the universe begin to exist or not? The final paper from Stephen Hawking indicates that the universe did have a beginning. Here are the details.
This question has rattled around in the psyche of the scientific community for more than a century now, ever since Einstein developed his general theory of relativity. The dominant view during most of that time held that the universe had existed forever (i.e., it had no beginning). Even though general relativity hinted that the universe might have a beginning, scientists proposed many models that circumvented this conclusion.
In 1964, Arno Penzias and Robert Wilson discovered the cosmic microwave background radiation—a discovery that established the validity of big bang models. A few years later, Stephen Hawking and Roger Penrose developed some powerful theorems that affirmed the conclusion that big bang models included the notion that the universe began to exist. Examining the theorems more closely reveals that the evidence for the beginning ultimately derives from the fact that the space-time trajectories of all matter in the universe cross, leading to a singularity (a region of infinite density) where the laws of physics break down.
However, physicists largely agree that infinities arising in a model indicate that the model is an inadequate description of reality. Consequently, Hawking developed other models without singularities over the last 40–50 years, specifically, his “no-boundary” proposal. In 2010, Hawking and Leonard Mlodinow published a book titled The Grand Design, where Hawking states, “Because there is a law such as gravity, the universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the universe going.” Hawking basically says that the universe exists, not because a God created it with a beginning. Rather, the laws of physics pop the universe into existence.
It’s this context that makes Hawking’s final publication (with Thomas Hertog) particularly interesting. In the paper, Hertog and Hawking seek to develop a model of inflation that is consistent with quantum mechanics rather than relying on a background universe evolving according to general relativity. After developing such a model, Hertog and Hawking make two interesting claims.
First, rather than producing a large (likely infinite) multiverse containing regions with great variability, inflation generates a comparatively small, rather smooth multiverse. Second, and more interesting to me, is their description of the past history of the universe.
Rather than affirm the conclusion of the previous “no-boundary” proposal, the new theory arrives at a different conclusion. According to Hertog, “now we’re saying that there is a boundary in our past.” Hertog also states, “when we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning.”
I am not claiming that Hawking believed the universe began to exist, or that the debate about the beginning in the scientific community is settled. What I find remarkable is that one of the most well-known cosmologists of our time supports a model of the universe that looks a lot like the one described in Genesis 1:1: “In the beginning, God created the heavens and the Earth.”