The idea of a universe without a beginning may sound like something from science fiction, yet a new theory of quantum gravity suggests it’s a real possibility. Bruno Bento, a physicist at the University of Liverpool, is among those exploring this concept, using a framework known as causal set theory. Causal set theory challenges the traditional view of space and time, suggesting that they are made of discrete “atoms” of space-time rather than being continuous. This fundamental shift could mean that the Big Bang was not the beginning of everything, but rather a particular moment in an endlessly evolving cosmos.

In the realm of physics, quantum mechanics and general relativity have provided powerful frameworks for understanding the universe. However, these theories have limitations—particularly when describing extreme conditions, like those at the centers of black holes or the beginning of the universe, where gravity becomes extremely strong. Traditional physics considers space and time as continuous, allowing for the possibility of infinitely small points. This, however, leads to mathematical breakdowns at singularities like the Big Bang, where traditional equations produce infinite densities and fail to work.

Causal set theory offers a different perspective by treating space-time as a series of discrete units, much like how pixels make up an image on a screen. Under this theory, space-time has a minimum size unit, meaning it cannot be infinitely divided. Bento and his colleague, Stav Zalel of Imperial College London, explored how causal set theory might apply to the origins of the universe. They found that if space-time is indeed broken down into finite atoms, then there may be no singularity at the beginning of the universe—because matter and energy cannot be compressed to an infinitely small point.

Bento and Zalel’s work implies that under causal set theory, the universe could be infinite in both directions of time. Their findings, published on the preprint platform arXiv on September 24, 2023, suggest that the universe might not have had a true beginning. Instead, what we call the Big Bang might simply have been a particularly dynamic phase in the universe’s endless history. In causal set theory, the passage of time is not a subjective experience but a physical process that unfolds one space-time “atom” at a time. As these atoms add up, the universe grows, layer by layer, potentially without any initial starting point.

This idea is still in its early stages, and researchers have not yet determined if it can fully account for the universe’s complex evolution. But Bento and Zalel’s research demonstrates that, at least mathematically, such a framework is feasible. According to Bento, this work doesn’t give a full explanation of the universe’s evolution from the Big Bang onwards but does provide a foundation to build on. The implications of a no-beginning universe could revolutionize our understanding of time, space, and existence itself.

As Bento explains, causal set theory makes time a fundamental part of the universe rather than an emergent phenomenon. The concept that the universe might have no beginning not only challenges conventional cosmology but also opens the door to entirely new questions about existence. While causal set theory is far from complete, it presents a thought-provoking new approach to the mysteries of our cosmos.