Embark on a journey through the cosmos, exploring our solar system, traversing the Milky Way, and venturing into the vast cosmic wilderness, rich with black holes and galaxies. The question remains: Is the universe truly infinite?

Can exploration go on forever, or is there a boundary at some point? This significant inquiry in cosmology seeks to determine the universe’s size and shape. Although we have some clues, they lead to more questions than answers, leaving much in mystery.

When discussing space with peers, we often emphasize its vastness and potential infinity—a concept that challenges our understanding. Cosmologists have grappled with such ideas for centuries. The key to grasping the universe’s size lies in understanding its shape, which has been subject to diverse theories.

The simplest model is a flat universe, reminiscent of a sheet. While reality is far more complex, this metaphor aids comprehension. A flat universe would mean conventional rules of geometry apply—triangles maintain a sum of 180 degrees and lines remain straight. However, in a curved universe, geometry becomes non-Euclidean, leading to unexpected results.

The universe’s structure is influenced by gravity and dark energy; gravity binds matter together while dark energy acts as a force expanding the cosmos. If these forces balance perfectly, the universe remains flat. If dark energy dominates, it resembles a Pringle shape, while differing configurations may yield a finite or infinite cosmos.

Should gravity prevail, the universe would be spherical and finite—a straightforward conclusion. However, extrapolating from various large-scale cosmological observations suggests that the universe is likely flat. Recent findings indicate dark energy might decrease over time, underscoring our limited understanding of the universe as a whole. Despite creating detailed maps of dark matter, it remains enigmatic, complicating our grasp of gravity and its implications. Therefore, describing the universe as “probably flat” requires cautious interpretation.

As a storyteller, I must confess a bias against infinity. While intriguing, the concept’s application in the physical realm presents difficulty. My inclination is that every reality necessitates some limitation, however expansive. Infinity can feel unquantifiable, and if equations falter, can we genuinely assume an eternal existence?

This perspective is not unique; many theories subscribe to the idea of a finite universe. Even with a flat structure, the connections between different spacetime regions remain puzzling. Should the universe be finite and flat, we encounter an intriguing dilemma: what lies beyond its boundaries? Is it another universe, or simply nothingness? The prospects are disconcerting, complicating the mathematics that describe our reality.

In a curved spacetime, options expand. Spherical structures lack edges; travel far enough in one direction, and you may find yourself back where it began. Other possibilities include shapes resembling donuts, Klein bottles, or intricate topologies with wormholes. While some theories posit shapes like peanuts, cones, or apples, adding extra dimensions complicates matters further.

Introducing infinity creates a more chaotic scenario—an eternal universe filled with limitless galaxies and star systems. The focus shifts from the universe’s edges to the entirety contained within it.

This concept can be exhilarating: the spectrum of possibilities appears endless, and it’s statistically likely that other life forms exist. However, contemplating an infinite universe can be overwhelming. While it’s thrilling to imagine the vastness of life out there, the thought that “the universe is eternal, so anything can happen” can seem a bit meaningless.

Yet, these feelings are subjective. Ultimately, physics relies on observation and mathematics. This aspect is what I appreciate about physics—its precision; but infinity lacks that precision. When you set off through space, you desire a destination, whether it’s an edge or home.

Unravel the Mysteries of the Universe: Cheshire, England

Join leading scientists for a weekend exploring the universe’s mysteries, featuring a tour of the iconic Lovell Telescope.