For centuries, humanity has sought to understand the fundamental components of the universe. From the early Greek philosophers who speculated on the existence of indivisible “atoms” to the quantum physicists of today, the pursuit of the smallest and most basic elements of reality has been an ongoing journey. But as our understanding of the subatomic world deepens, a perplexing question arises: What is beyond the subatomic? And can we ever reach the ultimate building block, or is it an endless, unraveling coil of smaller and smaller components?
In the early 20th century, the discovery of the atom’s internal structure revolutionized our understanding of matter. Scientists learned that atoms are not indivisible, but composed of smaller subatomic particles: protons, neutrons, and electrons. Later, the discovery of quarks and gluons, which make up protons and neutrons, added further complexity. These elementary particles, along with electrons, were considered the “building blocks” of the universe.
But the quest didn’t stop there. The Standard Model of particle physics—a theoretical framework describing the fundamental forces (except gravity) and the particles that make up all matter—provides the most complete understanding of these particles and their interactions. According to the Standard Model, quarks, electrons, and neutrinos are among the fundamental particles that cannot be broken down further. They interact through forces mediated by bosons like the photon, gluon, and W and Z bosons.
However, this is where things get complicated. While the Standard Model is incredibly successful at predicting and explaining a wide array of phenomena, it is incomplete. It leaves several key questions unanswered, including the nature of dark matter, dark energy, and the force of gravity. And crucially, it doesn’t definitively tell us whether there’s a level deeper than the subatomic.
One of the philosophical challenges that arises when contemplating the building blocks of the universe is the concept of infinite regression. If quarks and electrons are made of something even smaller, and those particles are made of something smaller still, where does it end? This issue gives rise to an unsettling notion: Could the universe be structured in such a way that there is no ultimate “bottom,” no fundamental particle that represents the final, indivisible piece of reality?
This idea of an endless chain of ever-smaller particles isn’t entirely foreign to science. In fact, string theory, one of the leading candidates for a “theory of everything,” suggests that the fundamental components of the universe may not be particles at all, but tiny, vibrating strings of energy. These strings, which exist at scales far smaller than we can currently observe, could form the basis of all matter and forces in the universe.
String theory sidesteps the problem of infinite regression by proposing that these strings represent the final, irreducible layer of reality. However, it also introduces new layers of complexity, such as the existence of multiple dimensions beyond the familiar three of space and one of time. The theory is still largely hypothetical, and it remains unproven due to the immense difficulty in testing its predictions.
The conundrum of what lies beyond the subatomic isn’t just a question of size; it’s also a question of existence. If everything is made of something smaller, how did that “something” come into being? This leads to a profound philosophical question: What makes the “something” in the first place?
In classical mechanics, the principle of causality—every effect has a cause—reigns supreme. But in the quantum world, where particles pop in and out of existence seemingly at random, our intuitive understanding of cause and effect starts to break down. Quantum fluctuations, for example, allow particles to appear from “nothing,” challenging the very idea that everything needs a preceding cause.
One intriguing possibility is that the universe itself could be self-generating, emerging from quantum fluctuations in a vacuum. Some physicists even suggest that the universe could be a “hologram,” a three-dimensional projection of information encoded on a two-dimensional surface at the edge of the cosmos. This concept, known as the holographic principle, could radically alter our understanding of the subatomic and beyond.
The deeper we go into the fabric of reality, the more difficult it becomes to know whether we’re reaching the end or if the bottom is still far beyond our grasp. Current technology allows us to probe down to incredibly small scales—using particle accelerators like the Large Hadron Collider—but even these tools have limits. As we push the boundaries of our understanding, we may encounter a point where human knowledge, or even the very nature of knowledge, reaches its limit.
If string theory or some other advanced model holds true, it could mean that the universe’s ultimate building blocks are hidden away in dimensions we cannot yet access or comprehend. Alternatively, there may be an endless series of layers, each giving rise to the next, in a cosmic Russian doll that never truly reveals a final, indivisible “something.”
What lies beyond the subatomic is not just a scientific question, but a deeply philosophical one, intertwining physics with metaphysics, and our desire for answers with the potential infinity of the universe’s complexity.
Image by AWF