the gravity of ghosts: radical matter and the reality of the void

‘Nothing is enough for the man to whom enough is too little.’ (Epicurus)

When it comes to nothing, everything is at stake. For millennia, the investigation of void space has been closely intertwined with the exploration of matter. The more scholars tried to neatly separate something from nothing, it became increasingly evident that that such an attempt is doomed. As of today, the significance of empty space manifests in multiple ways, which not only challenge our understanding of the universe but also yield radical consequences for matter. In the course of history, numerous battles were fought over nothingness, which have left their ghostly marks in our contemporary conceptions of emptiness. Meanwhile, the vacuum is not only a possibility, but a necessity and it can thus be hardly overestimated how profoundly nothing really matters.

Reality of the Void

Within modern science, efforts to define both material existence and the void continue to be influenced by ancient philosophers. Remarkably, modern notions of emptiness bear a strong resemblance to ideas predating Aristotle, despite many years of opposing beliefs.

The early atomists were trailblazers in conceptualizing nothingness, coining the term ‘void’ to describe a comprehensible concept. Pioneered by Leucippus and Democritus, the universe was understood to be comprising two fundamental and contrasting elements: indivisible entities known as atoms, and the void. This theory, known as atomism, elevated the void to a critical component of the cosmos, a departure from prior theories. The atomists proposed that all matter consisted of atoms, from the Greek átomos, meaning uncuttable or indivisible. These smallest parts of matter were regarded as eternal and unalterable, introducing a revolutionary perspective on the composition and nature of matter. [1]

Aristotle entered the stage as a formidable critic of the early atomists’ theories. He contested their explanation of motion using the concept of the void. According to Aristotle, the movement of objects could instead be explained by the displacement of other objects, suggesting that one object moves because another object vacates its place. This view stood in contrast to the atomists’ belief that the void, or empty space, was essential to explain motion. Aristotle’s firm rejection of the void was discussed as ‘horror vacui’ and proved as the predominant view in the Western tradition for centuries.

In contrast to Aristotelian conviction, is it now generally agreed there are areas in space not filled by material objects, whether in the vastness of cosmic space or in specially designed chambers. This is to say that the vacuum does indeed exist, however it would be wrong to assume that it is entirely devoid of matter. According to quantum field theory there are unavoidable fluctuations of virtual particles also in empty space that fundamentally undo mere nothingness. While these quantum vacuum fluctuations do not become tangible in a material sense, they produce physical effects that can be measured experimentally. Furthermore, it is recognized that an unidentified entity within seemingly vacant space, termed 'dark energy' due to our limited comprehension, is driving the acceleration of the universe's expansion. This elusive energy that resides in cosmic voids acts as the main driver behind the universe’s outward spread, being responsible not only for its history but ultimately determining its very destiny. [2]

Both virtual particles and dark energy exemplify how what appears as empty space holds hidden complexities that deeply influence the cosmos across scales. Needless to say, that in this sense, nothing really matters.