Much Ado About Zero

Define 0. Go ahead, I can wait.

Finished? You might have come up with one of the following:

Given this, zero is not nothing. It’s enigmatic yet foundational to our understanding of the world. The numeric zero sits neatly between two binaries (positive and negative numbers) on the number spectrum (aka the number line). It resists easy classification simply by existing. Yet, 0 is still a number. In fact, it’s critical to performing basic algebra.

Mathematically, zero evokes a non-binary quality. Defined in opposition to other numbers, 0 holds a mirror up to the construction of meaning in our society. It’s nominally empty yet endlessly rich and often misunderstood. Yes, zero is unmistakably queer.

Humans aren’t the only animals that can count. In fact, it’s a fairly common skill in nature. Desert ants count their steps, male tropical frogs count the number of mating calls made by their competitors, and lionesses consider the number of roars when deciding how to attack intruders.

However, fewer species are known to have a concept of 0. One of those animals that can process 0: crows. Scientists at the University of Tübingen in Germany trained carrion crows on the numbers 0-4 using food (mealworms or seeds, yum!) as a reward.

Brain recordings of the crows identified a specialized set of counting neurons in a region called the nidopallium caudolaterale.1 These neurons are most active in response to 0, decreasing in response to larger numbers. The frequency of neuronal activity is correlated to the number being considered, creating a number line effect.

The concept of zero is ancient and wholly originated outside of Europe. The first understandings of zero were as a placeholder in large numbers. By 30 BCE, at least 3 human cultures developed notations for it. The Chinese used a space or a circle, the Babylonians utilized a double wedge, and the Maya wrote a shell or flower symbol.

Notably, the Maya incorporated zero into spirituality (including a philosophy of death) and time. The Maya calendar begins new periods with numbered day 0, rather than day 1.2 In fact, the Maya time-zero (“nik”) references today, and the Q’anjob’al Mayan word for “today” (“nani”) translates to the English “center." This places today between past and present - just as 0 is centered between negative and positive numbers on a number line.

South Asian scientists extended zero even further. Around the 7th century, the idea of “śūnya” emerged, a Sanskrit expression of the English “empty.” This endows zero with two overlapping qualities: physicality and quantity. Śūnya connects the experience of zero with its quantitative potential. Śūnya also took on spiritual meanings in the Buddhist concept of śūnyatā.

At first, Christianity taught that zero is inherently sinful, so Europeans demonized it. However, 0’s utility in debt management was too tempting for 14th century Italian merchants. Market standing began relying on having a tally of credits and debits greater than zero. The accounting strategy spread, making the European 0 representative of financial well-being since its appropriation.

Today, humans learn about zero according to our local culture(s). Studies on American children suggest that their understandings of 0 emerge around age 4. By adulthood, we appreciate the multiple concepts associated with 0. In two recent studies, neuroscientists use neural recordings to gain insights into how the human brain represents zero.

First, researchers at University College London used a technique called magnetoencephalography (MEG) to measure neural activity over large brain regions while performing basic number tasks. These recordings revealed the brain’s “mental number line” with one region responding to 0, another to 1, another to 2, etc. In short, 0 is just another number to our brains.

A second, German group confirmed this conclusion with a different approach. The team measured brain activity with implanted electrodes, allowing single neuron measurements (compared to MEG’s bulk readout) in response to numbered stimuli. These data not only identified a mental number line but also contained a surprise: 40% of surveyed neurons responded to 0 - more than any other digit.

You may have asked this question before. If the Big Bang was the origin of our universe, then what could have possibly come before it? (Definitely not Young Sheldon.) Years of astrophysical experimentation has yielded critical insights as chronicled by Italian physicist Guido Tonelli in Genesis: The Story of How Everything Began.

Before the Big Bang created matter as we know it, a void existed. Despite its name, this void was not empty. Instead, it was packed with tiny particles moving around in a chaotic manner. Why, then, is it called the “void”?

All energies in the void were balanced: for every positive bit of energy, there is negative energy. Therefore, the net energy of the void was 0. Yet, the dynamicity of the not-so-empty void means the zero-balance was constantly in flux. As Tonelli writes:

Eventually, one slight fluctuations permanently upset the zero-balance, causing a massive expansion of the energy and particles. We call this moment the Big Bang, the origin of our universe.