Suppose we were time travelers, and could transmit one key item of modern knowledge to a great intellect of the ancient world – Aristotle, for instance. What would we choose to tell them, a single sentence that would most transform their view of the world? We could tell them the scale of the universe – that the stars are other suns, and that there are billions of them. Or that all species emerged, over billions of years, via natural selection. But I think what would enlighten them most of all would be the knowledge that all the stuff in the world is made of atoms – not of earth, air, fire and water, as the ancients believed. But what are the atoms themselves made of? Are they like an onion-skin with layer upon layer of structure, or will we soon reach bedrock, in the sense that the stuff of the universe will be fully understood? It might seem paradoxical that the biggest scientific instruments of all are needed in order to probe the very smallest things in nature. The micro-world is inherently “fuzzy” – the sharper the detail we wish to study, the higher the energy that is required and […]