CHAPTER 1
Enter the quantum
Until the 20th century it was assumed that matter was much the same on whatever scale you looked at it. When back in Ancient Greek times a group of philosophers imagined what would happen if you cut something up into smaller and smaller pieces until you reached a piece that was uncuttable (atomos), they envisaged that atoms would be just smaller versions of what we observe. A cheese atom, for instance, would be no different, except in scale, to a block of cheese. But quantum theory turned our view on its head. As we explore the world of the very small, such as photons of light, electrons and our modern understanding of atoms, they behave like nothing we can directly experience with our senses.
A paradigm shift
Realising the very different reality at the quantum level was what historians of science like to give the pompous term a ‘paradigm shift’. Suddenly, the way that scientists looked at the world became different. Before the quantum revolution it was assumed that atoms (if they existed at all – many scientists didn’t really believe in them before the 20th century) were just like tiny little balls of the stuff they made up. Quantum physics showed that they behaved so weirdly that an atom of, say, carbon has to be treated as if it is something totally different to a piece of graphite or diamond – and yet all that is inside that lump of graphite or diamond is a collection of these carbon atoms. The behaviour of quantum particles is strange indeed, but that does not mean that it is unapproachable without a doctorate in physics. I quite happily teach the basics of quantum theory to ten-year-olds. Not the maths, but you don’t need mathematics to appreciate what’s going on. You just need the ability to suspend your disbelief. Because quantum particles refuse to behave the way you’d expect.
As the great 20th-century quantum physicist Richard Feynman (we’ll meet him again in detail before long) said in a public lecture: ‘[Y]ou think I’m going to explain it to you so you can understand it? No, you’re not going to be able to understand it. Why, then, am I going to bother you with all this? Why are you going to sit here all this time, when you won’t be able to understand what I am going to say? It is my task to persuade