Reality Is Not What It Seems: The Journey to Quantum Gravity

by Carlo Rovelli

One night in 2012, during a long solitary drive from Italy to France, I realized that the only way to explain in a comprehensible manner the ongoing modifications of the notions of space and time was to tell the story from the beginning: starting from Democritus, all the way through to the quanta of space. After all, this is how I understand the story. I began to design the entire book in my mind while driving, and got increasingly excited, until I heard a police car’s siren telling me to pull over: I was driving far above the speed limit. The Italian policeman asked me politely if I was crazy to drive at that speed. I explained that I had just found the idea I’d been seeking for so long; the policeman let me go without a ticket, and wished me good luck with the book. This is that book.

The only possibility, Democritus concludes, is that any piece of matter is made up of a finite number of discrete pieces that are indivisible, each one having finite size: the atoms.

The father of Albert Einstein built power stations in Italy.

Tell me you're not a native English speaker!

It may appear strange and difficult to think of discrete elementary entities not in space and time, but weaving space and time with their relations. But how strange it must have seemed to listen to Anaximander, when he claimed that beneath our feet there was only the same sky that we can see above our heads? Or to Aristarchus, when he tried to measure the distance of the moon and the sun, discovering that they are extremely distant, and are therefore not the size of little balls, but gigantic—and the sun is immense compared to Earth. Or to Hubble, when he realized that the small diaphanous clouds between stars are vast seas of immensely distant stars. For centuries the world has continued to change and expand around us. We see further, understand it better, and are astonished by its variety, by the limitations of the images we had of it. The description we manage to produce to account for it becomes increasingly rarefied, yet simple. We are akin to small blind moles underground who know little or nothing about the world. But we continue to learn. . .

Many theoretical physicists are today looking for new theories by picking arbitrary hypotheses: “Let us imagine that . . .” I don’t think that this way of doing science has ever produced good results. Our fantasy is too limited to “imagine” how the world may be made,

The only truly infinite thing is our ignorance.

Yeah, that doesn't work. If there is only a finite amount to be known, it is not possible for ignorance to be infinite. This love of a bon mot at the expense of truth and clarity is a bad thing.

This acute awareness of our ignorance is the heart of scientific thinking.

Science is sometimes criticized for pretending to explain everything, for thinking that it has an answer to every question. It’s a curious accusation. As every researcher working in every laboratory throughout the world knows, doing science means coming up hard against the limits of your ignorance on a daily basis—the

This is true.