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

by Carlo Rovelli

It is like when it hails: what determines whether your car will be dented is not the total quantity of hail that falls but the size of the individual hailstones. There could be an enormous amount of hail, but it will do no damage if all the stones are small. In the same way, even if light is intense, which amounts to saying that there is a great deal of light packets, the electrons would not be extracted from their atoms if the individual grains of light are too small, that is, if the frequency of light is too low. This explains why it is the color and not the intensity that determines whether the photoelectric effect occurs or not.

The world is not made up of tiny pebbles. It is a world of vibrations, a continuous fluctuation, a microscopic swarming of fleeting microevents.

Maybe after all there is a grain of truth in the joke reported by Saint Augustine: What was God doing before creating the world? He was preparing Hell for those who seek to scrutinize deep mysteries.

As Dante’s Ulysses reminds his companions, we are not made “to live like brutes, but to seek virtue and knowledge.”