Seven Brief Lessons on Physics

by Carlo Rovelli

the gravitational field is not diffused through space; the gravitational field is that space itself. This is the idea of the general theory of relativity. Newton’s “space,” through which things move, and the “gravitational field” are one and the same thing.

each element corresponds to one solution of the main equation of quantum mechanics. The whole of chemistry emerges from a single equation.

Or does it mean, as it seems to me, that we must accept the idea that reality is only interaction?

Scientific thought is fed by the capacity to “see” things differently than they have previously been seen.

In every case in which heat exchange does not occur, or when the heat exchanged is negligible, we see that the future behaves exactly like the past.

The difference between past and future exists only when there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things that are hotter to things that are colder.

There is a detectable difference between the past and the future only when there is the flow of heat.

For a hypothetically supersensible being, there would be no “flowing” of time: the universe would be a single block of past, present, and future. But due to the limitations of our consciousness we perceive only a blurred vision of the world and live in time.

I believe that our species will not last long. It does not seem to be made of the stuff that has allowed the turtle, for example, to continue to exist more or less unchanged for hundreds of millions of years, for hundreds of times longer, that is, than we have even been in existence. We belong to a short-lived genus of species. All of our cousins are already extinct. What’s more, we do damage. The brutal climate and environmental changes that we have triggered are unlikely to spare us. For Earth they may turn out to be a small irrelevant blip, but I do not think that we will outlast them unscathed—especially