Gaurav Sagar’s Reviews > Reality is Not What it Seems: The Journey to Quantum Gravity > Status Update

Remember that a key result of quantum mechanics is precisely the fact that information is finite. The number of alternative results that we can obtain measuring a physical system is infinite in classical mechanics; but, thanks to quantum theory, we have understood that, in reality, it is finite. Quantum
mechanics can be understood as the discovery that information in nature is
always finite.

If we see the galaxies moving away and the universe expanding, it means that the galaxies were previously much closer and the universe was smaller: and something caused it to start expanding. The young Belgian priest suggests that the universe was originally extremely small and compressed, and started its expansion in a gigantic explosion. He calls this initial state the primordial atom. Big Bang.

There is a paradox at the heart of our understanding of the physical world. General relativity and quantum mechanics, the two jewels that the twentieth century has left us, have been prolific in gifts – for comprehending the world and for today’s technology. From the first of these, cosmology has developed, as well as astrophysics, the study of gravitational waves and of black holes.

The world is a sequence of granular quantum events. These are discrete, granular and individual; they are individual interactions of one physical system with another. An electron, a quantum of a field or a photon does not follow a trajectory in space but appears in a given place and at a given time when colliding with something else.

If in the previous chapter I appeared to be saying that Plato and Aristotle have only done harm to the development of science, I would like to correct this impression. Aristotle’s studies of nature – of botany and zoology, for example – are extraordinary scientific works, grounded upon meticulous observations of the natural world.