The World According to Physics

The trustworthiness of science comes not from certainty, but from its very openness about its uncertainty, always calling into question what we currently understand and being prepared to replace that knowledge with a deeper understanding if something better comes along. In other walks of life, this attitude might be regarded as fickle. But not in science. Scientific progress depends on scientists' unwavering commitment to the qualities of honesty and doubt.

By thinking about what we don't yet know, we can think about how we can best find out. It is the many questions we have asked over the course of our human history that have given us an ever-more-accurate picture of the world we know and love.

The true beauty of physics, for me, is found not only in abstract equations or in surprising experimental results, but in the deep underlying principles that govern the way the world is.

Some people turn to religion or some other ideology or belief system to find answers to life’s mysteries. But for me, there is no substitute for the careful hypothesising, testing, and deducing of facts about the world that are the hallmark of the scientific method. The understanding we have gained through science—and physics in particular—of how the world is made up and how it works is, in my view, not just one of many equally valid ways of reaching the ‘truth’ about reality. It is the only reliable way we have.

When it comes to the meaning of space and time the difficulty we have is not surprising, for we are ourselves imprisoned within them, and it is hard to free our minds from their confines and ‘see’ reality from the outside.

Let me first make two important assumptions, which I will discuss in more detail later on, but will now just say that they are both supported strongly by observational evidence: (1) that the laws of physics are the same everywhere in our universe, and (2) that space looks the same in all directions (the same density and distribution of galaxies).

When it comes to looking for new ideas in physics, there are, very broadly, two kinds of researchers. Imagine you’re walking home on a dark, moonless night when you realise that there’s a hole in your coat pocket through which your keys must have fallen at some point along your route. You know they have to be somewhere on the ground along the stretch of pavement you’ve just walked, so you retrace your steps. But do you only search the patches bathed in light beneath lampposts? After all, while these areas cover only a fraction of the pavement, at least you will see your keys if they are there. Or do you grope around in the dark stretches in between the pools of lamplight? Your keys may be more likely to be here, but