Three Roads to Quantum Gravity by Lee Smolin Page B

than the traditional picture of an eternal atom.
    We are very used to imagining that we see a three-dimensional world when we look around ourselves. But is this really true? If we keep in mind that what we see is the result of photons impinging on our eyes, it is possible to imagine our view of the world in a quite different way. Look around and imagine that you see each object as a consequence of photons having just travelled from it to you. Each object you see is the result of a process by which information travelled to you in the shape of a collection of photons. The farther away the object is, the longer it took the photons to travel to you. So when you look around you do not see space - instead, you are looking back through the history of the universe. What you are seeing is a slice through the history of the world. Everything you see is a bit of information brought to you by a process which is a small part of that history.
    The whole history of the world is then nothing but the story of huge numbers of these processes, whose relationships are continually evolving. We cannot understand the world we see around us as something static. We must see it as something created, and under continual recreation, by an enormous number of processes acting together. The world we see around us is the collective result of all those processes. I hope this doesn’t seem too mystical. If I have written this book well then, by the end of it, you may see that the analogy between the history of the universe and the flow of information in a computer is the most rational, scientific analogy I could make. What is mystical is the picture of the world as existing in an eternal three-dimensional space, extending in all directions as far as the mind can imagine. The idea of space going on and on for ever has nothing to do with what we see. When we look out, we are looking back in time through the history of the universe, and after not too long we come to
the big bang. Before that there may be nothing to see - or, at the very least, if there is something it will most likely look nothing like a world suspended in a static three-dimensional space. When we imagine we are seeing into an infinite three-dimensional space, we are falling for a fallacy in which we substitute what we actually see for an intellectual construct. This is not only a mystical vision, it is wrong.

II
    WHAT WE HAVE LEARNED

CHAPTER 5
    BLACK HOLES AND HIDDEN REGIONS
    I n the cultural iconography of our time, black holes have become mythic objects. In science fiction novels and films they often evoke images of death and transcendence, recalling the irreversibility of certain passages and the promise of our eventual emergence into a new universe. I am not a very good actor, but I was once asked by a friend, the director Madeline Schwartzman, to act in one of her films. Luckily I got to play a physics professor giving a lecture on black holes. In the film, called Soma Sema, the myth of Orpheus is merged with two major scientific and technological themes of our time: total nuclear war and black holes. Orpheus, my student, seeks through her music to be an exception to all three versions of the irreversible.
    Among those of us who think about space and time professionally, black holes play a central role. A whole subculture of astronomers is devoted to understanding how they form and how to find them. By now, dozens of candidate black holes have been observed. But what is most exciting is that there are probably vast numbers of them out there. Many if not most galaxies, including our own, seem to have an enormous black hole at their centre, with a mass millions of times that of our Sun. And there is evidence, both observational and theoretical, that a small fraction of stars end their lives as black holes. A typical galaxy such as ours could well contain tens or even hundreds of millions of these stellar black holes. So black holes are out there, and interstellar
travellers of the far