The End of Time: The Next Revolution in Physics

If, as I think they must be, things are properly considered in Platonia, Lucy never did leap to catch the swifts. The fact is, there never was one cat Lucy – there were (or rather are, since Lucy is in Platonia for eternity, as we all are) billions upon billions upon billions of Lucys. This is already true for the Lucys in one leap and descent. Microscopically, her 10²⁶ atoms were rearranged to such an extent that only the stability of her gross features enables us to call her one cat. What is more, compared with her haemoglobin molecules the features by which we identified her – the sharp eyes, the sleek coat, the wicked claws – were gross. Because we do not and cannot look closely at these Lucys, we think they are one. And all these Lucys are themselves embedded in the vast individual Nows of the universe. Uncountable Nows in Platonia contain something we should call Lucy, all in perfect Platonic stillness. It is because we abstract and ‘detach’ one Lucy from her Nows that we think a cat leapt. Cats don’t leap in Platonia. They just are.

You might argue that even if cats do not have a permanent identity, their atoms do. But this presupposes that atoms are like billiard balls with distinguishing marks and permanent identities. They aren’t. Two atoms of the same kind are indistinguishable. One cannot ‘put labels on them’ and recognize them individually later. Moreover, at the deeper, subatomic level the atoms themselves are in a perpetual state of flux. We think things persist in time because structures persist, and we mistake the structure for substance. But looking for enduring substance is like looking for time. It slips through your fingers. One cannot step into the same river twice.

Zeno of Elea, who belonged to the same philosophical school as Parmenides, formulated a famous paradox designed to show that motion is impossible. After an arrow shot at a target has got halfway there, it still has half the distance to go. When it has gone half that distance, it still has half of that way to go. This goes on for ever. The arrow can never reach the target, so motion is impossible. In normal physics, with a notion of time, Zeno’s paradox is readily resolved. However, in my timeless view the paradox is resurrected, but the arrow never reaches the target for a more basic reason: the arrow in the bow is not the arrow in the target.

There are two parts to my claim that time does not exist. I start from the philosophical conviction that the only true things are complete possible configurations of the universe, unchanging Nows. Unchanging things do not travel in time from Now to Now. Material things, we included, are simply parts of Nows. This philosophical standpoint must be matched by a physical theory that seems natural within it. The evidence that such a physical theory exists and seems to describe the universe forms the other part of my claim. This section has merely made the philosophy, the notion of being, clear. The physics, the guts of the story, is still to come.

THE BIG PICTURE

Before Newton was born, René Descartes raised a nightmarish prospect. How do I know, he asked, whether anything exists? Is some malignant demon conjuring up my thoughts and experiences? Perhaps there isn’t any world. How can we be sure of anything? Descartes famously argued that we can at least be certain of our own existence. Cogito ergo sum: I think, therefore I am. In fact, this did not get him very far, and his main argument for a real world was that God would not deceive us on such a fundamental matter.

Modern science has a better answer to the solipsists – those who, like Descartes in that extreme moment of doubt, deny existence outside their own thoughts. The starting point is that we do observe a great variety of phenomena. We can then ask whether we can postulate a world and laws that lead to the phenomena. If this is so, it does not explain how or why the world is there, but it does provide grounds for taking its existence more seriously.

You may think that time capsules and a brain preserved in aspic aware of seeing motion are getting dangerously close to solipsism and the machinations of a demon. Without anticipating the rest of the book, an outline may still be helpful. There are only two rules of the game: there must be an external world subject to laws and a correspondence between it and experiences.