The End of Time: The Next Revolution in Physics

This is magnificent poetry as a description of the mystical state in which mind comprehends all structure as unified. But the real wonder of unity is when it knits together rich variety. Bliss is comprehension of many things in harmony at once. I do not think that eternity is pure and endless light. Such light merely illuminates, for example, the millions of leaves of the forest of the American fall when we see them all at once.

Is Time Travel Possible?

Time travel of a sort is possible within general relativity as a classical theory, but is subject to strict limitations. You cannot travel back into the past and kill your parents before your conception. In quantum cosmology, you can travel back to a parallel universe, and there kill your parents before they conceive you. However, we have to be careful about the use of ‘you’. The person who ‘travels’ to these other worlds is not exactly you now. As the discussion of the haemoglobin molecule showed, the change within our bodies from one instant to another is stupendous. The fact that we have such an enduring sense of deep continuity of our personal identity is very remarkable. I see it as another manifestation of the creative power that brings everything into existence. Stephen Hawking long suspected that even if time travel is logically possible, it will have a very low probability in quantum cosmology. That is my feeling too. Platonia certainly contains Nows in which there are beings whose memories tell them they have travelled backwards in time. However, I think such Nows have a very low probability.

To tell the truth, I find the idea of time travel boring compared with the reality of our normal existence. Each time capsule that represents an experienced Now reflects innumerable other Nows all over Platonia, some of them vividly. In a very real sense, our memories make us present in what we call the past, and our anticipations give us a foretaste of what we call the future. Why do we need time machines if our very existence is a kind of being present everywhere in what can be? This is very Leibnizian. We are all part of one another, and we are each just the totality of things seen from our own viewpoint.

Doesn’t the Denial of Motion Take All Joy and Verve out of Life?

I do feel this issue keenly. The kingfisher parable should make that clear. In principle, there is no reason why we should not attempt to put our very direct sense of change directly into the foundations of physics. There is a long tradition, going back at least to Hamilton, that seeks to make process the most basic thing in the world. Roughly, the idea is that physics should be built up using verbs, not nouns. In 1929 the English philosopher Alfred North Whitehead published an unreadable – in my experience – book called Process and Reality in which he advocated process. It all sounds very exciting, but I just do not think it can be done, despite a valiant attempt by Abner Shimony. Having translated seventy million words of Russian into English, I can say with some feeling that sentences do have a subject and generally an object. I could have written this book using the one verb ‘to be’, which hardly counts as a verb. For this reason it seldom appears in Russian; when it does, it is most often as a surrogate: ‘to appear’. But a book without nouns is nothing. Not even James Joyce could write it. For some reason, disembodied verbs exert a fascination not unlike the grin of the Cheshire cat. But when Owen Glendower claimed to be able to ‘call up spirits from the vasty deep’, Hotspur answered: ‘Aye, and so can I and any man, but will they come when you call them?’ I should like to see it done.