John Leslie

John Leslie is professor emeritus of philosophy at the University of Guelph, and a fellow of the Royal Society of Canada. The End of the World: The Science and Ethics of Human Extinction is published by Routledge.

Fine-Tuned for Life: Cosmology

John Leslie, 1 January 1998

Our expanding universe has existed for roughly ten billion years. Even to get from Earth’s formation to our century took as long, Martin Rees remarks, as journeying half across America at the rate of one step per two thousand years. Our sun will shine steadily for five billion more years before swelling and vaporising our planet. The universe, however, will probably last for at least another hundred billion. It is widely expected to collapse eventually, but might first dilate by a factor of one followed by a million zeroes. Its expansion is possible even if it has always been infinitely large. Infinitely many galaxies, scattered across infinite space, could keep getting further apart. Infinity being a large number, some of the galaxies could well contain exact duplicates of you and me, Rees points out. With sufficiently many typing monkeys, even Hamlet would get typed many times.

Doom Sooner or Later

John Leslie, 5 June 1997

Freeman Dyson warns us in Imagined Worlds that he is now ‘an old scientist pretending to be a sage’ and that ‘we learn from science and from history that the future is unpredictable.’ As well as diagnosing our present ills, however, Dyson offers strong hopes that our descendants will colonise not just their own galaxy in its entirety, but others too. They could continue onwards for infinitely many years. Humans would have first to survive the difficulties of the next few centuries. On the grounds, however, that he has ‘nothing fresh to say’, Dyson resolves to pass over in silence ‘fashionable environmental problems such as global warming and overpopulation’ – although he does later indicate that his hopes are pinned on local, not global solutions. ‘People who try to impose global solutions should remember,’ he writes, ‘the words of the poet William Blake, “One Law for the Lion and Ox is Tyranny”.’’

Reacting to my account of the Hawking-Penrose debate, L.C. Laming (Letters, 19 September) asks how on earth there could be ‘regions so distant that no light from them could yet have reached us’. Surely, he suggests, light must have been able to ‘traverse totally the much smaller universe of the remote past’. The solution to Laming’s puzzle is that the cosmic expansion constantly added to...

Big Bang to Big Crunch

John Leslie, 1 August 1996

The Nature of Space and Time contains six lectures-three by Stephen Hawking, three by Roger Penrose – and a closing Hawking-Penrose debate. As Penrose indicates, it might be viewed as continuing the famous Bohr-Einstein exchange of some seventy years ago. Against the background of new cosmological theories, Hawking defends Bohr’s thesis that quantum theory has no radical incompleteness. Those who think it incomplete are wrongly treating its formulas as describing reality, rather than as predictive tools. Like Einstein, Penrose disagrees. Things then get somewhat tense. Hawking uses terms like ‘magic’ in dismissing theories which Penrose brought to the general public in The Emperor’s New Mind. Penrose throws some courteous cold water on the universe-creating mechanism made famous by Hawking’s A Brief History of Time.’

Anyone for Eternity?

John Leslie, 23 March 1995

To Frank Tipler, theology must either be nonsense or else become a branch of physical cosmology. Much to his astonishment, he tells us, strong signs of God and the hereafter can be seen in cosmology’s equations. Squeezed together by gravity, in some distant year the universe will be crushed down to a single point. In a crucial sense, all the same, intelligent life will have lasted for ever. And the ‘Omega Point’ to which everything is crushed will be a transcendent, divine culmination of information processing that has become infinite. It will unify an infinite collection of infinitely complex, loving minds, among which will be the infinitely improved minds of you and me.

John Leslie comes to tell us that the end of the world is closer than we think. His book is no ordinary millennial manifesto, however. Leslie is a sophisticated philosopher of science, and the...

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