Permutation City

by Greg Egan

Had the world shrunk to the size of his skull – and vanished from time altogether, except for the fifty computers which contributed at any one time to what he called ‘the present’? Maybe not – although in the eyes of some hypothetical space traveller the whole planet was virtually frozen in time, and flat as a pancake. Relativity declared that this point of view was perfectly valid – but Paul’s was not. Relativity permitted continuous deformation, but no cutting and pasting. Why not? Because it had to allow for cause and effect. Influences had to be localized, travelling from point to point at a finite velocity; chop up space-time and rearrange it, and the causal structure would fall apart. What if you were an observer, though, who had no causal structure? A self-aware pattern appearing by chance in the random twitches of a noise machine, your time coordinate dancing back and forth through causally respectable ‘real time’? Why should you be declared a second-class being, with no right to see the universe your way? Ultimately, what difference was there between so-called cause and effect, and any other internally consistent pattern?