Notes

Was thinking about a conversation that I had had with Robert Elliot at the University of New England. I  mentioned to him something I had read a long time ago in The Science in Science Fiction by Peter Nicholls. It was the Principle of Causality, stating, essentially, that effects happen after causes. This was the basic problem with travelling backwards through time, that it would violate the principle of causality. Robert said he thought that that was just a prejudice. He saw a cause as an engine that created an effect, which could just as easily occur in the past as in the future. Well, I know that the Principle of Causality is a cornerstone of physics, and I don't really think that it is a prejudice. I think it would be a prejudice if physicists were trying to define  causes in terms of temporal position, but they are not. Their claim that effects happen after causes is a posteriori, not a priori. He went on to talk about what logically consistent time travel is. Basically, i