Incidentally, I have forgotten the most important thing of all. Remember that Donovan’s dominating idea was to prove to me, and to the world, that he had been in the Cretaceous and hobnobbed with its flora and fauna. He was a physicist by inclination, and had the physicist’s flair for ingenious proofs. Before leaving, he loaded a lead cube with three quartz quills of pure radium chloride that he had been using in a previous experiment, and locked the whole thing up in a steel box.

The discovery of negative entropy introduces quite new and revolutionary conceptions into our picture of the physical world.

It would bring our sponsors down upon us like so many angry hornets. The Unchanging would yank time travel out of human hands—retroactively.