The Coming of the Quantum Cats

They had crossed over the wet green fields of Ireland and were two hundred miles out over the Atlantic before they finished checking the tickets. It wasn't the most fun job in the world. The passengers were itchy and irritable. They knew something was wrong. There had been the unexplained wait before they left the gate at Heathrow, the whispered conferences among the cabin crew, the unusual request for everyone to show tickets again after they were airborne. It had to be done, though. 640 boarding passes had been issued. 640 tickets had been picked up at the gate. Only 639 passengers were on the plane. Somebody, somehow, had entered the mobile gate at one end and never come out at the other. When every seat in both levels and all six compartments had been cross-checked against the printout, including all eighteen lavatories and nine baggage spaces, they still had no answer, but at least they had a name. "Well," said the purser glumly, "at least we know we didn't count wrong. But what do you suppose they're going to tell the family of this Dr. John Gribbin?"