Not All at Once

A microwave field in a small circuit was held as both: empty, and lit. One qubit beside it took a note of which. The fringes, the light-and-dark proof it was both, went out.

At thirty-eight billionths of a second the qubit swung round on its own and lost the note, and the fringes came back as if nobody had looked.

They added witnesses, up to eight, each swinging at its own rate. To forget, all eight would have to come round at the same moment. They didn't. The record held for as long as anyone measured, which the paper is careful to say is not the same as forever.

So that's what the eight are for, the Saturday ones on the town hall steps in coats too thin for October, each going by a different watch. Not that any one of them will remember it right. Eight can't all forget at once.