Possible is not explained
A passage from a novel, chosen for the method it shows. The data in the story are invented, so what travels is the move and not the result. What it does not establish is set out below.
"That's not possible," William said, which was not scientifically useful but was, Amaleto thought, an honest enough response to have.
"It's possible," she said. "It's just not explained. Those are different problems and we are going to treat them as different problems."