"Time?"
"Yes. And time travel."
The younger man shrugged.
"Practically nothing," he admitted. "Oh, I've read a few stories, of course. But that's all. I don't know what the theory of it all is, if that's what you mean."
"I thought so." Professor Duchard sighed. "That being the case, there is little use in my wasting energy trying to give you any real understanding of it.
"However, I can tell you this: time is not the immutable thing most people presume it to be. Actually, it is only another dimension. As a research physicist, I have for many years been convinced of this."
"You mean that time travel really is possible? That men can be transported into the future or the past—"
The other held up a restraining hand.
"Yes. Time travel is possible, if men could break through into that other dimension." A pause. "Yet up until tonight, I never believed that man had found a way to pass that barrier."
"But professor! Think what you're saying! You're telling me that I could go back and murder my own grandfather. That I could prevent myself from being born—"