up in a short while and the labs will reopen. The colleges are quite optimistic that—”
“If wishes were horses, beggars would ride,” he said sourly. Then, glancing at her, he seemed to shake himself free of the mood. “Or, if horses were vicious, rides would go begging.” He smiled. “I love transmuted clichés, don’t you?”
It was this sort of sudden, darting way of thinking Marjorie had come to associate with a species of scientist, the theoretical types. They were hard to understand, granted, but more interesting than the experimenters, like her John. She smiled back at him. “Surely your year here at Cambridge has taken you away from budget worries?”
“Um. Yes, I suppose it’s better to live here in somebody else’s past, rather than your own. It’s a lovely place to forget the world outside. I’ve been enjoying the leisure of the theory class.”
“In your ivory tower? This is a town of dreaming spires, as I think the poem goes.”
“Oxford’s the town of dreaming spires,” he corrected her. “Cambridge is more like perspiring dreams.”
“Scientific ambition?”
He grimaced. “The rule of thumb is that you don’t do much first-class work past forty. That’s mostly wrong, of course. There are lots of great discoveries made late in life. But on the average, yes, you feel the ability slipping away from you. It’s like composers, I guess. Flashes out of nowhere when you’re young, and … and more a sense of consolidation, layering things on, when you’re older.”
“This time communication thing you and John are onto certainly seems exciting. A lot of a dash there.”
Greg brightened. “Yes, it’s a real chance again. Here’s a hot topic and nobody’s around to dig in except me. If they hadn’t closed most of the Department of Applied Mathematics and Theoretical Physics, there’d be a squad of bright young guys swarming over it.”
Marjorie stepped further away from the rest of the party, towards the moist masses of green that regimented their garden. “I’ve been meaning to ask someone who knows,” she began with a touch of uncertainty, “just what this tachyon thing of John’s is. I mean, he explains it, but not much gets through my arts education, I’m afraid.”
Greg clasped his hands behind him in a studied way, staring up into the sky. Marjorie noted yet another sudden shift in him; his expression became remote, as though he were peering at some persistent interior riddle. He gazed up, as if unmindful of the awkwardly stretching silence between them. Above, she saw, an airplane scratched an arc, green tail light winking, and she had a curious, uneasy feeling. Its vapor trail spread, cold silver on a sky of slate.
“I think the hardest thing to see,” Greg said, starting as though he were composing an article in his head, “is why particles traveling faster than light should mean anything about time.”
“Yes, that’s it. John always jumps over that, into a lot of stuff about receivers and focusing.”
“The myopia of a man who has to actually make the damned thing work. Understandable. Well look, you remember what Einstein showed a century ago—that light was a kind of speed limit?”
“Yes.”
“Well, the mindless, popular description of relativity is—” here he arched his eyebrows, as if to put visible, disdaining quotation marks about the next phrase “—that ‘everything is relative.’ Meaningless statement, of course. A better shorthand is that there are no privileged observers in the universe.”
“Not even physicists are privileged?”
Greg smiled at the jibe. “Especially physicists, since we know what’s going on. Point is, Einstein showed that two people moving with respect to each other can’t agree on whether two events happen at the same time. That’s because light takes a finite time to travel from the events to the two people, and that time is different for each person. I can show you that with some simple mathematics—”
“Oh, don’t, truly.” She laughed.
“Agreed. This is a party, after all. Thing is, your husband has gone after some big fish here. His tachyon experiment takes Einstein’s ideas a step further, in a way. The discovery of particles traveling faster than light means those two moving observers won’t agree about which event came first, either. That is, the sense of time gets scrambled.”
“But surely that’s merely a difficulty of communication. A problem with the tachyon beams and so on.”
“No, dead wrong. It’s fundamental. See, the ‘light barrier,’ as it was called, kept us in a universe which had a disordered sense of what’s simultaneous. But at least we could tell which way time flowed!