Timescape

“You’re a plasma physicist, is that right, Dr. Markham?”

“Yes. I’m here on sabbatical leave. Most of my work has been in plasmas until the last few years. I wrote a paper on tachyon theory long ago, before they were discovered and became fashionable. I suppose that’s why the NSF asked me to be here.”

“Did you read the copy of the proposal that I sent you?” Peterson asked.

“Yes, I did. It’s good,” Markham said decisively. “The theory’s fine. I’ve been working on the ideas behind Renfrew’s experiment for some time now.”

“You think this experiment will work, then?”

“We know the technique works. Whether we can actually communicate with the past—that we don’t know.”

“And this set-up here—” Peterson swept an arm towards the laboratory bay “—can do that?”

“If we’re damned lucky. We know there were similar nuclear resonance experiments at the Cavendish and a few other places, in the States and the Soviet Union, functioning as far back as the 1950s. In principle they could pick up coherent signals induced by tachyons.”

“So we can send them telegrams?”

“Yes, but that’s all. It’s a highly restricted form of time travel. This is the only way anyone’s figured out how to send messages into the past. We can’t transmit objects or people.”

Peterson shook his head. “I did a degree involving social issues and computers. Even I—”

“Cambridge?” Markham broke in.

“Yes, King’s College.” Markham nodded to himself and Peterson hesitated. He disliked the American’s obvious placing of him in a category. He did the same thing himself, of course, but certainly with more genuine reason. Slightly irritated, he seized the initiative. “Look, even I know there’s a paradox involved here somewhere. The old thing about shooting your grandfather, isn’t it? But if he died, you wouldn’t exist yourself. Someone on the Council brought that up yesterday. We almost booted the whole idea out because of that.”

“A good point. I made the same error in a paper back in 1992. It turns out there are paradoxes and then, if you look at things the right way, paradoxes go away. I could explain, but it would take time.”

“Not now, if you don’t mind. The whole point, as I understand it, is to send these telegrams and tell somebody back in the 1960s or so about our situation here.”

“Well, something like that. Warn them against chlorinated hydrocarbons, sketch in the effects on phytoplankton. Getting a lead on certain kinds of research could give us the edge we need now to—”

“Tell me, do you think this experiment might be of any real help?”

Renfrew stirred impatiently but said nothing.

“Without being melodramatic,” Markham said slowly, “I believe it would save millions of lives. Eventually.”

There was a moment’s silence. Peterson recrossed his legs and picked an invisible piece of lint from his knee.

“It’s a question of priorities, you see,” he said at last. “We have to take the large view. The Emergency Council has been in session since nine this morning. There has been another full-scale dieback in North Africa due to drought and lack of food reserves. You’ll hear more about it in the news in due course, no doubt. Meanwhile, this and other emergencies have to take priority. North Africa’s not the only trouble spot. There’s a large diatom bloom off the South American coast, too. Thousands of people are dying in both places. You’re asking us to put money into an isolated experiment that may or may not work—one man’s theory, essentially—”

Markham interrupted swiftly: “It’s more than that. The tachyon theory is not new. There’s a group at Caltech right now—the gravitational theory group—working on another angle of the same problem. They’re trying to see how tachyons fit into the cosmological questions—you know, the expanding universe picture and all.”

Renfrew nodded again. “Yes, there was a paper in the Physical Review just recently, on huge density fluctuations.”

“They’re having their problems in Los Angeles, too,” Peterson said, considering. “Mainly the big fire, of course. If the wind changes, that could be disastrous. I don’t know what effect these things have on the Caltech people. We can’t afford to wait for years.”

Renfrew cleared his throat. “I thought funding of scientific experiments was to be given top priority.” He sounded slightly petulant.

Peterson’s answer held a hint of condescension. “Ah, you’re referring to the King’s speech on television the other day. Yes, well, of course, he wants to look good in his Coronation year. So he’s encouraging funding of scientific experiments—but of course, he knows nothing of science, he’s not even a politician. Very well meaning fellow, of course. Our committee advised him to stick to uplifting generalities in future. With a touch of humor. He’s good at that. Anyway, the basic fact is that money is short and we have to pick and choose carefully. All I can promise at this stage is that I will make a report to the Council I’ll let you know as soon as I can their decision about granting you emergency priority. Personally, I think it’s a bit of a long shot. I don’t know if we can afford to take chances.”

“We can’t afford not to,” Markham said with sudden energy. “Why keep on plugging the leaks here and there, sinking money into relief funds for drought and dieback? You can slap on patches but the dam’s going to burst. Unless—”

“Unless you tinker with the past? Are you sure tachyons can reach the past at all?”

Renfrew said, “We’ve done it. Tried some table-top experiments. They work. It’s in the report.”

“The tachyons are received, then?”

Renfrew nodded briskly. “We can use them to heat up a sample in the past, so we know they’ve been received.”

Peterson arched an eyebrow. “And if, after measuring this heat increase, you decided not to send the tachyons after all?”

Renfrew said, “That option’s not really available in these experiments. See, the tachyons have to travel a long way if they’re to go far back in time—”

“A moment, please,” Peterson murmured. “What has traveling faster than light have to do with time travel?”

Markham stepped toward a blackboard. “It comes straight out of special relativity, see—” and he launched into a description. Markham drew space-time diagrams and told Peterson how to understand them, stressing the choice of slanted coordinates. Peterson kept an intent expression through it all. Markham drew wavy lines to represent tachyons launched from one spot, and showed how, if they were reflected about in the laboratory, they could strike another portion of the lab at an earlier time.

Peterson nodded slowly. “So your point about the experiments you’ve done is that there’s no time to reconsider? You fire the tachyons. They heat up this indium sample of yours, a few nanoseconds or so before you triggered the tachyons in the first place.”

Renfrew agreed. “Point is, we don’t want to set up a contradiction, either. Say, if we connected the heat detector to the tachyon switch, so heat coming in would switch off the tachyons.”

“The grandfather paradox.”

“Right,” Markham broke in. “There are some subtle points involved with doing that. We think it leads to a sort of intermediate state, in which a little heat is generated and a few tachyons get launched. But I’m not sure.”

“I see…” Peterson struggled with the ideas, scowling. “I’d like to go into that some time later, once I’ve had a thorough reading of the technical material. Actually, I’m not depending on my own judgment alone in this—” he glanced around at the two intent men beside him “—as you’ve probably guessed. I got an assessment from Sir Martin at the Council, and from that fellow Davies you mentioned. They say it’s the straight stuff.”

Markham smiled; Renfrew beamed. Peterson held up a hand. “Hold on, though. I really stopped by here to get the scent of things, not to make the final decision. I’ve got to make my case to the Council itself. You want electronics flown in from the American labs, and that means wrangling with the NSF.”

“Are the Americans thinking along the same lines?” Renfrew asked.

“I don’t think so. The Council’s attitude is that we must pool our resources. I’m going to urge that you fellows get the backing and the Americans chip in.”