"The war's over."

"For now. Wars have a way of coming back." Rasmussen cursed himself, not having intended to give the conversation such a depressing turn. "I mean, imagine if they invented time travel first. They could come back and change the outcome of the war."

"I can't see the Vulcan Science Council sharing their results with the Romulans, can you?"

"No, I can't, really." He turned to see a man he'd noticed once or twice over the past couple of months come into the bar. It was the small, middle-aged guy who looked like a professor. The university was a hotbed of AI and cybernetics development.

The man saw him, and came over. "h.e.l.lo there. It's B.R., isn't it? I remember you from yesterday."

"Yesterday? It was more like eight weeks ago I last saw you."

"Was it?" He glanced at his watch. "Oh, terribly sorry. I thought I saw you yesterday, but I may have got just a tiny bit distracted. Must have been someone else."

"I wasn't out of the house yesterday, I'm afraid."

"Ah, inventing! Anything good?"

Rasmussen was simultaneously pleased and suspicious at the attention, and he strove to find the right expression. "Well, it's got potential. Like everything."

"Glad to hear it."

"So, what have you been working on, er, Prof? Doc?" He offered a palm.

"Professor. Dominic Kent." He shook Rasmussen's hand. "I'm in the history department, over at the university library."

"I see. I work on the future, you work on the past." It was as Rasmussen had thought. The guy practically had "dusty history professor" tattooed on his forehead.

"Exactly, yes. And I also love to work on the buffet in here, if you catch my meaning. There's nothing quite like it," he added to Jo.

"Best in Trenton," she agreed. "And, by the way, guys, it's open."

"Excellent," Kent crowed. Rasmussen couldn't disagree. They almost raced each other to the buffet.

Rasmussen saw Professor Kent twice more that week, exchanging a few pleasantries with the guy both times, but it was the third time that stuck in his mind. There was no chit-chat this time, because, Rasmussen was sure, the prof hadn't seen him.

Rasmussen had gone over to the university to consult some books in the library, and, when he came out a couple of hours later, he had noticed a familiar figure struggling to free his rental groundcar from a steel clamp around the wheel. Rasmussen laughed to himself as he thought of the staid professor illegally parking.

His laughter stopped, as Kent glanced both ways down the road, then knelt beside the wheel and drew a stubby metallic cylinder from his pocket. It was a laser-cutter, but when Kent drew it across the wheel, only the metal structure of the clamp fell off. The rubber of the tire not only didn't puncture, but seemed totally unaffected by the cutting beam.

Rasmussen recognized the concept immediately. He had, after all, been working on it for months. And here was this stuffy professor with a working model. Could he be an inventor too, and the story about being a historian just some bull to put Rasmussen off the scent while he stole the invention? Or had someone else already invented and even sold them?

A few hours on the comnet was enough to convince him that the prof didn't buy his cutter. That only left the possibility of his having invented it, or copied the concept from Rasmussen.

Rasmussen hadn't really intended to start following the professor around then, but somehow he just fell into it. It seemed the most logical way to make sure the guy wasn't following him. him.

It was kind of fun following Kent, and Rasmussen began to see what attracted people to being cops or private eyes. The novelty would wear off, he knew, but it was fun while it lasted. Every night for a week, the prof turned into the parking lot of a U-shaped beige-colored building, with fake red tiles on the roof, and a veranda around the inside of the U. A holographic sign projected from the ceiling proclaimed it to be the Cheep'N'Cheerful Motel. Cheep'N'Cheerful Motel. It wasn't exactly top cla.s.s, but it wasn't a flea trap either. It was middle of the road, clean without being flashy, cheap without being seedy or dangerous. It was, Rasmussen thought, anonymous and safe. Exactly the sort of place you'd go if you didn't want anybody to take any notice of you. It wasn't exactly top cla.s.s, but it wasn't a flea trap either. It was middle of the road, clean without being flashy, cheap without being seedy or dangerous. It was, Rasmussen thought, anonymous and safe. Exactly the sort of place you'd go if you didn't want anybody to take any notice of you.

One morning, Rasmussen got there early, to watch Professor Kent leave. The cutter prototype that he had brought along made short work of the door lock, its handle and a part of the door. The room was neat, tidy, and boring. It took Rasmussen about fifteen seconds to decide that there was nothing of the remotest interest in it. Then he went to check the garage that was beneath the room. The cutter removed the lock and part of the door again. He expected to find a workbench and tools. He didn't expect to find a car, because the prof had just driven away in his rental.

There was, bizarrely, a shuttlepod. For a moment Rasmussen thought he was hallucinating, but the jagged-edged silver craft remained resolutely solid.

He touched it, felt metal, and that was rea.s.suring. He couldn't find a control to open the door, nor could he see in through the darkened windshield. He didn't expect the cutter to have a problem getting him in.

It didn't even warm the surface.

"So, when are you from?" Rasmussen asked the instant Professor Kent pushed his door open. The prof was still reeling from the sight of the hole in the door, and Rasmussen went straight for the kill while he was off-balance.

"What?"

"It's a simple enough question, I'd have thought. When do you come from?"

"You mean where where do I come from. That'd be Cambridge." do I come from. That'd be Cambridge."

"I meant when when exactly are you from?" Rasmussen laughed companionably at Kent's attempt to look puzzled. "Oh, come on, you don't have to be coy with me. I'm a scientist, an inventor . . . I have had the occasional thought about the possibilities of time travel." exactly are you from?" Rasmussen laughed companionably at Kent's attempt to look puzzled. "Oh, come on, you don't have to be coy with me. I'm a scientist, an inventor . . . I have had the occasional thought about the possibilities of time travel."

"There's still a market for science fiction in the entertainment industry. You could make a fortune-"

"Professor, please. I've watched you over the past few weeks. I followed you after I saw you cut that wheel clamp. I've seen your . . . whatever that thing in the garage is, that's made of some substance I've never seen before."

"You had no right to do something like that! What are you, some kind of stalker?"

"Actually," Rasmussen said, "that's what I just thought you were. I thought you'd followed me, stolen my cutter invention, and made it work. So I wanted to steal it back. But then I figured out the truth. Besides, I have as much right as you to walk into a motel. All right, I maybe have less right than you to walk into this particular little room that you've rented, but I'm glad I did."

"You admit to breaking and entering? I should call security-"

Rasmussen gave a magnanimous wave. "Go right ahead, don't mind me."

"What?"

"Go on, if you want to. See, I don't think you can, really, because they'd ask you for identification, and while you've presumably got sufficiently legit ID to rent the room and the garage, I'm guessing you don't have ID that would stand up to a really thorough background check."

"You're drunk. And offensive, I might add." Kent tried to usher Rasmussen out, but the taller man didn't budge.

"I don't think it's offensive to hold the belief that a man who hasn't been born yet won't be able to produce a valid birth certificate. So, when are you from?"

"I'm . . . an alien." Rasmussen shook his head at that.

"No, you're human. You left a newspaper from next week on the chair too."

Kent slumped, and flopped into a chair. "All right, you win. Yes, I'm from the future. Fine. Isn't that enough? Does it matter exactly when?"

"Let's have a drink at The Hidden Panda, The Hidden Panda, and maybe some lunch, and talk about that." and maybe some lunch, and talk about that."

"Er . . . All right. Let me just change my coat." The professor hurried out, and Rasmussen followed him lazily. Kent was standing in the garage when Rasmussen caught up with him. The empty garage.

"What have you done with my-with my property?!"

"Anyone can hire a truck."

"Not anyone did this. You You did." did."

"Well, I can't have you zipping off back to whenever you come from without first having that chat."

Drinks calmed things down. For once, Rasmussen wasn't paying much attention to Jo.

"What if you brought a lot of technology back? You could become rich! Invent all those-"

He broke off as Kent shook his head vehemently.

"Can't do that. You'd be risking a violation of the conservation of reality."

"The conservation of what?!"

"Reality." The prof took a drink and sniffed. "Look, it's like this. Some people think that there might be an infinite number of parallel universes, and that every action, however small, is just one of however many possibilities, and there's a universe for all of them."

"Okay, so far so good. What's wrong with that?"

"Well. Look at this drink. Bourbon, a decent brand. What if it was a different brand of bourbon? Is there a separate reality, a separate fourteen-billion-year existence of a universe for each brand of bourbon in that gla.s.s at this moment?"

Rasmussen felt his head start to spin. He didn't think he'd had that much to drink yet. "That would seem rather excessive, but that's the natural-and may I say wonderfully so-world."

"Exactly!" He nodded and took a sip. "Except it's probably a load of b.o.l.l.o.c.ks."

"It is?"

"The theory of the conservation of reality goes like this: Time and s.p.a.ce as we know it both came into existence in the first couple of seconds of the Big Bang, right?"

"That's what I was taught," Rasmussen agreed.

"They're both pretty elastic. If a new planet forms out of a nebula, the universe can accommodate it, it's not a problem. With me so far?"

"So far." Just, Rasmussen thought.

"Right, so, if I come back and, say, drink this bourbon, thus causing the alcoholic who would have drunk it otherwise to not do so, and have a hangover, and not make it to work . . . Time can absorb that too."

"Okay . . ."

"But, if I come back with, say, a Klingon battle fleet of four hundred years hence and make sure the Federation never existed . . ."

"Time can't absorb that?"

"No. It'd have to cough it up and spit it out. A new timeline." Kent emphasized the words with a jabbing finger.

Rasmussen followed that fine. "Right. But, from the way you're talking, I'm presuming there's some kind of limit below which that doesn't happen?"

"Exactly!" Kent seemed delighted at Rasmussen's understanding.

"And what sort of limit is it?"

Kent shrugged. "b.u.g.g.e.red if I know. It's not an exact science, really. Oh, there are those who've made up little names for discrete units of unreality or paradox, but they're all just guessing like the rest of us. Smaller is safer though."

"That's a relief."

"Don't be too sure. Smaller is safer now, but may not always be, or have been. Depends on whether there's anything to the homeostatic factor of the universe."

"The what?" Rasmussen had never heard of that.

"There appears-in my time anyway-to be some truth to the homeostatic universe theory, which says that anything might exist or not exist according to whether the universe needs it to maintain its own best-balanced existence."

"You're drunk."

"No, no, no . . . So for example, magic and dragons. If the universe needs magic and dragons to exist, then they exist. If it needs them not to exist, then they don't. If it needs them to have never existed-even if it and they previously did-then they never existed. Even if it and they, et cetera, et cetera . . . You're right, I'm a little bit rat-a.r.s.ed, aren't I?"

"Just a tiny bit. Not so much that anybody else will have noticed."

"I need . . . medicine."

Two weeks after their conversation in The Hidden Panda, The Hidden Panda, Rasmussen was still pressuring Professor Kent to share his knowledge of the future in an equal partnership, and making sure he didn't find his time pod. He had hoped that encouraging the prof to talk about the laws of causality and conservation of reality would loosen his tongue enough to let slip about other historical events and technological developments. Rasmussen was still pressuring Professor Kent to share his knowledge of the future in an equal partnership, and making sure he didn't find his time pod. He had hoped that encouraging the prof to talk about the laws of causality and conservation of reality would loosen his tongue enough to let slip about other historical events and technological developments.

If he could reverse-engineer something so advanced as to be magical, he could make his fortune. Sadly, Kent was still taking the conversations away from those issues, and getting more out of Rasmussen about the recent Romulan War than Rasmussen was getting out of him.

He had at least inadvertently provided Rasmussen with some reading material. There had been a data slate-a current commercial model-in his pocket, but it was filled with files and reports about people with names like Picard, Seven, and Gowron. It was fascinating stuff, and he could have filled whole shelves in a library with these reports of starships and s.p.a.ce stations in distant areas of the galaxy that no one had ever heard of.

Now Kent was, as far as Rasmussen was concerned, playing the sick card.

At least the prof was saving money, as Rasmussen had let him move in to the spare room. He lived alone, since his wife had left him five years ago.

"I'll get you some medicine. There's a pharmacy two blocks away, and there's the university hospital if there's a more specialized problem."

"No, no hospital." Kent laughed uncomfortably. "Identification might be a problem, and as soon as they take a blood sample . . . They might see some things they really oughtn't to see."

"The pharmacy, then."

"They won't have the medicine I need. The condition won't be discovered for another three hundred years, because it will be almost that long before the random mutations occur that allow the condition to arise. There is no medication for it in this century. I need the medicine from the pod."

"Oh no, no. That's just a little convenient, isn't it?" Rasmussen said. "No, I don't buy that one, Prof!"

"Look, you b.l.o.o.d.y t.w.a.t, I have to-"

"No." And that, Rasmussen thought, was the end of it.

At least Kent wasn't snoring or wheezing the next morning, which was a nice change.

"Come on, Professor, it's a bright new day in beautiful downtown Trenton!" Kent didn't stir. "I've got sausages and tomatoes and mushrooms on the stove. That's what you Brits like for breakfast, isn't it? The full English. At least they do in this century, so I hope they still have that in your time . . ."

There was still no reaction from the older man, and the joke was wearing a bit thin, as far as Rasmussen was concerned. "All right, come on. Joke's over, and it's time to get your a.s.s out of bed and get to work." He reached down and grabbed the professor's shoulder, to shake him awake.

He instinctively knew something was wrong, even as he hauled the man over. By the time the professor's slack, pale face slumped into view, Rasmussen's brain had caught up with how cold the guy's skin felt under his hand.