You probably think I have a million stories to tell, being a bartender and all. The truth is, nobody talks to me much anymore. My place is just a few blocks down from the State University so most of my regulars are either Faculty staff or students. The Faculty guys usually just sit in a corner quietly by themselves, writing lecture notes or leafing through academic journals, while the students just drink until they pass out. Pretty much the same as when I did my letters.

Yeah, that's right; I've got a fancy diploma in a nice frame on my wall at home - Thermodynamic Engineering. Honours, actually. Surprised? There you go, don't judge a book and all that. So what am I doing serving slops in this joint? Well, that is one of my stories, but not one I generally like to tell. It even bores me now. However, there is one story I'll share with you. It happened just this evening, in fact.

As I said, I mostly get the university crowd in here. There's one chap that comes in almost every night, a lecturer by the name of Drake. Nice sort of bloke, friendly and easy going. He teaches physics, as I understand it. He's very popular with his students and they'll often buy him drinks while they discuss whatever bright young physics students discuss with their teachers.

Drake was late getting in tonight, but so were most of the Faculty regulars. Usually, this means there's some sort of staff meeting or something going on at the University. Because things were slow, I had time to check out some of the new customers as they walked in.

One guy in particular stood out when he came in through the door. He was maybe in his late fifties or early sixties and seemed familiar to me somehow. He was looking around the place like he had been here before. I couldn't place him, 'though. Yeah, I know bartenders are supposed to be good with faces. There you go, another myth broken.

Anyway, this guy walks over to the bar, hops up on a stool and looks at me. I mean really looks at me.

"Mat, isn't it?" he eventually says. "I remember you. You used to mix a great Screwdriver. Added a dash of lime juice or something."

Now, I'm confused already. I've only been working here about a year and I've just mastered pouring a beer off the wood. But one thing I have learnt is that it's easier to agree with whatever the customers say. So I nod.

"In fact," he says, "I think I'll have one of them now." He looks at his watch. "No, on second thought, make that two."

"No problem," I tell him. "Coming right up." I grab two glasses, clink some ice into them, splash in a couple of nips of Absolute and top up with OJ. On an impulse I squirt a few drops of lime juice into them as well.

"There you go, buddy," I say, putting the drinks in front of him and fetching a bowl of pretzels as well. "Seems like you know your way around here. Can't say I can place your face 'though."

He seems to find that amusing. "I haven't been around here for a long time, Mat. But some things you never forget. After all, it started here, you know."

"If you say so," I tell him, wiping the bar in front of him with a cloth. It didn't need it, but that's what bartenders do. You've seen the movies, haven't you?

"They call me a Professor now," he goes on. "Who would have thought, huh?" He took a sip of one of the drinks. "Yep, it's that splash of lime that makes the difference."

Just then, our friend Drake comes in. He takes off his overcoat and hangs it up on the rack by the door. As he walks over to the bar, this Professor guy reaches out and grabs hold of his arm.

"Doctor Drake," he says. "I thought you'd be in tonight. In fact, I was absolutely certain of it."

Drake looks at the Professor but shrugs.

"Sorry, do I know you? You're not Faculty are you?" he asks.

"Not now," the Professor says. "You could say I'm retired. Would you care to join me for a drink. I've come a long way just to talk with you."

"Sure," Drake says. Like I told you, he's a friendly enough guy who's happy to strike up a conversation with anyone, especially if there's a drink involved. He jumps up on the stool next to the Professor, who slides the second Screwdriver across the bar to him. The thing I noticed straight away, was how similar they both looked. They could be father and son, I remember thinking at the time.

"So, what did you teach?" asks Drake.

"Physics," the Professor tells him.

"No kidding?" says Drake. "That's my field too."

They seem to be getting on just fine, so I leave them to it. Every fifteen minutes or so, one of them waves me over and I serve up another round of drinks. The Professor seems to have no trouble matching Drake drink for drink and by about 10 o'clock they're both pretty mellow. They seemed to be talking a lot of physics stuff and I reckon if they'd had a blackboard handy they would have been drawing diagrams and formulas all over it.

Well, the Professor eventually gets up to go to the men's room and Drake waves me over again. He seems to be pretty excited about something.

"You know, Mat," he says to me. "I like to think I'm a pretty good judge of character. You, for instance, you're a nice guy and pretty switched-on. What you're doing stuck in this job is beyond me. And that Professor - something tells me he isn't half as screwy as he sounds. He's been telling me some amazing stuff for the last two hours. Trouble is, there's no way I'm going to remember any of this in an hour's time, let alone tomorrow. So, I want you to do me a favour. I want you to write down what I tell you on the back of this coaster."

He flips a coaster at me and I get a pencil from beside the cash register. I write down what he tells me, but I don't take much notice. Now I sort of wish I had. When I finish, Drake snatches up the coaster and tucks it into his shirt pocket, just as the Professor gets back and sits down. I do my bartender thing again with the cloth and wander up the other end of the bar to serve some other customers.

About an hour later, Drake stands up and shakes the Professor's hand. The Professor watches Drake stumble over to the door, put on his coat, and walk out into the night.

I go over and collect Drake's empty glass and put a fresh bowl of pretzels in front of the Professor. He's looking fairly pleased with himself.

"I had to tell him more than I wanted to," he says, half to me and half to himself. "But that's OK, I know he won't remember anything tomorrow."

"Yeah," I say. "He's pretty tanked. He was sure talking some weird stuff when you were in the men's room."

The Professor's smile fades straight away. "He didn't say anything about the time machine?" he asks, looking at me strangely.

I must admit, that until then, I thought he was just a regular guy.

"Time machine?" I say to him. "Like in the movies? Beam me up Scotty, and all that stuff?"

"That's a matter transporter," he says, with a perfectly straight face. "The beam-me-up bit, I mean. A time machine is completely different."

As I said before, one of the first things I learnt was to agree with the customers. "Of Course," I say. "No, I don't think he mentioned a time machine."

"Good," the Professer says. "That's good." He looks down into his drink. "I built one, you know," he says quietly. "Twenty years from now."

"Ah," I say.

"And you know what happened when I finished my magnificent time machine?" he goes on. "A very bad thing," he says. "A very, very bad thing. Believe me, you don't want to know the details. Just think of it as an end of the world type of thing."

"Right," I say. "Time machine. End of world. Got it."

"But," he says, "I got a chance to fix things. Just one chance. I was able to come back here, back to where it began and stop it. You see, it was in this very bar on this very night that I got the idea for my time machine. I can't remember much else about that night, but somebody gave me this coaster."

He reaches into his coat-pocket and pulls out an old stained San Miguel beer coaster. It seemed familiar, but I didn't want to look too closely at it because I was suddenly afraid of what I might see written on it.

"One of Drake's colleagues, or maybe even one of his bright young students, must have given it to him this evening," the Professor says. He - that is, I - woke up the next day with it clutched in my hand. From that moment I couldn't get the thought of a time machine out of my head. Despite all my scientific training, against all my logical reasoning, I was convinced that the possibility to move through time was a practical reality."

I hope you're with me still, because I pretty much zoned out myself at the time. I never drink while I'm behind the bar, but I tell you I was tempted just then.

The Professor reaches into his coat-pocket again and pulls out a neatly folded sheet of paper. He carefully unfolds it and shows it to me.

"And see this?" he asks. "Written on this piece of paper is the most incredible piece of mathematical work ever known. And you know what? I don't even know how it came about. I haven't been able to find any work leading up to it, no notes, no conference papers, no journal articles - nothing. I came across it by accident about nineteen-and-a-half years ago... I mean a few months from now. Anyway, I was clearing out the office of one of the research assistants at the university; a fellow by the name of Delton who was killed in a car accident. I never knew him, but by all accounts he was a spectacularly average scientist. That he could have worked this out is utterly impossible."

"What's so special about it?" I ask.

"It is the solution to an extremely complex mathematical equation," he says. "One that calculates the spatial position of every particle in the universe from any point in time. Quite simple and elegant really, but it enables a navigation and guidance system to be created for a time machine. When I found it among Delton's work records, I didn't think anything about it and put it in a file folder where I just happened to have the coaster. A couple of months later, I was browsing through that file and I made the connection between the two. The rest, as they say, is history. Or, in your case, the future."

"So, I had to keep young Drake from talking shop with any of his students in this bar tonight," he goes on. " Without this coaster, Delton's equation will mean absolutely nothing to Doctor Drake when he finds it six months from now."

"What about if someone gives Drake the coaster another time?" I say.

"That can't happen," says the Professor. "Because it didn't happen. I got - I mean Drake got - the coaster tonight. I stopped that, so I broke the chain. Doctor Drake won't make the time machine now."

He seems so happy about this I don't want to rain on his parade, and so I keep my mouth shut.

The Professor drains the last of his drink and slides off the bar stool. He straightens his tie and weaves his way across the room towards the front door. Just before he goes out, he turns and gives me a wave.

"Cheerio, Mat," he says.

"Good night, Professor Drake," I say.

You know, some people believe that you can't change your destiny. They think that your fate is preordained. Other's reckon that your future is what you make it. I don't know what I believe any more.

Oh, there is one other little detail I almost forgot. Remember that piece of paper the Professor was waving about? The one with that mathematical proof written out on it, all nice and clear? Well, he dropped it on he floor as he was walking out. Funny thing is, the fellow who picked it up later is a researcher at the university. Name's Delton. How's that for a coincidence, huh?

So, that's my story. Believe it or not; it's up to you. But look at the time, will you? It's only ten minutes to closing. Last orders please, ladies and gentlemen!