“But what are you doing here, in normal space?” asked Elissa. “According to the information service, you’ve been here forever.”

“Twenty-six days.” Sy grinned. “You know what’s wrong with S-space? You can’t get anything done there in a hurry. I had things I wanted to do, and things I wanted to know — fast — and I wasn’t sure that our Immortal friends would give permission. So I came here. I’ve been here for only nineteen minutes of S-time. By the time they register the fact that I’ve gone, I’ll be all finished.” “I had the same feeling,” said Peron. “We’re too slow in S-space. We have a lot less control over what happens to us there. But finished doing what?” “Several things. First, I’ve been testing Kallen’s Law — my name for it, not his. Remember what he said? ‘Anything that can be put into a data bank by one person can be taken out of it by another, if you’re smart enough and have enough time.’ That’s one problem with a computer-based society, and one reason why computers were so tightly controlled on Pentecost: it’s almost impossible to prevent access to computer-stored information. I decided that if there were another headquarters for the Immortals, and one that they preferred not to talk about, there must be clues to its location somewhere in the data banks. Well-hidden, sure, but they should be there. Is there a secret installation, and if so, where is it? Those were two questions I set out to answer. And I had another thing that worried me. When we met the Gossameres and Pipistrelles, Ferranti said that the Immortals couldn’t really communicate with them. But she did communicate with them, even if they didn’t send a message back. And I couldn’t be sure that was true, either. Suppose they did send a message? — we don’t know what the ship was receiving. I’m afraid I don’t have an answer yet to that one. I’ve been working here flat out, but it takes time.”

“Do you mean you have answered the other questions?”

“Think so.” Sy cradled his left elbow thoughtfully in his right hand. “Wasn’t easy. There’s a pretty strong cover-up going on. None of the data that’s available for the usual starship libraries will tell you a thing. I had to get there by internal consistency checks. What do you make of these data base facts? First, the official flight manifests show one hundred and sixty-two outbound trips initiated from Sol in the past S-month. The maximum fuel capacity of any single ship is 4.4 billion tons. And the fuel taken out of supplies in the Sol system in the past S-month is 871 billion tons. See the problem? I’ll save you the trouble of doing the arithmetic. There is too much fuel being used — enough for a minimum of twenty-six outbound flights that don’t show on the manifests.” “Did you check other periods?” asked Peron.

Sy looked at him scornfully. “What do you think? Let’s go on. This one is suggestive, but not conclusive. The navigation network around the Sol system is all computer controlled, and it’s continuously self-adapting to changing requirements. Generally speaking, the most-travelled approach routes to Sol are the ones with the most monitoring radars and navigation controls. The information on the placement of radars is available from the data banks, so you can use it to set up an inverse problem: Given the disposition of the equipment, what direction in space is the most-travelled approach route to and from Sol? I set up the problem, and let the computers grind out an answer. When I had it I was puzzled for days. The solution indicated a vector outward from Sol that seemed to lead nowhere at all — not to any star, or toward any significant object. It pointed at nothing. I was stuck.

“I put that to one side and chased another thought. Suppose there were a hidden Headquarters somewhere in space. It would communicate with the Sol system, not just with the ships — they only travel at a tenth of light-speed — but with radio signals, too. There are thousands of big antennae and phased arrays scattered all around the Sol system, and the computers keep track of their instantaneous pointings. So I accessed that pointing data base, and I asked the computer a question: Of all the places that the antennae and arrays point to, what direction was pointed to most often? Want to guess the answer?”

“The same one as you got from the navigation system solution,” said Peron. “That’s wild. But damn it, how does it help? You have the same mystery.” “Not quite.” Sy looked unusually pleased with himself. For the first time, Peron realized that even Sy liked to have an appreciative audience for his deductions. “You’re right in one way,” Sy went on. “I got the same answer as from the navigation system solution. I had a vector that pointed to nothing. But there’s one other thing about the antennae. The computer points them all very accurately, but of course they’re scattered all over the solar system, from inside the orbit of Mercury to out past Saturn. So if you want to beam a message to a precise point in space, rather than merely in a specified direction, each antenna would be aimed along a slightly different vector. In other words, the computer pointing must allow for parallax of the target. So I took the next step. I asked if there was parallax on the previous solution, for the most common antennae pointings, and if so, what was the convergence point? I got a surprising answer. There is parallax — it’s small, only a total of a second of arc — and the convergence point is twenty-eight light-years from Sol, in just the direction I’d determined before. But when you check the star charts and the positions of kernels and hot collapsed bodies, there’s nothing there. Nothing. The antennae are aimed at the middle of nothing. I called that place Convergence Point, just for lack of a better name. But just what place is it? That was the question. And that’s where I stuck again, for a long time. Know what finally gave me the answer?”

Elissa was sitting on the bed, her expression dreamy. “Olivia Ferranti. Remember what she told us — ‘You can’t learn all about the Universe crouching in close by a star.’ And you, Sy, you said maybe you should be looking at nothing to find new mysteries, rather than at the center of the galaxy. Convergence Point is a nothing point.”

Sy was looking at her in amazement. “Elissa, I was asking a rhetorical question. You’re not supposed to give me the right answer. How the devil did you work it out?”

Elissa smiled. “I didn’t. You gave it away yourself. You’ll never be a good liar, Sy, even though your face doesn’t give you away. It was your choice of words. Even before you knew the distance, the twenty-eight light-years, you said several times that the antennae were pointing ‘at nothing.’ But you couldn’t know there was no dark object there, if you went out far enough. And from your voice, it was the ‘nothing’ that was important, not the coordinates of the target point.”

Sy looked at Peron. “She’s a witch. If she reads you like that, you’ll never keep any secrets from her. All right, Elissa, take it one step farther. Can you tell me what’s so special about that particular nothing?”

Elissa thought for a few moments, then shook her head. “No data.” “That’s what I thought, too. How can nothing be special? But then I remembered what else Olivia Ferranti said: ‘You have to know what’s going on out in deep space.’ So I asked myself, what is deep space? I went back to the star charts and the kernel coordinates, and I asked the computer another question: Give me the coordinates of the point of open space within one hundred light-years of Sol that is farthest from every known material body. Uncertainties in our knowledge of distances make the answer slightly ambiguous, but the computer gave back only two candidates. One is ninety-one light-years away; half a year’s trip, even in S-space. The other is — no prizes for guessing — just twenty-eight light-years from Sol, in the right direction. Convergence Point is a real nothing point. Communication time: five S-days.”