"So what's the format?" asked Hek. "Hour, then day, then month, then year? That doesn't work. How about the other way around? The tenth year, the six hundred and forty-sixth day. That makes no sense either, since they're only four hundred or so days in a Terran year."

"No," said Rissa. "No, it's not that. It's the year — the whole thing is the year. Ten billion, six hundred and forty-six million, three hundred and ninety-seven thousand, two hundred and eighty-one."

"The year?" said Hek. "The year," said Rissa. "The Earth year. Anno Domini — after the birth of Christ, a prophet."

"But I've seen lots of human numbering before," said Hek.

"Yes, you separate big numbers into thousands groups — my people do it into ten thousands. But I thought you used — what do you call them? — those subscripted curlicuesT'

"Commas," said Rissa. 'Ze do use commas, or spaces."

She seemed to be having trouble keeping her balance; she moved over to the docking-bay wall and leaned against it.

"But… but imagine a time so far in the future that English isn't used anymore… a time in which it's been millions or billions of years since-" she pointed at Keith — "since anyone has used English.

They might indeed misremember the convention for writing big numbers, or how to make an apostrophe, or where the little extra doodad on a u went."

"It's got to be a fake," Keith said, shaking his head.

"If it is, it's a perfect one," said Azmi, waving a hand scanner. "We built some very long half-life radioactives into the cube's construction. The cube is now ten billion Earth years old plus or minus nine hundred million. The only way to fake that kind of dating would be to manufacture a counterfeit cube using the correct ratio of isotopes to give that apparent age. But even to the smallest detail this one matches our original — except for the radioactive decay and the surface scouring."

"But to have it signed with my name," said Keith. "Surely that's a mistake?"

"Perhaps somehow your name has come to be associated with Starplex," said Hek. "You are its first director, after all, and, frankly, we Waldahudin always thought you took too much of the credit. Maybe that was not a signature. Maybe it was the address, or the salutation, or-"

"No," said Rissa, eyes growing wide. Her voice was shaking with excitement. "No — it's from you."

"But… but that's crazy," Keith said. "There's no way I'm going to be alive ten billion years from now."

"Unless it's a relativistic effect," said Hek, "or perhaps suspended animation."

"Or…" said Rissa, her voice still shaking.

Keith looked at her. "Yes?"

She started jogging out of the bay.

"Where are you going?" barked Hek.

"To find Boxcar," she shouted. "I want to tell her that our life-prolongation experiments are going to succeed beyond our wildest dreams."

Glass rose from the clover-covered ground. "Perhaps you need some time to rest," he said. "I'll be back in a little while."

"Wait," said Keith. "I want to know who you are. Who you really are."

Glass said nothing, his head inclined to one side.

Keith got to his feet as well. "I've got a right to know. I've answered every one of your questions. Now, please, answer this one of mine."

"Very well, Keith." Glass spread his arms. "I'm you — Gilbert Keith Lansing — but you of the future. You don't know how long I'd been racking my brain trying to remember what the bloody G stood for."

Keith's jaw had dropped. "That — that can't be right. You can't be me."

"Oh, yes I am," said Glass. "Of course, I'm a little bit older." He touched the side of his smooth, transparent head, then made the wind-chime laughter sound. "See? I've lost all my hair."

Keith narrowed his eyes. "How far in the future are you from?"

"Well," said Glass, gently, "actually, you've got it backward. We are in my present. The appropriate question is, how far from the past are you from?"

Keith felt himself losing his balance. "You mean — you mean this isn't 2094?"

"Twenty-ninety-four what?"

"The Earth year 2094 — 2094 n.o. Two thousand and ninety-four years after the birth of Christ."

"Who ? Oh, wait — my reckoner just reminded me. Let me work it out; I know the current year in absolute counting from the creation of the universe, but… ah, okay. In your system, this is the year ten billion, six hundred and forty-six million, three hundred and ninety-seven thousand, two hundred and eighty-one."

Keith staggered back a half pace. "You sent back our time capsule."

"That's right."

"How — how did I get here?"

"When your pod passed through the shortcut, I locked you into stasis.

Time passed in the universe, but not for you.

When it got to be this year, I unlocked you. Don't worry, though. I intend to put you back where you came from." A pause. "Remember that pink nebula you saw as you came out of the gate? That's what's left of what used to be Sol." Keith 's eyes went wide.

"Don't be concerned," said Glass. "No one was injured when Sol went nova. It was all carefully engineered. See, that type of star doesn't naturally go nova; it just decays to a white dwarf. But we like to recycle. We blew it up so that its metals would enrich the interstellar medium."

Keith felt dizzy. "And how — how are you going to return me to my time?"

"Through the shortcut, of course. Time travel to the past works well; we just can't do it to thefuture — that's why we had to let you come forward in stasis through ten billion years. Ironically, it turns out that it's forward time travel, not backward travel, that results in unsolvable paradoxes, making it impossible. We'll send you back to the moment you left. You don't have to worry about your friends missing you; no matter how many hours you generously stay with us, we'll get you to Tau Ceti at the time you're expected."

"This is incredible."

Glass shrugged. "It's science."

"It's magic," said Keith.

Glass shrugged again. "Same thing."

"But — but — if you're really me, if you're really from

Earth, then why did you screw up on the simulation?"

"Pardon?"

"The Earth simulation. It has errors in it. Fields full of four-leaf clover, something only ever found as the occasional mutant, and birds that I've never seen before."

"Oh." The wind-chime sound. "My mistake. I took the simulation from some ancient recordings we had, but I was probably a bit sloppy. Let me just check with my reckoner… yup, my fault. It is a perfect simulation of Earth, but of Earth about one-point-two million years after you were born. The things that were out of place were species that hadn't yet evolved in your time. Come to think of it, you wouldn't have recognized the constellations, either, if I'd ever let it become nighttime."

"My God," said Keith. "I hadn't even begun to think about evolution.

If you're ten billion years older than me, then — then you're older than any form of life on Earth in my time."

Glass nodded. "By your time, life had been evolving on Earth for four billion years. But there are Earth-descended life-forms in this time that are products of fourteen billion years of evolution. You'll never believe what daisies evolved into — or sea anemones, or the bacteria that caused whooping cough. In fact, I had lunch a few days ago with someone who evolved from whooping-cough bacteria."

"You're kidding." "No, I'm not."

"But it's incredible…"

"No. It's just time. Lots and lots of time."

"What about humans? Did humans continue to breed, to have children?

Or did that stop when — when life prolongation was discovered?"

"No, humanity continues to evolve and change. New humans — those who've been evolving for the last ten billion years — don't mix much with old humans like me.