It wasn’t as simple as that, however, as Alia tried to tell us. “It is a question of information,” she said. “Spacetime is discrete, it comes in small packages, particles. Therefore a given volume can only store a finite amount of information. And that information can be fully described by information stored on the bounding surface of the volume.” She frowned at me. “Is that clear?”
Not to me. But Gea said, “Like a hologram. You have a two-dimensional surface that contains information about a three-dimensional object, the hologram, which is reconstructed when you shine laser light on it.”
“Or like Plato,” John said. “We are prisoners in a cave and all we perceive is shadows cast on the wall outside, shadows of reality.”
“Yes,” I said. “But now Alia is saying the shadows are the reality. I think.”
Gea said to me, “This is like the holographic principle. An early attempt at quantum gravity theory.”
“Never heard of it.”
“It was abandoned, decades ago.”
“Maybe that was a mistake…”
Alia’s time was like a surface bounding the past — bounding all of history, including our own long-vanished time. And everything that could be known about the past was contained in her time, in each successive instant. That wasn’t so hard to grasp; geologists, paleontologists and historians, even detectives, have to believe that the past can be reconstructed from traces stored in the present.
But Alia went further: by manipulating events in her present, she was able to change the information in the past — to project herself here, into what was to her history. It was as if you could tinker with a few dug-up dinosaur bones and change the lives of the creatures of which they were relics.
Something like that.
I was struck, though, by a resonance with something I’d read in uncle George’s manuscript: If time is circular, if future is joined to past, is it possible that messages, or even influences, could be passed around its great orbit? By reaching into the furthest future, would you at last touch the past?… George, or anyhow his strange friends, had intuited something of the truth, perhaps.
Tom laughed, an explosive giggle. “Sorry,” he said. “Every so often I just lose it. I mean, it’s just,” he waved a hand, “you’re asking me to accept that this is a superhuman being from the far future. This ape. Where’s the disembodied brain in a jar? I mean, what can she do but swing on tires?”
I think we all knew how he felt.
We talked on. It was a difficult dialogue. We were the ignorant talking to the uneducated. I got the impression Alia really didn’t know much about all this, and cared less — as a modern teenager wouldn’t know anything about the implants in her body, as long as they worked. And we knew too little to make much sense of what she said anyhow; we had to translate it into terms we understood, interpret the information she gave us in terms of our own modern theories, which might have been as partial, falsely based or just plain wrong as notions of planet-bearing crystal spheres.
And every so often, as we worked our way through these miasmas of interpretation and guesswork, we were confronted by vast conceptual gulfs.
“Our time must be strange to you,” Rosa said. “If you were born on a ship, among the stars. The way we live must seem very alien.”
“Oh, but I prepared,” Alia said. “In the course of my Witnessing. You don’t have to visit Earth to know what it must have been like!”
“I don’t understand,” Tom said.
Alia spread her arms wide, and her long hairs dangled like curtains. “There are things I like, and things I don’t like, that have got nothing to do with being born on a ship. I like open spaces, long prospects. I don’t like enclosed spaces or running water, or rats or spiders, or blood. I grew up in zero gravity, but I can be scared of heights! All these are responses ingrained deep into my system, and the systems of my ancestors, long before they left Earth. So, you see, even if I knew nothing of Earth, I could reconstruct it just from my own responses. In fact, that has been done a number of times, by cultures cut off from their origins — people who forgot where they came from. Even they can deduce something of Earth…”
“Astounding,” Rosa said. “You left Earth behind half a million years ago. You traveled across the stars. And yet you took the savannah with you, didn’t you?”
Sonia said, “You mentioned rats. Are there animals where you came from?”
“Animals? There are rats everywhere. They don’t all sing. There are bugs and birds.” Birds flocked on her starship, she said; I couldn’t think of a more exotic, charming image. “Earth’s biosphere shows more diversity than any other human world in the Galaxy, however. That’s one reason we know it really is Earth, the original.”
“Like Africa,” Rosa said. “There is more genetic variation there, too. As Africa is for us, the home of mankind, so Earth is for these future people.”
Sonia prompted, “And there are still animals on Earth?”
“Birds. Snakes. Insects. Bugs. That’s all, really.”
“They are the supertaxa,” Gea said. “Taxa have different evolutionary rates. Some speciate more rapidly than others; some lineages last longer than others; and some taxa — the birds, snakes, rats and mice, various weeds — have both a high speciation rate and a high longevity. And so when an extinction event strikes, the supertaxa provide the great survivors. What Alia describes is exactly what I would have expected to find on an Earth of the future, after our extinction event is done. Snakes and rats and birds.”
“But no big animals?” Sonia asked wistfully.
Gea said, “I want to show you something.” She produced a VR image of a lumpy-looking animaclass="underline" a rhino, but covered in shaggy brown fur.
Alia gaped. “Megafauna!”
Tom said, “That’s a Sumatran rhino, isn’t it?”
“Yes,” Gea said. “An unusual form, adapted for living in hilly rainforests. It went extinct, earlier this year. The last of them died in a zoo in Germany.”
“I’ve never seen anything like it.” Alia sounded as if this creature was as exotic as a dinosaur, to her. She glanced at me. “Michael, have you?”
“I’m not a wildlife buff,” I said. “If you followed me around all my life you’ll know that.”
Gea said, “The Sumatran rhino was a living fossil. It is the least changed of all large-mammal lineages since the Oligocene, thirty million years ago, halfway back to the dinosaurs. We live in extraordinary times. That species endured for thirty million years. Even the people in this room had the opportunity to meet it, to touch it, just months ago. And now it has vanished, a geological instant after its encounter with humanity. Just like that. As all the megafauna which survived the Ice Age have gone, one by one.”
Sonia said wistfully, “And they never came back, according to Alia. You’d think they could have been brought back from the DNA.”
“Perhaps there was never room,” Rosa said. “Not if the world remained owned by humans. For we would not allow anything bigger and hungrier than us to survive.”
“Besides, evolution goes forward, not backward,” Gea said. “The mega-mammals, once gone, will never return.”
Alia was watching us. “You all sound so guilty!”
Tom said, “Do people in the future look back on our time?”
“Oh, yes.”
“And do they judge us?”
“Judge you?” Alia laughed, a strange whooping sound, but then bit it off. “I’m sorry. I know this concerns you, in this age. If not, if you didn’t have this awareness, I guess you wouldn’t be attempting the hydrate stabilization project.”
“You know about that?” I asked.
“Of course. I Witness you, Michael Poole. But why should you be judged? Look — if one species of bird out-competes another, are you going to talk about morals? Of course not. It’s just a question of competition for space in an ecology.”