“Okay,” said Louise. “As you can see, we’ve mapped a lot more geomagnetic reversals than they have-over 300 in the last 175 million years. That’s because there’s a more complete record in sea-floor rocks than there is in meteorite finds.”
“Score one for our side,” said Jock, dryly.
“So,” continued Louise, “what I’ve done is pair up the reversals thatdo match-that is, the ones that both they and we have evidence for. As you can see, although their record has many holes in it, there’s a one-to-one correspondence almost all the way to the present.”
Jock looked at the sheets, Louise’s finger guiding his eyes. “Okay.”
“Well,” said Louise, “that makes perfect sense, of course. You know my theory: that there was only one long-term universe until consciousness dawned forty thousand years ago.”
Jock nodded. Although quantum-mechanical events caused countless brief splittings of the universe, and probably had since the beginning of time, those splittings made no macroscopic difference, and so the resulting universes had always collapsed back together after a nanosecond or two.
But the acts of conscious beings caused splits that could not be healed, and so, when the Great Leap Forward took place forty thousand years ago-when consciousness emerged-the first ever permanent split occurred. In one universe,Homo sapiens acquired that initial consciousness; in the other,Homo neanderthalensis did-and they had been diverging ever since.
“But wait a minute,” said Jock, peering at the Neanderthal chart. “If that one there is the last recorded magnetic reversal that we know about-“
“It is,” said Louise. “They’ve got it listed as about ten million months ago, which is 780,000 years ago.”
“Okay,” said Jock. “But if that’s the most recent one on our chart, what’s this one here?” He pointed to what was apparently another, more-recent reversal indicated on the Neanderthal chart. “Is that the one they said began twenty-five years ago?”
“No,” said Louise. She had too much of the academic in her for Jock’s taste. She was clearly leading him to make his own discovery, but she obviously already knew the answer herself. He wished she’d just tell him.
“Then when was that one?”
“Half a million months ago,” said Louise.
Jock made no effort to hide his irritation. “Which is?”
Louise’s full lips spread into a grin. “Forty thousand years ago.”
“Forty thou-! But that’s when...”
“Exactly,” said Louise, pleased with her pupil. “That’s when the Great Leap Forward occurred, when consciousnessemerged, when the universe split apart for good.”
“But...but how is it thatthey know about a magnetic reversal then and we don’t?”
“Remember what I said the first time we were talking about this? After the magnetic field dies away, it’s a fifty-fifty chance as to what polarity the new field will come up with. Half the time, it’ll be normal, and-“
“And half the time it will be reversed! So this event must have happenedafter the universes split-and since the universes were no longer in lockstep, it happened that the polarity came up reversed in the Neanderthal world-“
Louise nodded. “Leaving a record in meteorites.”
“But in our world, it came up with the same polarity it had had before the collapse-leaving no record.”
“Oui.”
“Fascinating,” said Jock. “But wait-wait! They had a reversal forty thousand years ago, right? But Mary says that when she took a compass reading in the Neanderthal world, it now has the same polarity as our world does, so...”
Louise nodded encouragingly; he was on the right track.
“...so,” continued Jock, “therewas a recent, rapid field collapse in the Neanderthal world, and this time, when the field came up again, just six years ago, it had flipped its polarity once more, back to matching what it is on this Earth.”
“Exactly.”
“All right then,” said Jock. “Well, that’s what I wanted to know.”
“But there’s more to it than that,” said Louise. “Much more.”
“Spit it out, girl!”
“Okay, okay. It’s like this. Earth-the one and only Earth that existed at that time-experienced a magnetic-field collapse forty thousand years ago. While the magnetic field was down, consciousness emerged-and I can’t think that that’s a coincidence.”
“You mean the collapsing of the magnetic field had something to do with why we developed art?”
“And culture. And language. And symbolic logic. And religion. Yes.”
“But how?”
“I don’t know,” said Louise. “But remember, anatomically modernHomo sapiens have existed since one hundred thousand years ago, but they didn’t get consciousness until forty thousand years ago. We had the same physical brains for sixty thousand years without ever making art or exhibiting any of the other signs of true sentience. Then-click!-something happened, and we were conscious.”
“Yes,” said Jock.
“You know some birds use magnetite in their brains to tell direction?”
Jock nodded.
“Well, we-Homo sapiens-have magnetite in our brains, too. No one knows why, since we obviously aren’t using it as a built-in compass. But when the magnetic field collapsed forty thousand years ago, I think something happened to the magnetite that caused the-the ‘booting up,’ shall we say, of consciousness.”
“So what’s going to happen when the magnetic field collapses again?”
“Well, on the Neanderthal world, nothing happened during their most recent collapse,” said Louise. “But...”
“But?”
“But they don’t use fossil fuels. They don’t have billions of cars. They don’t use chlorofluorocarbons for air-conditioning.”
“Yes? So?”
“So their atmosphere-and their ozone layer-is completely intact. Ours isn’t.”
“What’s that got to do with magnetic reversals?”
“Earth has two methods for shielding its surface from solar and interstellar radiation: the atmosphere, and the magnetic field. If one goes down, the other covers for it...”
Jock’s eyes went wide. “But one of ours isalready down.”
“Exactly. Our ozone layer is depleted; our atmosphere is chemically altered. When the magnetic field collapses again-and it looks like it’s starting to do that right now-there’s not going to be any backup shielding in place.”
“What’s going to happen?”
“Je ne sais pas,”said Louise. “We’ll have to do a lot more modeling before we’re sure. But...”
“Again with the buts! What? What?”
“Well, consciousness booted up during a field collapse-and this is going to be the mother of all field collapses, as far as its effects are concerned. This time, consciousness might...well, not to stretch the metaphor too much, but this time consciousness mightcrash.”
Epilogue
Ponter thanked the travel-cube operator, and disembarked. He could feel the eyes of females on him, feel their disapproving stares. But even though it was only another day until Two next became One, this couldn’t wait.
After most of a month back on her version of Earth, Ponter and Mary had returned to the Neanderthal world three days earlier. He’d said the timing would allow him to see both Adikor and his children on the same trip, which was certainly true. But, since Mary had to go back to staying with Lurt until Two became One, it also let him see a personality sculptor, in hopes of ridding himself of the insomnia and bad dreams that had been plaguing him.
But now Ponter was approaching Lurt’s lab-guided by Hak; Ponter himself had never been there before. Entering the all-stone building, he asked the first woman he saw to direct him to where Mare Vaughan was working. The astonished woman-a 146-pointed, and Ponter marched down the corridor. He walked into the room that had been indicated, and saw Mary and Lurt huddled over a worktable.
This is it,thought Ponter. He inh
aled deeply, and-
“Ponter!” said Mary, looking up. She was delighted to see him, but-
But, no. This washis world-and it wasn’t the right time. She tried to keep her tone calm. “What’s wrong?”
Ponter looked at Lurt. “I need to speak to Mare alone,” he said.
Lurt’s eyebrow went up. She squeezed Mary’s forearm, then left the room, closing the door behind her.
“What is it?” asked Mary. She could feel her heart pounding. “Are you okay? Has something happened to Jasmel or-“
“No. Everyone is fine.”
Still nervous, Mary tried to make light of things. “You shouldn’t be here, you know. Two aren’t One right now.”
But Ponter had an edge in his tone. “To...tohell with that,” he said.
“Ponter, what is it?”
Ponter took a deep breath, then said some words to her in his language. For the first time ever, the words were not immediately translated, and Mary saw Ponter tilt his head in the way that meant he was listening to Hak over his cochlear implants.
Ponter spoke again, sharply, and Mary heard the Neanderthal word”ka,” which she knew meant “yes.” Perhaps Hak had said, “Are you sure you really want to say that?” If he had, Ponter must have told him that yes, he did, and perhaps had admonished the Companion for interfering. There was silence for a couple of seconds, then Ponter opened his mouth again, but apparently that was enough of a cue for Hak to finally issue the English equivalent of Ponter’s earlier utterance. “I love you,” said the machine-synthesized voice.
How Mary had longed to hear those words! “I love you, too,” she said. “I love you so much.”
“We should build a life together, you and I,” said Ponter. “If-if you will have me, that is.”
“Yes, yes, of course!” said Mary. But then her spirits began to sag. “But...but it would be complex, making such a relationship work. I mean, you have a life here, and I have a lifethere . You have Adikor and Jasmel and Megameg, and I have...” She paused. She’d been about to say “no one,” but if only that were true. Shedid have a husband, estranged to be sure, but still her lawfully wedded spouse. And, sweet Jesus, she thought, if God disapproved of divorce, what would he make of a relationship across species lines?
“I want to try,” said Ponter. “I want to try to make this work.”
Mary smiled. “Me too.” But then she felt her smile fade. “Still, there’s so much to consider. Where would we live? What about Adikor? What about-“
“I know it will be difficult, but...”
“Yes?” said Mary.
Ponter closed the distance between himself and Mary, and he looked into her eyes. “But your people have traveled to the moon, and mine have opened a portal to another universe. Things that are difficultcan be done.”
“There will be sacrifices,” said Mary. “For both of us.”
“Perhaps,” said Ponter. “Perhaps not. Perhaps we can extract the marrow but still keep the bone for toolmaking.”
Mary frowned for a moment, then got it. “’Have our cake and eat it, too.’ That’s how my people would phrase it. But I guess you’re right: our people aren’t that dissimilar. Wanting it all, why, that’s just...” Mary trailed off, unable to find an appropriate word.
But Ponter knew it. Ponter knew exactly what it was. “That is just human,” he said, taking Mary in his arms.
Robert J. Sawyer, Humans
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