They had been disputing whether any nearby stellar systems might have Earthlike planets, and the elderly but still athletic Dane kept to his pragmatic, hard-nosed reputation. “If you have the means to experiment, do it! If not, then wait till experiments are possible. Theory by itself is only masturbation.”
The small club erupted in laughter. Still, Wyn was no spoilsport. And as everyone else seemed to want to speculate, he merely grumbled good-naturedly and went along.
“We’ll see about that Han interferometer,” said a woman geologist named Gorshkov, whom Stan had met off and on at conferences for decades. “The Chinese have been talking about it forever. Why can’t we answer the question with facilities in orbit right now?”
Stan shrugged. “The Euro-Russian and American telescopes are quite old by now, Elena. Yes, they’ve detected planets around nearby stars, but only giants like Jupiter and Saturn. Little rocky worlds like Earth are harder to find like picking out the reflected glint of a needle next to a burning haystack, I should think.”
“But don’t most astrophysical models predict that sunlike stars will have planets?”
This time it was a younger Dane, Teresa’s husky friend Lars. The fellow might look like an overbuilt mechanic or an American football hero, but he obviously read a lot.
“Yes and no,” Stan replied. “G-type stars like our sun must shed angular momentum in their infancy, and since ours gave nearly all its spin momentum to her retinue of planets, most astronomers think other stars that rotate like the sun must have planets too.
“Furthermore, astronomers think early protostars give off fierce particle winds, which drive away volatile elements. That’s why there’s so much hydrogen in the outer solar system, while Mercury and Venus, sitting close in, have been stripped of theirs.”
“But Earth came out just right,” Wyn nodded. “In the middle of a zone where water can stay liquid, right?”
“The Goldilocks effect.” Stan nodded. “Life could never have started, or kept going for long, without lots of water.
“But as for Earth being ‘in the middle’ of the solar system’s life zone, well, astronomers have argued over that for more than a century. Some used to think that if our world was only five percent closer to the sun we would have fallen into the Venus trap … heat death by runaway greenhouse warming. And if we’d been just five percent farther, Earth’s seas would have frozen forever.”
“So? What’s the modern estimate?”
“Currently? The best models show our sun’s life zone is probably very broad indeed, stretching from just under one astronomical unit all the way out past three or more.”
Someone whistled. Elena Gorshkov closed her eyes momentarily. “Wait a minute. That extends past Mars! So why isn’t Mars a living world?”
“Good question. There’s evidence Mars once did have liquid water, carving great canyons we have yet to visit, alas.” To that there was a general murmur of agreement. Several raised their glasses to opportunities lost. “Perhaps there were even seas there for a while, where early life-forms made a brave start before all the water froze into the sands. The problem with old man Mars wasn’t that he spun too far from the sun. The real difficulty was that the Romans named their war god after a pygmy. A midget world, too small to hold onto the necessary greenhouse gases. Too small to keep those famous shield volcanoes smoking. Too small, by half, for life.”
“Hmm,” Lars commented. “Too bad for Mars. But if G stars have broad life zones, there ought to be many other worlds out there where conditions were right … with oceans where lightning could begin the first steps. Evolution would have worked in those places, too. So where—?”
“So where the dickens is everybody!” Wyn Nielsen interjected, slapping the table.
So we return to the age-old question, Stan thought. Enrico Fermi had also asked it a hundred years ago. Where is everybody, indeed?
In a galaxy of half a trillion stars, there ought to be many, many worlds like Earth. Surely some must have developed life, even civilization, long ago.
On paper at least, star travel seems possible. So why, during all the time Earth was “prime real estate,” with no indigenous owners higher than bacteria or fish, was it never colonized by some earlier spacefaring race?
The amount of verbiage that had been spent on the subject—even excluding flying-saucer drivel—only expanded after the establishment of the World Data Net. And still there was no satisfactory answer.
“There are lots of theories why Earth was never settled by outsiders,” he replied. “Some have to do with natural calamities, like you lot are investigating here. After all, if giant meteorites wiped out the dinosaurs, similar catastrophes may have trounced other would-be space travelers. We ourselves may be wrecked by some stray encounter before we reach a level sufficient to—”
Stan’s voice caught suddenly. It was as if he’d been struck between the eyes, twice.
For a blessed time he had managed to banish all thought of the taniwha. So the sudden contextual reminder came like a blow. But the thing that really had him stopped in his tracks was a new thought, one that had swarmed into consciousness following the words—We ourselves may be wrecked by some encounter.…
He coughed to cover his discomfiture, and someone slapped him on the back. While he took a drink of warm beer, waving concerned helpers away, he thought. Could our monster have come from outside? Could it not be man-made?
He didn’t need to make a mental note to look into the idea later. This was one that would stick with him. If only I’d been able to break free and go to the meeting in Waitomo! Somehow, he must find a way to transmit this thought to Alex!
But now was not the time to lose his train of thought. There were appearances to maintain. Where was I …? Oh yes.
Clearing his throat, he resumed.
“My … own favorite explanation for the absence of extraterrestrials—or their apparent absence anyway—has to do with the very thing we were talking about before, the life zones around G stars like our sun. Astronomers now envision a very broad zone outward from our position, where a Gaia-type homeostasis could be set up by life. The farther out you go the less sunlight you have, of course. But then, according to the Wolling model, more carbon would remain in the atmosphere to keep a heat balance. Voilà.
“But note, there’s very little habitable zone left inward from our orbit. Earth revolves very close to the sun for a water planet. In our case, life had to purge nearly every bit of carbon from the atmosphere to let enough heat escape as the sun’s temperature rose. And in a couple of hundred million years even that won’t suffice. As old Sol gets hotter, the inner boundary will cross our orbit and well be cooked, slowly, but quite literally.
“In other words, we only have a hundred million years or so to come up with a plan.”
They laughed, a little nervously.
“So what’s your theory?” Nielsen asked.
Stan was wondering how to get the center of attention away from himself, so he could find an excuse to sneak away. But he’d have to do it smoothly, naturally. He spread his hands. “It’s really simple. You see, I think Earth must be relatively hot and dry, as water worlds go. Oh, it may not seem that way, with seventy percent of the surface covered by ocean. But that just means that normal life-zone planets must be even wetter!
“One consequence would be less continental land area to weather under rain.”
“Ah, I see,” a Turkish geochemist said. “Less weathering means less fertilizer to feed life in those seas. Which in turn means slower evolution?”
One of the paleontologists spoke from the fringes of the group. “And the life-forms would have less oxygen to drive fast metabolisms like ours.”
Stan nodded. “And of course, with less land area there’d be less chance of evolving these.” He held up ten wriggling fingers.
“Huh!” Elena Gorshkov commented, shaking her head. Several arguments erupted at the periphery as the scientists disputed amiably. Nielsen was
tapping away at the miniplaque on his lap, probably looking for refutations.
Good, Stan thought. These were bright people, and he liked watching them toss ideas about like volleyballs. Too bad he had to keep his most pressing scientific quandaries secret from them. To know such things as he did, and withhold them from his peers … it felt shameful to Stan.
“Aha,” Nielsen said. “I just found an interesting paper on continental weathering that supports what Stan says. Here. I’ll pipe it to the rest of you.”
People drew plaques and readers from their pockets and unfolded them to receive the document, drawn from some corner of the net by Nielsen’s quick-and-dirty ferret program. Distracted from his recent desire to leave, Stan too began reaching for his wallet display.
At that moment, though, his watch gave a tiny, throbbing jolt to his left wrist, just sharp enough to get his attention—the rhythm urgent.
While the chatter of excited discussion swelled again, Stan excused himself as if heading for the men’s room. Along the way he popped a micro-pickup from the watch and put it in his ear.
“Speak,” he said to the luminous dial.
“Stan.” It was the tinny voice of Mohotunga Bailie, his assistant, and it carried overtones of fear. “Get back. Right quick.” That was all. The carrier tone cut off abruptly.
Stan felt a chill, mixed thoroughly with sudden pangs of guilt. The taniwha—has it gone out of control? Oh Lord, I shouldn’t have left them alone!
But even as he thought it, he knew in his heart that Beta couldn’t have gotten away so suddenly. The physics just weren’t there for such a happenstance … not from the stable configurations of just an hour ago!
Then it must be one of the beams: This time we must have hit a city. How many died? Oh God, can you forgive us? Can anyone?
With pale, shaking hands he plunged outside where the pearly arctic twilight stretched around two thirds of the horizon. The aurora borealis made flickering, ionized curtains above the Greenland ice sheet. Stan half stumbled, half ran to his little four-wheeled scooter and kicked the starter, sending its balloon tires whining across the glittering moraine, spewing gravel behind it.
All the way back to the Tangoparu shelter, his mind was filled with dire imaginings of what could have put those dread tones in his stolid assistant’s voice. Then he crossed a hillock and the dome itself came into view, along with the big, olive-drab helicopter, parked just beyond. Stan’s heart did another flip-flop.
It wasn’t a problem with Beta after all, he realized suddenly. At least not directly. This was quite another type of calamity.
NATO, he realized, recognizing the uniforms of the armed men patrolling the shelter’s perimeter. Lord love a duck … I never thought I’d see those colors again. I’d forgotten they were still in business.
He knew only one reason the big armed aircraft would have come all this way at such a time of night, bringing soldiers to the door of his laboratory. And it surely wasn’t a social call.
They’ve found us, he realized, knowing he had only seconds to decide what to do.
Plano-Forbes: 2.5 billion
World Watch: 6.0 billion
Rocks-Runyon: 10.0 billion
These estimates of the Earth’s maximum sustainable human population were all made before 1990,. as the world’s attention began shifting from ideologies and nationalism toward matters of ecological survival. The three appraisals at first sight seem utterly at odds. Yet all were based on the same raw data.
In fact, their differences lie primarily in how each defined the word “sustainable.”
To Plano and Forbes, it meant a system lasting at least as long as ancient China had—several thousand years—that would provide all human children with education, basic amenities, and per capita energy use equal to half the consumption of circa 1980 Americans. A sustainable human population would use carbon-based fuels only as fast as vegetation recycled them and would set aside enough wilderness to preserve the natural genome.
These criteria proved impossible to maintain for long periods at population levels exceeding 2.5 billion.*
World Watch used looser constraints for their estimate. For instance, while “American” consumption levels were still seen as spendthrift, the authors did not call for rationing fossil fuels. Food was their critical concern, and although they failed to foresee many important negative and positive trends (e.g., greenhouse desertification vs. self-fertilizing maize) their major difference with Plano-Forbes arose from projecting “sustainability” only a hundred years or so at a stretch.
The Rocks-Runyon model has proven the most accurate one, in the simple sense that it correctly predicted we could (with difficulty) feed ten billion by the year 2040. It also clearly asks the least for the human future. Bare survival was its criterion—muddling through, with little worry spared for even a hundred years, let alone thousands of years, down the road.
And indeed, there are those who argue we shouldn’t be concerned so far ahead. After all, science progresses. Perhaps those generations will invent new solutions to make the problems we leave them seem academic.
Perhaps our descendants will be able to take care of themselves.
—From The Transparent Hand, Doubleday Books, edition 4.7 (2035). [ hyper access code 1-tTRAN-777-97-9945-29A.]
* These figures are challenged by groups promoting space colonization, who project that lunar and asteroidal resources, with limitless solar power, would permit Plano-Forbes life-styles for ten to twenty billion humans, sustainable for all foreseeable time. Their favorite analogy is Columbus’s discovery of the New World. The flaw in such schemes, however, is the initial investment needed before wealth from space can bring prosperity down to Earth. Governments and peoples, already living hand to mouth, will hardly put so much into projects whose bounty might profit their grandchildren, but not themselves.
• MANTLE
There was only one entrance to the deep cave complex. When armed men in blue helmets rained from the sky on jet-assisted parafoils, they had to hunt and thrash through the jungle for a time before they found that hidden opening. Then, silently, they began repelling down the shadowy chimney.
Sepak Takraw awakened to the sound of blaring alarms and at first thought it was only another Gazer run … whatever those were. The Kiwis working for George Hutton had remained closemouthed about the essential purpose of the gravity scans, though clearly they had to do with the Earth’s deepest interior. Whatever the Tangoparu techs were doing here in New Guinea, they sure took their work godawfully seriously—as if the world would end if they made one bleeding mistake!
Sepak had finally moved his sleeping roll up to a cleft in a narrow, extinct watercourse, because of the noise they made each time their big resonator thing fired up, sending bells and whoops echoing through the deep galleries. This time, however, when he stumbled toward the lighted chamber rubbing his eyes, he suddenly stopped and stared down at a scene of utter chaos. Had the New Zealanders finally done it this time, with all their noise? Invoked Tu, the Maori god of war?
They were dashing about like addled bowerbirds, and the bright cylindrical resonator swung wildly within its gimbaled cage as armed men swarmed into the hall. Sepak slipped into the shadows and kept very still. George bloody Hutton. What’ve you got me into! The government can’t be this upset over us keeping a few caves secret for a while!
Anyway, these weren’t regular police. Half the soldiers clearly weren’t even native Papuans! Sepak mouthed a silent whistle as commandos rushed past the dazed technicians to secure the area. No, these weren’t locals, nor even U.N. peacekeepers. By damn, they were real troops … ASEAN Marines!
Anyone who did the necessary ferreting knew Earth still bristled with sovereign military might. Perhaps even several percent of what used to exist in the bad old days. And even more weaponry lay “in reserve,” in treaty-sealed warehouses. Alliances still trained, still maintained a balance of power that was very real, for all its generations of stability. On
ly, on a planet aswarm with real-time cameras and volatile public opinion, those states and blocs generally took pains to use their martial forces gingerly.
So Sepak knew this wasn’t just a raid over some infraction of the secrecy laws. As the marines briskly rounded up the kiwi engineers, he searched in vain for emblems of the U.N. or other international agencies. He peered for the de rigueur Net-zine reporters.
Nothing. No reporters. No U.N. observers.
It really is national then, he realized. Which meant more was involved here than just the government of Papua-New Guinea. A whole lot more.
And these guys don’t want leaks any more than George Hutton did.
Sepak melted even farther back into the darkness.
By all the holy cargo of John Broom … George, what have you got me into?
Archaic or obsolete activities or occupations:
… flint knapping, entrail reading, arrow fletching … smithing, barrel making, art appraising … clock making, reindeer herding, dentistry, handwriting … game-show host, channeler, UFOlogist … drug smuggler, golf course manager, confidential banker … sunbathing, drinking tapwater …
New service professions:
… household toxin inspector, prenuptial genetic counselor, meme adjustment specialist … indoor microecologist, biotect, prenatal tutor, cerebrochemical balance advisor … Net-SIG consultant, voxpop arbitrageur, ferret designer, insurance lifestyle adjuster …
World human population figures:
1982: 4.3 billion
1988: 5.1 billion
2030: 10.3 billion
• EXOSPHERE
Teresa began her journey home as she had arrived, in the company of Pedro Manella. For probably the last time, she stepped into a little boat to be conveyed through the Cave of Glowing Worms—their living constellations still shimmering in a subterranean mimicry of night. Then she and Pedro took advantage of the darkness to slip behind a flock of whispering tourists, treading well-worn guide paths past phosphorescent signs lettered in a dozen languages. Finally, they emerged on the flanks of a forested mountain, in New Zealand.