“Oh no, they are very well supported empirically, they are very precise, very accurate.”
“Both precise and accurate?”
“Well, what, they’re the same, no?”
“No. In estimates of a value, accuracy means how far away you are from the true value. Precision refers to the window size of the estimate. A hundred plus or minus fifty isn’t very precise. But if your estimate is a hundred plus or minus fifty, and the true value is a hundred and one, it’s quite accurate, while still being not very precise. Often true values aren’t really determinable, of course.”
Michel had a curious expression on his face. “You’re a very accurate person, Sax.”
“It’s just statistics,” Sax said defensively. “Every once in a while language allows you to say things precisely.”
“And accurately.”
“Sometimes.”
They looked down into the country of the caldera.
“I want to help her,” Sax said.
Michel nodded. “You said that. I said I didn’t know how. For her, you are the terraforming. If you are to help her, then terraforming has to help her. Do you think you can find a way that terraforming helps her?”
Sax thought about it for a while. “It could get her outdoors. Outdoors without helmets, eventually without even masks.”
“You think she wants that?”
“I think everyone wants that, at some level. In the cerebellum. The animal, you know. It feels right.”
“I don’t know if Ann is very well attuned to her animal feelings.”
Sax considered it.
Then the whole landscape darkened.
They looked up. The sun was black. Stars shone in the sky around it. There was a faint glow around the black disk, perhaps the sun’s corona.
Then a sudden crescent of fire forced them to look away. That was the corona; what they had seen before had probably been the lit exosphere.
The darkened landscape lightened again, as the artificial eclipse came to an end. But the whole sun that returned was distinctly smaller than what had shone just moments before. The old bronze button of the Martian sun! It was like a friend come back for a visit. The world was dimmer, all the colors of the caldera one shade darker, as if invisible clouds obscured the sunlight. A very familiar sight, in fact — Mars’s natural light, shining on them again for the first time in twenty-eight years.
“I hope Ann saw that,” Sax said. He felt chilled, although he knew there had not been enough time for the air to have cooled, and he was suited up in any case. But there would be a chill. He thought grimly of the fellfields scattered all over the planet, up at the four– or five-kilometer elevation, and lower in the mid and high latitudes. Up at the edge of the possible, whole ecosystems would now start dying. Twenty percent drop in insolation: it was worse than any Terran ice age, more like the darkness after the great extinction events — the KT event, the Ordovician; the Devonian, or the worst one of all, the Permian event 250 million years ago, which killed up to ninety-five percent of all the species alive at the time. Punctuated equilibrium; and very few species survived the punctuations. The ones that did were tough, or just lucky.
Michel said, “I doubt it will satisfy her.”
This Sax fully believed. But for the moment he was distracted by thinking how best to compensate for the loss of the soletta’s light. It would be better not to have any biomes suffering great losses. If he had his way, those fellfields were just something Ann was going to have to get used to.
It was Ls 123, right in the middle of the northern summer/southern winter, near aphelion, which along with higher elevation caused the south’s winter to be much colder than the north’s; temperatures regularly dipped to 230 K, not much warmer than the primal colds that had existed before their arrival. Now, with the soletta and annular mirror gone, temperatures would drop further still. No doubt the southern highlands were headed for a record winterkill.
On the other hand, a lot of snow had already fallen in the south, and Sax had gained a great respect for snow’s ability to protect living things from cold and wind. The sub-nivean environment was quite stable. It could be that a drop in light, and subsequently in surface temperature, would not do that much harm to snowed-over plants, already shut down by their winter hardening. It was hard to say. He wanted to get into the field and see for himself. Of course it would be months or perhaps years before any difference would be quantifiable. Except in the weather itself, perhaps. And weather could be tracked merely by watching the meteorological data, which he was already doing, spending many hours in front of satellite pictures and weather maps, watching for signs. It made for a useful diversion when people came by to remonstrate with him for removing the mirrors, an event so common in the week following the event that it became tiresome.
Unfortunately weather on Mars was so variable that it was difficult to tell if the removal of the big mirrors was affecting it or not. A very sad admission of the state of their understanding of the atmosphere, in Sax’s opinion. But there it was. Martian weather was a violent semichaotic system. In some ways it resembled Earth’s, not surprising given that it was a matter of air and water moving around the surface of a spinning sphere: Coriolis forces were the same everywhere, and so here as on Earth there were tropical easterlies, temperate westerlies, polar easterlies, jet-stream anchor points and so on; but that was almost all one could say for sure about Martian weather. Well — you could say that it was colder and drier in the south than in the north. That there were rain shadows downwind of high volcanoes or mountain chains. That it was warmer near the equator, colder at the poles. But this sort of obvious generalization was all that they could assert with confidence, except for some local patterns, although most of those were subject to lots of variation — more a matter of highly analyzed statistics than lived experience. And with only fifty-two m-years on record, with the atmosphere thickening radically all the while, with water being pumped onto the surface, etc., etc., it was actually fairly difficult to say what normal or average conditions might be.
Meanwhile, Sax found it hard to concentrate there on east Pavonis. People kept interrupting him to complain about the mirrors, and the volatile political situation lurched along in storms as unpredictable as the weather’s. Already it was clear that removing the mirrors had not placated all the Reds; there were sabotages of terraforming projects almost every day, and sometimes violent fights in defense of these projects. And reports from Earth, which Sax forced himself to watch for an hour a day, made it clear that some forces there were trying to keep things the way they had been before the flood, in sharp conflict with other groups trying to take advantage of the flood in the same way the Martian revolutionaries had, using it as a break point in history and a springboard to some new order, some fresh start. But the metanationals were not going to give up easily, and on Earth they were entrenched, the order of the day; they were in command of vast resources, and no mere seven-meter rise in sea level was going to push them off stage.
Sax switched off his screen after one such depressing hour, and joined Michel for supper out in his rover.
“There’s no such thing as a fresh start,” he said as he put water on to boil.
“The Big Bang?” Michel suggested.
“As I understand it, there are theories suggesting that the — the dumpiness of the early universe was caused by the earlier — dumpiness of the previous universe, collapsing down into its Big Crunch.”
“I would have thought that would crush all irregularities.”
“Singularities are strange — outside their event horizons, quantum effects allow some particles to appear. Then the cosmic inflation blasting those particles out apparently caused small clumps to start and become big ones.” Sax frowned; he was sounding like the Da Vinci theory group. “But I was referring to the flood on Earth. Which is not as complete an alteration of conditions as a singularity, by any means. In fact there must be people down there who don’t think of it as a break at all.”