“I’m loaded with med nanites,” Carlos said. “Top-of-the-line, cutting-edge, full-spectrum health maintenance bots. Why am I the one whose biochemistry is out of whack?”
Because you’re a jerk? As capable as some nanites were, Dana supposed the tiny bots weren’t that perceptive. “Li, any thoughts on that?”
“My guess? It’s because of the nanites. I doubt they were programmed for prolonged cold-sleep conditions. Why would they be?
“With his metabolism slowed way down, bodily functions wouldn’t behave as the nanites expected. His biochemistry being slow to respond to treatment, the nanites would try bigger and bigger dosages. Eventually, at cold sleep’s glacial rate, as his body did react, he’d have way too many nano-synthed meds in circulation. His system would overshoot, and the nanites would have new problems to address—still without proper programming for cold-sleep responses. I’ll have to filter some bots from his blood sample and download the memory files to know for certain.”
Carlos propped himself up on an elbow. “And until then, Doctor?”
“You stay here, under observation.”
With his free hand, Carlos stroked his sheet. “As you wish.”
Dana guessed he would be discharged as soon as humanly possible. Or that he would get a sedative in his IV.
Rikki said, “Any word as to where we are? Why we slept so long?”
“We’re not sure yet,” Dana said. “Blake and Antonio are reviewing the data. In a little while, I’ll check on their progress.”
“Send the men here for a quick eval,” Li said. “And you, too, when you can spare a minute.”
Not till Carlos is gone from the infirmary, Dana resolved. “As soon as it’s practical.”
15
Dana decompressed with a snack and a fresh bulb of coffee before going to look for Blake. By then he had left the bridge. With Antonio and Marvin still babbling in tongues, she headed for the opposite end of the ship.
She found Blake in engine room two, frowning at the fuel readout. An access door had been removed, and instrument cables had been clipped to the paraphernalia within. A signal analyzer sat on the deck.
He followed her gaze. “Half the systems aboard need recalibration. Component properties will drift a lot in forty-five freaking years.”
“I suppose so.” One more thing that might have killed them.
“Is Carlos doing any better?”
“He’s well enough to kid around.” Dana saw no reason to volunteer that the supposed wit encompassed getting naked with Rikki. “How are we doing?”
“We almost didn’t make it,” Blake said.
“How’s that?”
“Our deuterium tanks are about dry.”
“We were supposed to be flying on the DED this whole while,” Dana said. “And I thought the DED drew enough power, from wherever, to also supply shipboard systems.”
“That’s the point.” Blake took a deep breath, then exhaled sharply. “You ready to hear what happened to us?”
“Sure.”
“If you ask me, the core issue is that no one had ever before seen a cosmic string. From a sufficient distance maybe it’s fair to consider it one-dimensional. Antonio and I made that assumption when we modded the nav program.”
“I gather that on approach to the string we got within that magic distance. Marvin mentioned needing the fusion drive to achieve orbit.”
“I wish the problem had only been on approach.” Blake grimaced. “Back to that one-dimensional-line simplification. Time and again Marvin needed both drives to maintain a safe distance.”
“The line isn’t so simple?”
“Back at the university, did you ever catch astrophysicists telling jokes?” Blake asked.
Huh? “Not funny?”
“Funny enough, just odd,” Blake said. “A bunch of their jokes begin something like, ‘Assuming a spherical cow…’”
“I don’t get it.”
“When a real calculation would be too complicated, they assume away the complexity. Imagine a galaxy with billions of stars, all of them in motion, within clouds of dust and gas, within an invisible halo of dark matter. You can’t very well calculate the exact mass distribution. So someone interested in, say, how a particular star will move within the galaxy might begin by assuming the stars and clouds form symmetric disks embedded in a symmetric sphere of dark matter. Just as he might consider that a cosmic string is a one-dimensional thread of uniform density.”
It felt good to laugh. “Got it. So mocking themselves, knowing that they sometimes oversimplify, a cow becomes a perfect sphere.”
“Right.”
Dana liberated a sturdy-looking crate from behind cargo netting, set it on the deck, and sat. “How did our cosmic string differ from a uniform line?”
“How didn’t it differ? Knotted and snarled, maybe. Or the density varies along the string’s length. Or there are overlapping pieces, or a dashed line of pieces, the primordial strings having long ago fragmented.”
Dana shivered. “They fragment?”
“They must have, and repeatedly. The very early universe was very much smaller. Any cosmic strings still intact from that era would have become stretched to millions of light-years, maybe longer. They would have dictated the structure of entire galactic clusters.”
“Okay, then,” she said. “Knotted and snarled and whatever. With none of that complexity in the nav program.”
“Uh-huh. And if we had crashed into the string…”
As thin as a proton, Dana remembered. “We’d have been sliced in two?”
“According to Antonio, each klick of length along the cosmic string has a mass comparable to Earth’s.” Blake paused. “So, yeah. Picture a dandelion puff meeting a chainsaw.”
After the fact, Dana saw that she had taken a lot on faith. Forty-five years after the fact. Such as trusting Marvin to navigate the ship along a cosmic string. How does one follow something too thin to see?
Cut yourself some slack, she chided herself. It’s not like you had the time to think about it, or decent options. And remember: we survived.
She said, “I still want to know what happened to us, and where we are. Did you coax either from Marvin?”
“More Antonio’s doing than mine, but yes. You remember how he first found the cosmic string?”
“Microlensing. There were enough background stars microlensing to navigate by?”
“Nothing so straightforward.” Blake hunted around the engine room until
