“I haven’t the slightest idea,” Schmidt said.

“Think, Hart,” Wilson said. He waved at the monitor image. “What happened to the restof the Polk?”

“It probably got vaporized,” Schmidt said.

“Right,” Wilson said, and waited.

“Okay,” Schmidt said. “So?”

Wilson sighed. “You were raised by a tribe of chimps, weren’t you, Hart?” he asked.

“I didn’t know I’d be taking a science testtoday, Harry,” Schmidt said, annoyed.

“You saidit already,” Wilson said. “The ship was probably vaporized. Whoever did this to the Polktook the time to cut, slice and blast into molecules most of it. But they probably didn’t cart all the atoms off with them.”

Schmidt’s eyes widened. “A big cloud of vaporized Polk,” he said.

“You got it,” Wilson said, and the display changed to show a large, amorphous blob, tentacles stretching out from the main body.

“That’s the ship?” Schmidt asked, looking at the blob.

“I’d say yes,” Wilson said. “One of the extra scans I had Captain Coloma run was a spectrographic analysis of the local neighborhood. It’s not a scan we’d usually do.”

“Why not?” Schmidt asked.

“Why would we?” Wilson said. “Searching your immediate environment for molecule-sized bits of frigate isn’t a standard protocol. Spectrographic analysis is usually reserved for science missions where someone’s sampling atmospheric gases. Spaceships themselves typically don’t have to be concerned with gases unless we’re near a planet and we have to figure out how far out the atmosphere extends. And with systems we’ve already surveyed, all that information is already in the database. I’m guessing whoever did this probably knew all of that. They weren’t concerned that an invisible cloud of metallic atoms would give them away.”

“They didn’t think we’d see it,” Schmidt said.

“And normally they’d be right,” Wilson said, and pulled out the view to capture all the other debris fields. “None of the other debris fields show the same density of molecular particles, and what particles there are aren’t the same sorts of metals we use to make our ships.” He pulled the view in again. “So this is almost certainly what’s left of the Polk,and it was almost certainly intentionally attacked and methodically destroyed.”

“Which means that someone leaked the information,” Schmidt said. “This mission was meant to be secret.”

Wilson nodded. “Yes, but that’s not anything you and I have to worry about at the moment. We’re still looking for the black box. The good news, if you want to call it that, is that this narrows down considerably the volume of space we need to search.”

“So we go back to the first scan and start picking through those remaining bits of the Polk,” Schmidt said.

“We coulddo that,” Wilson said. “If we had a month.”

“This is where you make me look stupid again, isn’t it,” Schmidt said.

“No, I’m going to spare you this time because the answer isn’t obvious,” Wilson said.

“That’s a relief,” Schmidt said.

“To go back to your suggestion, even if we did go through the earlier scans, we’d be unlikely to come up with anything,” Wilson said. “Remember that the CDF wants the black box to be found only by its own people.”

“That’s why the black box is black,” Schmidt said.

“Not just black, but aggressively nonreflective,” Wilson said. “Covered with a fractal coating that absorbs most radiation that hits it and scatters the rest of it. Sweep it with a sensor scan and nothing comes back directly. From the point of view of a sensor array, it doesn’t exist.”

“All right, Harry Wilson, supergenius,” Schmidt said. “If you can’t see it and can’t sweep for it, then how do you find it?”

“I’m glad you asked,” Wilson said. “When I was thinking about the black box, my brain wandered to the phrase ‘black body.’ It’s an idealized physical object that absorbs every bit of radiation thrown at it.”

“Like you said this thing does,” Schmidt said.

“Sort of,” Wilson said. “The black box is not a perfect black body; nothing is. But it reminded me that any object in the real world that absorbed all the radiation thrown at it would heat up. And then I remembered that the black box came equipped with a battery to power its processor and inertial dampener. And that the battery is not one hundred percent efficient.”

Schmidt looked at Wilson blankly.

“It’s warm,Hart,” Wilson said. “The black box had a power source. That power source leaked heat. That heat kept it relatively warm long after everything else around it entropied itself into equilibrium.”

“The battery is dead,” Schmidt said. “Even if it was warm, it wouldn’t be anymore.”

“That depends on your definition of ‘warm,’” Wilson said. “The design of the black box means that it has some areas inside of it acting like insulators. Even if the battery’s dead, it’ll take longer for the black box to reach a temperature equilibrium with space than it would if it were a solid shard of metal. I don’t need it to be warm like the inside of this room, Hart. I just need it to be a fraction of a degree warmer than everything else around it.”

The display screen flickered and the ghostly blob of attenuated Polkmolecules was replaced by a thermal map that was a deep blue-black. Wilson gave the thermal map his attention.

“So you’re looking for something that’s ever so slightly above absolute zero,” Schmidt said.

“Space is actually a couple of degrees above absolute zero,” Wilson said. “Particularly inside a planetary system.”

“Seems like an irrelevant detail,” Schmidt said.

“And you call yourself a scientist,” Wilson said.

“No, I don’t,” Schmidt said.

“Good thing, then,” Wilson said.

“So what happens if it has entropied out?” Schmidt said. “If it’s the same temperature as everything else around it?”

“Well, then, we’re screwed,” Wilson said.

“I don’t love your bracing honesty,” Schmidt said.

“Ha!” Wilson said, and suddenly the image in the display pitched inward, falling vertiginously toward something that was invisible until almost the last second, and was an only slightly lighter blue-black than everything around it even then.

“Is that it?” Schmidt asked.

“Let me change the false color temperature scale,” Wilson said. The object, spherical, suddenly blossomed green.

“That’s the black box,” Schmidt said.

“It’s the right size and shape,” Wilson said. “If it’s not the black box, the universe is messing with us. There are some other warmer objects out there, but they’re not the right size profile.”

“What are they?” Schmidt asked.

Wilson shrugged. “Possibly chunks of the Polkwith sealed pockets of air in them. Right now, don’t know, don’t care.” He pointed at the sphere. “This is what we came for.”

Schmidt peered closely at the image. “How much warmer is it than everything around it?” he asked.

“Point zero zero three degrees Kelvin,” Wilson said. “Another hour or two and we would never have found it.”

“Don’t tell me that,” Schmidt said. “It makes me retroactively nervous.”

“Science is built on tiny variances, my friend,” Wilson said.

“So now what?” Schmidt asked.

“Now I get to tell Captain Coloma to warm up the shuttle, and you get to tell your boss that if this mission fails, it will be because of her, not us,” Wilson said.

“I think I’ll avoid putting it that way,” Schmidt said.

“That’s why you’re the diplomat,” Wilson said.

VII.

The discussion with Captain Coloma was not entirely pleasant. She demanded a rundown of the protocol used to locate the black box, which Wilson provided, quickly, his eye on the clock. Wilson suspected the captain hadn’t expected him to locate the black box within the time allotted to him and was nonplussed when he had, and was now trying to manufacture a reason not to let him at the shuttle. In the end she couldn’t manufacture one, although for security reasons, she said, she didn’t release the shuttle pilot. Wilson wondered, if something bad happened to the shuttle while it was in his possession, what good it would do to have a shuttle pilot on board the Clarke. But in this as in many things, he let it go, smiled, saluted, and then thanked the captain for her cooperation.