Джек Макдевитт - Cryptic - The Best Short Fiction of Jack McDevitt

Her paper had been accepted yesterday by Nature . Letting the cat out of the bag now wouldn’t jeopardize anything. She’d kept everyone, other than Greg, in the dark. Even Tim.

“We classify anything less than thirteen Jupiter masses as a planet,” she began, “because these objects never develop sufficient internal pressure to ignite their deuterium, let alone their hydrogen. Yet we now see objects eight times Jupiter’s mass displaying surface abundances that can only come from deuterium burning. That’s impossible with one thousandth ofa percent deuterium. But deuterium ignition works just fine if these objects are born with eight Jupiter masses and fifty percent hydrogen and fifty percent deuterium, and they’re somehow sparked.” She smiled at Tim, who was sitting looking lost.

“By analogy,” she continued, “a trace of air mixed with gasoline is stable, but a fifty-fifty mixture is highly combustible. A spark would set off a conflagration. Since nature can’t make, or ignite, fifty-fifty deuterium-hydrogen objects, especially near the kind of massive stars that collapse into black holes…” she paused for effect, “…it’s hard to see that the chimeras can be anything other than artificial .”

The room went dead silent. A gust of wind struck the windows and she thought briefly of Kwame’s cabin. At the doorway, a small group of professors had gathered. She wondered whether Greg had alerted his colleagues.

History being made today in the Bishop Library.

Tim looked stunned. “Kristi,” he said, in a voice she did not recognize, “you’re not making this claim seriously?”

“I am,” she said. A wave of guilt passed through her. Maybe she should have taken him aside. Warned him what was coming. “They’re artificial as in synthetic . As in not made by nature . As in manufactured by Little Green Guys . I would argue they were deliberately placed in orbit around black holes that were born without companions. Some of each chimera’s solar wind now falls toward its black hole. That superheats the wind so it radiates X-rays. Hence the chimeras coincide with catalogued X-ray sources. They used to be invisible. Now you can’t miss them.”

Guilt, hell. She was Hubble discovering that the universe extended far beyond the Milky Way, Rubin finding the dark matter that surrounds all galaxies. She was on top of the world. “At first I suspected they were an experiment, test objects of some kind. But that would be an experiment hugely wasteful of resources when you could get away with masses a million times smaller.”

The professors at the door were crowding into the room.

“No, the chimeras’ creators needed something self-luminous, something that would last a long time, but something that would cost as little as possible because they had to make two thousand copies. A fifty-fifty deuterium-hydrogen mixture is the nuclear fuel that can be ignited in the lowest possible host mass. It’s the cheapest interstellar beacon you can make if you insist on a hundred-million year warranty. Nature can’t make these objects. But somebody can.” She took a sip of water as her words sank in.

“The helium makes sense, too,” she continued. “It’s the ash, the by-product of pure deuterium-hydrogen fusion, brought up by convection from the core. The helium content of the chimeras is limited to one percent or less because they’re all younger than a million years. Each one will continue burning its core deuterium and will shine at its present luminosity for another hundred million years.”

Tim was going to say something else but Greg broke in. He was beaming. “Kristi, two of the chimeras are not associated with black holes. What can you tell us of them?”

“One of them,” she said, “is moving at nearly three percent of the speed of light through Taurus. A second is in orbit around a G-dwarf in Scorpius. It’s just under seven Jupiter masses, the lightweight of the entire sample, and the least luminous. I really don’t know for certain, but I’d speculate that the first object is being towed or pushed toward a newborn black hole. And I wouldn’t be surprised if the second one is on the assembly line.”

The applause was tentative this time. Until the people at the doorway joined in.

Greg had a final word: “My initial reaction, when Kristi ran all this by me, was the same as Tim’s. But there’s one more piece of evidence that convinced me. Kristi?”

She was at her charming best, at a moment she would always remember. “A thirty-meter telescope at geosync orbit,” she said, “is an amazing instrument. But the chimeras are faint and I couldn’t find anything but deuterium, hydrogen, and helium in any of their spectra. When I realized that they had to be copies of each other, I removed the Doppler shift of each one and then co-added the two thousand spectra. The result is almost fifty times more sensitive to trace elements.”

She touched the video controller and the summed spectrum appeared, undulating and smooth, with four sharp, narrow dips. “See those four absorption lines? Only one element makes those lines. Plutonium. The nastiest, most dangerous substance we know. “Each chimera is seeded with pure Plutonium-244, which will last as long as the chimera itself. It’s the closest thing to a universal skull and crossbones I can imagine.

“Ladies and gentlemen, the chimeras are beacons. Celestial lighthouses. Space-faring travellers are being warned away from the shoals. Away from the Milky Way’s two thousand solo black holes, which are otherwise nearly undetectable.”

“Magnificent,” said one of the professors. “If true.”

She smiled, as her audience collectively let out its breath. “The evidence is all there, Professor. And, if Greg doesn’t mind, I could use a glass of Cabernet. If we could quit now.”

Greg Cooper had been sitting in the control center of the Weber gravity wave observatory, eating popcorn and calibrating Icewave , when he realized he had about a minute to live.

He’d been writing a letter to Kristi Lang, hinting at the discovery he was about to make public, and suddenly it was over. The order-of-magnitude calculation took ten seconds, and told him he was a dead man. Bad karma. He choked off a wave of panic and self-pity. No time for regret. He knew exactly what was coming. The portholes would fluoresce ferociously, down-converting the X- and gamma rays to optical photons for a few spectacular seconds. The last thing he’d ever see.

Warn the people on Clarke. Get the tourists back inside.

He opened a channel. “Mayday, Ana, Mayday. Incoming hard radiation. Get everyone back onboard, into the shelter. Do it now!”

Five kilometers away, Ana Vassileva, the observatory manager, gaped at the transmission. The real-time solar X-ray images and radiation monitor live feed were working perfectly. It was near solar minimum, so Ana wasn’t surprised to see nothing at all brewing on Sol. “What are you blathering about, Greg? I haven’t seen a sunspot, let alone a serious flare, in weeks. Sol’s asleep.”

“Ana, the local spatial strain went totally offscale twenty seconds ago…. A gravity tsunami just went by. Einstein never dreamed something this big could happen. There’s a gamma ray burst right behind it. Get everyone into the shelter!”

“My God,” she said, “Marnie’s out there in the shuttle.”

Ana wasted no time. She hit the alarm and klaxons sounded through the station and its cash-cow hotel. Tourists dropped everything, crowded in the passageways, and headed toward the water- and lead-lined chamber nestled in the heart of Clarke. A middle-aged woman with blonde hair askew grabbed Ana in the hallway. “What’s going on?” she demanded. “This had better not be a drill, damnit, we had one yesterday.”