Starfire

28

As soon as John was settled in front of the displays, Wilmer Oldfield turned to Amanda Corrigan. “Ready to begin? It’s your discovery.”

“But I had no idea what I’d found.” Amanda wriggled in embarrassment and looked at the audience. Seven people, including Maddy hovering at the back. That was too many for Amanda’s comfort. She turned back to Wilmer Oldfield. “You explained it to me. Can’t you talk about it?”

“I’ll do the first bit, then we’ll see.” Wilmer moved to the display control panel and glanced at John. “Ask questions anytime, because I don’t know the best place to start. Let’s go with the first Sniffers we sent out, and what they measured. They were high-acceleration probes with low-cross-section instruments.” He moved the pen across the control pad, and a thin, wobbly line with a distinct curve appeared on the display.

Wilmer stared at it with disgust. “These bloody gadgets. Isn’t there a board someplace that I can draw on?”

“Behind you.” Lauren Stansfield stepped over to a wall and opened two small doors to reveal a white board. Maddy noticed that Lauren alone, of all the people in the room, was wearing custom-made clothing. The pin on her left breast glowed with the varying colors of a fire opal. Expensive — even if no one else in the room but Maddy knew it.

“Write with this,” Lauren went on. “Erase with this pad — a touch is enough, the pen is electronic.”

“Right.” Wilmer drew a small circle. “Here we are. And here’s Alpha C.” Another small circle. “And here’s the path of a Sniffer.”

He drew a wavering line between the two stellar systems. To Maddy’s eye it was no better than his effort at the control panel, but Wilmer nodded at it in satisfaction.

“Good enough. Now let’s look at the particles flung out by the Alpha C supernova. If you didn’t know any better, you’d expect them to spread out pretty much equally in all directions. Spheres, like this, expanding in time.”

He drew a set of rough circles, each centered on the point that depicted Alpha Centauri.

“If that’s what was happening, the particle density would go down as the inverse square of the distance from the supernova, as the surface area they pass through goes up. Then the number of particles that a Sniffer measured would be less for the Sniffers that were launched later, simply because they meet the particle flux farther from Alpha C.

“But we know that the particles and radiation didn’t come out equally in all directions — the gamma pulse proved that twenty-seven years ago. Instead, a shell of gases around the supernova bottled up everything inside. That shell expanded and thinned, until finally it was weak enough to rupture. Then everything — gamma rays and particles — could squirt out from inside in one particular direction. Like this.”

Wilmer erased the set of spheres and replaced them with a narrow cone, its point on Alpha Centauri and its axis running toward the solar system.

“Think of it like a searchlight beam. No matter how tightly focused the beam is, as you go farther away from the searchlight the circle of light that it throws gets bigger, and the brightness of the light in that circle becomes less. With lasers, the spread can be very small, so sometimes it looks like the beam’s not spreading at all. Sort of like this.”

He replaced the cone by a long, narrow cylinder, running between Alpha Centauri and Sol.

“That looks like the worst case imaginable.” Wilmer laid down the marker. “For it to happen, the particles thrown out by Alpha C would have to come straight at Sol, with no beam spreading at all. Looked impossible, so we didn’t worry about that case. The most reasonable situation seemed like the second one, the particles lying in a narrow cone that gradually widened as they went farther from Alpha C. And that’s exactly what the first Sniffers found. Sniffer-B met the particle wave farther away from the supernova, and the particle counts that it measured were less than for Sniffer-A. The density was falling like the inverse square of the distance. No worries.

“Then we get the latest Sniffer data. It meets the particle wave much closer to Sol and farther from Alpha C, and it’s also a different instrument design. Not easy to compare results. But your gal did it.” He nodded toward Amanda Corrigan, who blushed like an eight-year-old. “First thing she finds is bad news. We have the blip storm on the way real soonish, and we’re no way ready for it. You’ve all been working to batten down before it gets here. But Amanda noticed something else about the blip measurements. They didn’t match the blip that she could pull out of the old Sniffer data, once she knew to look for it. The most recent Sniffer data was taken farther from Alpha C, close to us. The particle counts in the blip should have been lower than in the old data — the inverse square falloff — or, at the very worst, no bigger. But the data don’t show that. They show the number of counts per unit volume increasing as the storm gets closer to the solar system. And that seemed flat impossible.”

Wilmer picked up the marker again and stepped to the board. “Star and me happened to be around, so Amanda came to us. The only thing we could think of was the obvious one. The particle beam pattern isn’t doing any of the things I drew. It’s doing this.”

He drew two wobbly curved arcs from Alpha Centauri toward the Sun, making a form like a very long and thin cucumber. “The particle beam spreads until it gets to here.” He marked a point roughly halfway between the two stellar systems. “Then it begins to converge again as it approaches Sol.”

Wilmer placed the marker carefully back on its holder and went to sit down. No one spoke until John asked, “Converges? Converges how much?”

“Not my department.” Wilmer turned to Amanda Corrigan. “How much?”

“I don’t know. We don’t have enough data points yet to make a good extrapolation.”

“We need an answer, even without data. Wilmer? Can theory help?”

“I can only go back to what Star has been saying all this past month. Alpha C didn’t just blow up and randomly squirt radiation and particles this way. It was made to explode. The gamma pulse and the particle beam were made to aim right for us. If you’ll accept those as working assumptions, plus a few other things, then we can calculate an answer.”

“Made to happen?” One of the data analysts spoke — Raymond, thought Maddy. No, Raoul. “You mean somebody out there decided to make a supernova, just so they could wipe out humans? You’re saying aliens exploded Alpha Centauri?”

Wilmer frowned. “You have expanded on Star’s hypothesis. She did not say that, and I am saying only that we are involved in an event inconsistent with the standard theories of stellar evolution.”

“But if it’s not that, and aliens—”

John interrupted. “We’ll worry about alternative theories later. You say that you’ve done a calculation and have an answer?”

“Star has.” Wilmer nodded to his young protégé, who was bouncing excitedly on the edge of her seat. “Go on, girl. Tell ’em, before you burst.”

“Yer have ter make some more assumptions before yer can get an answer.” Star hopped up and went to the board. “Like, symmetry about the midpoint, and a parametric form for the strong-force modification that we assume holds the particle bundles together. But given that, and assuming that everything else goes linearly, the best guesstimate I can make says we get hit with everything emerging from a solid angle of one two-hundredth of a steradian of Alpha C. That’s instead of everything coming from mebbe one three-thousandth, if we had a spreading cone.”

“Translation?” said Lauren Stansfield. “I can’t think in those units.”

“The blip storm that arrives tomorrow will be about fifteen times as severe as we thought,” Wilmer said. “It’s not a blip anymore.”

“A factor of fifteen. That’s bad, but not totally disastrous.” Lauren Stansfield was examining a sheet of notes. “Sky City will survive. From what Will says, the shield won’t be totally destroyed. Earth will be worse off.”

“Maybe.” John had been watching Wilmer Oldfield’s face. “That’s not the whole story. Is it?”

“Looks like not. The convergence we’re talking about applies to the whole particle flux, not just the small peak. Assuming Star’s numbers hold up — we’ll have a better test of that when the latest Sniffer hits the wave front — then everything scales by the same factor. The maximum particle density will be up by a factor of fifteen. Same factor for the energy that hits Earth.”

“Fifteen.” John was already moving to the message console. “I assume the direction the particles comes from doesn’t change.”

Wilmer shrugged. “Tiny bit. Not enough to notice — the beam convergence factor is less than one in a thousand. It’s the energy delivered that we have to worry about. Without convergence, we predicted a maximum energy per square meter hitting the top of Earth’s atmosphere at about three thousand watts per square meter. That compares with about fifteen hundred watts per square meter coming from the Sun as radiation. Now we’re saying the energy from the particle storm will peak at more like forty-five thousand watts per square meter.”

“Thirty times as much as the Sun?” John was opening simultaneous circuits to Bruno Colombo, Nick Lopez, and Urbain Tosca. Let Bruno be as mad as he liked over the breach of regular protocol.

“Thirty times as much energy as the Sun,” Wilmer corrected. “But it’ll be coming in a very different form. Instead of light you have charged particle bundles. We’ll have strong forward scattering, tons of ionization, and God knows what secondary effects.”

“One worry at a time.” The lines were opening, and John could hear startled voices at the other end. Direct messages from the Sky City engineering information center were without precedent. “I ought to have known that something like this was going to happen — the work on the shield and the field generators has been going too smoothly.”

Maddy, ignored at the back of the room, wondered if she had misunderstood everything. She had followed few of the exchanges, except Raoul’s suggestion that the whole Alpha Centauri supernova had been intentional and created by aliens. But regardless of explanations, weren’t they saying that in less than two days Earth would be hit by a particle storm thirty times as bad as anyone had expected? And if that was the case, why was everyone so calm?

She knew the answer. No wailing, no moaning about the imminent end of the world — because everyone with her was either an engineer or a physicist.

Maddy looked around, inspecting the others one by one. You didn’t have to go all the way to Alpha Centauri to find aliens. There was a roomful of them right here.