"I vaguely recall calculus," I said. Ed McGuire nodded in agreement.

"Oy," Alan said. "Fine. I'm going to use small words here. Please don't be offended."

"We'll try not to," Ed said.

"Okay. First off, the universe you're in-the universe we're in right at this moment-is only one of an infinite number of possible universes whose existence is allowed for within quantum physics. Every time we spot an electron in a particular position, for example, our universe is functionally defined by that electron's position, while in the alternate universe, that electron's position is entirely different. You following me?"

"Not at all," said Ed.

"You nonscientists. Well, just trust me on it, then. The point is: multiple universes. The multiverse. What the skip drive does is open a door to another one of those universes."

"How does it do that?" I asked.

"You don't have the math for me to explain it to you," Alan said.

"So it's magic," I said.

"From your point of view, yes," Alan said. "But it's well allowed in physics."

"I don't get it," Ed said. "We've been through multiple universes then, yet every universe we've been in has been exactly like ours. Every 'alternate universe' I ever read about in science fiction has major differences. That's how you know you're in an alternate universe."

"There's actually an interesting answer to that question," Alan said. "Let us take as a given that moving an object from one universe to another is a fundamentally unlikely event."

"I can accept that," I said.

"In terms of physics, this is allowable, since at its most basic level, this is a quantum physics universe and pretty much anything can can happen, even if as a practical matter it doesn't. However, all other things being equal, each universe prefers to keep unlikely events to a bare minimum, especially above the subatomic level." happen, even if as a practical matter it doesn't. However, all other things being equal, each universe prefers to keep unlikely events to a bare minimum, especially above the subatomic level."

"How does a universe 'prefer' anything?" Ed asked.

"You don't have the math," Alan said.

"Of course not," Ed said, rolling his eyes.

"But the universe does prefer some things over others. It prefers to move toward a state of entropy, for example. It prefers to have the speed of light as a constant. You can modify or mess with these things to some extent, but they take work. Same thing here. In this case, moving an object from one universe to another is so unlikely that typically the universe to which you move the object is otherwise exactly like the one you left-a conservation of unlikeliness, you might say."

"But how do you explain us moving from one place to another?" I asked. "How do we get from one point in s.p.a.ce in one universe, to an entirely different point in s.p.a.ce in another?"

"Well, think about it," Alan said. "Moving an entire ship into another universe is the incredibly unlikely part. From the universe's point of view, where where in that new universe it appears is really very trivial. That's why I said that the word 'drive' is a misnomer. We don't really in that new universe it appears is really very trivial. That's why I said that the word 'drive' is a misnomer. We don't really go go anywhere. We simply anywhere. We simply arrive arrive."

"And what happens in the universe that you just left?" asked Ed.

"Another version of the Modesto Modesto from another universe pops right in, with alternate versions of us in it," Alan said. "Probably. There's an infinitesimally small chance against it, but as a general rule, that's what happens." from another universe pops right in, with alternate versions of us in it," Alan said. "Probably. There's an infinitesimally small chance against it, but as a general rule, that's what happens."

"So do we ever get to go back?" I asked.

"Back where?" Alan said.

"Back to the universes where we started from," I said.

"No," Alan said. "Well, again, it's theoretically possible you could, could, but it's extremely unlikely. Universes are continually being created from branching possibilities, and the universes we go to are generally created almost instantly before we skip into them-it's one of the reasons why we but it's extremely unlikely. Universes are continually being created from branching possibilities, and the universes we go to are generally created almost instantly before we skip into them-it's one of the reasons why we can can skip to them, because they are so very close to our own in composition. The longer in time you're separated from a particular universe, the more time it has to become divergent, and the less likely you are to go back to it. Even going back to a universe you left a second before is phenomenally unlikely. Going back to the one we left over a year ago, when we first skipped to Phoenix from Earth, is really out of the question." skip to them, because they are so very close to our own in composition. The longer in time you're separated from a particular universe, the more time it has to become divergent, and the less likely you are to go back to it. Even going back to a universe you left a second before is phenomenally unlikely. Going back to the one we left over a year ago, when we first skipped to Phoenix from Earth, is really out of the question."

"I'm depressed," Ed said. "I liked my universe."

"Well, get this, Ed," Alan said. "You don't even come from the same original universe as John and I, since you didn't make that first skip when we did. What's more, even the people who did did make that same first skip with us aren't in the same universe as us now, since they've since skipped into different universes because they're on different ships-any versions of our old friends that we meet up with will be alternate versions. Of course, they will look and act the same, because except for the occasional electron placement here and there, they make that same first skip with us aren't in the same universe as us now, since they've since skipped into different universes because they're on different ships-any versions of our old friends that we meet up with will be alternate versions. Of course, they will look and act the same, because except for the occasional electron placement here and there, they are are the same. But our originating universes are completely different." the same. But our originating universes are completely different."

"So you and I are all that's left of our universe," I said.

"It's a pretty good bet that universe continues to exist," Alan said. "But we are almost certainly the only two people from it in this this universe." universe."

"I don't know what to think about that," I said.

"Try not to let it worry you too much," Alan said. "From a day-to-day point of view, all this universe hopping doesn't matter. Functionally speaking, everything is pretty much the same no matter what universe you're in."

"So why do we need starships at all?" Ed asked.

"Quite obviously, to get where you're going once you're in your new universe," Alan said.

"No, no," Ed said. "I mean, if you can just pop from one universe to another, why not just do it planet to planet, instead of using s.p.a.ceships at all? Just skip people directly to a planet surface. It'd save us from getting shot up in s.p.a.ce, that's for sure."

"The universe prefers to have skipping done away from large gravity wells, like planets and stars," Alan said. "Particularly when skipping to another universe. You can skip very close to to a gravity well, which is why we enter new universes near our destinations, but skipping out is much easier the farther away you are from one, which is why we always travel a bit before we skip. There's actually an exponential relationship that I could show you, but-" a gravity well, which is why we enter new universes near our destinations, but skipping out is much easier the farther away you are from one, which is why we always travel a bit before we skip. There's actually an exponential relationship that I could show you, but-"

"Yeah, yeah, I know, I don't have the math," Ed said.

Alan was about to provide a placating response when all of our BrainPals flicked on. The Modesto Modesto had just received news of the Coral Ma.s.sacre. And in whatever universe you were in, it was horrifying stuff. had just received news of the Coral Ma.s.sacre. And in whatever universe you were in, it was horrifying stuff.

Coral was the fifth planet humans settled, and the first one that was indisputably better acclimated for humans than even Earth itself. It was geologically stable, with weather systems that spread a temperate growing zone across most of its generous landma.s.ses, and laden with native plant and animal species genetically similar enough to Earth's that they fulfilled human nutritional and esthetic needs. Early on, there was talk of naming the colony Eden, but it was suggested that such a name was karmically tantamount to asking for trouble.

Coral was chosen instead, for the corallike creatures that created gloriously diverse island archipelagos and undersea reefs around the planet's equatorial tropical zone. Human expansion on Coral was uncharacteristically kept to a minimum, and those humans who did live there largely chose to live in a simple, almost pre-industrial way. It was one of the few places in the universe where humans attempted to adapt to the existing ecosystem rather than plow it over and introduce, say, corn and cattle. And it worked; the human presence, small and accommodating, dovetailed into Coral's biosphere and thrived in a modest and controlled way.

It was therefore entirely unprepared for the arrival of the Rraey invasion force, which carried in its numbers a one-to-one ratio of soldiers to colonists. The garrison of CDF troops stationed above and on Coral put up a brief but valiant fight before being overwhelmed; the colonists likewise made the Rraey pay for their attack. In short order, however, the colony was laid waste and the surviving colonists literally butchered, as the Rraey had long ago developed a taste for human meat when they could get it.

One of the snippets broadcast to us via BrainPal was a segment of an intercepted food program, in which one of the Rraey's most famous celebrity chefs discussed the best way to carve up a human for multiple food uses, neck bones being particularly prized for soups and consommes. In addition to sickening us, the video was anecdotal proof that the Coral Ma.s.sacre was planned in enough detail that they brought along even second-rate Rraey celebrities to take part in the festivities. Clearly, the Rraey were planning to stay.

The Rraey wasted no time toward their primary goal for the invasion. After all the colonists had been killed, the Rraey transported down platforms to begin strip-mining Coral's islands. The Rraey had previously tried to negotiate with the Colonial government to mine the islands; corallike reefs had been extensive on the Rraey homeworld until a combination of industrial pollution and commercial mining had destroyed them. The Colonial government refused permission for mining, both because of Coral's colonists' wishes to keep the planet whole, and because the Rraey's anthropophagous tendencies were well known. No one wanted the Rraey overflying the colonies, looking for unsuspecting humans to turn into jerky.

The Colonial government's failing was in not recognizing what a priority the Rraey had made coral mining-beyond its commerce, there was a religious aspect involved that Colonial diplomats grossly misinterpreted-or the lengths that the Rraey were willing to go to undertake the operation. The Rraey and the Colonial government had mixed it up a few times; relations were never good (how comfortable can you really be with a race that sees you as a nutritious part of a complete breakfast). By and large, however, they kept to their knitting and we to ours. It was only now, as the last of the Rraey's native coral reefs choked toward extinction, that the extent of their desire for Coral's resources came to slug us in the face. Coral was theirs, and we'd have to hit them harder than they had hit us to get it back.

"It's pretty f.u.c.king grim," Lieutenant Keyes was telling the squad leaders, "and it's going to be grimmer by the time we get there."

We were in the platoon ready room, cups of coffee growing cold as we accessed page upon page of atrocity reports and surveillance information from the Coral system. What skip drones weren't blasted from the sky by the Rraey reported back a continuing stream of inbound Rraey ships, both for battle and for hauling coral. In less than two days after the Coral Ma.s.sacre, almost a thousand Rraey ships hovered in the s.p.a.ce above the planet, waiting to begin their predation in earnest.

"Here's what we know," Keyes said, and popped up a graphic of the Coral system in our BrainPals. "We estimate that the largest portion of Rraey ship activity in the Coral system is commercial and industrial; from what we know of their ship design, about a quarter of the ships, three hundred or so, have military-grade offensive and defensive capabilities, and many of those are troop transports, with minimal shielding and firepower. But the ones that are battleship cla.s.s are both larger and tougher than our equivalent ships. We also estimate up to one hundred thousand Rraey forces on the surface, and they've begun to entrench for invasion.

"They're expecting us to fight for Coral, but our best intelligence suggests they expect us to launch an attack in four to six days-the amount of time it will take us to maneuver enough of our big ships into skip position. They know CDF prefers to make overwhelming displays of force, and that is going to take us some time."

"So when are we going to attack?" Alan asked.

"About eleven hours from now," Keyes said. We all shifted uncomfortably in our chairs.

"How can that work, sir?" Ron Jensen asked. "The only ships we'll have available are those that are already at skip distance, or those that will be in the next few hours. How many of those can there be?"

"Sixty-two, counting the Modesto, Modesto," Keyes said, and our Brain-Pals downloaded the list of available ships. I briefly noted the presence of the Hampton Roads Hampton Roads in the list; that was the ship to which Harry and Jesse were posted. "Six more ships are increasing speed to reach skip distance, but we can't count on them to be there when we strike." in the list; that was the ship to which Harry and Jesse were posted. "Six more ships are increasing speed to reach skip distance, but we can't count on them to be there when we strike."

"Christ, Keyes," said Ed McGuire. "That's five to one on the ships, and two to one on ground forces, a.s.suming we can land them all. I think I like our tradition of overwhelming force better."

"By the time we have enough big ships in line to slug it out, they'll be ready for us," Keyes said. "We're better off sending in a smaller force while they're unprepared and doing as much damage as possible right now. There will be a larger force in four days: two hundred ships, packing heat. If we do our job right, they'll have short work of whatever remains of the Rraey forces."

Ed snorted. "Not that we'll be around to appreciate it."

Keyes smiled tightly. "Such lack of faith. Look, people, I know this isn't a happy hike on the moon. But we're not going to be stupid about this. We're not going to slug it out toe to toe. We're going to come in with targeted goals. We're going to hit troop transports on the way in to keep them from bringing in additional ground troops. We're going to land troops to disrupt mining operations before they get going and make it hard for the Rraey to target us without hitting their own troops and equipment. We'll hit commercial and industrial craft as opportunities present themselves, and we'll attempt to draw the big guns out of Coral orbit, so when our reinforcements arrive, we'll be in front and behind them."

"I'd like to go back to the part about the ground troops," Alan said. "We're landing troops and then our ships are going to try to draw Rraey ships away away? Does that mean for us ground troops what I think it does?"

Keyes nodded. "We'll be cut off for at least three or four days."

"Swell," Jensen said.

"It's war, you jacka.s.ses," Keyes snapped. "I'm sorry it's not terribly convenient or comfortable for you."

"What happens if the plan doesn't work and our ships are shot out of the sky?" I asked.

"Well, then I suppose we're f.u.c.ked, Perry," Keyes said. "But let's not go in with that a.s.sumption. We're professionals, we have a job to do. This is what we're trained for. The plan has risks, but they're not stupid risks, and if it works, we'll have the planet back and have done serious damage to the Rraey. Let's all go on the a.s.sumption we're going to make a difference, what do you say? It's a nutty idea but it just might work. And if you get behind it, the chances of it working are that much better. All right?"

More shifting in chairs. We weren't entirely convinced, but there was little to be done. We were going in whether we liked it or not.

"Those six ships that might make it to the party," Jensen said, "who are they?"

Keyes took a second to access the information. "The Little Rock Little Rock, the Mobile, Mobile, the the Waco, Waco, the the Muncie, Muncie, the the Burlington Burlington and the and the Sparrowhawk, Sparrowhawk," he said.

"The Sparrowhawk Sparrowhawk?" Jensen said. "No s.h.i.t."

"What about the Sparrowhawk Sparrowhawk?" I asked. The name was unusual; battalion-strength s.p.a.ceships were traditionally named after midsize cities.

"Ghost Brigades, Perry," Jensen said. "CDF Special Forces. Industrial-strength motherf.u.c.kers."

"I've never heard of them before," I said. Actually I thought I had, at some point, but the when and where escaped me.

"The CDF saves them for special occasions," Jensen said. "They don't play nice with others. It'd be nice to have them there when we got onto the planet, though. Save us the trouble of dying."

"It'd be nice, but it's probably not going to happen," Keyes said. "This is our show, boys and girls. For better or worse."

The Modesto Modesto skipped into Coral orbital s.p.a.ce ten hours later and in its first few seconds of arrival was struck by six missiles fired at close range by a Rraey battle cruiser. The skipped into Coral orbital s.p.a.ce ten hours later and in its first few seconds of arrival was struck by six missiles fired at close range by a Rraey battle cruiser. The Modesto Modesto's aft starboard engine array shattered, sending the ship wildly tumbling a.s.s over head. My squad and Alan's were packed into a transport shuttle when the missiles. .h.i.t; the force of the blast's sudden inertial shift slammed several of our soldiers into the sides of the transport. In the shuttle bay, loose equipment and material were flung across the bay, striking one of the other transports but missing ours. The shuttles, locked down by electromagnets, thankfully stayed put.

I activated a.s.shole to check the ship's status. The Modesto Modesto was severely damaged and active scanning by the Rraey ship indicated it was lining up for another series of missiles. was severely damaged and active scanning by the Rraey ship indicated it was lining up for another series of missiles.

"It's time to go," I yelled to Fiona Eaton, our pilot.

"I don't have clearance from Control," she said.

"In about ten seconds we're going to get hit by another volley of missiles," I said. "There's your f.u.c.king clearance." Fiona growled.

Alan, who was also plugged into the Modesto Modesto mainframe, yelled from the back. "Missiles away," he said. "Twenty-six seconds to impact." mainframe, yelled from the back. "Missiles away," he said. "Twenty-six seconds to impact."

"Is that enough time to get out?" I asked Fiona.

"We'll see," she said, and opened a channel to the other shuttles. "This is Fiona Eaton, piloting Transport Six. Be advised I will perform emergency bay door procedure in three seconds. Good luck." She turned to me. "Strap in now," she said, and punched a red b.u.t.ton.

The bay doors were outlined with a sharp shock of light; the crack of the doors blasting away was lost in the roar of escaping air as the doors tumbled out. Everything not strapped down launched out the hole; beyond the debris, the star field lurched sickeningly as the Modesto Modesto spun. Fiona fed thrust to the engines and waited just long enough for the debris to clear the bay door before cutting the electromagnetic tethers and launching the shuttle out the door. Fiona compensated for the spun. Fiona fed thrust to the engines and waited just long enough for the debris to clear the bay door before cutting the electromagnetic tethers and launching the shuttle out the door. Fiona compensated for the Modesto Modesto's spin as she exited, but just barely; we sc.r.a.ped the roof going out.

I accessed the launch bay's video feed. Other shuttles were blasting out of the bay doors by twos and threes. Five made it out before the second volley of missiles crashed into the ship, abruptly changing the trajectory of the Modesto Modesto's spin and smashing several shuttles already hovering into the shuttle bay floor. At least one exploded; debris struck the camera and knocked it out.

"Cut your BrainPal feed to the Modesto, Modesto," Fiona said. "They can use it to track us. Tell your squads. Verbally." I did.

Alan came forward. "We've got a couple of minor wounds back there," he said, motioning to our soldiers, "but nothing too serious. What's the plan?"

"I've got us headed toward Coral and I've cut the engines," Fiona said. "They're probably looking for thrust signatures and BrainPal transmissions to lock missiles on, so as long as we look dead, they might leave us alone long enough for us to get into the atmosphere."

"Might?" Alan said.

"If you've got a better plan, I'm all ears," Fiona said.

"I have no idea what's going on," Alan said, "so I'm happy to go with your plan."

"What the h.e.l.l happened back there anyway?" Fiona said. "They hit us as we came out of skip drive. There's no way they could have known where we would be."

"Maybe we were just in the wrong place at the wrong time," Alan said.

"I don't think so," I said, and pointed out the window. "Look."

I pointed to a Rraey battle cruiser to port that was sparkling as missiles thrust away from the cruiser. At extreme starboard, a CDF cruiser popped into existence. A few seconds later the missiles connected, hitting the CDF cruiser broadside.

"No f.u.c.king way," Fiona said.

"They know exactly where our ships are coming out," Alan said. "It's an ambush."

"How the f.u.c.k are they doing that?" Fiona demanded. "What the f.u.c.k f.u.c.k is going on?" is going on?"

"Alan?" I said. "You're the physicist."

Alan stared at the damaged CDF cruiser, now listing and struck again by another volley. "No ideas, John. This is all new to me."

"This sucks," Fiona said.

"Keep it together," I said. "We're in trouble and losing it is not going to help."

"If you've got a better plan, I'm all ears," Fiona said again.

"Is it okay to access my BrainPal if I'm not trying to reach the Modesto Modesto?" I asked.