“For what purpose?”

“It uses the material it’s in—either concrete, plastic, or steel—as fuel to make copies of itself.”

“Okay. But what’s it do once it’s made enough copies? What’s its purpose?”

“As near as I can tell, that is its purpose. There are structures on it that seem to have other functions, but I can’t say yet what they are. Probably some kind of command and control system.”

Smith let that process for a moment. “Okay, let me get this straight. If I set a bunch of these loose on a piece of concrete, they’ll eat the concrete and spit out replicas of themselves. One will become two. Two will become four. Four will become eight. And so on until they run out of concrete.”

“Unless some of those command and control structures are designed to shut it off, yes.”

“So the weakness in the material is caused by these little robots eating holes in it for fuel.”

“Exactly. The structural problems are just a by-product. The machines aren’t as strong as the surrounding material. It’s like drilling holes in a piece of steel and filling them with Styrofoam. Eventually you’d be able to just break it apart with your fingers.”

“But if these things can eat concrete, plastic, and steel, why not rock? Why not people?”

“There are actually three distinct versions here, each designed to use one—and only one—of those fuels. So if you put them on rock or a person they’d just lie dormant. Like a car with no gas.”

Smith nodded silently. The potential for this as a weapon was obvious. Toss a handful on a tank and eventually it would fall apart as the steel and plastic degraded. Like biological weapons, though, they would create logistical problems. What would happen if a stiff wind blew them back onto your own tank?

“Jon,” Maple started again, reaching out and gripping Smith’s forearm. “I can’t stress enough how dangerous these machines are. I’m not exaggerating when I say they make nukes look like wooden clubs. Remember what I was saying about how these can’t use dirt as fuel? Well, what if I changed the design to make them do just that? They’d start making copies of themselves and their numbers would climb at a geometric rate. Depending on how fast they work, in a few months—maybe even a few weeks—the only thing left of the planet would be endless trillions of microscopic robots fighting over the last bit of fuel to make another copy.”

31

31

Above the Senkaku Islands
East China Sea