Cixin Liu - Death's End

Vadimov laughed. “Please don’t take offense. But saying we want to throw resources at the problem until the laws of physics bend is going to make our agency the laughingstock of the world. Please don’t repeat it in front of the PDC.”

“I already know you’re all laughing at me.”

Everyone held their tongue. The staff just wanted the meeting to be over. Wade looked at everyone in turn, then returned his gaze to Cheng Xin. “No, not everyone. She’s not laughing.” He pointed at her. “Cheng, what do you think?”

Under Wade’s keen gaze, Cheng Xin felt as if he were pointing a sword at her, not a finger. She looked around helplessly. Who was she to talk?

“We need to implement MD here,” said Wade.

Cheng Xin was even more baffled. MD? McDonald’s? Doctor of medicine?

“But you’re Chinese! How can you not know MD?”

Cheng Xin looked at the other five Chinese in the room; they looked just as confused.

“During the Korean War, the Americans discovered that even common Chinese soldiers taken as prisoners seemed to know a lot about their own field strategies. It turned out that your commanders had presented the battle plans to the troops for mass discussion, hoping thereby to find ways to improve them. Of course, if you become Trisolaran prisoners of war in the future, we don’t want you to know that much.”

A few of those present laughed. Cheng Xin finally understood that MD meant “military democracy.” The others in the conference room enthusiastically supported Wade’s proposal. Of course, these elite experts didn’t expect a mere technical aide to have any brilliant ideas, but they were mostly men, and they thought that by giving her a chance to talk, they would have a perfect excuse to appreciate her physical attributes. Cheng Xin had always made an effort to dress conservatively, but this sort of harassment was something she had to deal with constantly.

Cheng Xin began: “I do have an idea—”

“An idea for bending the laws of physics?” The speaker was an older Frenchwoman named Camille, a highly respected and experienced consultant from the European Space Agency. She looked at Cheng Xin contemptuously, as though she didn’t belong in the room.

“Well, more like getting around the laws of physics.” Cheng Xin smiled at Camille politely. “The most promising resource at our disposal is the stockpile of nuclear weapons from around the world. Without some technical breakthrough, these represent the most powerful sources of energy we can launch into space. Imagine a spaceship or probe equipped with a radiation sail, similar to a solar sail: a thin film capable of being propelled by radiation. If we set off nuclear bombs behind the sail periodically—”

A few titters. Camille laughed the loudest. “My dear, you have sketched for us a scene out of a cartoon. Your spaceship is filled with a pile of nuclear bombs, and there’s a giant sail. On the ship is a hero who bears more than a passing resemblance to Arnold Schwarzenegger. He tosses the bombs behind the ship, where they explode to push the ship forward. Oh, it’s so cool!” As the rest of the staff joined in the mirth, she continued. “You may want to review your homework from freshman year in college and tell me: one, how many nuclear bombs your ship will have to carry; and, two, with that kind of thrust-to-weight ratio, what sort of acceleration you can achieve.”

“She didn’t manage to bend the laws of physics, but she did fulfill the other aspect of the chief’s demand,” another consulting expert said. “I’m just sorry to see such a pretty girl fall under the spell of brute force.” The wave of laughter reached a crescendo.

“The bombs will not be on the ship,” Cheng Xin replied calmly. The laughter ceased abruptly; it was as if she had put her hand on the surface of a struck cymbal. “The probe itself will be a tiny core equipped with sensors attached to a large sail, but the total mass will be light as a feather. It will be easy to propel it with the radiation from extravehicular nuclear detonations.”

The conference room became very quiet. Everyone was trying to think where the bombs would be. While the others were mocking Cheng Xin, Wade’s mien had remained chilly and unmoved. But now, that smile, like water seeping from a crack in the ice, gradually reappeared on his face.

Cheng Xin retrieved a stack of paper cups from the drinking water dispenser behind her and laid them out on the conference table in a line. “We can use traditional chemical rockets to launch the nuclear bombs in advance, and distribute them along the first segment of the probe’s route.” She took a pencil and moved its tip along the line, from one cup to the next. “As the probe passes each bomb, we detonate it right behind the sail, accelerating it faster and faster.”

The men now moved their gazes away from Cheng Xin’s body. They were finally willing to take her proposal seriously. Only Camille continued to stare at her, as though at a stranger.

“We can call this technique ‘en-route propulsion.’ This initial segment is the acceleration leg, and it takes up only a tiny fraction of the overall course. As a very rough estimate, if we use one thousand nuclear bombs, they can be distributed along a path of about five astronomical units stretching from the Earth to Jupiter’s orbit. Or we could even compress it further and distribute the bombs within Mars’s orbit. That’s definitely achievable with our current technology.”

The silence was broken by a few whispers. Gradually, the voices grew louder and more excited, like a drizzle turning into a rainstorm.

“You didn’t just come up with this idea, did you?” asked Wade. He had been listening to the discussion intently.

Cheng Xin smiled at him. “It’s based on an old idea in aerospace circles. Stanislaw Ulam first proposed something like it back in 1946. It’s called nuclear pulse propulsion.”

“Dr. Cheng,” Camille said, “we all know about nuclear pulse propulsion. But those previous proposals all required the fuel to be carried aboard the ship. The idea of distributing the fuel along the spacecraft’s route is indeed your invention. At least, I’ve never heard the suggestion before.”

The discussion grew heated. The assembled experts tore into the idea like a pack of hungry wolves presented with a piece of fresh meat.

Wade slammed the table again. “Enough! Don’t get bogged down on details right now. We’re not evaluating feasibility; rather, we’re trying to figure out if it’s worthwhile to study the idea’s feasibility. Focus on big-picture barriers.”

After a brief silence, Vadimov said, “The best thing about this proposal is that it’s easy to get started.”

Everyone immediately caught on to Vadimov’s meaning. The first step in Cheng Xin’s plan involved launching a large number of nuclear bombs into orbit around the Earth. Not only did humanity possess such technology, the bombs were already on launch vehicles: the ICBMs in service could easily be repurposed for this use. American Peacekeepers, Russian Topols, and Chinese Dongfengs could all directly launch their payloads into near-Earth orbits. Even intermediate-range ballistic missiles, if retrofitted with booster rockets, could do the job. Compared to the post-Crisis nuclear disarmament plans that required destroying the missiles, this plan would be far cheaper.

“Excellent. For now, let’s pause our discussion of Cheng Xin’s en-route propulsion idea. Any other proposals?” Wade looked around the room.

A few seemed to want to speak up, but finally decided to remain quiet. None of them thought their own ideas could compete with Cheng Xin’s. Eventually, everyone’s eyes focused on her again, but this time, the meaning was completely different.