Death's End

The envoy had already left, and the dinghy, now occupied only by Cheng Xin and Cao Bin, continued on course to Halo City. A ring-shaped structure appeared in space ahead, and Cao Bin ordered the dinghy to approach it and decelerate. The smooth metallic surface of the ring reflected the stars as long streaks and distorted the image of the dinghy, bringing to mind the Ring that Blue Space and Gravity had encountered in four-dimensional space. The dinghy stopped and hovered next to the ring. Cheng Xin estimated that the ring’s diameter was about two hundred meters across, and the band about fifty meters thick.

“You’re looking at the circumsolar particle accelerator,” Cao Bin said, his tone awed.

“It’s… rather small.”

“Oh, sorry; I wasn’t clear. This is but one of the coils in the particle accelerator. There are thirty-two hundred coils like this, each about one point five million kilometers apart, forming a large circle around the Sun in the vicinity of Jupiter’s orbit. Particles pass through the center of these coils, where they’re accelerated by the force field generated by the coil toward the next coil, where they’re accelerated again…. A particle might travel around the Sun multiple times during the process.”

When Cao Bin had spoken to Cheng Xin about the circumsolar particle accelerator in the past, she had always pictured it as a giant doughnut hanging in space. But in reality, to build a solid “Great Wall” around the Sun, even within the orbit of Mercury, would have been an impossible feat approaching the level of God’s Engineering Project. Cheng Xin finally realized that while an enclosed tubular ring was necessary for terrestrial particle accelerators to maintain vacuum, it was not necessary in the vacuum of space. The particles being accelerated could simply fly through space, being accelerated by one coil after another. Cheng Xin couldn’t help turning to look past the coil for the next one.

“The next coil is one point five million kilometers away, four or five times the distance from the Earth to the moon. You can’t see it,” Cao Bin said. “This is a supercollider capable of accelerating a particle to the energy level of the big bang. Ships are not allowed anywhere near the orbit of the accelerator. A few years ago, a lost freighter drifted into the orbit by mistake and was hit by a beam of accelerated particles. The ultrahigh-energy particles struck the ship and produced high-energy secondary showers that vaporized the ship and its cargo of millions of tons of mineral ore in an instant.”

Cao Bin also told Cheng Xin that the circumsolar particle accelerator’s chief designer was Bi Yunfeng. Of the past sixty-plus years, he had spent thirty-five of them working on this project and hibernated for the rest. He had been awakened last year, but was much older than Cao Bin now.

“The old man’s lucky, though. He had worked on a terrestrial accelerator back during the Common Era, and now, three centuries later, he got to build a circumsolar particle accelerator. I’d call that a successful career, wouldn’t you? But he’s a bit of an extremist, and a fanatic supporter of Halo City independence.”

While the public and the politicians opposed lightspeed ships, many scientists supported the effort. Halo City became a holy site for scientists who yearned for lightspeed spaceflight and attracted many excellent researchers. Even scientists working within the Federation scientific establishment often collaborated with Halo City—openly or in secret. This caused Halo City to be on the cutting edge in many areas of basic research.

The dinghy left the coil and continued its voyage. Halo City was straight ahead. This space city was built along the rarely seen wheel plan. The structure provided strength but had little interior volume, lacking “world-sense.” It was said that the inhabitants of Halo City did not need world-sense, because for them, the world was the entire universe.

The dinghy entered the axis of the giant wheel, where Cheng Xin and Cao Bin had to enter the city through an eight-kilometer spoke. This was one of the least convenient aspects of a wheel plan. Cheng Xin was reminded of her experience more than sixty years ago at the terminal station of the space elevator, and she thought about the great hall that reminded her of an old train station. But the feeling here was different. Halo City was more than ten times larger than that terminal station, and the interior was rather spacious and didn’t look run-down.

On the escalator of the spoke, gravity gradually set in. By the time it reached 1G, they were in the city proper. The science city was made up of three parts: the Halo Academy of Sciences, the Halo Academy of Engineering, and the Control Center for the circumsolar particle accelerator. The city was in fact a ring-shaped tunnel thirty-some kilometers in length. Although it wasn’t nearly as open or spacious as the large, hollow shells of other cities, one didn’t feel claustrophobic, either.