Death's End

Widnall zoomed out a bit to get a better sense of the position of the strange new object with respect to the double stars, and to try to observe the spin of the nebula. On the screen, the nebula again turned into a small patch of white against the black abyss of space.

About six thousand AU from the Trisolaran system, he found another “soap bubble.” This one was much bigger than the first, with a diameter of about fifty AU, spacious enough to contain the Trisolaran system or the Solar System.

“My God!” Vasilenko cried out. “Do you know where that is?”

Widnall stared at the screen for a while and said, tentatively, “That’s where the Second Trisolaran Fleet went into lightspeed, isn’t it?”

“Exactly.”

“You’re certain?”

“My old job was to observe this part of space. I know it better than the palm of my hand.”

The conclusion was inescapable: Ships using curvature propulsion left behind trails as they accelerated to lightspeed. The trails apparently did not fade with time, but expanded and altered the nature of the space around them.

The first, smaller bubble was inside the Trisolaran system. There were several possible explanations for its existence. Perhaps the Trisolarans did not know initially that curvature propulsion would leave behind such trails, and the bubble was an accident created during engine tests or test flights; or perhaps they did know about the trails, but left them within the star system by mistake. But it was certain that they wanted to avoid purposefully leaving such trails. Eleven years ago, the Second Trisolaran Fleet had cruised for a full year using conventional means, and only when they were six thousand AU from their home world did they engage the curvature engines to enter lightspeed. The purpose was to start the trails as far from the home world as possible, though by that time it was already too late.

At the time, the behavior of the Second Trisolaran Fleet had puzzled people. The most convincing explanation was that they were trying to avoid ill effects on the home world caused by 415 ships entering lightspeed. However, it was clear now that they were trying to avoid exposing the location of Trisolaris by the trails of curvature propulsion. The Second Trisolaran Fleet had exited lightspeed when it was still six thousand AU from the Solar System for the same reason.

Widnall and Vasilenko stared at each other, and they could each see the terror building in the other’s eyes. They had reached the same conclusion.

“We have to report this right away,” said Widnall.

“But it’s not time yet for our scheduled report. A report now would be treated as an alarm.”

“This is an alarm! We have to tell people not to expose us.”

“That’s a bit of a stretch. We’ve just begun researching lightspeed ships. It would be impressive if we managed to build one in half a century.”

“But what if an initial test generates such a trail? Maybe they’re already conducting such trials somewhere in the Solar System!”

And so this information was transmitted to Fleet Command with an alarm-level neutrino beam, then passed on to the PDC. There, it was leaked and mistaken as a photoid attack alarm, which caused the global panic two days later.

The curvature trails were left behind when ships entered lightspeed, just as a rocket launching from the ground left burn marks on the launch pad. Once the ship was at lightspeed, it continued to coast by inertia, and left no more trails. It was a reasonable conjecture that dropping out of lightspeed would leave behind similar marks. It was still unknown how long such trails would persist in space. A guess was that the trails represented some kind of distortion in space due to curvature propulsion, and might last a long time—maybe even forever.

It was reasonable to conclude that Sophon had claimed Trisolaris appeared more dangerous than the Solar System when observed from a distance because of the ten-AU-diameter curvature propulsion trail left behind within the Trisolaran system, which is what caused the dark forest strike against Trisolaris to come so quickly. The trail and the broadcast of Trisolaris’s location mutually provided confirmation and made the danger value of the Trisolaran system skyrocket.

During the following month, Observation Unit #1 discovered six more curvature propulsion trails in different parts of space. All of these were approximately spherical, though their sizes varied widely, ranging from fifteen to two hundred AU. One of these bubbles was only six thousand AU from the Solar System, apparently the mark left by the Second Trisolaran Fleet as it dropped out of lightspeed. The directions and distances of the other trails, however, seemed to indicate that they had nothing to do with the Second Trisolaran Fleet. It appeared that curvature propulsion trails were common in the universe.