Rebirth: Starting from Lighting Up the Tech Tree

Eight hundred and thirty meters. Han Lu's hand trembled slightly as she pasted the design drawings onto the white wall. This number meant the new ship would be six times the length of the Pioneer. The Pioneer served only as a scale reference on the drawings, looking as small as a fish. Four hundred days after the Pioneer's return, in the design hall of the 402 Deep Space Headquarters in Hangzhou, a thirty-seven-meter-long white wall was covered with such drawings. In the lower right corner of the drawings was a line of draft: Xinghai (Starry Sea). The name hadn't been officially decided yet, but everyone was already calling it that.

Han Lu turned the design review meeting into a three-week marathon. Three hundred and seventy top aerospace engineers from around the world flocked to Hangzhou in batches, working from 8 am to 10 pm every day, with each drawing undergoing three rounds of cross-verification. Han Lu wrote a rule in the review minutes: any parameter that cannot be independently derived by two people is not allowed to be displayed. Over three weeks, more than four hundred drawings were changed, and discarded drafts filled half a room. Fang Ze wrote a sentence in the acceptance record: "I used to think that the Pioneer's four hundred tons was the limit, but now, looking at the Xinghai's parameters, the Pioneer isn't even a part." Chen Hao leaned over to look at the parameter table, his hand hovering in mid-air. Total length 830 meters, maximum diameter 42 meters, crew of 55, target speed 50% of the speed of light, designed range 4.2 light-years, estimated travel time 8.5 years. The propulsion system was labeled with four words: quantum field driven.

Chen Hao asked, "What is quantum field driving?"

Yu Ying walked to the white wall. She had spent three days reviewing all forty-seven propulsion plans submitted by teams worldwide, ultimately settling on this one. She drew a line on the whiteboard. One end of the line read "human spaceship," and the other end "Proxima Centauri." An ellipse was drawn in the middle of the line. She explained, "The spaceship itself doesn't move. We use the quantum entanglement field between the nodes of the network to create a spatial compression bubble around the spaceship. This compresses the space in front of the spaceship and stretches the space behind it. The spaceship is stationary inside the bubble. But the bubble is moving. Space is moving. This is the essence of quantum field driving. The crew inside the spaceship can walk, eat, and sleep just like on Earth. They won't feel any acceleration."

The meeting room was silent for three seconds. Fang Ze spoke first. "Sounds like surfing." Yu Ying nodded. "Yes. But surfing requires the sea. Our sea is the space itself." Han Lu muttered in the corner, "An 830-meter surfboard, that's pretty extravagant." Liu Wei peeked at the oval on the whiteboard from the back row, then withdrew. He later said that the oval looked like a closed eye, and he didn't know when it would open.

Then Yu Ying turned to the next page. Her tone changed. From the clear and confident explanation of the plan just now, it became something heavier. She said that quantum field drive has three physical bottlenecks. First, propulsion efficiency. We need to convert more than 95% of the energy into spatial curvature modulation. Currently, the highest efficiency that humans can achieve is less than 10%. That's almost ten times less. Second, energy density. The energy power required to maintain the space compression bubble is equivalent to four hundred times the total energy production of all humanity at present. Not four times, but four hundred times. Third, the limits of human endurance. The tidal forces inside the space compression bubble will create shear effects between human organs. Bones and internal organs bear different forces, as do blood vessels and nerves. This difference will be fatal during sub-light-speed travel. A person will be torn apart by different parts of their own body inside the spaceship.

She drew a line under the third bottleneck. "The first two bottlenecks are engineering problems," she said. "Engineering problems can be solved with money and time. The third bottleneck is a physics problem. Physics problems require a natural law that we haven't discovered yet."

Chen Hao leaned back in his chair, silent for a long time. Han Lu's pen circled in her notebook. Fang Ze was scribbling something on his draft paper, head down. No one asked any questions in the meeting room. It wasn't that there weren't any questions, but rather that there were too many, and they didn't know where to begin.

Zuo Cheng sat in the last row of the conference room, silent. The system panel appeared in his mind. The parameters of the three physical bottlenecks corresponded one-to-one with the prerequisites for the twelfth branch. Propulsion efficiency corresponded to the blades driven by the quantum field, energy density to the blades for interstellar navigation, and the limits of human endurance to the blades for space compression navigation. In other words, once the twelfth branch was activated, these three bottlenecks would be broken through simultaneously.

He had the system panel analyze the possible directions of the twelfth branch. The system's response was extremely brief: The activation conditions for the twelfth branch cannot be directly obtained at the current civilization level. The condition information is stored in the core database of the home port. Access permissions: Requires at least three members of the Weaving Civilization Community to submit a joint recommendation to the home port.

Zuo Cheng stared at this line of text for a long time. This was the first time the system had told him he couldn't do it. It wasn't that he didn't have enough points, enough branches, or enough civilization level. It was that he needed someone else's approval. Every step he had taken in the past eleven years was his own. He earned the points himself, activated the branches himself, and improved his civilization level himself. The technology tree had never required him to ask anyone for help. Now it was telling him the door was over there, and the key was in someone else's hands. He suddenly realized something. The first eleven branches tested whether he was strong enough. The twelfth branch tested whether his civilization was good enough—good enough that others would be willing to speak up for him.

On the last night after the three-week review period, only Zuo Cheng remained in the design hall. Yu Ying was asleep in the chair next to him, her coat draped over her lap. Zuo Cheng pulled her coat up to cover her shoulders. Then he walked to the blank space on the far right of the white wall, picked up a pen, and wrote a line. Three bottlenecks. Three letters of recommendation. A spaceship. A decision.

He sat down next to Yu Ying without waking her. He stared at the wall covered with blueprints all night. The Starship on the wall gleamed with a pale blue light under the lamp. The 830-meter line stretched from the left to the right of the blueprint, like a sleeping whale. Outside the window, the Pioneer's tracklight slowly swept across its near-Earth orbit. It had already circled thousands of times. It was unaware that the spaceship that would replace it was still on the blueprints.

In the early hours of the morning, he opened the system panel. The icon for the twelfth branch was still grayed out. But this time, the grayness wasn't due to a lack of conditions. It was because the conditions were in someone else's hands. He wrote a sentence in the system log: This is the first time I need to prove myself to someone else. Before, I only needed to prove myself to myself.

He closed the panel and wrote a to-do list at the end of the log. The first item wasn't design parameters or engineering plans. The first item was: write three letters.