Rebirth: Starting from Lighting Up the Tech Tree

One hundred days after the Pioneer's return. Zuo Cheng stood in front of the main screen at the Deep Space Tracking and Control Center. One hundred and seventy-seven points of light on the screen slowly rotated. The network covered all the node planets. Ninety-two were sending signals. Ninety-two civilizations across the universe awaited a voice never before heard. Today, humanity would send that voice.

In front of Zuo Cheng was an ordinary microphone. The microphone was connected to a quantum modulator, the other end of which was the deep-space broadcast array of the seventh node of the Web. The array pointed in 177 directions. He spoke a few words. If anyone was waiting on the Web's broadcast channel on any node planet, they would hear these words simultaneously.

The broadcast was simultaneously transmitted in three formats: Chinese, the Founders' Code, and universal mathematical symbols automatically generated by the interstellar communication protocol. The full text of the broadcast was less than two hundred words: We are humankind. We come from the Solar System. We were born on a planet called Blue Star. Our civilization is still young. We have only just learned to fly. We have only just learned to hear. From this day forward, the universe no longer means boundless emptiness. The universe is a community with ninety-two neighbors. We received the first "hello" from the direction of Centaurus. We received the timing signal from the direction of our home port. We heard the wind on the outskirts of the Solar System. That wasn't the wind. It was you. Today, we officially announce that humanity has joined the Web-Weaving Civilization Community. We are not here as guests. We are here as neighbors. We are ready. Please guide us.

The instant the broadcast was sent, the energy output of all nine nodes of the galactic network surged to 98% of their design peak. The deep-space broadcast array injected this message of less than two hundred words into the backbone of the entire galactic network. All screens in the control center flickered simultaneously. Yu Ying stood behind Zuo Cheng, her hand resting on the back of her chair. Chen Hao's coffee cup froze in mid-air. Han Lu opened her mouth, but no sound came out.

Forty-seven seconds. The first response arrived. From the direction of Centaurus. The Listener Civilization's response consisted of only two lines. First line: Welcome. Second line: You took four billion years. But you have finally arrived. Yu Ying whispered behind Zuo Cheng: They have been waiting. In the next hour, more response signals lit up on the Weaving Control Panel. A node at the end of the Orion Arm sent the first one hundred terms of the Fibonacci sequence. A node in the direction of the Galactic Center sent an encoded audio, which, after decoding, was music never heard before. A node on the outer edge of the Perseus Arm sent an image, which, after decoding, was a visible light image of a star. The star's spectral type was exactly the same as the Sun's. It was not the Sun of Earth. It was the Sun as seen by an alien civilization. It was telling humanity: We know what you are. We have seen your star. Within twenty-four hours, fifty-one of the ninety-two active nodes responded. The remaining forty-one remained silent. The signal might be too far away and still en route, the host civilization might not have learned to receive it yet, or they might have already perished, leaving only nodes running automatically. But fifty-one responses mean that on the very first day of humanity's interstellar civilization era, it received greetings from fifty-one civilizations. Zuo Cheng saw a note on the system panel: This is the 10,472nd full-network broadcast since the network was built. Without exception, all the senders of the previous 10,471 have perished. You are the 10,472nd. And also the first still in the ascendant phase. Broadcasting does not represent arrival, but departure. And departure is the most difficult step in the history of all civilizations. The system added an interstellar broadcast log module to record all interstellar communications sent and received by human civilization. Zuo Cheng closed the panel and walked out of the control center.

He didn't go back to his office. He went to the incubator. That small room. There were two lines of text on the whiteboard. The first line was the original text from eleven years ago: We're going to do something different. The second line was written by Shen Yiming a hundred days ago: It's finished. Now we're going to do something even more different. Zuo Cheng picked up a pen and added a third line below: We are human. We come from Blue Star. We are on our way to Centaurus. This is our story. The story isn't finished yet. He put down the pen. Yu Ying stood at the door, holding Zuo Weiyang. Zuo Weiyang blinked as she looked at the newly written words on the whiteboard in her mother's arms. Then she reached out and pointed out the window. The sun was setting. The sunset painted the entire city of Hangzhou golden. Ninety-two civilizations in the universe simultaneously received a greeting from a new neighbor.

As Zuo Cheng walked out of the incubator building, Han Lu handed him a document. The cover read: Preliminary Design Proposal for a Web-like Deep Space Spaceship. The target system: Proxima Centauri. Travel time: ten years. The core technology gap: the twelfth branch. Han Lu said: Eleven branches have been activated; only one remains. Zuo Cheng opened the first page. It listed the spaceship's design parameters: continuous cruising at 50% of the speed of light, dual-mode support of onboard hibernation and a consciousness network, and a crew of fifty. The next page was blank. Han Lu said: "Wait for you to fill it in. You are the captain." Zuo Cheng closed the document, looking at the last glimmer of gold on the horizon. He said: "No need to fill it in. On the day all twelve branches are complete, every word on the first page will become real." On the horizon, the Pioneer's tracklight swept across once more. It had completed all its missions and now circled quietly in near-Earth orbit every day, like a living history textbook placed in orbit. The next spaceship's track would extend from near-Earth orbit to Alpha Centauri. A line forty-two trillion kilometers long. One end of the line is human history. The other end is human future.

Forty-two hours and seventeen minutes after the full-scale network broadcast, the next timing heartbeat from the home port arrived as scheduled. This time, the timing signal carried additional data. Humanity's broadcast had been relayed from the home port to all 177 nodes in the galaxy. The last line of the additional data was the home port's reply. The reply used the Founder's code, containing only one word. Translated into Chinese, it meant "neighbor." For five billion years, the home port had received countless broadcast signals from civilizations. Most were distress calls. A few were farewells. This was the first time someone had said, "We've come to be neighbors." Zuo Cheng wrote a line in the system log: "Sown by the Founder five billion years ago. The technology tree awakened on me eleven years ago. Today, humanity has ninety-two neighbors. The home port will close in three hundred million years unless the network is fully activated. If each generation takes a step forward, the first person will probably have reached Alpha Centauri. The last person will have left the galaxy." Outside the window, the lights of Hangzhou's myriad homes were lighting up. The Pioneer moved slowly in the night sky above. Zuo Weiyang slept soundly in Yu Ying's arms. His life began anew ten years ago in a library. Human life begins anew today in the universe. But the starting point is the same. Someone spoke a sentence in the darkness. Someone heard it. Someone answered. This is civilization.