This is Zuihou away from the sun once, this time away, there will be no return.

As the distance got farther and farther away, the sun became more and more dim, and Xiao Yu's mood became a little heavy for no reason.

The road ahead is long, and what awaits Xiao Yu will be a long journey of 10.5 light years, and a long time of 6,300 years.

What kind of strange things will happen during your trip? What kind of dangers will be encountered? Xiao Yu didn't know. But Xiao Yu still decided to go. What dominates a scientist's mind is a crazy desire to explore, so crazy that even life can be sacrificed.

Therefore, Xiao Yu did not choose to continue to develop in the solar system, but immediately chose to set off after obtaining the ability of interstellar navigation.

In fact, to be precise, Xiao Yu's current technology can only be said to have obtained the ability to travel interplanetally. Because at the speed of nuclear fusion power, interstellar navigation is enough for thousands of years to keep out all living beings with a lifespan of less than 10,000 years. However, after Xiao Yu combined with the computer, he abandoned his physical body, only his spirit, and his lifespan was almost endless.

Humans have calculated that the minimum threshold for interstellar voyage is to reach 5% of the speed of light, which is 15,000 kilometers per second. In this case, it would take about 200 years to reach the Tianyuan Four Galaxy from the solar system, which is already within an acceptable range compared to the lifespan of human beings at that time.

However, before the development of a new generation of engines, the speed of 15,000 kilometers per second was a bit extravagant for Xiao Yu.

Once again, returning from Jupiter to Titan, Xiao Yu did not land. On Titan, two large photonic computers have been transplanted by Xiao Yu to the Sun and Yuanhang respectively, and the current base is completely controlled by the computers on the small spaceship at the beginning.

Although it seems to Xiao Yu that this computer is too backward and the computing speed is too slow, but now on Titan, ninety-nine bases have stopped running, all kinds of machinery have been mothballed, and only some simple maintenance tasks are left, which are left to this computer to do, which is enough.

Titan's atmosphere has very low oxygen levels and low temperatures, so you don't have to worry about rust and damage to your machinery. Xiao Yu hopes that these machines and equipment can survive for a long time, and that they will still be intact after tens of thousands of years.

Because a large part of Venus's atmosphere has been stripped away, resulting in a decrease in the surface temperature of Venus, it is likely that intelligent life will evolve on Venus in the infinite future. Therefore, Xiao Yu hopes that these things he left behind can point out a little direction of evolution for the intelligent creatures on Venus, and by the way, also in the solar system, leave a little evidence of the existence of human beings.

Looking at Titan shrouded in fog in space, Xiao Yu's heart was full of emotion.

"Twenty years, that's it." Xiao Yu was silently thinking in his heart.

In the blink of an eye, twenty years have passed since I left the earth.

In the past 20 years, a lot has happened, and the time of living on earth without worries seems like just yesterday.

Scenes of the past flowed through Xiao Yu's heart.

The first time I was away from Earth, the fear of facing a collision between the wood and the moon, the surprise of eating a big meal for the first time, the difficulty of moving on Titan, the excitement of mastering controlled nuclear fusion, and so on, one by one, one by one.

"Let's go, let's go, in the solar system, although safe, although comfortable, but without experiencing wind and rain, how can there be great achievements. Let's go, let's go, the boundless universe is the ultimate goal of my exploration. ”

Xiao Yu threw thousands of thoughts out of his mind, manipulated the huge fleet, and flew towards Saturn.

In the Saturn system, Xiao Yu will do a refueling trip, and then, Xiao Yu will leave the solar system and set off for Tianyuan IV.

Xiao Yu frantically replenished fuel, stayed in Saturn's atmosphere for half a month, and left Saturn until he couldn't fit it anymore.

After Zuihou reluctantly glanced at Titan, Xiao Yu resolutely moved forward and galloped towards the outer solar system.

At this time, Xiao Yu had already filled half of the spaceships of the entire fleet, including the three county-level spaceships, the Yuanhang, the Sun, and the Tianyuan, as well as nearly five hundred village-level and township-level spaceships, with all kinds of supplies. If it weren't for the fact that some of the spaceships had to be mobile in order to deal with possible accidents, Xiao Yu even had plans to load all the spaceships with supplies.

During this period of time, Xiao Yu has deeply realized a truth. In the universe, the place where meteorites fly around is not the most dangerous place, but the most dangerous place is the empty place. Because there, any star has a distance of at least thousands of years, there is nothing, and if something happens, you can't get any supplies, you can only wait for the energy to run out, and then die, turning into a cold cosmic stone, drifting with the tide in infinite time.

This is only a galaxy-level voyage, and if it is a river-level voyage, it is even more terrifying. There, in order to get a piece of scrap iron, you may need to travel at the speed of light for millions of years.

The long time is the biggest enemy of interstellar navigation.

Xiao Yu was full of thoughts, thinking about things wildly, while manipulating the fleet to slowly accelerate. At the beginning, when he left the earth, Xiao Yu was extremely eager to leave the solar system, but when he really wanted to leave the solar system, Xiao Yu was reluctant to give up.

Xiao Yu remembered someone. It was a girl, very young, very beautiful, full of energy, pure and lovely. When she was still on Earth, this girl was a researcher at Xiao Yu's research institute.

That girl likes Xiao Yu, but Xiao Yu is all about science, disdainful of the relationship between men and women, and even criticized the girl because of this incident, causing the girl to leave Xiao Yu's research institute gloomily.

Xiao Yu never thought that he had done anything wrong, but at this time, Xiao Yu actually had a little regret in his heart.

"She's ...... now. Dead, right? With seven billion human beings, they have entered death together. But it seems that since she left the institute, and then until the destruction of the earth, for a total of seven years, I have not received any information from her, and I don't know what happened to her. ”

Xiao Yu thought, manipulating the three-dimensional color projector of the Sun, weaving a figure out.

In the cabin of the Sun, with the movement of the three-dimensional color projector, a girl gradually appeared.

"Well, no, her eyes should be bigger. Uh, well, a little thinner waist, a little more stiff nose, a little bigger breasts......"

Xiao Yu modified various data, and gradually, the three-dimensional color projector projected the figure of a smiling girl in the air.

She just stood there, looking ahead with tenderness in her eyes, as if she had a lot to say.

Xiao Yu generated a piece of code, and after executing it, the girl made a sound.

"Director Xiao, are you okay?"

Her voice was gentle, shy and timid, exactly the same tone as what she said on Earth.

Xiao Yu looked at her figure in a daze, and muttered, "Chen Mo, I'm fine, I'm still alive, what about you?" ”

"I'm dead, I died twenty years ago." The girl said with a slight smile.

"Yes, you are dead, you died twenty years ago, and I, have gained infinite life. But I don't have a body anymore. Xiao Yu said gloomily.

Stripping the body from the mind is a very risky act. When he was on Earth, Xiao Yu happened to get an unknown substance from the universe, and after studying it for several years, he took great risks to strip his spirit from his body. Before he fully mastered all the qualities of this substance, Xiao Yu would never dare to take risks again.

In other words, even if there is another body, Xiao Yu will not choose to combine with it. Because of the combination, Xiao Yu will not be able to come out, and Xiao Yu will be restricted by his body again, and he will be born, old, sick and die.

"Chen Mo, wait for me, wait for me to fully grasp the genetic code of human beings, I will resurrect you." Xiao Yu muttered.

When he left from the earth, Xiao Yu had a human gene bank and sperm bank, but when he was dodging the collision of the wood and moon, he was hit by a meteorite and lost all of them.

"I'll wait for you." Chen Mo smiled slightly, and after saying this, Chen Mo's body turned into a piece of light and shadow in an instant and disappeared.

"When you are resurrected, I will accept your confession." Xiao Yu whispered, looking at the light and shadow that Chen Mo's body turned into in a daze.

"Hu ......" collected his mind from his infinite thoughts, Xiao Yu sighed lightly, put aside these chaotic thoughts, and continued to manipulate the huge fleet to escape towards the outer solar system.

Gradually, a few months passed in a flash.

Xiao Yu's fleet has reached the orbit of Uranus.

"It's almost time to reach the orbit of Uranus, and here, leave a tombstone of human civilization." Xiao Yu thought.

Uranus's orbit is about 2.7 billion kilometers from Earth's orbit. Looking at the Sun from the orbit of Uranus is just a bright spot in the sky, and it is no longer possible to see the essential difference from the rest of the stars.

Xiao Yu sighed, using his reserves of metal materials to build a tombstone, and using nuclear fusion jishu to create a battery, a battery that can last at least millions of years, to power an everlasting lamp.

This tombstone will revolve around the sun on a cycle of 130 years, and for up to a million years, this everlasting lamp will remain on, illuminating the line engraved on the tombstone.

"The Tomb of Seven Billion Humans!"

"One of the human beings, Xiao Yuli!"