Frequency of Interstellar Civilization Activities

Zhang Yuan quickly established a mathematical model: "Simplely regard the Milky Way as a plane, that is, R^2. Consider one of the spaceships doing standard Brownian motion, or two spaceships doing independent standard Brownian motion.

" When the distance between the two spaceships is less than a small constant, such as 0.01, they are considered to have met. "

"Because the two-dimensional Brownian motion is recurrent in the neighborhood, as long as the time is long enough, the two spaceships will definitely meet. "

"Consider two independent standard Brownian motions A(t), B(t). A(1)+B(1) and A(2) are equally distributed, because B(2)=B(1)+[B(2)-B(1)] is also the sum of two independent standard normals. This means that the distribution of the sum of two independent standard Brownian motions at time t is equal to the distribution of a standard Brownian motion at time 2t.

Zhang Yuan frowned and said, "From this simple model, the probability of observing an alien civilization with a moving spacecraft is twice that of a stationary one. " In other words, assuming that we can observe a civilization capable of interstellar voyages once every 1300 years on average, it takes 2600 years for earth civilization to observe once. "

Lin Xuanxuan opened her small mouth slightly. This is some information that came out of nothing!

She felt a little proud again, and secretly sighed that she had a good vision.

Soon, Zhang Yuan shook his head. This is just a simple model, and the sample is too large. There must be a big difference between the real situation and the estimate.

" If interstellar civilizations are not so rare, then this universe may be more exciting than we imagined! Of course ,

Zhang Yuan is not the only smart person in the spaceship. With such a simple encounter, various ideas have emerged. The

first question: how big is this alien spaceship, and where is it going?

According to astronomical observations, It is at least as big as Mercury! And it is moving at 40% of the speed of light. The light spots are caused by friction and collision between the ultra-high-speed moving hull and the tiny particles in the universe, and then the light is produced.

Because of the extremely high sailing speed, the observed images are stretched a little like noodles.

Its direction of movement is approximately at an angle of 123 degrees to that of the Earth Times, and its destination is unknown. Anyway, it is definitely not the Earth, nor is it Gliese 581.

Seeing this, Zhang Yuan was slightly relieved. Anyway, it has nothing to do with their destination, just like...

The second question, did the alien spaceship discover the Earth Times?

Probably not, the Earth Age name is still too small. In the dim universe, it can be said that you can't see your fingers. If there is no external electromagnetic radiation, it is difficult to find an object 0.12 light-years away.

But the other party once sent a series of short signals, and I don't know whether they were sent in a targeted manner or sent in groups in all directions.

Zhang Yuan clicked on the series of signals, about 600 bytes, and many peaks and troughs were repeated, indicating that it was an electromagnetic signal with logical meaning.

Unfortunately, because the amount of data is so small, it is impossible for people to decipher these alien texts.

Then there is no more, even if the other party reported goodwill, humans would not dare to observe it boldly, let alone write a reply, or scan it with radar. Besides, it is impossible for the radar of the Earth Age to scan something 0.12 light-years away.

Zhang Yuan felt a little regretful, there is never a shortage of matter in the universe, and the most precious thing is information. Human beings who have never communicated with interstellar civilizations, missed this time, and don't know that the next time will be the year of the monkey... Sure enough,

there are many similar views in the following posts.

[The technology of this civilization must be much stronger than ours. ]

[Sure, didn't you see that it was a planet-level spaceship? There should be no way to accelerate this kind of planet to 40% of the speed of light by using nuclear fusion...]

[I think it uses vacuum zero-point energy, or black hole energy. It may be an anti-gravity propulsion device. We don't seem to see the plasma flame at the jet. ]

[It would be great if there were more observational data...]

After all, I have never felt the fear of the unknown. In these recent posts, people's thoughts are indeed more optimistic and open. Itchy, I also want to express some of my own views.

"Look at it, confiscate it!" Lin Xuanxuan snatched his mobile phone, "I'm here today, the patient has to look like a patient. I don't care what you do after you leave the hospital." A week later

, Zhang Yuan was officially discharged from the hospital and started normal work.

He is already a high-level manager. As the aging of the spaceship intensifies, he no longer has a lot of time for himself as before.

His work has become even busier. Basically every week, he will organize a manpower to maintain the entire spaceship.

Moreover, apart from the alien spacecraft that he met by chance, Zhang Yuan also learned that some other stories that happened in the past few hundred years...

are not good things.

The first thing is that the old captain left the spaceship he loved in the third year after he hibernated.

His successor is Captain Lim of the Scientific Council.

Even if I have experienced this feeling many times, even if I am mentally prepared, it is still not so comfortable.

As soon as they opened their eyes or closed their eyes, some people disappeared...

The second thing is, unfortunately, since the death of Mr. Aiding on Earth, the spaceship has completely lost contact with the Earth.

There will never be another great man of his age.

What is going on with the earth's civilization is already a complete unknown.

Zhang Yuanchang sighed, and immersed himself in his work...

A

year passed quickly, sending off one colleague after another, and then it was time for a breakup meal, and hibernation again up.

The only one who can really accompany him for a long time is Lin Xuanxuan, his life partner.

While eating, Zhang Yuan suddenly felt that it is really nice to have someone who is always with him... Without this life partner, life might be even worse.

"...How old are you this year?" Lin Xuanxuan asked.

"Me? Uncle over 1,300 years old, what?" Zhang Yuan just buried his head in his meal.

"Real age!"

"... 30?" Zhang Yuan calculated carefully, and suddenly found that he was thirty years old. And it just so happens that today is my birthday. In this environment, it's really a bit confusing to tell the passage of time, and he has never had the habit of celebrating birthdays.

"30-year-old uncle, happy birthday!" Lin Xuanxuan took out a bright red apple and handed it to him.

"Thank you for this beautiful young lady...and your body temperature!" Zhang Yuan joked. I am used to fighting and fighting, and there will always be an instinctive sense of randomness, just like real relatives.