Therefore, Mars is not a key planet for human beings, and there is only such a lonely space city above, which is mostly in the nature of scientific research and transit stations.

Martian enthusiasts are thinking about melting two levels of carbon dioxide to improve the Martian atmosphere for a livable future.

"If, after human civilization, the population explodes, and the earth and the moon cannot live, it will be possible to develop Mars...... Compared to other planets, this planet is still relatively good for people. No extraterrestrial microorganisms have been found so far, and the safety is okay. Senior Brother Zhao suddenly said.

Zhang Yuan responded: "I think there seems to be no such possibility in the foreseeable future. Because the rate of growth of the civilized population is not high. ”

To the extent that natural resources, social systems and productive forces allow, the more the population the better, especially the highly qualified population.

But capitalism is the contraceptive for population growth.

In the old era, limited by resource constraints, the earth's population used to stagnate at 7 billion to 8 billion for a long time.

After the Fourth World War and the "light of nuclear fusion", the entire civilization once ushered in a wave of fertility peaks. But now, the population growth rate is slowly slowing down, and the annual growth rate is less than 1%.

From the current population of 10 billion, it is actually very difficult to grow to 100 billion or even trillions. For many families, having a second child is already a painful thing.

As for the low-quality population in some countries, no amount is of much use.

Zhang Yuan suddenly thought: "If in the future, artificial womb technology and robot raising are developed, do you think it will change this pattern?" ”

Senior Brother Zhao shook his head: "The artificial womb technology has liberated women, and it is a major technology that affects the course of the entire world. With artificial womb technology, what feminist movement can finally stop. ”

“…… But I don't think it's going to change the fundamentals of population growth. Because the important thing about children is nurturing, not the process of giving birth. Parenting consumes a lot more energy than giving birth! ”

"As for machine raising, what a strong artificial intelligence is needed! Moreover, the ethical aspect may be discussed for a long time......"

"On the contrary, I am more worried about the womb revolutionary strategy of some small countries, and the large number of foreign immigrants will lead to a decline in the influence of the main people. The clash of ideologies and cultures is likely to allow bad money to replace good money. This has happened many times in history. ”

Zhang Yuan sighed, "Alas, that's true. ”

After visiting the observatory for a while, Zhang Yuan suddenly discovered that there was an electronic reading room hidden here, called "Star Library", where a small number of people were reading books.

He thought to himself that in this kind of place, people who can still enjoy loneliness must be some top masters. Maybe you can try it later......

After a casual tour, the two turned around and returned to the rail car.

The final stop of the journey is the tail of the mothership, where the fusion engine is located.

Nuclear fusion engine, its maximum ring diameter is more than 400 meters. The tip of the iceberg alone is enough to make people feel shocked.

When he saw this behemoth, Zhang Yuan felt that his heart began to burn.

The long-term work here, the level of happiness and the sense of accomplishment are definitely much stronger than cleaning the cabin.

On a recent inspection screen, a blue-white plasma cluster is being discharged, and various parameters are displayed nearby.

Zhang Yuan squinted his eyes, and he saw a temperature marked on it, about 750 million degrees!

"You're here!"

"Professor Ding."

Seeing a figure emerging from the room in front of him, Zhang Yuan hurriedly said hello.

Academician Ding was learning about the changes in various parameters here, and happened to meet them.

"Zhang Yuan, it seems that you like it here. To fully understand this big thing, you may have to learn some mechanics, nuclear physics, plasma, there are a lot of things to learn. ”

Zhang Yuan is naturally quite positive, "Can I do some work now?" ”

"Read some papers first, if you don't understand, you can ask your brother, you can also monitor the trajectory of plasma turbulence here, and study the structure of the entire engine by the way, for example, the thermal value of helium cold solid cladding, the impact of periodic impact on the helium turboexpander of the cryogenic system, etc., the subject can be chosen by yourself, and I will open a certain database permission for you."

"If you fully understand how the whole engine works, the rest of the space engineering will be trivial to you."

Zhang Yuan answered and found his seat.

He pinned himself to his seat with gusto, trying to find a few papers in the database to read.

Here he was even able to read the control codes of various machines!

Of course, there is only permission to read, not to modify.

Zhang Yuan was very pleased to find that many of the work in the entire nuclear fusion control project was done by his father, and his curiosity and eagerness to try it were naturally even greater.

He thought to himself: "The work on nuclear fusion sounds lofty, if Li Zhendong meets it, I don't know how long I can brag about it......"

Nuclear physics, similar to high-energy physics, is a theory that studies the microscopic depths. Nuclear physics is biased towards horizontal applications, while high-energy physics is biased towards microscopic and deep theories.

But in this era, high-energy physics began to decline.

The main reason is that what can be explored clearly has been gradually explored clearly, and what is not understood is still not understood.

In the 23rd century, the Xia Academy of Sciences once spent a lot of money to build a larger collider, but the final result was that it could not hit any particles that exceeded expectations, and the project became a classic white elephant project.

The Standard Model based on the non-abelian gauge field seems to have become the upper limit for human understanding of nature.

According to the estimates of some scientists, if you want to test a higher theory and discover some physical phenomena that exceed expectations, you need to build a Circumsolar System Collider! In other words, the length of the collider has to circle the solar system.

For humans, it is an impossible task.

This conjecture is known as the "Great Desert of Energy Levels" conjecture.

Matter in nature, under different accelerator energies, will produce very different properties.

At an energy of 10 electron volts, one can observe the disintegration of atoms into nuclei as well as electrons.

In the range of 10^6 to 10^7 electron volts, one can observe the disintegration of the nucleus again, decomposing into neutrons and protons.

At an energy of 10^11 electron volts, electroweak particles can be observed, which is the proof of the electroweak unified theory.

LHCs in Europe were able to reach an energy level of 10^13 electron volts, and the Higgs boson was discovered.

Xia Guo's collider consumed hundreds of billions of funds, and once again raised the energy level to 10^15 electron volts.

And then what?

There was no then, 10^15 electron volts, no new physics was observed

However, the "energy level desert" conjecture holds that at the energy level of 10^24 electron volts, there will be no new physical phenomena. According to the current theory, if you want to continue the study of high-energy physics, please increase the energy level by another billion times!

This is also the origin of the Circumsolar System Accelerator, which requires an accelerator with a circumference of 1,000 billion kilometers to do this.

1,000 billion kilometers!

But that's not all there is to high-energy physics. The 1,000 billion kilometer accelerator is likely to only observe the unity of strong force, electromagnetic force and weak force, and has not yet wrapped gravity into it.

For a thorough study of quantum gravity or the fabled theory of everything, build a 1,000 light-year accelerator, the Ring of the Galaxy!