Interstellar migration is no longer just a fantasy: controlled nuclear fusion technology will make everything possible.

The history of human civilization is the history of discovering and utilizing energy. Primitive people learned to use fire to promote human evolution tens of thousands of years ago, people learned to use gunpowder to change the form of war thousands of years ago, the improved steam engine pushed people into the first industrial revolution 200 years ago, 140 years ago, the invention of generators and motors brought people into the "electrical age", 80 years ago, the application of oil and nuclear energy continued to change people's lifestyles, and now it is the turn of controlled nuclear fusion.

We all know that the earth goes around the sun and receives the light and heat of nuclear fusion from the sun. If humans can master controlled nuclear fusion technology, they can build stars similar to the sun as needed. Building some satellite cities around artificial stars, on the one hand, can meet the needs of expanding human living space, on the other hand, it can also explore more distant planets based on artificial galaxies. In fact, this theory was put forward by physicist Freeman Dyson as early as 1960. In Freeman Dyson's theory, human beings can build a celestial body to wrap the sun, so as to absorb the energy of the sun to the maximum extent and use it for human beings. Therefore, people are used to calling this artificial celestial body "dyson sphere". However, due to technical limitations, "Dyson Sphere" has been in the imagination stage. Now people have officially launched a substantial impact on the threshold of controlled nuclear fusion's technology, and it is only a matter of time to break through controlled nuclear fusion's technology.

There is also the "Kardashev" rating which is supported by the "dyson sphere" theory. 1964, the Soviet astronomer Kardashev divided the biological civilization in the universe into three grades according to the degree of energy application. 1 civilization means that life on the planet can effectively discover and use the energy on this planet and satellites. At present, mankind has not fully mastered and utilized the energy on the earth and the moon, which belongs to the level of 0.75 civilization. Level 2 civilization means that the living things on the planet can effectively discover and use the energy in the star system. When humans can effectively use most of the energy in the solar system, they can be considered as level 2 civilization. The symbol of tertiary civilization is that life on the planet can effectively discover and use the energy in large galaxies. According to this symbol, human beings should make effective use of the energy in the Milky Way to be considered as a third-level civilization.

At the same time, the degree of civilization can also reflect the space flight and communication ability of organisms to a certain extent. 1 civilization can realize the communication between the parent star and the satellite, the second civilization can realize the communication between the planets, and the third civilization can realize the communication between the galaxies. At this time, other planets already have more advanced alien civilizations than human civilization, so they at least have the ability to fly between planets. In an ideal state, if the planet where a civilization is located is in a stable stage, it will not be hit by celestial bodies. As long as there is enough time, it will definitely evolve and upgrade. If human beings can maintain the current high-speed development, it may take hundreds of years to realize the communication between planets, and it will take thousands of years to break through the communication between galaxies. At that time, time, distance and energy may not be the three major factors that hinder the communication between galaxies, and I dare not imagine what the earth will look like in a thousand years.

Theoretically speaking, even if human beings don't actively look for alien civilization, if there is a higher level of alien civilization, they will actively look for human beings. But at present, human beings will remain lonely for a long time to come, and even the evidence of the existence of alien creatures has not been found, let alone alien civilization. Looking at it from another angle, it is not excluded that the vastness of the universe is to avoid easy contact between two advanced civilizations. After all, when civilizations of different systems interact with each other, there is a high probability that they will fight for living space and energy. It can also be said that the discovery of alien civilization is a kind of protection for mankind.