When can humans migrate to other planets?

Moving to another planet is a long-cherished dream of mankind. Stephen Hawking, a famous physicist, recently accepted the Copley Medal awarded by the Royal Society, saying that human beings must emigrate to other planets in order to get rid of the fate of extinction. Hawking believes that as long as human beings are trapped on a unique planet, their long-term survival is in danger. Threats such as asteroid impact on the earth and nuclear war will destroy us sooner or later. However, if we expand into space and build self-sufficient settlements, our future should be secure. There is no place like the earth in the solar system, so we must find another planet and use more advanced space rockets to help people move to a planet suitable for survival. This is the second time in six months that he has made such amazing remarks.

Griffin, director of the National Aeronautics and Space Administration (NASA), also said that historically, species on a single planet cannot survive forever. "We have conclusive evidence that, on average, every 30 million years, species on earth will suffer mass destruction; One day we will definitely immigrate to another planet, but I don't know when that day will be. "

There are four criteria for migration destination.

What difficulties need to be overcome in emigrating to another planet, and when will it be realized? The first level of immigration: where to migrate. At the beginning of the 20th century, some people thought that Mars and Venus might be good choices, but NASA soon found that other planets around the sun were not suitable for us to live in. People on the surface of Venus must live at a temperature high enough to melt lead. As for Mars, living on it is like living twice as high as Mount Everest.

Dr. Margaret Tenbar, an astronomer at the Carnegie Institute in Washington, DC, summed up four criteria of "the most suitable galaxy for life": 1, at least 3 billion years, enough to form planets and show complex life; 2. The volume of the central star should not exceed 1.5 times that of the sun, otherwise it is difficult to produce planets suitable for life; 3. There should be enough iron to form Earth-like planets; The central star should be neither a red giant nor a white dwarf, so that the complex life on the surrounding planets can exist for a long time. According to this standard, he concluded that there are five galaxies in the universe that meet the standard: one is CVn, the dog constellation 26 light years away from the earth; The second is HD10307; , 42 light years away from the earth; 3. HD 2 1 14 15, and its metal content is about half that of the sun; The fourth is Scorpio SCO18; ; Fifth, Pegasus 5 1.

Level 2: How do humans get to these planets? According to calculation, Alpha Centauri, the closest star to the Earth, is about 4.23 light years. At the current speed of the space shuttle, it will take 158000 years to arrive. This requires the vehicle to reach the speed of light. The American sci-fi movie Star Trek sets such a background: in the middle of the 20th century, engineer Koklen invented the "warp drive" which can fly faster than light. Because "warp speed technology" is the threshold to enter the galactic civilization family, human beings have been accepted into the interstellar Federation, and the level of civilization has reached a new level. In fact, scientists are moving towards this goal. According to New Scientist magazine, the US Air Force and NASA are currently secretly studying a "hyperspace engine". Scientists expect to make a prototype of "Hyperspace Engine" and test it within five years. Once the "hyperspace engine" is proved to be feasible, it only takes three hours to get from the earth to Mars, and it takes 80 days to get from the earth to the planet with a distance of 1 1 light-year. Some scientists predict that the time to actually manufacture a suitable spacecraft and fly to the destination planet will be in the 26th century, and the estimated arrival time is 65,438 years.

The third level: how to solve the problem of life support after human beings arrive at the planet. The United States, Russia and other countries have cultivated peas, wheat, corn, rice, onions, orchids and other plants 100, and animals such as fruit flies, spiders and fish can also grow and reproduce in weightlessness. If this technology can be applied to the future planet, the problem of human survival will be solved.

However, it is also a question whether human beings can reproduce after living in weightlessness for a long time. A French scientist found that under weightlessness, the important structure of living cells can't be formed normally, which means that human beings can't survive and reproduce in near weightlessness for a long time. However, some scientists say that after human beings settle on another planet, the race and body structure will also change with the environment, and perhaps the problem of reproduction can be completed in another way.

return to earth

Moving to other planets seems hopeless, but can we change our minds? Dr. O 'Neill of Princeton University believes that the best way is to build a space city in space and gradually move all human beings to the space city. After hundreds or even thousands of years of recovery, the earth will become a group of animals, the weather will become stable, and human beings can return to the earth without human intervention.

O 'Neill's Space City consists of a pair of cylinders. The inner wall of the Space City has a natural environment suitable for the growth of plants. There are roads, residential areas, commercial areas, work areas, etc. At one end of the space city is a solar power station, and at the other end is a hatch for the space shuttle or spacecraft to park.