Why are humans looking for Earth-like planets?For the continuation of human civilization
Four billion years ago, at the edge of the spiral arms of Orion, in the Milky Way’s “suburbs”, an unremarkable solar system gave birth to a life planet called Earth.The birth of life made the Earth no longer ordinary, and the continued evolution of life also changed the ecology of the Earth, until millions of years ago, the intelligent life human beings came into being.After the emergence of human beings, the Earth has also been upgraded from an ordinary life planet to a rarer civilization planet in the universe.And human beings also live up to the expectations of the earth’s will, after more than two million years of evolution, finally embarked on the road of civilization tens of thousands of years ago, through efforts, embarked on the road of science and technology hundreds of years ago.After entering the age of science and technology, human beings also have the ability to go out of the earth to explore the universe and explore the mysteries of all things.Only when we step out of the earth do we realize how small the earth is and how vast the universe is.With the rapid development of science and technology, and the deepening of our understanding of the universe, we also know that earth can not be our permanent home.The more I know, the more I will feel the smallness of human beings and the fragility of human civilization. In many people’s eyes, the earth is the home of human beings and provides a hotbed for human survival.But in the view of scientists, the earth is also a shackle of human beings, human life and death, closely linked with the fate of the earth.Once the earth has a major change, then human will also disappear, and there are too many things that can threaten the earth’s ecology. In the universe, solar radiation, cosmic radiation, asteroids and so on can threaten the Earth and the survival of human beings.Sixty-five million years ago, an asteroid struck earth, causing a huge ecological disaster that wiped out the dinosaurs, who had ruled the planet for 160 million years.If we are not to suffer the fate of the dinosaurs, we need to break free from the shackles of earth.Except from space, the threat of human activity also may lead to the collapse of the ecosystem on the earth, as we all know, although the rapid development of science and technology brings us many benefits, but the resulting all sorts of environmental problems is more and more serious, the global warming trend of rising, is likely to be completely out of hand in the future one day, the earth from now on no longer suitable for human survival.Even if none of the above problems occur, the earth can safely develop, but in a billion years, if we want to continue, we will have to leave the Earth, leave the solar system.The reason has to do with the sun around us, as we all know, the sun is a star with nuclear fusion going on inside it all the time, and as nuclear fusion goes on, the sun gets brighter and brighter.In a billion years, according to scientists, the increasing brightness of the sun will heat the Earth’s surface so much that the oceans will evaporate and natural disasters will render the surface inhospitable to life, forcing humans to leave the planet.Where should humans go after they leave Earth?Some friends may say that we can move to Mars, the idea is good, but in fact, even after a series of changes in the Environment of Mars, human beings can not fully adapt to, let alone Mars is relatively small, not to allow a large number of human survival.As the sun continues to evolve, billions of years later, the expansion of the sun will reach the orbit of Mars, at which time Mars will also become a purgatory planet, when the sun reaches the end of its life, the entire solar system will become unsafe, human beings can only leave the solar system.Thus, human civilization can only continue beyond the solar system.As carbon-based life, human beings have very high requirements on living environment. The space environment is not suitable for human beings to survive for a long time. To survive, we still need to find earth-like planets very similar to the Earth.There are so many stars and planets in the universe that it is impossible to count them. There are more than 100 billion stars and trillions of planets in a single galaxy.While the number of living planets is relatively small, it’s still incredibly large from a galactic perspective, from a cosmic perspective.For human survival requirement, of course, there is only life doesn’t work, a lot of life to survive in the harsh environment, and people can’t, we need more perfect ecological planet can, not only must have the appropriate temperature, atmosphere and liquid water, but also needs a strong magnetic field protection, the lack of any one, the human is unable to survive.Scientists are looking for earth-like planets in the universe, in addition to looking for extraterrestrial life, but also for the future of human beings, to find a second home for human beings, the third home and so on.So have scientists found such habitable worlds so far?The answer is no.According to scientists, an Earth-like planet must be at least 95 percent similar to Earth in order for it to be habitable. But none of the planets found so far are as similar as 90 percent. The most similar planet is Gliese 581g, about 20 light-years away.Also in the star’s habitable zone, Gliese 581g is a rocky planet with a high probability of having an atmosphere, liquid water and life.However, according to scientists’ observations, the planet is tidally locked by the star. The whole planet is half day and half night, and only the boundary between black and white also has the appropriate temperature, suitable for the evolution of life.Therefore, it is not easy to find a planet suitable for human life. Of course, the universe is vast and vast. We still believe that there are many planets suitable for human life, and we will find them sooner or later.For us, interstellar migration is more about getting to the target planet, knowing that the universe is light-years away, and that even the speed of light is a snail’s pace, and that distant galaxies, even at the speed of light, take impossibly long to reach.Einstein’s theory of relativity tells us that the speed limit for objects is the speed of light, and even if our spacecraft is powerful enough, it can only go as fast as sublight speed, and at that speed, we have a very limited range of interstellar travel.If we want to achieve the kind of faster-than-light flight in science fiction, we need to use the power of space. The speed of objects is limited by the speed of light, but there is no upper limit to the speed of space, because the universe is expanding at a speed far beyond the speed of light.Of course, it is not easy to use the power of space to achieve faster-than-light travel, and we need to know enough about space.And these, all need our efforts to develop science and technology, as long as the power of science and technology is strong enough, the whole universe will also be the backyard of human beings, we do not have to worry about the survival of human beings.