Are there people on other planets besides the earth?

By the end of 20 17, the scientific community had no clear information to prove that there were people on other planets besides the earth.

The scientific community generally believes that "life will only appear on planets around stars that can emit light and heat, but not all stars necessarily have planets." According to nebula theory, stars are formed by the contraction of rotating primitive nebulae. During contraction, due to the conservation of angular momentum, the rotation is accelerated, and the nebula is gradually flattened due to centrifugal force. When the central temperature reaches 7 million degrees, a thermonuclear reaction from hydrogen to helium occurs and stars are born. In this process, the outside of the disk will condense into several small celestial bodies-planets.

It is very rare for a planet to have all the conditions that life must meet. The earth in the solar system is a unique lucky one. Detailed calculations show that among the above 40 billion single stars, at best, only 65.438+0 million are surrounded by planets that can make life evolve to an advanced stage.

Another limitation is that extraterrestrial life should have similar chemical composition to life on earth. Astronomical observation shows that, with a few exceptions, the distribution of chemical elements in the whole universe is quite uniform, so there is every reason to believe that the materials needed to form all organic molecules can also be found on distant planets. In fact, many complex organic molecules have been found in many places. Therefore, it can be considered that as long as life can be formed in theory somewhere, it will actually form life. In this way, there will be 6.5438+0 million planets in the Milky Way, but life on each planet should be at different stages of evolution.