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According to the Big Bang theory, the universe originated from a high-temperature and high-density fireball, called the "cosmic egg", and then the Big Bang occurred, and the matter was dispersed in space, gradually forming nebulae, stars, planets, and eventually galaxies.
In 1965, two physicists in the United States discovered that there was a thermal background radiation from all over the sky and an afterglow from the cosmic background, which was called "cosmic microwave background radiation", which was evidence of the Big Bang.
Life on Earth originated in water, and life forms evolved from water to land and then to air.
How did life beyond Earth begin?
Scientists have discovered a "twin brother" beyond the earth - Kepler 452b, which is as similar as 98% to the earth, will there be traces of life on it?
1. The Big Bang.
Scientists have conducted many studies and proposed theories about how matter gradually formed galaxies and planets in space, but the theory that best explains the origin of everything is the Big Bang theory.
In the early 20s of the 20th century, the American astronomer Hubble observed the redshift of galaxies, which informed that galaxies were constantly moving away, and it was inferred that the universe was in a state of expansion.
In the 70s of the 20th century, American astronomers discovered that there was a thermal background radiation in the sky from all over the place.
On this basis, the Big Bang theory was confirmed, and it was believed that the universe originated from a high-temperature, high-density fireball, which was called the "cosmic egg".
The matter in the Cosmic Egg is so dense that it cannot be seen directly, but when the Cosmic Egg expands, the gas gradually decreases in thinness, the temperature becomes lower, and it merges with the cosmic microwave background, and the effect of the Big Bang can be observed.
Cosmic microwave background radiation appeared about 300 million years after the Big Bang and is the afterglow of the Big Bang.
When the Big Bang erupted, the first explosion did not bring matter together, but caused the matter in the universe to gradually disperse.
The gas is initially distributed in a homogeneous state, but due to the small inhomogeneity in the gas, a gravitational pull is generated, which causes the gas to accumulate.
The density of the gas gradually increases, and due to the collision between the nucleus and the electron, the electron will break away from the nucleus and recombine to form an atom, so that the nucleus and the electron will no longer collide with each other, and the gas will become transparent.
Over the next million years, the gravitational pull between the nucleus and the atoms caused the gas to gradually gather to form a nebula, and the gas cloud in the nebula gradually became denser under the gravitational pull.
At the beginning of the universe, gas clouds were not dense enough to allow nuclear fusion to occur, but the nuclei in the gas cloud would keep approaching, and in the process of approaching, huge temperatures would be generated, eventually reaching the temperature of nuclear fusion, and these fusion aggregates were stars.
Galaxies are made up of many stars and gas and other materials in galaxies, and there is a stellar aggregate at the center of the galaxy, which is called a black hole.
2. The origin of the planets.
The origin of the planets is also a mysterious question, and people have different opinions about the origin of the planets, but the most convincing is the idea that stars form protoplanetary disks.
During star formation, protoplanetary disks of dust and gas gradually form protoplanets, which eventually coalesce to form planets.
And now there is a new theory that planets originated from black holes.
At the beginning of the birth of galaxies, the protoplanetary disk, the parent body of stars and planets, will gradually form planets, and in the process of planet formation, the gravitational pull of the planets will gradually accumulate the material in the black hole to form planets.
This could also explain the phenomenon that the composition of the planets differs from the matter in the stars.
3. The formation of the earth.
Millions of years ago, the Earth's climate was very hot, and a large amount of gaseous matter in the sky caused the Earth to be constantly impacted, which will greatly affect the Earth.
In the process of the evolution of the earth, the material on the earth will constantly melt, so the earth is a hot planet, and its temperature is very high, which also provides the possibility of life on the earth.
On Earth, life is produced from water, and the earliest life on Earth is cyanobacteria, which is a single-celled organism capable of photosynthesis, and it also contains chlorophyll in its body, which is why cyanobacteria are able to photosynthesize.
In cyanobacteria, an organ called chloroplasts can also be found, and through the study of chloroplasts, scientists have learned that chloroplasts may come from the endosymbiosis of chloroplast cells, which in turn come from cyanobacteria cells.
This further confirms that cyanobacteria are the earliest life on Earth and the ancestors of all life on Earth.
On Earth, life forms in different periods can be confirmed by different fossils, which is the process of biological evolution on Earth.
4. Kepler 452b.
In 2015, NASA released a major study in which they discovered a "twin brother" beyond Earth, Kepler 452b, a planet that is 98% similar to Earth, a discovery that aroused great interest.
Kepler-452b is a planet orbiting a star similar to the Sun, Kepler-452, which orbits more nearly as round as Earth, has a radius of 1.6 times that of Earth, and has a mass of 5 times that of Earth.
Its surface temperature is also hotter than Earth's, but because the stars it orbits are cooler than the Sun that orbits Earth, it may have liquid water like Earth.
However, scientists cannot directly detect the presence of life on Kepler-452b, they only speculate on the possible presence of life on Keple-452b from the conditions of Kepler-452b.
From the perspective of Kepler-452b's environment, although its surface temperature is suitable for the production of life, the star around it will run out of energy faster than the sun, and it will become a red giant star at that time, and the temperature of Keple-452b will be even hotter, which is not suitable for biological survival.
And the atmosphere of Kepler 452b is also a big problem, the atmosphere on the earth is an important condition for life to survive, but the atmosphere on Kepler 452b may also be affected by the continuous exhaustion of energy by stars, resulting in a thin atmosphere, which is not conducive to the production of life.
Kepler 452b is 1400 light years away from the earth, which means that if you want Kepler 452b to explore, you need to fly faster than light, but at present, human beings have not developed faster-than-light flight technology.
However, scientists have found that if a wormhole exists, then humans can fly to Kepler 452b through the wormhole to explore, but the wormhole theory has yet to be verified, so humans still know nothing about the life on Kepler 452b.
V. Conclusion.
The origin and evolution of life is one of the most mysterious questions in the universe, life on Earth is the result of a combination of factors, and the existence of life on other planets is still a mystery.
Scientists need more advanced technology and tools to explore Kepler-452b, which will have a significant impact on human understanding of the universe.
In the exploration of the universe by human beings, it is also necessary to rely on the continuous efforts of scientists to study, hoping that they can uncover the mysteries of the universe as soon as possible.