According to scientific research, our universe was born about 13.8 billion years ago. At that time, all matter and energy in the universe were gathered together and condensed into a very small volume with extremely high temperatures and densities. This led to a massive explosion, known as the Big Bang. The explosion caused matter to disperse everywhere, and the universe began to expand continuously, with temperatures gradually decreasing. Subsequently, all the galaxies, stars, planets, and life forms in the universe appeared. In the extremely short period after the Big Bang, the universe underwent a series of changes. Over time, matter gradually formed structures such as stars and galaxies. Our solar system was formed after the Big Bang, but it is important to note that our solar system is not the first batch of galaxies born in the universe. Research by scientists suggests that our solar system evolved 4.6 billion years ago, formed by the gravitational collapse of a small part of a vast molecular cloud. Here is the main process of the formation of the solar system:

1. Molecular cloud collapse: A huge molecular cloud began to collapse under the influence of gravity, containing gas and dust. Some regions within the molecular cloud formed dense cores of protostars.

2. Protostar formation: The protostar core continued to collapse, becoming hot and dense enough to initiate nuclear fusion reactions, and the Sun began to form.

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3. Formation of the rotating disk: A rotating disk of gas and dust formed around the protostar, also known as the protoplanetary disk or the primordial solar system disk.

4. Planet formation: After the birth of the Sun, it absorbed a large amount of surrounding matter, so the mass of the Sun accounts for 99.86% of the total mass of the solar system. The remaining eight major planets and other matter account for 0.14% of the total mass of the solar system. From the proportion, we can see that the mass of the Sun is very large.

5. Subsequent evolution: In the early stages of the solar system's formation, there were many collisions between planets, which led to the evolution of planetary shapes and orbits and cleared some of the material in the planetary disk. Over time, the planets began to cool down and stabilize, with their atmospheres and crusts gradually forming and evolving through geological activities and celestial collisions. After about 50 million years, the temperature and pressure at the core of the Sun became extremely high, and its hydrogen began to fuse, generating internal energy to resist gravitational contraction until a hydrostatic equilibrium was reached. The Sun became a main-sequence star and has continued to this day.

Among the eight major planets in the solar system, Earth is the only one that has given birth to life. The emergence of life has added much color to Earth, especially after the appearance of humans, who have unraveled many mysteries on Earth. According to scientific research, Earth was able to give birth to life mainly because it met the basic conditions for the emergence of life. For example, there is a stable cosmic environment, with planets of various sizes in the solar system moving in their own orbits without interference. Earth is in a relatively safe interstellar space, reducing the risk of collisions with other celestial bodies. Since life began on Earth, the Sun has not undergone significant changes, providing stable light for Earth. Secondly, there is a suitable Earth-Sun distance. The moderate distance between Earth and the Sun allows the average temperature on the Earth's surface to be moderate, enabling water to exist in a liquid state. Thirdly, there is the appropriate volume and mass of the Earth. The moderate volume and mass of the Earth enable it to attract and retain a large amount of gas, forming an atmosphere.The atmosphere not only provides the gases necessary for the respiration of living organisms, such as oxygen, but also plays a role in insulation, maintaining a relatively stable temperature environment, and can weaken the hazards of cosmic rays and solar winds to life. Fourth is the Earth's rotation and revolution periods: the Earth's rotation period is appropriate, making the alternation of day and night not too long or too short, which is conducive to maintaining suitable temperature changes and climatic conditions. The revolution period is also quite suitable, forming regular seasonal changes. Finally, the Earth has a strong magnetic field, which can resist high-energy charged particles and radiation from the universe, reducing their harm to Earth's organisms and providing a natural protective barrier for life. These various factors combined make the Earth a planet with life. Humans, as the most intelligent life on Earth, have been continuously studying and exploring the mysteries of the world since their birth. Now, humans have been able to leave the Earth to explore the universe, which indicates that the speed of human technological development is very fast.

After humans left the Earth, they wanted to know how big the universe is and whether there is extraterrestrial life in the universe. With these questions, humans began to explore the universe. In 2015, scientists accidentally discovered a planet located in the habitable zone, which is Kepler-452b. This planet is located in the constellation Cygnus, about 1400 light-years away from Earth. Kepler-452b orbits a star very similar to the Sun, Kepler-452, which is 1.5 billion years older than the Sun, with a diameter about 1.1 times that of the Sun, a mass exceeding 4% of the Sun, and a brightness 20% brighter than the Sun. The surface temperature is almost the same. The distance of Kepler-452b to the star is similar to the distance of the Earth to the Sun. Scientists have accurately determined its revolution period to be 385 days, just a bit longer than the Earth's revolution period. The diameter of Kepler-452b is 1.6 times that of the Earth, the radius is 50% larger than the Earth, the mass is 5 times that of the Earth, the surface gravity is about twice that of the Earth, and the average temperature is 265K.

Scientists have found through research that Kepler-452b is located in the habitable zone and has been operating in the habitable zone for 6 billion years. According to the suitable zone conditions, there may also be liquid water theoretically. Scientists believe that if there are other conditions suitable for the existence of life, then life may be nurtured, and this planet may be a rocky planet, which makes many people believe that there should be life on this planet. However, we cannot determine this fact now, after all, humans can only see the approximate position of this planet, but cannot see the specific situation on it. However, even if there is no life similar to Earth on this planet, it may also give birth to other life forms. In the universe, the types of life should be diverse. Earth life belongs to carbon-based life, and carbon has four valence bonds, which can form a variety of complex organic molecules with other atoms. These organic molecules can build various macromolecules needed for life, such as proteins, nucleic acids (DNA and RNA), carbohydrates, and fats.

The chemical properties of carbon are relatively stable, but also have enough activity, which can participate in various chemical reactions under appropriate conditions, thereby supporting the synthesis and decomposition of substances, energy conversion and other basic metabolic activities in the life process. In addition to carbon-based life, scientists also believe that there are other life forms in the universe, such as sulfur-based life. At present, the basis for scientists to search for extraterrestrial life is water as the fundamental source, plus oxygen and suitable temperature. However, on other planets, some life does not need water, nor does it need oxygen, but is based on sulfur. However, scientists believe that sulfur-based life is a very low-level life, and most of these organisms are some microorganisms, which are mainly based on sulfur.

Silicon-based life, in 1891, scientists from the University of Potsdam first discussed the possibility of the existence of life based on silicon in their own papers.

This view was accepted by British chemist James Emerson Reynolds, who believed that silicon compounds' thermal stability could survive in high-temperature environments. Thirty years later, British geneticist John Haldane proposed that life based on semi-molten silicates might be found deep inside a planet, and iron could provide energy for them. Scientists believe that if silicon-based life really exists in the universe, then they may look more like crystals. The structure of this organism may be connected by bio-silicon similar to glass fibers, forming exquisite and transparent structures. Moreover, silicon-based life can survive in very harsh environments and is more suitable for development in the universe. Although scientists have not yet found or discovered silicon-based life in the universe, scientists believe that this kind of life must exist in the universe. So even if there is no carbon-based life on Kepler-452b, there may also be other life forms.However, landing on this planet personally is an extremely difficult task, as it is 1600 light-years away from Earth. A light-year is a unit of distance, equivalent to the distance light travels in one year. It's hard to imagine how vast a 1600 light-year distance is for humans. The fastest spacecraft currently launched by humans is the Parker Solar Probe, which traverses the solar system at a speed of 635,266 kilometers per hour, or about 176 kilometers per second. Yet, this speed is far from the speed of light, which is approximately 300,000 kilometers per second. Even at the speed of light, it would take 1600 years to reach, indicating that human spacecraft cannot make the journey. Therefore, for humans to fly to this planet, they must increase the speed of their spacecraft. Currently, scientists can think of methods such as warp drive technology. However, warp drive technology is still in the theoretical stage, and it requires continued effort to truly realize this technology.

In addition to Kepler-452b, scientists have also discovered other Earth-like planets, such as Proxima Centauri b. It is an exoplanet orbiting the star Proxima Centauri in the constellation Centaurus. Proxima Centauri is very close to our solar system, only 4.2 light-years away. Proxima Centauri b is the closest known exoplanet to our solar system and is also the closest known exoplanet within the habitable zone. This planet may also have liquid water and rocks. Proxima Centauri b is only 7 million kilometers away from Proxima Centauri and completes an orbit in just 11 days. Since Proxima Centauri is a red dwarf star with a mass only 0.123 times that of the Sun, its surface temperature is very low, at 2800 degrees Celsius, which keeps Proxima Centauri b within the habitable zone of the star system. Given that this planet is in the habitable zone, the possibility of life originating there is quite high, although we do not yet know for certain. In addition, scientists believe that there is a 100% chance of life on Gliese 581g.

In a past interview, when the planet's discoverer, Stephen Vot, was asked about the possibility of life on Gliese 581g, he was optimistic and stated, "I am not a biologist, nor have I played this role on television, but considering the resilience and habits of life, I believe there is a 100% chance of life on Gliese 581g." Why do scientists think there is a 100% chance of life on Gliese 581g? According to scientific research, the diameter of this planet is about 1.2 times that of Earth, so its volume is slightly larger than Earth's. Moreover, its average surface temperature is about -31 degrees Celsius to 12 degrees Celsius, which, although cold for humans, is within a temperature range that can support life under certain conditions. Considering many factors, scientists believe this planet must support life, but this is just a scientific speculation.

What is the truth? Scientists are still actively researching. Reading this, many people might wonder why scientists are so determined to search for extraterrestrial life. Firstly, from a scientific exploration perspective, searching for extraterrestrial life helps us to better understand the nature and origin of life. Secondly, from the perspective of human future development, Earth's resources are limited. If we can find extraterrestrial environments and resources suitable for human habitation or utilization, it will provide new possibilities and choices for the long-term development of humanity. Moreover, if there is no other life in the universe, and only humans are a civilization or only Earth has given birth to life, it would be a terrifying prospect for humans. This implies that our world could also be virtual. Long ago, scientists proposed the concept of a virtual universe, and the famous entrepreneur Musk stated that the probability of humans living in a real world is less than one in a billion.

If there are advanced civilizations in the universe that use various resources, formulas, and laws to create a virtual world, we would not be able to recognize whether this world is virtual, as we cannot find bugs in the universe. However, these are just current scientific speculations. What is the truth? Scientists are actively researching it. As the most intelligent life on Earth, humans are continuously advancing and developing their technology. Although humans cannot yet unravel all the mysteries of the universe, as long as we persist in our efforts, with the development of human technology in the future, humans will surely be able to find extraterrestrial life. What do you think about this?