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Language:English 英文
【Maintaining Energy Balance - Part 2: Earth and Life 维持能量的平衡下编-地球生命编】
About 4.6 billion years ago, a huge molecular cloud (mainly composed of hydrogen, helium, and interstellar dust), possibly due to the shock wave of a nearby supernova explosion or the gravitational disturbance of the Milky Way's spiral arms, began to collapse and form the solar system. During the collapse, the cloud's rotation accelerated, and material gathered toward the center, forming a flat rotating disk structure (protoplanetary disk); the extremely dense central part gradually formed the primordial Sun. The central material contracted and heated up, forming a young protostar (primordial Sun); at this time, the temperature gradient inside the surrounding disk was significant: high temperature inside (rock/metal condensation), low temperature outside (ice and gas could remain). Evolution of disk material: dust particles aggregated through electrostatic forces and collisions into planetesimals (kilometer-sized bodies), then through gravitational accretion formed larger bodies. The remaining protoplanetary disk after the Sun formed. Planetesimals merged through frequent collisions to form planets. Primordial Earth also formed at this time, mainly composed of dust (silicates, metal oxides, etc.) and a small amount of gas (H₂, He). Dust particles collided and aggregated into kilometer-sized planetesimals, further accreting surrounding material to form proto-Earth (the prototype of primitive Earth). The kinetic energy released during accretion converted into thermal energy, causing the early Earth to be completely molten; dense iron-nickel materials sank to form the core, while lighter silicate materials rose to form the mantle and primitive crust. About 4.53 billion years ago, a Mars-sized body Theia collided violently with proto-Earth, and the ejected debris aggregated in orbit to form the Moon. This collision tilted Earth's rotation axis (about 23.5°), laying the foundation for subsequent seasonal changes. The rotational and orbital kinetic energy of celestial bodies balances gravitational forces, stabilizing the solar system.
Perhaps the formation of celestial bodies is accidental, or perhaps the careful arrangement of the Creator. Earth is located in the habitable zone for carbon-based life. It has the stable nuclear light of the Sun for billions of years, the necessary material resources provided by supernovae, and the protective care of Jupiter and the Moon; thus Earth can have the formation of life and the continuation of civilization. Looking at the observable universe today, this is a very, very special existence. People living on Earth today should be grateful to the universe, quoting a Western saying: Thank God!
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