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Anonymous users2024-02-12A Brief History of Time mainly expounds the laws of motion of matter.
The theory of relativity is a basic theory about space-time and gravity, mainly founded by Albert Einstein, and is divided into special relativity (special relativity) and general relativity (general relativity). The basic assumptions of the theory of relativity are the principle of invariance of the speed of light, the principle of relativity, and the principle of equivalence. The theory of relativity and quantum mechanics are the two fundamental pillars of modern physics.
Classical mechanics, which laid the foundation of classical physics, is not suitable for objects moving at high speed and objects under microscopic conditions. The theory of relativity solves the problem of high-speed motion; Quantum mechanics solves problems under microscopic subatomic conditions. The theory of relativity has greatly changed mankind's "common sense" concept of the universe and nature, and has put forward new concepts such as "simultaneous relativity", "four-dimensional space-time" and "curved space".
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Anonymous users2024-02-11Einstein's theory of general relativity is generally considered to be the correct theory for describing the evolution of the universe. In the framework of classical general relativity, Hawking and Penrose proved that under very general conditions, there must be singularities in space time, and the most famous singularities are the singularities in black holes and the singularities in the universe. At the singularity, all laws, as well as predictability, fail.
The singularity can be seen as the edge or boundary of space-time. The evolution of the universe can be derived from Einstein's equations only given the boundary conditions at the singularity. Since boundary conditions can only be given by the Creator outside the universe, the fate of the universe is in the hands of the Creator.
This is the problem that has plagued the first driving force of human intelligence since Newton's time.
If space and time had no boundaries, then there would be no need for God to make the first push. This can only be done in the theory of quantum gravity. Hawking believed that the quantum state of the universe is in a ground state, and that space and time can be seen as a finite and unbounded four-dimensional plane, just like the surface of the earth, but with two more dimensions.
All structures in the universe can be attributed to the smallest fluctuations allowed by the uncertainty principle of quantum mechanics. From some simple model calculations, inferences can be drawn that are consistent with astronomical observations, such as the cluster structure of galaxies, stars, etc., the isotropy and uniformity of large-scale, the flatness of space and time, that is, space and time are basically flat, and thus make the development of galaxies and even life possible, as well as the direction arrow of time, and so on. The significance of Stephen Hawking's quantum cosmology is that it really makes cosmology a full-fledged science, a self-contained theory that in principle, we can predict everything in the universe based on the laws of science alone.
In this book, Hawking takes readers on a journey through the strange realm of outer space, giving an in-depth introduction to distant galaxies, black holes, quarks, "flavored" particles and "spin" particles, antimatter, "arrow of time", etc., and expounding on ancient issues such as what the universe is, space and time, and the theory of relativity, so that readers can have a preliminary understanding of the special theory of relativity, the mystery of time and the origin of the universe and other cosmology.
Satisfied o( oThank you.
--Reading "Robinson Crusoe".
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Shen Congwen "Border City".
The place of Chadong builds a city by the water and the mountain, and on the side of the mountain, the city wall is like a long snake, and the edge of the mountain climbs to it. On the waterfront side, there is room for a wharf by the river outside the city, and small caravans are moored in the bay. When the ship goes down, it transports tung oil and green salt, dyed canopy. >>>More
Once upon a time, there was a man from Zheng Guo who wanted to go to the market to buy shoes. He measured his feet at home, put them in his seat, and went to the bazaar, forgetting to take them. >>>More
Observe the plant cactus.
There is a strange plant in my house, and its name is cactus. Do you know where the name of the cactus comes from? Let me tell you: because it resembles the palm of a human hand, people call it a cactus! >>>More