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"A Brief History of Time" is a popular science book by British physicist Stephen William Hawking, first published in 1988. The book consists of twelve chapters, which tells the most cutting-edge knowledge about the nature of the universe, including: our cosmic image, space and time, the expanding universe, the principle of uncertainty, the black hole, the origin and destiny of the universe, etc. Remote galaxies, black holes, particles, antimatter and other knowledge, and the ancient propositions of the origin, space and time of the universe and relativity. In the book, Hawking explores the unresolved conflicts in existing cosmological theories and points out the problems of unifying quantum mechanics, thermodynamics, and general relativity. The book is positioned to give those to cosmology. The average reader of interest understands his theory and its mathematical principles.

In this book, Hawking leads readers to explore the strange areas of outer space, and introduces the distant galaxies, black holes, quarks, "flavored" particles and "spin" particles, antimatter, "time arrows", etc. Explain the ancient problems of the universe, space and time, and relativity, so that readers can understand the mystery of cosmology such as the special theory of relativity and the origin of time and the universe. The main content of "a brief history of time" can be summarized as the following aspects:

1. The starting point of time - the starting point of the Big Bang. The universe is constantly expanding. It should initially shrink to a point. This moment is called the moment of the Big Bang. The density of the universe at this point is infinite, which is what is called a singularity in mathematics.

2. The end of time - black holes. The star will shrink due to gravitation, which will form a "black hole." The black hole has a strong gravitational surface and the time will end here.

3. How did God initiate the universe? - The origin and destiny of the universe. One is the origin of the universe called the disordered boundary condition explained by the principle of choice; the other explanation is called the “surge model”, which considers that the universe expands with acceleration at the beginning of the moment, in a time much less than 1 second. The radius of the universe has increased by 100 trillion times.

4. The unity of physics - the ultimate theory. Humans are seeking to establish a complete, coordinated, unified theory for every event in the universe, in which no specific constants need to be chosen to conform to the facts.

It is generally believed that Einstein's general theory of relativity is the correct theory for describing the evolution of the universe. In the framework of classical general relativity, Hawking and Penrose prove that under very general conditions, there must be singularities in space and time. The most famous singularity is the singularity in the black hole and the singularity of the big bang. . At the singularity, all laws and predictability are invalid. A singularity can be seen as the edge or boundary of space time. Only when the boundary conditions at the singular point are given can the evolution of the universe be obtained from the Einstein equation. Since the boundary conditions can only be given by the Creator outside the universe, the destiny of the universe is manipulated in the hands of the Creator. This is the first driving force that has plagued human wisdom since the Newton era.

If space and time have no boundaries, then you don't have to work with God to make the first push. This can only be done in quantum gravity theory. Hawking believes that the quantum state of the universe is in a ground state. Space and time can be regarded as a finite and unbounded four-dimensional surface. Just like the surface of the earth, there are only two more dimensions. All structures in the universe can be attributed to the minimum fluctuations allowed by the uncertainty principle of quantum mechanics. From some simple model calculations, inferences consistent with astronomical observations can be derived, such as clustering structures of galaxies, stars, etc., large-scale isotropic and uniformity, spatial and temporal flatness, that is, space and time basics. The upper is flat, and thus makes the development of galaxies and even life possible, as well as the direction arrows of time and so on.

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