1. The light we see from very distant galaxies was emitted millions of years ago. In the case of the farthest objects we see, the light was emitted 8 billion years ago. issued. So when we look at the universe, we are looking at its past. ——Hawking? "A Brief History of Time"

2. Why do we never see the broken cups gathering together, leaving the ground and jumping back to the table? The usual explanation is that this violates the second law of thermodynamics. Stated that disorder or entropy always increases with time in any closed system. In other words, it's a form of Murphy's Law: Things tend to get worse: a full cup on the table is a highly ordered state, while a broken cup on the floor is a disordered state. One could easily go from a cup on the table earlier to a broken cup on the ground later, rather than the other way around. ——Hawking? "A Brief History of Time"

3. Now we know that any particle has an antiparticle that will annihilate it. (For a force-carrying particle, the antiparticle is itself.) There could also be entire anti-worlds and anti-people made of antiparticles. However, if you encounter someone who is against you, be careful not to shake hands! Otherwise, both of you will disappear in a giant flash of light. ——Hawking? "A Brief History of Time"

4. Before the 20th century, no one had ever suggested that the universe was expanding or contracting. This interestingly reflects the thinking atmosphere at that time. It is generally believed that the universe has either existed in an unchanging state for an infinite period of time, or that it was created in a finite past in more or less the way we see it today. This may be partly due to people's tendency to believe in eternal truths, but also to the comforting notion that the universe must be immortal and unchanging, even though we are subject to birth, old age, illness and death. ——Hawking? "A Brief History of Time"

5. On the other hand, philosophers who take it as their duty to find out the roots cannot keep up with the progress of scientific theories. In the 18th century, philosophers considered the entirety of human knowledge, including science, as their domain and discussed questions such as whether the universe had a beginning. However, during the 19th and 20th centuries, science became too technical and mathematical for philosophers, or anyone except a few experts. Philosophers have narrowed the scope of their questioning so much that even Wittgenstein, the most famous philosopher of this century, said: "The only remaining task of philosophy is the analysis of language." This is from Aristotle What a degeneration of the great tradition of philosophy since Kant! ——Hawking? "A Brief History of Time"

6. The matter in the universe is composed of positive energy. ——Hawking? "A Brief History of Time"

7. All structures in the universe originate from the smallest fluctuations allowed by the uncertainty principle of quantum mechanics. ——Hawking, "A Brief History of Time"

8. Common sense tells us that without external intervention, things will always tend to increase their disorder. ——Hawking's "A Brief History of Time"

9. In the infinite universe, there are countless "worlds" being created and destroyed. However, as the infinite universe itself, it exists forever. Life is not only on the earth, but also on the earth. There are them on the planet, and there may also be them on those distant planets that are invisible. ——Hawking, "A Brief History of Time"

10. God hates naked singularities! ——Hawking, "A Brief History of Time"

11. A good theory must meet the following two requirements: First, the theory must be able to accurately describe a large number of observations - these observations are based on only a few arbitrary Secondly, this theory can make clear predictions about the results of future observations. ——Hawking, "A Brief History of Time"

12. Which came first, the chicken or the egg? ——Hawking? "A Brief History of Time"

13. In an unchanging universe, the endpoint of time is something that must be given by existence outside the universe; there is no physics at the beginning of the universe. the inevitability. ——Hawking, "A Brief History of Time"

14. Humanity's deepest desire to seek knowledge is enough to justify the continuous exploration we engage in. ——Hawking, "A Brief History of Time"

15. When most people firmly believe in an essentially static universe, the question of whether it had a beginning is really a metaphysical or theological question.

——Hawking's "A Brief History of Time"