Hawking, the king of the universe, has five words to evaluate him.

Miracle, greatness, optimism, science, giant

Recommend a new popular science of Hawking: Yesterday's Tomorrow-Future History.

Humans are always eager to know what they hope will happen in the future, which is why prophecy, divination and theoretical physics appear. Although almost all predictions are wrong in this history full of tragedies and tableware, people still believe that they can predict the future.

The earliest predictions came from religion. According to the religious theory of detonator (detonator chicken), the religious belief in the primitive commune period was primitive collectivism, which may be one of the reasons why it can predict the future-it can use the collective wisdom. The duty of religion is to predict what will happen in the future so as to provide guidance for people to do. The first prediction comes from the prediction of stars, which is basically the same as our work. Although their prediction methods are different from ours, it is undeniable that they can accurately predict solar and lunar eclipses. Although we laugh at them now and don't understand why there will be a solar eclipse, who knows if people in the future will laugh at us? We still don't know why the iphone fell, and then Newton will run over to think about the boring problem of gravity in surprise.

It was probably Galileo who first produced the correct physics thought. He did the famous experiment on the leaning tower of Pisa. Although the story is not credible, he did do similar experiments. It sounds strange that two iron balls with different weights will land at the same time, but it's true. He put forward a paradox to refute Aristotle's experience: if two different stones fall at the same time, the speed of the big stone is 8 and the speed of the small stone is 4. If two stones are tied together, the big stone will slow down because of the drag of the small stone. The combined weight of the two stones is greater than that of the big stone, so the combined speed of the two stones should be greater than 8, so the speed of the two stones tied together is greater than 8 and less than 8. Galileo thought there was only one possibility: big and small stones fell at the same speed. This story was later described as the story of the tortoise and the bastard, but we don't know whether the ambulance will come if the bastard is thrown from the leaning tower of Pisa. Under this paradoxical thinking, a new scientific cause-kinematics has been established, and the basis of this science is the study of motion characteristics. Exercise is the mother of machines, which makes the earth livable and can tear down the sky. To this end, Galileo also gave his lifelong freedom, which is a tragedy.

The development of physics after Galileo was much easier, but the biggest progress in physics was in Newton's time. Newton is famous for asking boring questions, such as why apples only fall, but it is these boring questions that promote the development of physics. He summed up the answers to these boring questions and published them in his paper, the most famous of which are Newton's three laws and the law of universal gravitation. So since more than 300 years ago, we have discovered the physical laws that restrict the universe in most cases.

Even so, before Boltzmann, no one had asked such a boring question: "What is the future? What is the difference between the future and the past? " Such a boring and deadly question is too boring for even a boring expert like Newton to ask. Boltzmann gave a not boring answer to this question, which is an inference of the second law of thermodynamics. The second law of thermodynamics says that the entropy (disorder degree) of an object always increases with time. So the future is a state of high entropy, and history is a state of low entropy. Or we can put it another way. The reason why we think that entropy increases with time is because we think that the future is the future with large entropy. This is because our brains also obey this rule. This is a magical result for gravity. When a meteorite falls to the earth, the disorder decreases, so its time will go backwards or slow down. This is an effect predicted by general relativity. Although it is described in the book "On Quantum Thermodynamics of Gravitational Field" by Detonator (Chicken), Detonator thinks that this time-flow difference causes what we think is mass and gravity, and predicts that the gravity of matter with high entropy increase rate will be great, and it is the first time that human soul has mass.

In the 65438+60s, Maxwell summed up Faraday's thought and made it mathematical, and put forward the so-called Maxwell equation to describe electricity, magnetism and light. He drew a great conclusion from his own equation: the speed of light is only related to the vacuum dielectric constant and magnetic flux constant, so the speed of light remains unchanged! This led Einstein to put forward the famous principle of invariance of light speed: the speed of light measured by any observer in the inertial system is the same! This is the basic principle of relativity. However, if the latest work results are correct, the vacuum dielectric constant may be decreasing or the speed of light may be increasing. Of course, this effect is not aimed at observers, so Einstein's hypothesis is still valid on the whole.

Einstein concluded from this that the mass of any object with higher speed will increase, the observation time will slow down and the length will become shorter. Nothing can exceed the speed of light for the simple reason that negative numbers have no real square root. Relativity is famous for its conciseness. Ironically, the correlation formula between speed and temperature obtained by detonator (chicken) recently is more complicated than other formulas. But relativity and Newton's gravity are incompatible. Newton thought that the propagation speed of gravity can exceed the speed of light, and the gravity between two objects measured by a high-speed object will be much greater than that measured by a low-speed object, which is inconsistent with the facts. So we need a theory of relativity that includes gravity.

An apple fell on Newton's head. Because motion is relative, we can equivalently say that when Newton and the ground accelerate upward, the apple does not move. If the earth is flat, we think this statement is fine, but the key is that the earth is round. If an apple falls on one person's head, at the north and south poles, two people can think that they are being pulled farther and farther, but they are still in the same position, so this equivalent statement is not valid. Einstein realized this contradiction a long time ago and tried to solve it. Maybe he ate too much and was inspired. He once had an inspiration after dinner. If space-time is not flat, but curved, then this equivalent statement is true. This theory is based on non-Euclidean geometry, which is now called general relativity. It has caused the biggest change in the world that we have known since Euclid wrote The Elements of Geometry: our time and space are not rigid, but flexible. In fact, we can understand non-Euclidean geometry with a very simple example. In Euclidean geometry, it is impossible to make a circle as long as a straight line. In fact, if the earth is flat, you just need to draw a straight line along the equator.

Almost at the same time as the theory of relativity, another theory has developed, that is, quantum mechanics. Planck's explanation of "ultraviolet disaster" is deeply rooted in people's hearts. Matter is fluctuating and can be explained by some wave packets. The most important point is that we put forward a basic principle of current physical theory: only the physical quantities measured by experiments have practical physical significance. These have promoted the development of quantum mechanics. There is a basic theorem in quantum mechanics, that is, the uncertainty principle, which stipulates that we cannot accurately obtain the position and velocity of a particle. The more accurate one is, the less accurate the other is. This is the first time that we have an incomplete agnosticism about the world we live in. Later Feynman developed it and put forward the historical summation model. He thinks that the history of particles is uncertain, and there are countless possibilities for particles from A to B. When all the situations are considered, the history we get appears in one of Newton with the greatest probability. There is an interesting inference in quantum mechanics: a cat is dead and alive, and the living cat mourns itself at the dead cat's memorial service. This incredible story takes place in the quantum world: an electron can be in two places at the same time and can interfere with itself.

A black hole is an inference of general relativity, which means that its gravity is so great that light can't escape, but are there really no particles that can escape? No, the uncertainty principle means that if the position of a particle is accurate enough, its velocity will not be accurate enough for it to escape, so the smaller the black hole, the easier it will escape, which is called Hawking radiation.

Well, this tragic history of predicting the future is like this. Now it is summarized as follows: Although people have got many wrong predictions in history, we think that people's road to predicting the future is bright. We need to ask more and more boring questions and solve them in areas we don't know yet.