Apart from illness and gossip, what has Hawking brought us?

20 18 March 14, Steven? Hawking died at the age of 76. He is an outstanding theoretical physicist, a popular science writer all over the world, a leader with amazing opinions, and a tenacious patient suffering from rare diseases. He is a legend who was "sentenced to death" by doctors in his twenties and lived optimistically for more than 50 years.

For most people, Hawking is a pure cultural symbol-everyone knows his name, but few people really understand what he has done. In fact, Hawking has done a lot of scientific research all his life, which can be summarized in one sentence: "How to understand our universe". There are two famous contributions, one is to prove that "BIGBANG starts from singularity" and the other is to prove that "black holes have temperature".

How did the universe come from?

In 1960s, Hawking was faced with two choices, either to study microscopic particle physics or to study macroscopic cosmology.

Hawking chose the latter, and his first concern was the singularity in cosmology. This problem can be traced back to 19 15, when Einstein proposed the general theory of relativity to describe the dynamics of curved spacetime. In the theory of relativity, if the differences in dimensions are not considered, then the space-time of the universe is like an infinitely extended "tablecloth". If we set up a space-time coordinate system on the tablecloth like drawing latitude and longitude on the earth, we will see many square grids, and each grid represents a space-time unit.

If the universe is not empty, but has matter, then the gravitational field generated by matter will distort the lattice. The stronger the gravitational field, the more serious the distortion. 1965, mathematician Roger? Penrose proved that when the strength of the gravitational field exceeds a certain limit, such as when a massive star collapses into a black hole, the space-time lattice at the center of the black hole may be extremely distorted, forming a "singularity".

If we regard the direction of one set of parallel lines in the grid as time and the direction of another set of parallel lines as space, and mark time with arrows to indicate the direction of time passing, we will find that the singularity is like a spring, and the space-time grid flows out continuously under the guidance of the time arrow, or it is like a leak in a bathtub, and the space-time grid is pushed in by the time arrow.