Who can talk about the theory of eternal inflation? Dear friends

Alan Guth, a scientist at the Massachusetts Institute of Technology, suggested that the early universe may have a very rapid expansion period. This kind of expansion is called "inflation", which means that the universe is expanding at an increasing rate, not decreasing as it is now. According to Gus' theory, at the moment after the Big Bang, space-time expanded rapidly by 1078 times in less than 10-34 seconds (how many zeros are not needed to indicate how extreme these two numbers are).

Gus thinks that the universe started with a very hot and quite disorderly big bang. These high temperatures show that particles in the universe move very fast and have high energy. As we discussed earlier, at such a high temperature, strong and weak nuclear forces and electromagnetic forces are expected to be unified into one force. When the universe expands, it will get cold and the particle energy will drop. Finally, the so-called phase transition appeared, and the symmetry between forces was destroyed: strong force became different from weak force and electromagnetic force. A common example of phase change is that water freezes into ice when it cools. Liquid water is symmetrical. It is the same at any point and in any direction. However, when ice crystals form, they have definite positions and are arranged in a certain direction, which destroys the symmetry of water.

When treating water, as long as you are careful enough, you can make it "supercooled", that is, you can lower the temperature below freezing point (0℃) without freezing. According to Gus, the behavior of the universe is similar: the temperature of the universe can be reduced below the critical value without destroying the symmetry between different forces. If this happens, the universe is in an unstable state, and its energy is greater than that when symmetry is broken. This special extra energy presents an anti-gravity effect: it behaves like a cosmological constant. When Einstein tried to build a stable model of the universe, the cosmological constant was introduced into general relativity. Because the universe has expanded like the Big Bang model, the repulsive effect of this cosmological constant makes the universe expand at an increasing speed. Even in some areas where the number of particles exceeds the average, the repulsive effect of this effective cosmological constant exceeds the gravity of matter. In this way, these areas also expand in the form of accelerated expansion. When they expand, the particles of matter become more and more separated, leaving an expanding universe with almost no particles, which is still in a supercooled state. Any irregularity in the universe is smoothed out by this expansion, just like the wrinkles on it when you blow a balloon. Therefore, the smooth and consistent state of the universe can evolve from many different inconsistent initial States.

In such a universe, the expansion is accelerated by the cosmological constant and not slowed down by the gravity of matter, the light in the early universe has enough time to travel from one place to another. This answers the question raised before, why different regions in the early universe have the same properties. And the expansion speed of the universe automatically becomes very close to the critical value determined by the energy density of the universe. In this way, it is not necessary to assume that the initial expansion rate of the universe has been chosen very carefully, which can explain why the current expansion rate is still so close to the critical value.

Gus thinks that the universe started with a very hot and quite disorderly big bang. These high temperatures show that particles in the universe move very fast and have high energy. As we discussed earlier, at such a high temperature, strong and weak nuclear forces and electromagnetic forces are expected to be unified into one force. When the universe expands, it will get cold and the particle energy will drop. Finally, the so-called phase transition appeared, and the symmetry between forces was destroyed: strong force became different from weak force and electromagnetic force. A common example of phase change is that water freezes into ice when it cools. Liquid water is symmetrical. It is the same at any point and in any direction. However, when ice crystals form, they have definite positions and are arranged in a certain direction, which destroys the symmetry of water.

When treating water, as long as you are careful enough, you can make it "supercooled", that is, you can lower the temperature below freezing point (0℃) without freezing. According to Gus, the behavior of the universe is similar: the temperature of the universe can be reduced below the critical value without destroying the symmetry between different forces. If this happens, the universe is in an unstable state, and its energy is greater than that when symmetry is broken. This special extra energy presents an anti-gravity effect: it behaves like a cosmological constant. Cosmic constant is Einstein's attempt to establish a stable