The origin of mass-energy equation
To understand this problem, we must first understand the mass-energy equation. In other words, what we should understand is the relationship between matter, mass and energy.
This starts from 1905. This year is the highest moment in Einstein 's life. During this year, Einstein published several groundbreaking papers one after another. (All discoveries that surpass Nobel Prize level) Among them, the last two articles were later collectively called Special Relativity by us.
The mass-energy equation is published in the last paper of this year. Therefore, to understand the premise of mass-energy equations, we must first figure out what the special theory of relativity is?
Then we have to continue to push the timeline forward. Before Einstein, there were two huge crises in the scientists, namely: ether and bold radiation.
The latter gave birth to quantum mechanics , while the former gave birth to the theory of relativity. The so-called " ether " is actually something that scientists imagine. Specifically, the problem lies in the speed of light. There is no absolute speed in Newtonian mechanics , that is, there is no situation where it runs as fast as any inertial coordinate system. But the speed of light found in Maxwell's equation proposed by Maxwell has no reference system. That is to say, the speed of light derived from Maxwell's theory should be the same under any inertial reference system, and the two are inconsistent.
So, scientists assumed that "ether" is the medium of light transmission to eliminate this contradiction. Unfortunately, many scientists finally proved through various experiments that "ether" does not exist, and the more famous one is the Michael Sun Morey experiment.
At this time, many scientists were puzzled and couldn't figure out what was wrong. At this time, Einstein extracted two basic assumptions from the theoretical system of both parties based on Newton and Maxwell:
The principle of relativity The principle of light speed is constant and only these two are used to build the theoretical framework of the entire special theory of relativity. The whole process is a bit similar to the geometric reasoning problem we are doing in junior high school. From this time on, Einstein subverted human understanding of movement. He found that sports meet changes the time and space of a moving object, thus proposing the time expansion and ruler shrinkage effects, and published a paper.
Later he continued to dig deeper, so he discovered that motion will also change the mass of an object, and solved it through the kinetic energy theorem to obtain the mass-energy equation.
But getting the equation does not mean that you can understand the physics meaning. So how should we understand it?
In fact, this part of the understanding is the biggest misunderstanding about the theory of relativity. In many popular science, when describing atomic bomb explosion, it will be said that "mass converts energy." Discovered? This is directly described as a conversion relationship. However, we must know that Einstein's paper is called "Mass-Energy Equivalence", and he wants to express the relationship between quality and equivalence. In other words, mass and energy are actually the same thing. They are two sides of an object. There is energy in mass and mass in energy. The mass-energy equation only describes the correspondence between them. (Because this misunderstanding is deeply rooted, the university textbooks that talk about this part are now emphasized. If you don’t believe it, you can read a university textbook that talks about mass and energy equations at will.)
In other words, the explosion of atomic bomb actually means that part of the mass is lost, and this part of the mass is released in the form of energy. If we let an atomic bomb detonate in a closed space, there will be no energy exchange between this space and the outside world. If there is an ideal scale, we will find that it has not changed from beginning to end.
After understanding these, we will return to matter, mass and energy. In fact, mass and energy describe matter. We can say how much mass a matter has, and at the same time, we can say how much energy it contains.
So, in fact, the definition of energy and mass in physics is different from that in most people's phenomena, and the relationship between energy and matter is also different from what most people imagine.
Energy and matter
So, what many people wonder is whether the so-called "pure energy" can be converted into the so-called "matter". Then we continue to disassemble. Matter is actually composed of atom . Atoms are composed of electrons and atom nucleus . The nucleus is composed of protons and neutrons. Of course, you can also get quark .
In other words, this problem can actually become the so-called "pure energy" or whether we say " photon " can be converted into "particles of matter". The answer is: Yes, as long as the temperature is high enough.
This is actually related to Big Bang . In the early stage of the Big Bang, the temperature of the universe was very high. In that environment, the energy of photons was particularly high. When the energy of a pair of photons was higher than the energy of a pair of electrons and positrons , the collision of the pair of photons could produce a pair of electrons and positrons, provided that the temperature reached about 6 billion degrees. Particles such as protons, neutrons, , π meons can also be obtained in this way, but the required temperature is different, and we call this temperature a threshold temperature.
However, if we look closely, we will find that a bunch of positive and negative particles are produced at the same time. That is to say, these positive and negative particles can actually be annihilated and converted into "pure energy".
Our universe is dominated by positive matter, because in the early days of the universe, every 1 billion positive and negative particles collided, a positive particle would be left, but scientists have not yet figured out the specific reason. However, it is not too much to say that all particles that make up all things are now survivors of one in a billion.
