In fact, many people understand the truth that everything in the universe is composed of smaller matter, but whether this smaller matter has an end or is endless, many people cannot tell clearly.
In human history, a considerable number of philosophers believe that the end of matter must be a basic object that cannot be subdivided. For example, the ancient Greek philosopher Democritus's atomism . Atomic theory holds that everything in the universe is composed of an irreducible atom .
Of course, there are many philosophical ideas that oppose atomism, such as the concept of " one flower, one world" in Buddhism.
In fact, these two ideas are basically subjective assumptions without any experimental proof.
This kind of problem has to be solved by physics in the end.
In the system of modern physics, it is more inclined to support Democritus's atomic theory.
Of course the concept of atoms in ancient Greece is completely different from the modern concept of atoms. The same thing is that, according to the current understanding of physics, matter is subdivided into elementary particles that cannot be divided again.
In quantum mechanics , objects must be divided into elementary particles that cannot be subdivided in the end. At present, there are 61 kinds of elementary particles discovered by mankind. All matter in the universe is composed of elementary particles, including the well-known photons , electrons, neutrinos , quarks and other particles, which are all elementary particles.
The movement laws of elementary particles are completely inconsistent with Newtonian mechanics . Quantum mechanics also evolved into a relatively successful quantum field theory after more than half a century of development and improvement.
Today, physicists use quantum field theory to describe elementary particles. The reason why quantum field theory is extremely complex is that the characteristics of microscopic particles are very abnormal. The most significant anomaly of
is the wave-particle duality of . On a microscopic scale, particles can appear as both waves and particles.
These particles do not even have a fixed spatial position. The particles will be scattered in different positions at the same time, permeating the entire space. We only know where the particle is at the moment we measure it. At the same time, the particle's wave function state will collapse and no longer disperse.
So here comes the embarrassment, how should we describe the spatial position of particles?
Before measurement, the particles fill the entire space in the form of waves. Although the position information of the particle will be obtained after measuring the particle, this position information is completely random. If the particle is measured again, the position information of the particle will be different.
The Schrödinger equation mainly describes the wave nature of particles. Although this equation has achieved great success in the wave nature of particles, it ignores the particle nature and cannot take into account the special relativity effect.
In the microscopic world , particles moving close to the speed of light are very common. When the particle speed approaches the speed of light, the mass will increase and time will slow down. This is the effect of special relativity.
The Schrödinger equation mainly describes the fluctuation changes of particles in space. Special relativity describes the change of particles in time.
In order to perfectly describe the movement patterns of particles, we must take into account the changes in space and time of particles. This led to the birth of quantum field theory. In quantum field theory, particles are just quantized waves.
Many people may be a little confused when they see this. What is the wave of quantum ?
Since particles have wave-particle duality, they are both waves and particles. If we want to use wave-particle duality to solve specific problems, it will be very troublesome. It will be very troublesome to deal with the duality of being a wave and a particle.
In order to facilitate calculations, we can either uniformly describe particles as wave properties, or uniformly describe particles as particle properties.
Once we describe particles uniformly as particle nature, it will be difficult to take into account the volatility.But if we describe particles uniformly as wave properties, we can take into account particle properties very well.
Quantized waves are the embodiment of uniformly describing particles as wave nature while taking into account the particle nature. Because quantizes , it is an indivisible and discontinuous concept. If the wave is continuous, then it loses its particle nature. It is precisely because the wave is discontinuous and quantized that the particle nature of the wave is reflected.
To visualize this, think of waves as waves on the ocean. Each wave represents a different elementary particle, but it must be noted that the waves on the sea surface are continuous, while the waves in quantum field theory are discontinuous and discrete.
Many people may ask here, what does discontinuity mean?
For example, waves in the real ocean may have countless heights, such as 1 meter, 0.5 meters, 2 meters, 2.5 meters, 3 meters, 1.25 meters, 1.75 meters.
Because the height of this wave is a continuous transition, the wave height from 0 meters to 3 meters must go through the process of 0.5 meters, 1.75 meters..., so the height will experience any value between 0 and 3 meters.
But the waves in quantum field theory are quantized, that is, discontinuous. The height of the wave is either one meter, or two meters, or three meters. It is impossible to have transitional height values such as 0.5 meters and 1.25 meters.
Because in the concept of quantization, the height of one meter is the basic height and cannot be further divided. The height of the wave can only be an integer multiple of one meter.
In quantum field theory, particles are the intensification of waves. The intensification of waves must also be an integer multiple to increase the number of particles. For example, if the height of the wave suddenly changes from 1 meter to 2 meters or 3 meters, the number of particles can be increased. If it is not an integer multiple, Changes cannot intensify new particles.
In addition, the real ocean surface may be calm, but the waves in quantum field theory cannot be calm, and there is a minimum energy state.
Assuming that a one-meter-high wave is the wave with the lowest height, then a one-meter-high wave will always exist in space and cannot disappear. This one-meter-high wave is the minimum energy, also called vacuum zero-point energy. The reason why virtual particles can appear out of thin air, which is what we often call pairs of positive and negative particles, is because there are waves of different integer heights in the vacuum.
The collision between waves can form a wave with a new integer height. For example, the collision of two one-meter-high waves will form a 2-meter-high wave. At this time, particles will emerge from the vacuum. But soon, other waves will immediately hit the newly generated wave, causing it to disappear, so the particle will disappear quickly.
Scenes like this are constantly happening in the vacuum, which is very lively, so Dirac also uses the ocean to describe the phenomenon of vacuum. This is the famous Dirac Sea.
The quantized wave ocean is the core idea of quantum field theory. Each elementary particle is a kind of quantum, and different elementary particles have different quantum fields, such as photon fields, electron fields, quark fields, etc.
There are 61 known elementary particles in the standard model (except graviton ), so there are at least 61 kinds of quantum fields.
In the standard model, each elementary particle propagates in its quantum field and interacts with each other. After particles accelerate and collide, new particles are produced because different quantum fields interact to form new quantum fields. Just like different waves hitting each other create new waves. The newly generated wave may be an unknown new particle.
