Matter in our daily life is made up of atoms. In the past, it was thought that atoms were basic particles, and the word atom came from the ancient Greek word "inseparable". It was later discovered that the nucleus was composed of protons and neutrons. The elementary particles in the first and middle period of the 20th century refer to protons, neutrons, electrons, photons and various mesons, which are the smallest particles that can be detected by human beings at that time. With the development of experiments and quantum field theory, it is found that protons, neutrons and mesons are composed of more basic quarks and gluons. At the same time, humans have discovered a series of leptons with similar properties to electrons and a series of gauge bosons with similar properties to photons and gluons. These are the basic particles understood by modern physics.
Elementary particles (subatomic particles) are classified as follows:
Fermion
Basic fermions are divided into two categories: quarks and leptons.
quark
Current experiments show that there are six kinds of quarks and their antiparticles in * *. These six quarks can be divided into three generations. they are
First generation: u (upper quark) d (lower quark)
The second generation: s (strange quark) c (charm quark)
Third generation: b (bottom quark) t (top quark)
Their quality relationship (see above). In addition, it is worth pointing out that they were not discovered by early scientists because quarks never existed alone (except the top quark, which is too heavy and decays too fast for early experiments). They always form mesons in pairs (see the figure below), or three together form protons, neutrons and other baryons (see the figure below). This phenomenon is called quark confinement theory. This is why early scientists mistakenly thought that mesons and baryons are basic particles.
Monetary unit in Greece.
* * * There are six leptons and their antiparticles. Three of them are electrons and heavy electrons with similar properties. All three species have a companion neutrino. They can also be divided into three generations:
The first generation: (electron) (electric neutrino)
Second generation: (μ meson) (muneutrino)
The third generation: (Tao Zi) (τ neutrino)
Please click to enter a picture description.
boson
According to bose-einstein statistics, a boson is a particle whose spin is an integer.
Gauge boson
This is a kind of particle that acts as a medium and transmits the interaction between particles. They are called "gauge bosons" because they are closely related to the Young-Mills gauge field theory of elementary particle theory.
There are four kinds of interactions in nature, so gauge bosons can also be divided into four categories.
Gravitational interaction: gravitons (still theoretical)
Electromagnetic interaction: photons
There are three kinds of weak interactions: W and Z bosons, * * *: W+, W-, Z0.
Strong interaction (interaction between quarks): gluons
Particle physics proves that when the energy in the early universe is extremely high, electromagnetic interaction and weak interaction come from the same kind of interaction, which is called "weak current interaction". Many particle physicists suspect that in the earlier universe, when the energy is higher (Planck scale), it is likely that all four interactions are unified. This theory is called "The Theory of Everything". But it is difficult to verify at present, because the energy that the accelerator can reach is still very low relative to the Planck scale. At present, the main development direction of grand unification theory is superstring theory.
? Planck-scale particle
gluon
Gluon is a mediator with strong interaction with color and reverse color, which has never been observed by the detector because of the closed color. However, like single quarks, they produce hadron jets. In the high-energy environment, the elimination of electrons and positrons sometimes produces three jets: a quark, an antiquark and a gluon, which is the first evidence to prove the existence of gluons.
Higgs boson
Higgs boson is a kind of boson with mass, which has no spin, no charge and is very unstable. It will decay immediately after it is produced. Among the 6 1 elementary particles predicted by the standard model, the Higgs boson is the last particle confirmed by experiments.
The+-sign in the figure represents the smallest inseparable unit of positive and negative electromagnetic information-quantum bit.
(john wheeler, a famous physicist, once famously said: Everything comes from bit by bit.
After the prosperity of quantum information research, this concept has been sublimated to everything from quantum bits.
Note: One point is one point.