The field of physics research can be divided into the following four aspects:
1. condensed matter physics: studying the macroscopic properties of matter. These stages contain a large number of components, and the interaction between team members is very strong. The most familiar condensed phases are solids and liquids, which are formed by bonds between atoms and electromagnetic forces. More condensed matter phases include superfluid and Bose-Einstein condensed matter (found in some atomic systems with very low temperatures); Superconducting phases of conducting electrons in some materials: ferromagnetic and antiferromagnetic phases in atomic lattice. Condensed matter physics has always been the biggest research field. Historically, it originated from solid state physics. 1967 was first put forward by philip anderson and adopted this name.
2. Atomic, molecular and optical physics: study the interaction between matter and matter, light and matter within the scope of atomic size or several atomic structures. These three areas are closely related. Because they use similar methods and related energy levels. They all include classical and quantum processing methods; Deal with problems from a micro perspective. Atomic physics studies the shell of atoms, focusing on the quantum control of atoms and ions; Cooling and trapping; Low temperature collision dynamics: accurate measurement of basic constants; Collective effect of electrons in structural dynamics. Atomic physics is influenced by the nucleus. However, nuclear phenomena such as nuclear division and nuclear synthesis belong to high-energy physics. Molecular physics focuses on polyatomic structure and its interaction with matter and light. Optical physics here only studies the basic characteristics of light and the interaction between light and matter in the microscopic field.
3. High energy/particle physics: particle physics studies the basic composition of matter and energy and their interaction; Also known as high energy physics. Because many elementary particles do not exist in nature, they only appear when they collide with other particles in a high-energy particle accelerator. According to the interaction standard model of elementary particles, there are 12 elementary particle models of known substances (quarks and light particles). They interact through strong, weak and electromagnetic basic forces. The standard model also predicts the existence of the Higgs boson.
4. Astrophysics: Astrophysics and astronomy are physical theories and methods used to study the structure and evolution of stars, the origin of the solar system and related problems in the universe. Because astrophysics covers a wide range. It uses many physical principles. Including mechanics, electromagnetism, statistical mechanics, thermodynamics and quantum mechanics. 193 1 year, Karl discovered the radio signals from celestial bodies. Started radio astronomy. Space exploration has expanded the field of astronomy. The interference of the earth's atmosphere makes the observation space need infrared, ultra-ultraviolet, gamma rays and x-rays. Physical cosmology studies the formation and evolution of the universe on a large scale. Einstein's theory of relativity plays a central role in modern cosmic theory. At the beginning of the 20th century, Hubble discovered that the universe was expanding, which promoted the discussion of the steady-state theory of the universe and the Big Bang. 1964 The discovery of the cosmic microwave background proves that the Big Bang theory may be correct. The Big Bang model is based on two theoretical frameworks: Einstein's general theory of relativity and cosmological principles. Cosmology established ACDM universe evolution model; Including the expansion of the universe, black energy and black matter. Many possibilities and discoveries can be expected from the new data of Fermi gamma-ray telescope and the improvement of the existing universe model.
Physics: physical phenomena, material structure, material interaction, and laws of material movement.
The scope of physics research-the level and order of magnitude of the material world
Spatial proportion:
Atoms, nuclei, elementary particles, DNA length, smallest cell, Hubble radius of Sun Mountain, galaxy clusters, distance between galaxies and stars, solar system, supercluster, etc. "Man Snakes the Tail" vividly shows the size of material space.
Microscopic particles: proton 10? m
Mesoscopic substance
Macroscopic substance
Cosmic Matter 10m Cosmic Quasars
Time scale:
Life of elementary particles 10? s
Cosmic life is 10.
According to the spatial scale: quantum mechanics, classical physics, cosmic physics.
According to the speed: relativistic physics, non-relativistic physics.
According to the size of the object: micro, meso, macro and cosmology.
According to the movement speed: low speed, medium speed and high speed.
According to research methods: experimental physics, theoretical physics and computational physics.
Classification introduction
Newtonian mechanics and rational mechanics study the basic laws of mechanical motion of objects and the laws about relativity of time and space.
● Electromagnetism and electrodynamics study electromagnetic phenomena, laws of electromagnetic motion of matter and electromagnetic radiation.
● Thermodynamics and statistical mechanics study the statistical laws and macroscopic manifestations of thermal motion of matter.
Relativity studies the effects of high-speed motion of objects and related dynamic laws.
● Quantum mechanics studies the motion phenomena and basic laws of microscopic matter.
In addition, there are:
Particle physics, nuclear physics, atomic and molecular physics, solid physics, condensed matter physics, laser physics, plasma physics, geophysics, biophysics, astrophysics and so on.
research field
The field of physics research can be divided into the following four aspects:
1. condensed matter physics-study the macroscopic properties of matter. These stages contain a large number of components, and the interaction between team members is very strong. The most familiar condensed phases are solids and liquids, which are formed by bonds between atoms and electromagnetic forces. More condensed matter phases include superfluid and Bose-Einstein condensed matter (found in some atomic systems with very low temperatures); Superconducting phases of conducting electrons in some materials: ferromagnetic and antiferromagnetic phases in atomic lattice. Condensed matter physics has always been the biggest research field. Historically, it originated from solid state physics. 1967 was first put forward by philip anderson and adopted this name.
2. Atomic, molecular and optical physics-the study of substance-substance and light-substance interactions within the scope of atomic size or several atomic structures. These three areas are closely related. Because they use similar methods and related energy levels. They all include classical and quantum processing methods; Deal with problems from a micro perspective. Atomic physics studies the shell of atoms, focusing on the quantum control of atoms and ions; Cooling and trapping; Low temperature collision dynamics: accurate measurement of basic constants; Collective effect of electrons in structural dynamics. Atomic physics is influenced by the nucleus. However, nuclear phenomena such as nuclear division and nuclear synthesis belong to high-energy physics. Molecular physics focuses on polyatomic structure and its interaction with matter and light. Optical physics here only studies the basic characteristics of light and the interaction between light and matter in the microscopic field.
3. High energy/particle physics-particle physics studies the basic components of matter and energy and their interactions; Also known as high energy physics. Because many elementary particles do not exist in nature, they only appear when they collide with other particles in a high-energy particle accelerator. According to the interaction standard model of elementary particles, there are 12 elementary particle models of known substances (quarks and light particles). They interact through strong, weak and electromagnetic basic forces. The standard model also predicts the existence of the Higgs boson. Looking for it.
4. Astrophysics-Astrophysics and astronomy are physical theories and methods used to study the structure and evolution of stars, the origin of the solar system and related problems of the universe. Because astrophysics covers a wide range. It uses many physical principles. Including mechanics, electromagnetism, statistical mechanics, thermodynamics and quantum mechanics. 193 1 year, Karl discovered the radio signals from celestial bodies. Started radio astronomy. Space exploration has expanded the field of astronomy. The interference of the earth's atmosphere makes the observation space need infrared, ultra-ultraviolet, gamma rays and x-rays. Physical cosmology studies the formation and evolution of the universe on a large scale. Einstein's theory of relativity plays a central role in modern cosmic theory. At the beginning of the 20th century, Hubble discovered that the universe was expanding, which promoted the discussion of the steady-state theory of the universe and the Big Bang. 1964 The discovery of the cosmic microwave background proves that the Big Bang theory may be correct. The Big Bang model is based on two theoretical frameworks: Einstein's general theory of relativity and cosmological principles. Cosmology established ACDM universe evolution model; Including the expansion of the universe, black energy, black matter. Many possibilities and discoveries can be expected from the new data of Fermi gamma-ray telescope and the improvement of the existing universe model. Especially in the next few years, there may be many discoveries about dark matter.
History of physics
Galileo galilei (1564-1642), the founder of modern human physics, laid the foundation for the scientific development of modern human physics.
● 1900- 1926 Establish quantum mechanics.
● Fermi Dirac statistics was established in 1926.
● 1927 established the Bloch wave theory.
● 1928 sommerfeld put forward the band conjecture.
1929 Peierls put forward the concepts of forbidden band and hole, and Bette put forward the concept of fermi surface in the same year.
● 1947, Bardeen, bratton and shockley of Bell Laboratories invented the transistor, marking the beginning of the information age.
● 1957, Pippard measured the first photon of Fermi surface superlattice nanomaterial.
1958 jack kilby invented the integrated circuit.
● Large-scale integrated circuits appeared in 1970s.
The relationship between physics and physical technology;
The invention and use of heat engine provided the first mode: technology-physics-technology.
● The process of electrification provides a second mode: physics-technology-physics.
Nowadays, the relationship between physics and science and technology coexist, cross and promote each other. Without yesterday's basic science, there would be no technological revolution today. For example: the use of nuclear energy, the generation of laser, tomography (CT), superconducting electronics, particle scattering experiments, the discovery of X-rays, the theory of stimulated radiation, the microscopic theory of low-temperature superconductivity, and the birth of electronic computers. Almost all major new (high-tech) fields were established in physics a long time in advance.
The method and scientific attitude of physics: putting forward a proposition → theoretical explanation → theoretical prediction → experimental verification → theoretical correction.
Modern physics is a precise science combining theory with experiment, and its production process is as follows:
① Physical propositions are generally extracted from new observed facts or experimental facts, or derived from existing principles;
② First, try to explain propositions, logical reasoning and mathematical calculus with known theories. If the existing theory cannot be perfectly explained, it is necessary to modify the original model or put forward a brand-new theoretical model;
④ The new theoretical model must make predictions, and the predictions can be confirmed by experiments;
⑤ All physical theories are ultimately based on observation or experimental facts. When a theory is inconsistent with the experimental facts, it will be revised or overturned.
How to study physics?
Feynman, a famous physicist, said: Science is a method that teaches people how to know a thing, what to know, to what extent, how to treat doubts and uncertainties, and what laws evidence obeys; How to think about things, make judgments, and distinguish between authenticity and superficial phenomena? Einstein, a famous physicist, said: to cultivate the general ability of independent thinking and independent judgment, we should always focus on professional knowledge. If a person grasps the basic theory of his own subject and learns to think and work independently, he will certainly find his own way and adapt to progress and change better than those who mainly train in acquiring detailed knowledge.
● Learning point of view: Learn physics logically and harmoniously as a whole, and understand the relationship between various branches of physics.
● The essence of physics: physics does not study the mechanism of natural phenomena (or can't study it at all). We can only feel the laws of nature in some phenomena and try to explain anything that happens in nature with these laws. Our limited intelligence is always trying to understand and change nature, which is the goal pursued by physics and even all natural sciences.
Related sciences based on physics: chemistry, astronomy, physical geography, etc.
Subject nature
Basic attribute
Physics is a regular summary of people's understanding of material transformation in inanimate nature. There should be two kinds: movement and transformation. On the one hand, in the early days, people expanded their sensory horizons. On the other hand, in modern times, people indirectly understood the internal composition of matter by inventing and creating scientific instruments for observation and measurement and the results of experiments. Physics can be divided into microscopic and macroscopic parts from different research angles and viewpoints. Macroscopically, the whole effect is directly considered without analyzing the individual effect of particle swarm, which has appeared in the earliest stage. With the development of science and technology, the theory of microphysics has been gradually improved.
Secondly, physics is a kind of intelligence.
As born, a German scientist who won the Nobel Prize in Physics, said: "If it is because my published work contains the discovery of a natural phenomenon, it is better to say that it contains a basis for scientific thinking methods about natural phenomena." Physics is recognized as an important science, not only because it profoundly reveals the laws of the objective world, but also because it has formed a unique and effective system of ideas and methods in the process of development and growth. Because of this, physics has become the crystallization of human wisdom and the treasure of civilization.
A large number of facts show that the ideas and methods of physics are not only valuable to physics itself, but also have important contributions to the development of the whole natural science and even social science. According to statistics, since the middle of the 20th century, more than half of the Nobel Prize winners in chemistry, biology, medicine and even economics have a physics background. This means that they have learned wisdom from physics and achieved success in non-physical fields. On the other hand, there has never been a case in which a scientist who is not a physics major won the Nobel Prize in physics. This is the power of body intelligence. No wonder some foreign experts pointed out that a nation without sports literacy is a stupid nation!
In a word, physics is a summary of the laws of nature and a theoretical understanding of the scientific nature of experience.
Six attributes
1. Truth: The theories and experiments of physics reveal the mysteries of nature and reflect the objective laws of material movement.
2. Harmony and unity: The movement of celestial bodies in the mysterious space described by Kepler's three laws shows how harmonious and orderly it is. Several great unifications in physics also show the feeling of beauty. Newton unified all macroscopic objects in the sky and on the ground with three laws and the law of universal gravitation. The establishment of Maxwell's electromagnetic theory unified electricity and magnetism. Einstein's equation of mass and energy unifies mass and energy. The wave-particle duality theory of light unifies particles and fluctuations. Einstein's theory of relativity unified time and space again.
3. Simplicity: The mathematical language of physical laws embodies the simplicity and portability of physics. Such as Newton's second law, Einstein's mass-energy equation and Faraday's law of electromagnetic induction.
4. Symmetry: Symmetry generally refers to the symmetry of the shape of an object, and the deep symmetry is manifested in the development and change of things or the symmetry of objective laws. For example, the spatial lattice structure of various crystals in physics is highly symmetrical. Vertical throwing motion, simple harmonic vibration, wave mirror symmetry, magnetoelectric symmetry, symmetry of acting force and reaction force, positive particle and antiparticle, positive matter and antimatter, positive charge and negative charge, etc.
5. Predictability: The correct physical theory can not only explain the physical phenomena discovered at that time, but also predict the physical phenomena that could not be detected at that time. For example, Maxwell's electromagnetic theory predicted the existence of electromagnetic waves, Rutherford predicted the existence of neutrons, Fresnel's diffraction theory predicted that there was a Poisson bright spot in the diffraction center of a disk, and Dirac predicted the existence of electrons.
6. Exquisite: The physical experiment is exquisite, and the ingenious design method makes the physical phenomenon more obvious.