The Apprentice is Too Diligent and the Master is a Bit Lazy

Condensed matter physics studies the macroscopic properties of matter. These phases contain a huge number of components, and the interactions between components are extremely strong. The most familiar condensed matter phases are solids and liquids, which are formed by bonds between atoms and electromagnetic forces. More condensed phases include superfluid and Bose-Einstein condensates (found in some atomic systems at very low temperatures); superconducting phases exhibited by conducting electrons in some materials; ferromagnetic and antiferromagnetic phases. Condensed matter physics has been the largest field of research. Historically, it has grown out of solid physics. It was first proposed by Philip Anderson in 1967 and adopted this name.

Atomic, Molecular and Optical Physics The study of matter-matter and light-matter interactions on the scale of atomic dimensions or structures of a few atoms. These three fields are closely related. Because they use similar methods and related energy scales. They both include classical and quantum approaches; dealing with problems from a microscopic perspective. Atomic physics deals with the shell of atoms, focusing on quantum control of atoms and ions; cooling and trapping; low-temperature collision dynamics; accurate measurements of fundamental constants; and collective effects of electrons in structural dynamics. Atomic physics is influenced by the nucleus. However, nuclear internal phenomena such as nuclear fission and nucleosynthesis belong to high-energy physics. Molecular physics focuses on polyatomic structures and their interactions with matter and light. Optical physics here only studies the basic properties of light and the interaction between light and matter in the microscopic field.

High Energy/Particle Physics Particle physics is the study of the fundamental building blocks 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 in high-energy collisions with other particles in particle accelerators. According to the standard model of interaction of elementary particles, there are 12 kinds of elementary particle models (quarks and light particles) of known matter. They interact through the strong, weak and electromagnetic fundamental forces. The Standard Model also predicts the existence of a Higgs-Bose particle. Now looking for.

Astrophysics Astrophysics and modern astronomy are the application of physical theories and methods to the study of the structure and evolution of stars, the origin of the solar system, and related issues of the universe. Because of its broad scope, astrophysics draws on many principles of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, and quantum mechanics. In 1931, Karl discovered radio signals from celestial bodies and started radio astronomy. The frontiers of astronomy have been expanded by space exploration. Interference from Earth's atmosphere necessitates viewing space using infrared, extreme ultraviolet, gamma rays, and x-rays. Physical cosmology studies the formation and evolution of the universe on the large scale of the universe. Einstein's theory of relativity plays a central role in modern theories of the universe. In the early 20th century, Hubble discovered that the universe was expanding from the picture, which promoted the discussion between the steady state theory of the universe and the big bang. The discovery of the cosmic microwave background in 1964 proved that the Big Bang theory might be correct. The big bang model is based on two theoretical frameworks: Einstein's general theory of relativity and cosmological principles. Cosmology has established the adm universe evolution model, which includes the expansion of the universe, dark energy and dark matter. Many possibilities and discoveries can be expected from new data from the Fermi Gamma-ray Telescope and improvements to existing models of the universe. Especially in the next few years, there may be many discoveries surrounding dark matter.

The famous physicist Feynman said: "Science is a method. It teaches people: how some things are known, what is known, to what extent, how to deal with doubts and uncertainties, what evidence obeys How to think about things, how to make judgments, how to distinguish between true and false and superficial phenomena?" The famous physicist Einstein said: "The development of the general ability of independent thinking and independent judgment should always be placed in the first place, and professional Knowledge comes first. If a man has mastered the fundamentals of his subject, and has learned to think and work independently, he will surely find his way, and he will find his own way, and will do so much better than a man whose training is mainly to acquire detailed knowledge. , he will definitely adapt better to progress and change.

Physics is a regular summary of people's knowledge of the movement and transformation of matter in nature. There should be two types of movement and transformation. One is the extension of early people's sensory vision; the other is that modern people have invented and created scientific instruments for observation and measurement, and obtained results from experiments to indirectly understand the internal composition of substances. From different research angles and perspectives, physics can be roughly divided into microcosmic and macrocosmic two parts: macrophysics does not analyze the individual effects of particle groups, but directly considers the overall effect, which has appeared in the earliest days; the birth of microphysics , originated from the inability of macrophysics to explain new experimental phenomena such as black body radiation, photoelectric effect, and atomic spectrum. It is a revision of macroscopic physics, and it is gradually perfected with the development of experimental technology and theoretical physics.

Secondly, physics is a kind of intelligence.

As the Nobel Prize winner in physics and German scientist Born said: "It is not so much because my published work contains the discovery of a natural phenomenon, but rather because it contains a scientific way of thinking about natural phenomena." fundamentals.” The reason why physics is recognized as an important science is not only because it has made profound revelations about the laws of the objective world, but also because it has formed a set of unique and fruitful sciences in the process of development and growth. system of thought. Because of this, physics has deservedly become the crystallization of human intelligence and the treasure of civilization.

A large number of facts show that physical ideas and methods are not only valuable to physics itself, but also make important contributions to the development of the entire natural sciences and even social sciences. According to statistics, since the middle of the 20th century, more than half of the winners of the Nobel Prize in Chemistry, Biology and Medicine, and even the Economics Prize have a background in physics, which means that they have learned a lot from physics. Intelligence, in turn, succeeds in the non-physical realm. On the contrary, there has never been a case where a scientist with a non-physics major has won the Nobel Prize in Physics. This is the power of physical intelligence. No wonder some foreign experts pointed out sharply: A nation without physical accomplishment is a stupid nation!

In short, physics is a summary of the general laws of nature and a theoretical understanding of the scientific nature of experience.

Atoms are the smallest particles that cannot be divided into chemical reactions. A positive atom consists of a dense nucleus surrounded by negatively charged electrons. The nucleus of a negative atom is negatively charged, and the surrounding negative electrons are positively charged. The nucleus of a positive atom consists of positively charged protons and neutrally charged neutrons. The antiprotons in the nucleus of the negative atom are negatively charged, thereby making the nucleus of the negative atom negatively charged. When the number of protons is the same as the number of electrons, the atom is electrically neutral; otherwise, it is a positively or negatively charged ion. Depending on the number of protons and neutrons, there are different types of atoms: the number of protons determines which element the atom belongs to, and the number of neutrons determines which isotope of that element the atom is. [3] Atoms make up molecules and molecules make up substances of the same kind that repel each other, and different kinds of charges attract each other.

The order of magnitude of atomic diameter is about 10?1?m. The mass of an atom is extremely small, its order of magnitude is generally 10-27kg, and its mass is mainly concentrated on protons and neutrons. Electrons are distributed outside the nucleus, and electron transitions produce spectra. Electrons determine the chemical properties of an element and have a great influence on the magnetism of atoms. All atoms with the same number of protons make up elements, and most of each element has an unstable isotope that can undergo radioactive decay.

The notion that matter is composed of discrete units that can be arbitrarily divided has been around for millennia, but these ideas are based on abstract, philosophical reasoning rather than experiment and experimental observation. With the passage of time and the transformation of cultures and schools, the nature of atoms in philosophy has also changed greatly, and this change often has some spiritual factors.

Nevertheless, the basic concept of the atom is still adopted by chemists thousands of years later, because it can explain some chemical phenomena very concisely.

Atomism is the most succinct and scientific form of elementalism. Dampier, a British historian of natural science, believes that atomic theory is "closer to the modern point of view than any theory before or after it" in science. The founder of atomic theory was the ancient Greek Leucippus (500 BC ~ about 440 BC), who was the teacher of Democritus. When ancient scholars discussed the atomic theory, they usually confused the two theories. Leucippus' theory was developed and perfected by his student Democritus, so Democritus is recognized as the main representative of atomism.

According to Democritus, the original or fundamental elements of all things are "atoms" and "void". "Atom" means "indivisible" in Greek. Democritus used this concept to refer to the most basic particles of matter that constitute concrete things. The fundamental characteristic of the atom is "full and solid", that is, there is no gap inside the atom, it is solid, inaccessible, and therefore indivisible. Democritus believed that atoms are eternal, immortal; atoms are infinite in number; atoms are in a state of constant motion, and its only form of motion is "vibration". The volume of atoms is small, It is invisible to the eyes, that is, it cannot be perceived by the senses, and can only be understood through reason.

After more than 20 centuries of exploration, scientists confirmed the real existence of atoms through experiments in the 17th to 18th centuries. At the beginning of the 19th century, the British chemist J. Dalton put forward the atomic theory with modern significance on the basis of further summarizing the experience of the predecessors. The introduction of this atomic theory ushered in a new era of chemistry, and he explained many physical and chemical phenomena.

An atom is the smallest unit of an element that retains its chemical properties. An atom consists of a dense nucleus and a number of negatively charged electrons surrounding the nucleus. The nucleus of an atom consists of positively charged protons and neutrally charged neutrons. Atoms are the smallest particles of chemical change, molecules are made up of atoms, and many substances are directly made up of atoms.

The English name of atom is transformed from Greek, which means indivisible. The notion of the indivisibility of the atom was proposed long ago by Greek and Indian philosophers. In the 17th and 18th centuries, chemists discovered the basis of physics: for some substances, they cannot be further decomposed by chemical means. In the late 19th and early 20th centuries, physicists discovered subatomic particles and the internal structure of atoms, proving that atoms are not indestructible. The principles of quantum mechanics can provide good models for atoms

In 932, Joliot Curie and his wife discovered that this kind of ray can knock out protons from paraffin; in the same year, Rutherford’s student James Chadwick (Jameshadwik) determined that this is the neutron [8], and the isotope is Redefined as elements with the same number of protons but different numbers of neutrons.

In 1950, with the development of particle accelerators and particle detectors, scientists could study collisions between high-energy particles. They discovered that neutrons and protons are types of hadrons, made of smaller particles called quarks. The standard model of nuclear physics has also been developed, which can successfully explain the interaction between the entire atomic nucleus and subatomic particles at the subatomic level.

In 1985, Steven Chu and his colleagues at Bell Laboratories developed a new technique for cooling atoms using laser light. William Daniel Phillips' team managed to place nanoatoms in a magnetic trap. These two techniques, together with a method based on the Doppler effect developed by Claude Cohen-Tannoude's team, allow small numbers of atoms to be cooled down to temperatures in the microkelvin range, allowing them to be manipulated with great precision. The research laid the foundation for the discovery of Bose-Einstein condensate [11].

Historically, individual atoms were considered too small for scientific study. In 2012, scientists had successfully used a single metal atom linked to an organic ligand to form a single-electron transistor. In some experiments, atoms are slowed down and trapped by laser cooling, which could lead to a better understanding of matter.

Schrodinger (Erwinsger) used the hypothesis of wave-particle duality proposed by Louis de Broglie (llie) in 1924 to establish a mathematical model of an atom to describe electrons as a three-dimensional waveform. However, it is mathematically impossible to obtain precise values ​​of position and momentum at the same time. Werner Heisenberg (Wernerheisenberg) proposed the famous uncertainty principle. What this concept describes is that for a certain position of the measurement, only an indeterminate range of momentum can be obtained, and vice versa. Although the model is difficult to imagine, it can explain some previously observed properties of atoms that could not be explained, such as the spectral lines of atoms larger than hydrogen. Therefore, people no longer use Bohr's atomic model, but consider atomic orbitals as regions with high probability of electrons (electron cloud).