Sir isaac newton (1643 65438+1October 4th-1727 March 3rd1), chairman of the Royal Society, a famous British physicist, is an encyclopedic "all-rounder" and author of Mathematical Principles of Natural Philosophy and Optics.
He described gravity and three laws of motion in the paper "Laws of Nature" published by 1687. These descriptions laid the scientific view of the physical world in the next three centuries and became the basis of modern engineering. By demonstrating the consistency between Kepler's law of planetary motion and his theory of gravity, he showed that the movements of ground objects and celestial bodies all follow the same natural law; It provides strong theoretical support for the sun-centered theory and promotes the scientific revolution.
In mechanics, Newton expounded the conservation principle of momentum and angular momentum and put forward Newton's law of motion [1]. In optics, he invented reflecting telescope, and based on the observation that a prism diverges white light into the visible spectrum, he developed the color theory. He also systematically expressed the law of cooling and studied the speed of sound.
In mathematics, Newton and Gottfried Wilhelm Leibniz shared the honor of developing calculus. He also proved the generalized binomial theorem and put forward Newton's method to approximate the zero point of function, which contributed to the study of power series.
In economics, Newton put forward the gold standard.
Astrophysics is divided into solar physics, solar system physics, stellar physics, stellar astronomy, planetary physics, galaxy astronomy, cosmology, cosmology and celestial evolution chemistry. In addition, radio astronomy, space astronomy and high energy astrophysics are also its branches.
Astrophysics is the physics that studies the universe, including the physical properties of stars (luminosity, density, temperature, chemical composition, etc.). ) and the interaction between stars. Astrophysics uses physical theories and methods to explore the structure, evolution and origin of the solar system and many problems related to cosmology. Because astrophysics is a very extensive knowledge, astrophysicists usually apply many different academic fields, including mechanics, electromagnetism, statistical mechanics, quantum mechanics, relativity, particle physics and so on. Due to the interdisciplinary development in modern times, chemistry, biology, history, computer, engineering, paleontology, archaeology, meteorology and other disciplines have been mixed. There are about 300 to 500 main branches of astrophysics, which has become the largest leading discipline in physics, the leading science leading the significant development of modern science and technology, and the oldest traditional science.
Most experimental data of astrophysics are obtained by observing electromagnetic radiation. Cold stars, such as interstellar matter or interstellar clouds, emit radio waves. After the Big Bang, the microwave left after the red shift is called cosmic microwave background radiation. Studying these microwaves requires a very large radio telescope.
Space exploration has greatly expanded the field of astronomy. Due to the interference of the earth's atmosphere, infrared, ultraviolet, gamma-ray and X-ray astronomy must use artificial satellites to do observation experiments outside the earth's atmosphere.
Optical astronomy usually uses telescopes equipped with charge-coupled elements and spectrometers for observation. Because the atmosphere will interfere with the quality of observation data, it is necessary to equip with adaptive optical system or use space telescope to get the best image. In this frequency domain, the visibility of stars is very high. By observing the chemical spectrum, we can analyze the chemical composition of stars, galaxies and nebulae.
Theoretical astrophysicists' tools include analytical models and computer simulations. The analytical model of astronomical process can often make scholars understand the mystery more deeply; Computer simulation can show some very complicated phenomena or effects.
The two theoretical pillars of the Big Bang model are general relativity and cosmological principles. Because of the success of the initial nuclear synthesis theory and the confirmation of the cosmic microwave background radiation experiment, scientists have confirmed that the BIGBANG model is correct. Scholars have created λλCDM model to explain the evolution of the universe, which covers the concepts of cosmic expansion, dark energy and dark matter.
Theoretical astrophysicists and measurement astrophysicists play two main researchers in this subject respectively, and they are divided into two occupations. Theoretical astrophysicists usually play the role of researchers. They make bold assumptions, constantly bring forth new ideas, and don't care much about data verification. If the hypothesis is too high, it will often become pseudoscience, and it is generally radical among astrophysics researchers.
Observational astrophysicists are usually proficient in theoretical astrophysics, and to some extent, they also have the ability to develop their own theories. They are usually practitioners of physical positivism, only believe in observation data, and often falsify or confirm the hypotheses put forward by theoretical astrophysics. Generally speaking, they are conservatives among astrophysics researchers.
There are 200 billion stars in the Milky Way, and their physical states are very different. Spheres, infrared stars, celestial maser sources and Herbig-Arrow celestial bodies may all be transitional celestial bodies from interstellar clouds to stars.
The T-shaped star of Taurus becomes irregular and has no fixed period; When the nova explodes, it throws a lot of matter, and the luminosity suddenly increases by tens of thousands to millions of times; The radius of some red giant stars is more than 1000 times that of the sun; The density of white dwarfs is from 100 kg to 10 ton per cubic centimeter, and the density of neutron stars is as high as 1 00 billion tons per cubic centimeter.
Various stars provide samples for studying the formation and evolution of stars. In addition, the special physical conditions on celestial bodies are often not available on earth, and it is an important function of astrophysics to explore physical laws by using celestial phenomena.
Through various means of observation, people's vision has been extended to the "depth" of the universe of 654.38+0.5 billion light years. This is the "observed universe", or "our universe", that is, the total galaxy.
The research shows that the cosmic matter consists of nearly 100 chemical elements and 289 isotopes in the periodic table of chemical elements. Minerals and molecules that do not exist on earth have been found in different cosmic substances.
By analyzing the electromagnetic radiation of celestial bodies with physical techniques and methods, various physical parameters of celestial bodies can be obtained. According to these parameters, it is the task of measuring astrophysics and theoretical astrophysics to explain the physical process and its evolution with physical theory.
The theories of radiation, nucleus, gravity, plasma, solid and elementary particles in theoretical physics have laid the foundation for the study of quasars, cosmic rays, black hole pulsars, interstellar dust and supernova explosions.