Dictionary of physical terms. Terms (dictionary) - physics What is a term in physics definition
Absolute zero is the lowest possible temperature at which a substance contains no thermal energy.
Antiparticle - each type of particle has its own antiparticles. When a particle collides with an antiparticle, they annihilate, leaving only energy.
Anthropic principle - the principle according to which we see the Universe as it is, and not otherwise, because if it were different, we would not be here and we could not observe it.
An atom is the basic unit of ordinary matter, which consists of a tiny nucleus (composed of protons and neutrons) surrounded by electrons revolving around it.
The big collapse is a singularity at the end of the evolution of the universe.
The Big Bang is a singularity at the beginning of the evolution of the Universe.
Weight is a force generated by the action of a gravitational field on a body. Weight is proportional to mass, but not identical to it.
Virtual particle - in quantum mechanics, a particle that cannot be directly detected, but whose existence generates measurable effects.
Gamma radiation is electromagnetic radiation with a very short wavelength generated by radioactive decay and collisions of elementary particles.
A geodetic line is the shortest (or longest) path between two points.
The event horizon is the boundary of a black hole.
Wavelength - the distance between two adjacent troughs or two adjacent wave crests.
Duality is a correspondence between seemingly different theories that leads to identical physical results.
Quantum mechanics is a theory developed on the basis of Planck's quantum principle and Heisenberg's uncertainty principle.
Planck's quantum principle is the notion that light (or any other classical waves) can only be emitted and absorbed in discrete portions (quanta) whose energy is proportional to the wavelength.
A quark is a charged elementary particle that participates in the strong interaction. Protons and neutrons are made up of three quarks.
Coordinates are numbers that specify the position of a point in space and time.
Corpuscular wave dualism – in quantum mechanics, the concept that there is no difference between waves and particles; particles can sometimes behave like waves, and waves can behave like particles.
The cosmological constant is a mathematical device used by Einstein to endow space-time with a tendency to expand.
Cosmology is the science that studies the universe as a whole.
Redshift is the reddening of the light of a star moving away from us, which is due to the Doppler effect.
A wormhole is a thin tube of space-time that connects distant regions of the universe. Wormholes may also connect parallel or nascent universes and provide the possibility of time travel.
Magnetic field - the field responsible for magnetic forces. Now considered together with the electric field as a manifestation of a single electromagnetic field.
Mass - the amount of matter in the body; its inertia, or resistance to acceleration.
Microwave background radiation is the radiation left over from the hot early Universe and has by now experienced such a strong redshift that it has turned from light into microwaves (radio waves with a wavelength of several centimeters).
The Einstein Rosen Bridge is a thin tube of space-time that connects two black holes. See also Wormhole.
A neutrino is an extremely light (possibly massless) particle that is subject only to weak forces and gravity.
A neutron is an uncharged particle, very similar to a proton. Neutrons make up about half of the particles in an atomic nucleus.
A neutron star is a cold star held in balance by the Pauli exclusion principle, which causes repulsion between neutrons.
General relativity – Einstein's theory based on the idea that the laws of physics should be the same for all observers, no matter how they move.
Gives an explanation of the gravitational interaction in terms of the curvature of the four-dimensional space-time.
Absence of boundary conditions – the notion that the universe is finite but has no boundaries.
The positron is the positively charged antiparticle of the electron.
A field is an entity distributed in space and time, as opposed to a particle, which exists at only one point at a time.
The exclusion principle (Pauli exclusion principle) is the idea that two identical particles of some types cannot simultaneously (within the limits set by the uncertainty principle) have the same position and speed.
Uncertainty principle - a principle formulated by Heisenberg and stating that it is impossible to accurately determine both the position and speed of a particle at the same time; the more precisely we know one thing, the less precisely the other.
Proportionality - the expression "The value of X is proportional to Y" means that when Y is multiplied by an arbitrary number, the same thing happens to X; the expression "the value of X is inversely proportional to Y" means that when Y is multiplied by an arbitrary number, X is divided by the same number.
A spatial dimension is any of these three dimensions, that is, any dimension other than time.
Space time is a four-dimensional space, the points of which are events.
A proton is a positively charged particle, very similar to a neutron. In most atoms, protons make up about half of all particles in the nucleus.
Radar is a system that uses pulses of radio waves to determine the position of objects by measuring the time it takes the pulse to reach the object and bounce back.
Radioactivity is the spontaneous decay of an atomic nucleus, turning it into another type of nucleus.
A light second (light year) is the distance traveled by light in one second (one year).
The strong force is the strongest of the four fundamental forces and has the shortest range. The strong force holds quarks inside protons and neutrons, and also holds protons and neutrons together to form atoms.
A singularity is a point in space-time where the curvature of space-time (or some other physical quantity) reaches an infinite value.
The weak force is the second weakest of the four fundamental forces with a very short range. Affects all particles of matter, but does not affect the particles carriers of interactions.
An event is a point in space-time characterized by time and place.
Spectrum - a set of frequencies that make up the wave. The visible part of the solar spectrum can be seen in the rainbow.
Special relativity – Einstein's theory based on the idea that the laws of physics should be the same for all observers no matter how they move, in the absence of gravitational phenomena.
Dark matter is matter in galaxies, their clusters, and possibly between clusters that cannot be observed directly, but can be detected by its gravitational pull. Dark matter can account for up to 90% of the mass of the universe.
Grand unified theory is a theory that combines the electromagnetic, strong and weak interactions.
String theory is a physical theory in which particles are described as waves on strings. Strings have length but no other dimensions.
Acceleration - the rate at which the object's speed changes.
An elementary particle accelerator is a facility capable of accelerating moving charged particles by transferring energy to them using electromagnets.
Phase (waves) - position in the cycle of the wave process at a fixed point in time; a measure of whether a given reading falls on a wave crest, trough, or some intermediate state.
A photon is a quantum of light.
Frequency (waves) - the number of complete oscillation cycles per second.
A black hole is a region of space-time that nothing, not even light, can escape due to very strong gravity.
Electric charge is a property of a particle due to which it can repel (or attract) other particles that have a charge of the same (or opposite) sign.
Electromagnetic interaction - the interaction that occurs between particles that have an electric charge; the second strongest of the four fundamental forces.
An electron is a particle with a negative electric charge that revolves around the nucleus of an atom.
An elementary particle is a particle that is considered to be indivisible.
The electroweak unification energy is the energy (about 100 gigaelectronvolts) above which the distinction between electromagnetic and weak interactions disappears.
Nuclear fusion is the process in which two nuclei collide and fuse to form a heavier nucleus.
The nucleus is the central part of the atom, which consists only of protons and neutrons held together by a strong force.
1. A material point is a body whose dimensions can be neglected when solving specific problems. 2. A reference system is a coordinate system; a reference body with which it is associated and a device for measuring time. 3. Movement is a vector connecting the initial position of the body with the final position of the body 4. Trajectory is an imaginary line along which the body moves. 5. Path - the length of the trajectory 6. Average speed - the ratio of the entire path traveled at different speeds to the entire time of movement.
7. Rectilinear movement - movement along one straight line 8. Rectilinear uniform movement - this is a movement in which the body, moving in a straight line for equal periods of time, travels equal distances. 9. Speed with uniform movement is a vector quantity equal to the ratio of the movement of the body for any period of time to this period. 10. Uniformly accelerated movement is movement with constant acceleration. 11. Acceleration-Speed, speed change. 12. Schedule
Speed-dependence of speed on the time of movement 13. Braking distance is the distance traveled by the body from the beginning of braking to its complete stop. 14. Force is a vector quantity, it is a quantitative measure of the interaction of bodies. 15. An inertial frame of reference is such a frame of reference, relative to which the body moves in a straight line and uniformly, or is at rest if no forces act on it. 16. "Newton's first law": There are frames of reference called inertial, with respect to
which the body moves uniformly, rectilinearly or is at rest if the sum of the forces acting on it is equal to zero. 17. "Newton's second law": The acceleration caused by a force acting on a body is directly proportional to the force and inversely proportional to the mass of the body 18. "Newton's third law": The reaction force is equal to the force of the action on a support or suspension. 20. Free fall is movement under the force of gravity 21."
The law of universal gravitation ": The force of mutual attraction of two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. 22. The gravitational constant is a physical quantity equal to the force with which two bodies are attracted, weighing 1 kg at a distance of 1 meter. 23. The momentum of a body is a vector quantity equal to the product of the body's mass and its speed 24. "Law of Conservation of Momentum": The vector sum of the momenta of bodies that make up a closed system does not change
over time for any interactions of bodies with each other. 25. Inertia is the ability of a body to continue moving after the force has ceased to act on it. 26. Mass is a measure of inertia. 27. Mechanical vibrations are any periodically repeated mechanical movements. 28. Period is the time during which the body makes one oscillation. 29. Frequency is a physical quantity equal to the number of oscillations per unit time.
30. The oscillation amplitude is a value equal to the maximum deviation from the equilibrium position. 31. Free oscillations are oscillations caused by an initial deviation from the equilibrium position. 32. Harmonic oscillations are oscillations described by the equation of sine and cosine. 33. Resonance is the phenomenon of a sharp increase in the amplitude of the system's oscillations when the frequency of the natural oscillations of the system coincides with the frequency of the external driving force.
34. Waves - Any disturbances propagating in space from the place of origin. 35. Elastic waves are perturbations propagating in an elastic medium. 36. Longitudinal waves are waves that oscillate along the direction of wave propagation. 37. Transverse waves are waves that oscillate perpendicular to the direction of wave propagation. 38. Wavelength is the distance between the nearest points that oscillate in the same phase.
39. Sound vibrations are vibrations with a frequency of 20 Hz to 20 kHz, which the human ear can perceive. 40. Infrasound is an oscillation with a frequency below 20 Hz 41. Ultrasound is a sound with a frequency above 20 kHz 42. Electric current is an ordered movement of charged particles 43. Dielectrics are substances that do not conduct electric current 44. Resistance is a physical quantity, characterizing the ability of a substance to conduct electricity
current. 45. "Ohm's Law": The current in a circuit is directly proportional to the voltage and inversely proportional to the resistance. 46. Serial connection is such a connection in which all elements of the circuit are connected in series one after another. 47. Parallel connection is such a connection in which all elements of the circuit are connected in parallel to each other. 48. Magnetic field is a special kind of matter through which magnetic interactions are carried out. 49. A uniform magnetic field is a field whose lines are parallel
each other with the same frequency. 50. An inhomogeneous magnetic field is a field whose lines are curved and located at different frequencies. 51. Solenoid-coil, on which a large number of turns of current-carrying wire are wound. 52. "Rule of the Gimlet": If the direction of the translational movement of the Gimlet coincides with the direction of the current in the conductor, then the direction of rotation of the Gimlet handle coincides with the direction of the magnetic field lines.
53. "Rule of the right hand": If you grasp the solenoid with the palm of your right hand, pointing four fingers in the direction of the current in the turns, then the thumb set aside ninety degrees will show the direction of the magnetic field lines inside the solenoid. 54. "Rule of the left hand": If the left hand is positioned so that the lines of the magnetic field enter the palm perpendicular to it, and four fingers are directed to the flow, then the thumb set aside ninety degrees will show the direction
force acting on the conductor. 55. Magnetic field induction is a vector quantity that characterizes the strength of the magnetic field at each point in space. 56. One Tesla is such an induction of a magnetic field that acts on a conductor one meter long with a current of one Ampere with a force of one Newton. 57. Magnetic flux is a physical quantity that characterizes the change in the vector of magnetic induction passing through the space bounded by the circuit.
58. An electromagnetic field is a special kind of matter formed from alternating electric and magnetic fields parading each other. 59. "Basic position of Maxell's theory": Any change in the magnetic field leads to the emergence of an alternating electric field, and any change in the electric field generates an alternating magnetic field. 60. An electromagnetic wave is a system of variables generating each other and propagating in space
electric and magnetic fields. 61. Ultraviolet radiation is electromagnetic radiation with a shorter wavelength. 62. Light interference is the phenomenon of the superposition of two coherent waves, in which an interference pattern is formed. 63. Coherent waves are waves with the same frequency and constant phase difference. 64. An interference pattern is a picture of the distribution of oscillation amplitudes in space that does not change with time. 65. Alpha radiation is a stream of helium atom nuclei 66. Betta
radiation is a flow of electrons 67. Gamma radiation is a flow of photons 68. Radioactivity is the ability of an atom of a substance to spontaneously emit Alpha, Betta and Gamma rays. 69. Alpha decay is the phenomenon of radiation from one or more nuclei of a helium atom. 70. Isotopes are atoms of the same substance with different masses of the nucleus. 71. Nucleons is a general designation for protons and neutrons.
hadrons- the class of elementary particles participating in the strong interaction. Everything belongs to hadrons baryons And mesons, including resonances.
Hadron jets- directed beams of hadrons produced by the collision of high-energy particles in deeply inelastic processes.
antiparticles- particles that differ from similar ones in the sign of electric charge. The names "particle" and "antiparticle" are largely arbitrary.
"Fragrance"- characteristic of quarks, including the entire set quantum numbers(electric charge, strangeness, "charm", etc. except for "color").
baryons- a group of "heavy" elementary particles with a half-integer back and a mass not less than the mass of a proton. Baryons include proton, neutron, hyperons, part of resonances, etc.
boson- a particle with zero and integer spin, subject to Bose-Einstein statistics. The bosons are photons, gravitons(not open yet) mesons, bosonic resonances, gas molecules, gluons and etc.
Vacuum- a special kind of matter, which corresponds in quantum field theory to the lowest energy state of quantized fields. Characterized by the absence of any real particles, at the same time constantly generates short-lived virtual particles.
virtual particles- in quantum theory, short-lived particles for which the connection between energy, momentum and mass is broken: E 2 ≠p 2 c 2 + m 2 c 2 . Virtual particles are carriers of interactions.
Hypercharge (Y) is one of the characteristics of hadrons. Hypercharge is expressed through other hadron quantum numbers - baryon charge, strangeness, "charm", "beauty".
Hyperons- unstable elementary particles with a mass greater than the nucleon. Refer to hadrons and are baryons.
Gluons- hypothetical, electrically neutral particles, carriers of the strong interaction between quarks in quantum chromodynamics. Spin = 1, rest mass = 0.
Goldstone boson- a hypothetical particle with zero spin and zero mass. Introduced in quantum field theory to distinguish between vacuum states.
Gravitational collapse- astrophysical process of compression of space objects under the action of their own gravitational forces.
graviton- quantum of the gravitational field, having zero mass and electric charge, the spin is 2. Gravitons are carriers of gravitational interaction; experimentally not yet discovered.
Dirac monopole- a hypothetical particle with one magnetic pole. Its existence was predicted in 1931 by P. Dirac.
Doppler effect- change in the frequency of oscillations when the source moves relative to the observer.
Unified field theory- a general theory designed to unite all the variety of properties of elementary particles and the features of their interaction. At present, only electric, magnetic, and weak nuclear interactions have been combined within the framework of the ETP.
Charge parity- (C-parity), a quantum number characterizing the behavior of neutral particles. In weak interactions, the symmetry associated with charge parity is broken.
Isotopic invariance- symmetry of strongly interacting particles. On the basis of isotopic invariance, multiplets are formed that make it possible to effectively classify all hadrons.
instanton- a special state of vacuum, which corresponds to a strong fluctuation of the gluon field. In the theory of self-organization, an instanton is one of the main structures generated by vacuum.
Gauge symmetry- the general name of the class of internal symmetries in quantum field theory and quantum chromodynamics. Gauge symmetries are related to the properties of elementary particles.
Quasars- powerful extragalactic sources of electromagnetic radiation. There is an assumption that cosmic rays are the active nuclei of distant galaxies.
Quantization of space - time- the general name of generalizations of quantum field theory based on the hypothesis of the existence of fundamental length and fundamental time interval as universal physical constants.
Quantum mechanics(wave mechanics) - a theory that establishes the method of description and the laws of motion of microparticles, as well as their connection with physical quantities directly measured by experience.
quantum chromodynamics(QCD) - quantum field theory of the strong interaction of quarks and gluons, modeled on quantum electrodynamics based on "color" gauge symmetry.
Quarks- material particles, of which, according to modern concepts, all hadrons consist. To understand the dynamics of various processes involving hadrons, six quarks are currently considered sufficient: u, d, s, c, b, t. There are indirect confirmations of the existence of the first five quarks.
quantum numbers- integer or fractional numbers that determine the possible values of physical quantities characterizing quantum systems. Quantum numbers include: main (n), orbital (l), magnetic (m e), spin (m s), strangeness, "charm", "beauty", etc.
Chiral symmetry- in quantum field theory, one of the fundamental dynamic symmetries, through which a good description of the processes of scattering and decay of hadrons at low energies and at very high energies becomes possible. Chiral symmetry also includes enantiomorphisms (right-left).
K-mesons(kaons) - a group of unstable elementary particles that participate in strong interaction. Charge asymmetry of decays K 0 L →π - + e + (μ +) + v e (v μ) and k 0 L →π + + e - (μ -) + v e (v μ ), where the probability of the second decay is greater than the first one by 10 ~"\ indicates the violation of one of the fundamental symmetries of nature (CP invariance).
Compton wavelength- the value of the dimension of length, characteristic of relativistic quantum processes λ 0 = h / mc .
Cosmology- the doctrine of the universe as a whole. The conclusions of cosmology are based on the laws of physics and data from observational astronomy, taking into account philosophical principles.
Mesons- unstable elementary particles belonging to hadrons. According to the quark model, matter consists of a quark and an antiquark.
Neutrino- light (possibly massless) electrically neutral particle with spin 1/2. Participates only in weak and gravitational interactions. Neutrinos have an enormous penetrating power, and their detection will make it possible to study in detail the states of the early Universe.
Reversible process- in thermodynamics and statistical physics, the process of transition of a system from one state to another, allowing the possibility of returning it to its original state.
Time reversal- mathematical operation of changing the sign of time in the equations of motion. Objectively, real time as an attribute of matter is irreversible, and therefore the operation of changing the sign of time is possible only as an epistemological technique that facilitates the solution of a physical problem.
Operators- in quantum theory, a mathematical symbol used to perform some action on a physical quantity.
orbital moment- angular momentum of a microparticle due to its motion in a force field with spherical symmetry.
Basic state quantum system - a stable state with the lowest possible internal energy.
open systems- thermodynamic systems that exchange matter, energy, momentum with the environment. Recently, open systems have been studied in chemistry and biology.
Partons are the virtual components of hadrons, which manifest themselves in deeply inelastic processes.
Plasma- one of the main types of matter, is a partially or fully ionized gas. The vast majority of the Universe is in the plasma state: stars, galactic nebulae, interstellar medium. Under laboratory conditions, plasma is formed in discharges, combustion processes, MHD generators and special installations (for example, "Tokamak").
Positron- (e+) elementary particle with a positive electric charge numerically equal to the charge of an electron. Is antiparticle with respect to the electron.
Vacuum polarization- a quantum-relativistic phenomenon, which consists in the birth of virtual pairs of charged particles-antiparticles from vacuum under the influence of an external field.
Space and time- attributive (inalienable) properties of matter. Space expresses the order of coexistence of objects, time - the order of change of events. Space and time are objective, that is, they do not depend on a person, and their characteristics are determined solely by the nature of the movement of the corresponding forms of matter.
Proton- a positively charged elementary particle, the nucleus of a hydrogen atom. It has been suggested that the proton is an unstable particle with a half-life of ~10 30 years, but experimental confirmation of this hypothesis has not yet been carried out.
Pulsars- Variable sources of cosmic electromagnetic radiation.
Resonances- short-lived excited states of hadrons (lifetime t ~ 10 -22 ÷10 -24 s). Unlike other unstable particles, resonances decay mainly due to the strong interaction. To date, more than 300 resonances have been discovered.
Relativistic effects- physical phenomena observed at speeds comparable to the speed of light. These include: slowing down time, shortening lengths, increasing body weight, etc.
Superconductivity and high-temperature superconductivity- a property of many conductors, consisting in the fact that their electrical resistance abruptly drops to zero when cooled to the temperature of liquid hydrogen and helium. At present (March 1987) a transition to the superconducting state of a number of materials at high temperatures has been discovered, which will be of exceptional national economic importance.
Symmetry- a) in physics - a kind of proportionality of laws. In a more general sense, symmetry is a kind of relationship between two objects that is characterized by both moments of identity and moments of difference. The most widely used in physics isotopic, "color", gauge and other symmetries, without which modern physical theory would be impossible; b) in philosophy, symmetry is one of the general scientific concepts, denoting the formation of moments of identity in the different. Symmetry is represented in the objective world in the form of specific forms of symmetry.
Soliton- structurally stable solitary wave in a nonlinear dispersive (scattering) medium. Solitons are intensively used in the construction of quantum nonlinear field theory.
Compliance principle- in the methodology of science, one of the principles according to which any subsequent scientific theory should include, as a limiting (special) case, the previous theory. In relation to correspondence are, for example, Newtonian mechanics and the special theory of relativity.
Spin- own moment of momentum of elementary particles, has a quantum nature, due to the internal "rotation" of the particle.
Spontaneous symmetry breaking- spontaneous violation of a stable, equilibrium, symmetrical state, provided that it is removed from the state with minimal energy. The solution of many problems of quantum field theory, including the appearance of particles with zero mass and zero spin, is associated with spontaneous symmetry breaking.
supergravity- Gauge theory of supersymmetry, which allows to generalize the general theory of relativity. In the framework of supergravity, in principle, it is possible to combine all known types of interactions.
supersymmetry- symmetry connecting fields whose quanta are bosons with fields whose quanta are fer ions. The most interesting application of supersymmetry is supergravity.
CPT symmetry- one of the fundamental symmetries, according to which, in quantum field theory, the equations are invariant under the combined C (charge), P (spatial) and T (time reversal) transformations.
Unitary symmetry- approximate symmetry inherent in the strong interaction of elementary particles. In electromagnetic and weak interactions is violated. It was possible to classify hadrons on the basis of unitary symmetry.
fluctuations- random deviations of physical quantities from their average values. Fluctuations occur in any quantities as a consequence of random factors.
Fermions are particles obeying Fermi-Dirac statistics. Fermions have half-integer spin. Fermions include quarks, leptons (electron, muon, all types of neutrinos).
Photon- elementary particle, quantum of electromagnetic radiation. The rest mass of a photon is zero. Photons are bosons.
Parity- quantum mechanical characteristic of the state of a microparticle, reflecting the symmetry properties of the wave function of this particle with respect to spatial transformations.
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