The natural world is a complex place. Harmonies allow people and scientists to distinguish the order in it. In physics, it has long been understood that the principle of symmetry is closely related to the laws of conservation. The three most famous rules are: conservation of energy, momentum and momentum. The persistence of pressure is a consequence of the fact that the attitudes of nature do not change at any interval. For example, in Newton's law of gravity, one can imagine that GN, the gravitational constant, depends on time.
In this case no energy will be saved. From experimental searches for energy conservation violations, one can set strict limits on any such change over time. This symmetry principle is quite broad and is applied in quantum as well as in classical mechanics. Physicists sometimes refer to this parameter as the homogeneity of time. Similarly, conservation of momentum is a consequence of the fact that there is no special place. Even if the world is described using Cartesian coordinates, the laws of nature will not care thatconsider source.
This symmetry is called "translational invariance" or homogeneity of space. Finally, conservation of angular momentum is related to the familiar principle of harmony in everyday life. The laws of nature are invariant under rotations. For example, not only does it not matter how a person chooses the origin of coordinates, but it doesn't matter how he chooses the orientation of the axes.
Discrete class
The principle of space-time symmetry, shift and rotation are called continuous harmonies, because you can move the coordinate axes by any arbitrary amount and rotate by an arbitrary angle. The other class is called discrete. An example of harmony is both reflections in a mirror and parity. Newton's laws also have this principle of bilateral symmetry. One has only to observe the movement of an object falling in a gravitational field, and then study the same movement in a mirror.
While the trajectory is different, it obeys Newton's laws. This is familiar to anyone who has ever stood in front of a clean, well-polished mirror and is confused about where the object was and where the mirror image was. Another way to describe this principle of symmetry is the similarity between left and opposite. For example, three-dimensional Cartesian coordinates are usually written according to the "right hand rule". That is, the positive flow along the z-axis lies in the direction that the thumb is pointing if the person rotates their right hand around z, starting at x Oy and moving towards x.
Unconventionalcoordinate system 2 is opposite. On it, the Z-axis indicates the direction in which the left hand will be. The statement that Newton's laws are invariant means that a person can use any coordinate system, and the rules of nature look the same. And it's also worth noting that parity symmetry is usually denoted by the letter P. Now let's move on to the next question.
Operations and types of symmetry, principles of symmetry
Parity is not the only discrete proportionality of interest to science. The other is called time change. In Newtonian mechanics, one can imagine a video recording of an object falling under the force of gravity. After that, you need to consider running the video in reverse. Both "forward in time" and "backward" moves will obey Newton's laws (reverse movement may describe a situation that is not very plausible, but it will not violate the laws). Time reversal is usually denoted by the letter T.
Charge conjugation
For every known particle (electron, proton, etc.) there is an antiparticle. It has exactly the same mass, but the opposite electrical charge. The antiparticle of an electron is called a positron. A proton is an antiproton. Recently, antihydrogen has been produced and studied. Charge conjugation is a symmetry between particles and their antiparticles. Obviously they are not the same. But the principle of symmetry means that, for example, the behavior of an electron in an electric field is identical to the actions of a positron in the opposite background. Charge conjugation is denotedletter C.
These symmetries, however, are not exact proportions of the laws of nature. In 1956, experiments unexpectedly showed that in a type of radioactivity called beta decay, there was an asymmetry between left and right. It was first studied in the decays of atomic nuclei, but it is most easily described in the decomposition of the negatively charged π meson, another strongly interacting particle.
It, in turn, decomposes either into a muon, or into an electron and their antineutrino. But decays on a given charge are very rare. This is due (through an argument that uses special relativity) to the fact that a concept always emerges with its rotation parallel to its direction of motion. If nature were symmetrical between left and right, one would find the neutrino half time with its spin parallel and the part with its antiparallel.
This is due to the fact that in the mirror the direction of movement is not modified, but by rotation. Associated with this is the positively charged π + meson, the antiparticle π -. It decays into an electron neutrino with a parallel spin to its momentum. This is the difference between his behavior. Its antiparticles are an example of charge conjugation breaking.
After these discoveries, the question was raised whether the time reversal invariance T had been violated. According to the general principles of quantum mechanics and relativity, the violation of T is related to C × P, the product of conjugation of charges and parity. SR, if this is a good symmetry principle means that the decay π + → e + + ν must go with the samespeed as π - → e - +. In 1964, an example of a process that violates CP was discovered involving another set of strongly interacting particles called Kmesons. It turns out that these grains have special properties that allow us to measure a slight violation of CP. It was not until 2001 that SR disruption was convincingly measured in the decays of another set, B mesons.
These results clearly show that the absence of symmetry is often just as interesting as the presence of it. Indeed, soon after the discovery of SR violation, Andrei Sakharov noted that it is a necessary component in the laws of nature for understanding the predominance of matter over antimatter in the universe.
Principles
Until now it is believed that the combination of CPT, charge conjugation, parity, time reversal, are preserved. This follows from the rather general principles of relativity and quantum mechanics, and has been confirmed by experimental studies to date. If any violation of this symmetry is found, it will have profound consequences.
So far, the proportions under discussion are important in that they lead to conservation laws or relationships between reaction rates between particles. There is another class of symmetries that actually determines many of the forces between particles. These proportionalities are known as local or gauge proportionalities.
One such symmetry leads to electromagnetic interactions. The other, in Einstein's conclusion, to gravity. In laying out his principle of generalIn theory of relativity, the scientist argued that the laws of nature should be available not only in order for them to be invariant, for example, when rotating coordinates simultaneously everywhere in space, but with any change.
The mathematics to describe this phenomenon was developed by Friedrich Riemann and others in the nineteenth century. Einstein partially adapted and re-invented some for his own needs. It turns out that in order to write equations (laws) that obey this principle, it is necessary to introduce a field that is in many ways similar to electromagnetic (except that it has a spin of two). It correctly connects Newton's law of gravity to things that are not too massive, moving fast or loose. For systems that are so (compared to the speed of light), general relativity leads to many exotic phenomena such as black holes and gravitational waves. All of this stems from Einstein's rather innocuous notion.
Mathematics and other sciences
The principles of symmetry and conservation laws that lead to electricity and magnetism are another example of local proportionality. To enter this, one must turn to mathematics. In quantum mechanics, the properties of an electron are described by the "wave function" ψ(x). It is essential to the work that ψ be a complex number. It, in turn, can always be written as the product of a real number, ρ, and periods, e iθ. For example, in quantum mechanics, you can multiply the wave function by the constant phase, with no effect.
But if the principle of symmetrylies on something stronger, that the equations do not depend on the stages (more precisely, if there are many particles with different charges, as in nature, the specific combination is not important), it is necessary, as in general relativity, to introduce a different set of fields. These zones are electromagnetic. The application of this symmetry principle requires that the field obey Maxwell's equations. This is important.
Today, all interactions of the Standard Model are understood to follow from such principles of local gauge symmetry. The existence of the W and Z bands, as well as their masses, half-lives, and other similar properties, have been successfully predicted as a consequence of these principles.
Immeasurable numbers
For a number of reasons, a list of other possible symmetry principles has been proposed. One such hypothetical model is known as supersymmetry. It was proposed for two reasons. First of all, it can explain a long-standing riddle: "Why are there very few dimensionless numbers in the laws of nature."
For example, when Planck introduced his constant h, he realized that it could be used to write a quantity with mass dimensions, starting with Newton's constant. This number is now known as the Planck value.
The great quantum physicist Paul Dirac (who predicted the existence of antimatter) deduced the "problem of large numbers". It turns out that postulating this nature of supersymmetry can help solve the problem. Supersymmetry is also integral to understanding how the principles of general relativity canbe consistent with quantum mechanics.
What is supersymmetry?
This parameter, if it exists, relates fermions (particles with half-integer spin that obey the Pauli exclusion principle) to bosons (particles with integer spin that obey so-called Bose statistics, which leads to the behavior of lasers and Bose condensates). However, at first glance, it seems silly to propose such a symmetry, because if it were to occur in nature, one would expect that for each fermion there would be a boson with exactly the same mass, and vice versa.
In other words, in addition to the familiar electron, there must be a particle called a selector, which has no spin and does not obey the exclusion principle, but in all other respects it is the same as the electron. Similarly, a photon should refer to another particle with spin 1/2 (which obeys the exclusion principle, like an electron) with zero mass and properties much like photons. Such particles have not been found. It turns out, however, that these facts can be reconciled, and this leads to one last point about symmetry.
Space
Proportions can be proportions of the laws of nature, but do not necessarily have to be manifested in the surrounding world. The space around is not homogeneous. It is filled with all sorts of things that are in certain places. Nevertheless, from the conservation of momentum, man knows that the laws of nature are symmetrical. But in some circumstances proportionality"spontaneously broken". In particle physics, this term is used more narrowly.
Symmetry is said to be spontaneously broken if the lowest energy state is not commensurate.
This phenomenon occurs in many cases in nature:
- In permanent magnets, where the alignment of spins that causes magnetism in the lowest energy state breaks rotational invariance.
- In the interactions of π mesons, which blunt the proportionality called chiral.
The question: "Does supersymmetry exist in such a broken state" is now the subject of intense experimental research. It occupies the minds of many scientists.
Principles of symmetry and laws of conservation of physical quantities
In science, this rule states that a particular measurable property of an isolated system does not change as it evolves over time. The exact conservation laws include the reserves of energy, linear momentum, its momentum, and electric charge. There are also many rules of approximate abandonment that apply to quantities such as masses, parity, lepton and baryon number, strangeness, hyperzary, etc. These quantities are conserved in certain classes of physical processes, but not in all.
Noether's theorem
Local law is usually expressed mathematically as a partial differential continuity equation that gives the ratio between quantity quantity andits transfer. It states that the number stored in a point or volume can only be changed by that which enters or exits the volume.
From Noether's theorem: every conservation law is related to the basic principle of symmetry in physics.
Rules are considered fundamental norms of nature with wide application in this science, as well as in other fields such as chemistry, biology, geology and engineering.
Most laws are precise or absolute. In the sense that they apply to all possible processes. By Noether's theorem, symmetry principles are partial. In the sense that they are valid for some processes, but not for others. She also states that there is a one-to-one correspondence between each of them and the differentiable proportionality of nature.
Particularly important results are: the symmetry principle, conservation laws, Noether's theorem.
