- Part one -
The closest to realizing Einstein's dream came the little-known Polish physicist Theodor Kaluca, who, back in 1921, set out to generalize Einstein's theory by including electromagnetism in the geometric formulation of field theory (just as the geometry of space-time describes gravity). This should have been done so that the equations of Maxwell's theory of electromagnetism would continue to hold. Kaluza understood that Maxwell's theory could not be formulated in the language of pure geometry (in the sense that we usually understand it), even assuming the presence of curved space. Kaluza took the next step after Einstein, added to the four-dimensional space-time a fifth (unobservable) change in which electromagnetism is a kind of "gravity" (the weak and strong interaction was not known then). The question arises:why don't we feel this fifth dimension in any way (unlike the first four)?
In 1926, Swedish physicist Oskar Klein suggested that we do not notice the extra dimension because it has, in a sense, “collapsed” to a very small size. A small loop extends from each point in space into the fifth dimension. We do not notice all these loops due to their small size. Klein calculated the perimeter of the loops around the fifth dimension using the known value of the elemental electric charge of the electron and other particles, as well as the magnitude of the gravitational interaction between the particles. It turned out to be equal to 10-32 cm, i.e. 1020 times smaller than the size of an atomic nucleus. Therefore, it is not surprising that we do not notice the fifth dimension: it is twisted on scales that are much smaller than the dimensions of any of the structures we know, even in the physics of subnuclear particles. Obviously, in this case, the question of motion does not arise, say,atom in the fifth dimension. Rather, this dimension should be thought of as being within the atom.
For some time, the Klauz-Klein theory was forgotten, but when the strong, weak and electromagnetic interactions were combined into a single theory, and it remained to find a general theory for them and for gravity, the Klauz-Klein theory was remembered again. In order to perform all the necessary symmetry operations, it was necessary to add 7 more dimensions (the whole space as a whole turned out to be 11-dimensional). And so that these additional dimensions are not felt, they must be rolled up on a very small scale. However, now the question arises: if one dimension can only be rolled into a circle, then seven dimensions can be rolled into a figure of various topologies (either into a 7-dimensional torus, or into a 7-dimensional sphere, or into some other figure). The simplest model, to which most scientists are inclined, can serve as a 7-dimensional sphere (7-sphere). As expectedthe four currently observed dimensions of space-time have not collapsed, since this state corresponds to the lowest energy (to which all physical systems tend). There is a hypothesis according to which in the early stages of the life of the universe, all these dimensions were deployed.
A huge variety of natural systems and structures, their features and dynamism are determined by the interaction of material objects, i.e. their mutual action on each other. It is interaction that is the main reason for the movement of matter, therefore, interaction, like movement, is universal, i.e. is inherent in all material objects, regardless of their nature of origin and systemic organization. Features of various interactions determine the conditions of existence and the specifics of the properties of material objects.
Interacting objects exchange energy and - the main characteristics of their movement. In classical physics, interaction is determined by the force with which one material object acts on another.
For a long time it was believed that the interaction of material objects, even at a great distance from each other, is transmitted through empty space instantly. This statement is consistent with the concept of action at a distance. By now, another concept has been experimentally confirmed - the concept of short-range action: interactions are transmitted through physical fields with a finite speed not exceeding the speed of light in a vacuum. This, in essence, field concept in quantum field theory is supplemented by the statement: for any interaction, there is an exchange of special particles - field quanta.
The interactions of material objects and systems observed in nature are very diverse. However, as shown by physical studies, all interactions can be attributed to four types of fundamental interactions: gravitational, electromagnetic, strong and weak.
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Gravitational interaction is manifested in the mutual attraction of any material objects with mass. It is transmitted through the gravitational field and is determined by a fundamental law of nature - the law of universal gravitation. The law of universal gravitation describes the fall of material bodies in the Earth's field, the motion of the planets of the solar system, stars, etc.
In accordance with the quantum field theory, the carriers of the gravitational interaction are gravitons - particles with zero mass, quanta of the gravitational field. Electromagnetic interaction is caused by electrical charges and is transmitted by means of electric and magnetic fields. An electric field arises in the presence of electric charges, and a magnetic field - when they move. A changing magnetic field generates an alternating electric field, which, in turn, is a source of an alternating magnetic field.
Due to electromagnetic interaction, atoms and molecules exist, and chemical transformations of matter take place. Various states of aggregation, friction, elasticity, etc. are determined by the forces of intermolecular interaction, electromagnetic in nature. Electromagnetic interaction is described by the fundamental laws of electrostatics and electrodynamics: Coulomb's law, Ampere's law, etc., and in generalized form - by Maxwell's electromagnetic theory, which relates the electric and magnetic fields. The receipt, transformation and application of electric and magnetic fields, as well as electric current serve as the basis for creating a variety of modern technical means: electrical appliances, radios, televisions, lighting and heating devices, computers, etc.
According to quantum electrodynamics, the carriers of electromagnetic interaction are photons - quanta of the electromagnetic field with zero mass. In many cases, they are recorded by instruments in the form of electromagnetic waves of different lengths. For example, visible light perceived by the naked eye, through which the bulk (about 90%) of information about the world is reflected, is an electromagnetic wave in a rather narrow wavelength range (about 0.4-0.8 microns), corresponding to the maximum solar radiation.
The strong interaction ensures the bonding of nucleons in the nucleus. It is determined by nuclear forces possessing charge independence, short-range action, saturation, and other properties. Strong interactions are responsible for the stability of atomic nuclei. The stronger the interaction of nucleons in the nucleus, the more stable the nucleus, the greater its specific binding energy. With an increase in the number of nucleons in the nucleus and, consequently, the size of the nucleus, the specific binding energy decreases and the nucleus can decay, which is what happens with the nuclei of the elements at the end of the periodic table.
It is assumed that the strong interaction is transmitted by gluons - particles that "stick together" the quarks that are part of protons, neutrons and other particles.
All elementary particles, except for the photon, participate in the weak interaction. It determines the majority of decays of elementary particles, the interaction of neutrinos with matter, and other processes. Weak interaction manifests itself mainly in the processes of beta decay of atomic nuclei of many isotopes, free neutrons, etc. It is generally accepted that the carriers of the weak interaction are vions - particles with a mass approximately 100 times the mass of protons and neutrons.
To date, a unified theory of describing interactions has not yet been fully developed, but most scientists are inclined towards the formation of the Universe as a result of the Big Bang: at the zero moment of time, the Universe arose from a singularity, that is, from a point with zero volume and infinitely high density and temperature. The very "beginning" of the Universe, that is, its state corresponding, according to theoretical calculations, to a radius close to zero, eludes even a theoretical concept. The point is that the equations of relativistic astrophysics remain valid up to a density of about 1093 g / cm3. The Universe, compressed to such a density, once had a radius of the order of one ten-billionth of a centimeter, that is, it was comparable in size to a proton! The temperature of this microverse, by the way, which weighed at least 1051 tons, was incredibly high and, apparently,close to 1032 degrees. The Universe was such a tiny fraction of a second after the start of the "explosion". At the very "beginning" both density and temperature turn to infinity, that is, this "beginning", using mathematical terminology, is that special "singular" point for which the equations of modern theoretical physics lose their physical meaning. But this does not mean that there was nothing before the "beginning": we simply cannot imagine what was before the conditional "beginning" of the Universe. (3)that there was nothing before the "beginning": we simply cannot imagine what was before the conditional "beginning" of the Universe. (3)that there was nothing before the "beginning": we simply cannot imagine what was before the conditional "beginning" of the Universe. (3)
When the age of the Universe reached one hundredth of a second, its temperature dropped to about 1011 K, falling below the threshold value at which protons and neutrons can be produced, some of these particles escaped annihilation - otherwise there would be no matter in our modern Universe. One second after the Big Bang, the temperature dropped to 10 10 K, and neutrinos stopped interacting with matter. The universe has become practically "transparent" for neutrinos. Electrons and positrons still continued to annihilate and emerge again, but after about 10 seconds the level of radiation energy density dropped below their threshold, and a huge number of electrons and positrons turned into radiation from a catastrophic process of mutual annihilation. At the end of this process, however, there remains a certain number of electrons, sufficient touniting with protons and neutrons, give rise to the amount of matter that we observe today in the Universe.
The further history of the Universe is calmer than its turbulent beginning. The rate of expansion gradually slowed down, the temperature, like the average density, gradually decreased, and when the Universe was one million years old, its temperature became so low (3500 degrees Kelvin) that protons and nuclei of helium atoms could already capture free electrons and turn into neutral atoms. From this moment, in essence, the modern stage of the evolution of the Universe begins. Galaxies, stars, planets appear. Eventually, many billions of years later, the universe became what we see it.
But this is not the only hypothesis. According to one of the hypotheses, the Universe began to expand chaotically and randomly, and then, under the action of some mechanism of dissipation (damping), a certain order arose. Such an assumption of complete primary chaos, as opposed to complete primary symmetry, is attractive because it does not require “creating” the Universe in any strictly defined state. If scientists manage to find a suitable damping mechanism, then this will make it possible to match a very wide range of initial conditions with the now observable form of the Universe.
One of the most common hypotheses about the dissipation mechanism is the hypothesis of the creation of particles and antiparticles from the energy that is produced by tidal effects in a gravitational field. Particles and antiparticles are born in a curved "empty" space (similar to the case of space curved by a black hole), and space reacts to such a birth by decreasing the curvature. The more the space-time is curved, the more intense the creation of particles and antiparticles occurs. In an inhomogeneous universe, such effects should have equalized everything, creating a state of homogeneity. It is even possible that all matter in the Universe arose in this way, and not from a singularity. Such a process does not require the birth of matter without antimatter, as in the original singularity. The difficulty with this hypothesis, however, is thatthat so far it has not been possible to find a mechanism for separating matter and antimatter that would not allow most of them to annihilate again.
On the one hand, the existence of inhomogeneities could save us from the singularity, but George Ellis and Stephen Hawking, using mathematical models, showed that, taking into account some very plausible propositions about the behavior of matter, at high pressures, the existence of at least one singularity cannot be ruled out, even if deviations from uniformity. The behavior of an anisotropic and inhomogeneous universe in the past near the singularity could be very complex, and it is very difficult to build any models here. It is easier to use Friedman's models, which predict the behavior of the universe from birth to death (in the case of a spherical topology). Although deviations from uniformity do not rid our universe of a singularity in space-time, nevertheless, it is possiblethat most of the currently available matter in the Universe did not fall into this singularity. Explosions of this kind, when matter of superhigh, but not infinite density, appears in the vicinity of a singularity, were called "whine." However, the Hawkin-Ellis theorem requires that the energy and pressure remain positive. There is no guarantee that these conditions are met at ultra-high densities of matter.
There is an assumption that quantum effects, but not in matter, but in space-time (quantum gravity), which become very significant at high values of space-time curvature, could prevent the disappearance of the Universe in a singularity, causing, for example, a "bounce" matter at a sufficiently high density. However, due to the lack of a satisfactory theory of quantum gravity, the reasoning does not give clear conclusions. If we accept the hypothesis of "whine" or quantum "bounce", it means that space and time existed before these events.
Already after the discovery of the expansion of the Universe, in 1946, British astrophysicists Herman Bondi and Thomas Gold suggested that, nevertheless, since the Universe is homogeneous in space, it must be homogeneous in time. In this case, it should expand at a constant rate, and in order to prevent a decrease in the density of matter, new galaxies should be continuously formed, which will fill the gaps formed from the dispersal of existing galaxies. Substance for building new galaxies continuously appears as the universe expands. Such a universe is not static, but stationary: individual stars and galaxies go through their life cycles, but on the whole the universe has no beginning or end. To explain how matter appears without violating the law of conservation of energy,Fred Hoyle invented a new type of field - creating a field with negative energy. When a substance is formed, the negative energy of this field is amplified and the total energy is conserved.
The production frequency of atoms in this model is so low that it cannot be detected experimentally. By the mid-60s, discoveries had been made indicating that the universe was evolving. Then, background thermal radiation was discovered, indicating that the Universe was in a hot dense state several billion years ago, and therefore cannot be stationary.
Nevertheless, from a philosophical point of view, the concept of a non-born and non-dying universe is very attractive. It is possible to combine the philosophical merits of the stationary universe with the big bang theory in models of an oscillating universe. Such a cosmological model is based on the Friedmann model with contraction, supplemented by the assumption that the universe does not perish when singularities occur at both time “ends”, but passes a superdense state and makes a “jump” into the next cycle of expansion and contraction. This process can continue indefinitely. However, in order not to accumulate entropy and background radiation from previous expansion-contraction cycles, it will be necessary to assume that at the stage of high density all thermodynamic laws are violated (therefore, entropy does not accumulate),however, it is assumed that the laws of the theory of relativity will be preserved. In its extreme expression, such a point of view assumes that all laws and world constants in each cycle will be new, and since nothing is preserved from cycle to cycle, then we can talk about universes physically unrelated to each other. With the same success, one can assume the simultaneous existence of an infinite ensemble of universes, some of them may be similar to ours. These conclusions are purely philosophical in nature and cannot be refuted either by experiment or observation. (13)With the same success, one can assume the simultaneous existence of an infinite ensemble of universes, some of them may be similar to ours. These inferences are purely philosophical in nature and cannot be refuted either by experiment or observation. (13)With the same success, one can assume the simultaneous existence of an infinite ensemble of universes, some of them may be similar to ours. These conclusions are purely philosophical in nature and cannot be refuted either by experiment or observation. (13)
As there are many hypotheses for the creation of the Universe, the search for a theory of everything is just as varied - the standard model, string theory, M-theory, extremely simple theory of everything, Grand Unification theories, etc.
The Standard Model is a theoretical construction in elementary particle physics that describes the electromagnetic, weak and strong interactions of all elementary particles. The standard model does not include gravity. Until now, all the predictions of the Standard Model have been confirmed by experiment, sometimes with fantastic accuracy of a millionth of a percent. It is only in recent years that results have begun to appear in which the predictions of the Standard Model differ slightly from experiment, and even phenomena that are extremely difficult to interpret within its framework. On the other hand, it is obvious that the Standard Model cannot be the last word in particle physics, because it contains too many external parameters, and also does not include gravity. Therefore, the search for deviations from the standard model has been one of the most active areas of research in recent years.
String theory is a branch of mathematical physics that studies the dynamics and interactions of not point particles, but one-dimensional extended objects, the so-called quantum strings. String theory combines the ideas of quantum mechanics and the theory of relativity, therefore, a future theory of quantum gravity will probably be built on its basis. String theory is based on the hypothesis that all elementary particles and their fundamental interactions arise as a result of vibrations and interactions of ultramicroscopic quantum strings on scales of the order of the Planck length of 10-35 m. This approach, on the one hand, avoids such difficulties of quantum field theory as renormalization, on the other hand, leads to a deeper look at the structure of matter and space-time.
Quantum string theory arose in the early 1970s as a result of the comprehension of Gabriele Veneziano's formulas related to string models of hadron structure. The mid-1980s and mid-1990s saw the rapid development of string theory, and it was expected that in the near future a "theory of everything" would be formulated on the basis of string theory. But, despite the mathematical rigor and integrity of the theory, no options have yet been found for experimental confirmation of string theory. The theory that arose to describe hadronic physics, but did not quite fit for this, found itself in a kind of experimental vacuum of description of all interactions.
M-theory (membrane theory) is a modern physical theory created with the aim of combining fundamental interactions. The so-called "brane" (multidimensional membrane) is used as the basic object - an extended two-dimensional object or with a large number of dimensions. In the mid-1990s, Edward Witten and other theoretical physicists found strong evidence that various superstring theories represent different limiting cases of an as yet undeveloped 11-dimensional M-theory. In the mid-1980s, theorists concluded that supersymmetry, which is the centerpiece of string theory, could be incorporated into it not in one but in five different ways, leading to five different theories: type I, types IIA and IIB, and two heterotic string theories. Only one of them could claim to be a "theory of everything", and the onewhich at low energies and compactified six extra dimensions would agree with real observations. Questions remained about which theory was more adequate and what to do with the other four theories.
An exceptionally simple theory of everything - a unified field theory that unites all known physical interactions that exist in nature, proposed by the American physicist Garrett Lisi on November 6, 2007. The theory is interesting for its elegance, but it requires serious refinement. Some well-known physicists have already expressed their support for it, but a number of inaccuracies and problems have been discovered in the theory.
Grand Unification theories - in elementary particle physics, a group of theoretical models that describe in a unified way the strong, weak and electromagnetic interactions. It is assumed that at extremely high energies, these interactions combine. (10)
We can say with complete confidence that future discoveries and theories will enrich, and not reject, the Universe that Pythagoras, Aristarchus, Kepler, Newton and Einstein revealed to us - a Universe as harmonious as the Universe of Plato and Pythagoras, but built on the harmony contained in mathematical laws; The Universe is no less perfect than the Universe of Aristotle, but it draws its perfection in the abstract laws of symmetry; The Universe, in which the boundless void of intergalactic spaces is flooded with soft light, carrying messages from the depths of time that are still incomprehensible to us; The universe, which has a beginning in time, but has no beginning or end in space, which, perhaps, will expand forever, and perhaps one fine moment, having stopped expanding, will begin to contract. This universe is not at all like the onewhich was depicted in the brave minds of those who were the first to dare to ask the question: "What is our world really like?" But I think that upon learning about it, they were not upset.
- Part one -