How many dimensions do we live in. Fourth dimension

The standard scientific concept states that we live in a three-dimensional world that has length, width, and height. Sometimes a fourth dimension is added to three - time ... Meanwhile, there are a variety of theories that "add" dimensions to the universe. Only their authors are mostly not scientists, but the authors of science fiction books and films.

The term was coined by writer Samuel Delaney. He drew attention to the fact that in many fantastic works the heroes leave their "native" world and find themselves in another dimension.

Delaney suggested that paraspace could actually exist. In doing so, it affects our world. When we experience "otherworldly" sensations, see or hear something that does not exist in our reality, these may be echoes of "paraspace", in other words, a parallel world. Although, perhaps, it is also within our dimension ...

flatland

This is a world consisting of only two dimensions, described in 1884 by the minister and scientist Edwin Abbott in a book he wrote. Her main character is a square. In the world where he lives, the more facets and angles an individual has, the higher his social status.

In a flat world there is no sun and no stars. Once in a millennium, someone from the inhabitants of the three-dimensional world gets into Flatland. But the inhabitants of Flatland are not ready to believe in the existence of a third dimension ... However, Abbott's work is more of a satire on Victorian England than a science fiction novel.

"Super Sargasso Sea"

It is described by famous writer and paranormal researcher Charles Fort. He claims that there is a "special" dimension where all the things that disappear in our world end up. Sometimes they can "return" from there and then reappear... This is how the phenomenon of rains from animals and inanimate objects that take place in different parts of the globe can be explained. By the way, having studied their geography, Fort came to the conclusion that the "Super-Sargasso Sea" stretches from Great Britain to India.

L-space

This term was coined by writer Terry Pratchett. L-space is a special dimension that is a library. But not in the usual sense, but in the sense of the global information field. There you can find any books that have ever been written, that will be written, and, finally, those that were only conceived, but never written ... Some books can be dangerous, so certain rules must be observed in L-space ... Only senior librarians are privy to all rules.

hyperspace

The term is used in many works of science fiction. It means something like a tunnel through which you can travel to other dimensions faster than the speed of light.

For the first time, the idea, perhaps, was expressed as early as 1634 by Johannes Kepler in the book "Somnium". Her characters must get to the island, located 80 thousand kilometers above the ground. Only demons can open the way there, using opium to put travelers to sleep, and then transport them to their destination using their acceleration power.

Pockets of the Universe

MIT physicist Alan Gut put forward the hypothesis of cosmic inflation. One of its main ideas is that our universe is constantly expanding and, as it expands, gives rise to an increasing number of space-time "pockets" - autonomous universes, each of which has its own physical laws.

Theory of ten dimensions

This theory, also called superstring theory, does not have three or four dimensions, but many more. At least ten. All of them can affect our world, although we do not see and for the most part do not perceive them.

The fifth dimension exists, as it were, in parallel with ours, this is what we call a "parallel world". The sixth is the plane on which all universes like ours exist. The seventh is the worlds that arose under conditions essentially different from ours.

The eighth is the dimension where the endless histories of the worlds in the seventh dimension are "stored". In the ninth are worlds whose physical laws differ from ours. Finally, the tenth dimension contains all of this combined. So more than ten dimensions the human mind is simply not able to imagine ...

The presence of protective grounding is one of the main electrical safety requirements. The reliability of the grounding elements is controlled by the specialists of the electrical laboratory by measuring the metal bond. According to the current rules and regulations, such a check is mandatory if the facility has carried out repairs to electrical equipment, retrofits or installation work. What is hidden under the term "metal bond" and why it is measured, we will describe in detail in this publication.

What is a "metal bond"?

Under this term, it is customary to understand the connection (electrical circuit) formed by the electrical installation and the ground electrode. The main requirement for metal communication is the continuity of the ground circuit. Violation of this condition threatens the formation of a high potential difference in the circuits of the electrical installation, which is a threat to life and may lead to equipment failure.

Over time, there may be an increase in transient resistances in the ground circuit, which leads to the formation of metal bond defects, let's look at the nature of this phenomenon.

What caused the increase in transient resistance?

By transitional contacts are meant contacting metal elements. It is impossible to achieve their perfect polishing; all the same, there will be tubercles and microscopic dents on the surface. The area of ​​the contacted surfaces changes under the influence of various external factors (temperature, pressing force, surface contamination, etc.), which leads to an increase in contact resistance. The photographs of the copper contact below, taken using an electron microscope, show the formation of a copper oxide film on the surface.

Such an oxide film has dielectric properties, although they are not great, but this may be enough to break the metal bond. As a result, the connection will heat up and sooner or later lead to burnout of the contact, which will immediately affect the quality of the metal bond. An equally common reason is the human factor, which is why after installation work it is required to measure the metal bond.

Why check the metal connection?

Taking into account the above information, the following reasons for checking the metal bond can be indicated:

1. Monitoring the continuity of the ground circuit. It includes both electrical measurements and inspection of protective conductors and other grounding elements for their integrity.
2. Measurement of the resistance of transitional contacts (performed between the electrical installation and the ground electrode), as well as the general parameters of the circuit.
3. The potential difference between the body of a grounded electrical installation and the ground electrode is checked. The test is carried out in operating mode and off.

As you can see, the main purpose of the test is to measure the parameters of the grounding circuits, since they characterize the quality of the metal connection, and, accordingly, the electrical safety of the installation.

Metal bond measurement technique

In accordance with the requirements of the PUE, metal elements of electrical installations are subject to grounding. Measurements of the metal connection are made between the main and the element to be checked. According to the norms, the contact resistance in one transition should be 0.01 Ohm ± 20%.

If the meter confirms a good connection, the next node is tested. When there are several transitions between the ground electrode and the grounded electrical installation, their total resistance should not exceed 0.05 Ohm.

If the resistance exceeds the allowable limits, you should check the condition of the contacts, clean them, connect and re-measure.

Most electrical laboratories measure metal bonding according to the following algorithm:

1. A visual inspection of the contacts of the grounding conductors is carried out. Effective in the search for a "bad" contact, special devices - thermal imagers, they quickly allow you to detect a problematic connection.
2. Welded joints are tested for strength by applying a mechanical load.
3. All grounded structural elements are tested for metal bonding.
4. Checking the presence of electric current on grounded elements.
5. The results obtained are recorded in a special protocol.

The above measurement technique has proved its effectiveness.

Norms and rules

According to the PUE standards, grounding conductors, as well as those used for potential equalization, must be securely connected in order to ensure the continuity of the ground circuit. At the same time, a welding connection is prescribed for steel conductors, other methods of contact are allowed only if there is protection against the destructive effects of the air. When bolted connections are used, appropriate measures must be taken to prevent loosening of the contact connection.

All connections of the earthing circuit and the earthed device must be located in such a way that they have free access, since inspection must be carried out in order to check the continuity of the electrical connection. An exception to this rule is sealed contacts.

The Rules also state that for contact with grounding devices, bolted or welded connections can be made. If the devices of electrical installations are subject to strong vibration or they are often moved to another place, then a flexible protective wire is used.

More detailed information about the rules and regulations can be obtained from the PUE (p. 1.7.).

Periodicity

According to the norms of PTEEP and PUE, metal bond testing is carried out according to the schedule determined by the technical department of the facility. As a rule, in this case, Table. 37 p. 3.1 PTEEP, where the following frequency of metal bond measurement is established:

• In premises and facilities belonging to a higher hazard category, measurements of transient resistances in grounding circuits should be carried out annually, in other circumstances - at least once every three years.
• For lift and lifting equipment - 1 year.
• Stationary electric stoves - 1 year.

As a rule, metal bond testing is carried out in conjunction with other types of electrical measurements (insulation resistance, checking the integrity of electrical wiring, etc.).

In addition, mandatory measurements of metal bonding are carried out in the following cases:

1. If repairs or re-equipment of electrical equipment was carried out.
2. When testing new electrical installations.
3. After the installation work.

Instruments for measuring

Considering that metal bond measurements are carried out at the level of hundredths of an ohm, conventional measuring instruments, for example, multimeters, are not suitable for this purpose. When making ground resistance measurements, more accurate instruments are used, sensitive enough to measure low level resistances.

Most of these devices are equipped with additional functions, for example, the Metrel MI3123 shown in the figure can also measure soil conductivity and leakage current.

Fixing the results in the measurement protocol

All measurement results are recorded in a special test report. The data is recorded in a table, indicating the name of each examined compound. The report also provides information on the number of nodes inspected, their location, and displays the maximum value of the total resistance of the protection circuit contacts.

If the absence of a metal bond is detected during the testing process, information about this must be recorded in the document and at the same time in the annex to the protocol (defective statement).

Briefly about prevention.

Regularly measuring metal grounding does not mean abandoning prevention. To ensure the continuity of the protective circuits, it is necessary to regularly check the state of the contact connections and, if necessary, tighten them. It is equally important to clean the contacts of dust, oxide film and dirt.

When detecting the presence of electrical voltage on one of the structural elements, it is necessary to take care of its high-quality grounding. Otherwise, the risk of an emergency situation increases.

It is not worth skimping on checking the quality of the protective earthing device, since the losses can become more costly than paying for a call to the electrical laboratory.

We live in a three-dimensional world: length, width and depth. Some may object: "But what about the fourth dimension - time?" Indeed, time is also a dimension. But the question of why space is measured in three dimensions is a mystery to scientists. New research explains why we live in a 3D world.

The question of why space is three-dimensional has tormented scientists and philosophers since ancient times. Indeed, why precisely three dimensions, and not ten or, say, 45?

In general, space-time is four-dimensional (or 3+1-dimensional): three dimensions form space, the fourth dimension is time. There are also philosophical and scientific theories about the multidimensionality of time, which suggest that there are actually more dimensions of time than it seems: the arrow of time familiar to us, directed from the past to the future through the present, is just one of the possible axes. This makes possible various science fiction projects, such as time travel, and also creates a new, multivariate cosmology that allows for the existence of parallel universes. However, the existence of additional time dimensions has not yet been scientifically proven.

Let's return to our 3+1-dimensional dimension. We are well aware that the measurement of time is associated with the second law of thermodynamics, which states that in a closed system - such as our universe - entropy (a measure of chaos) always increases. The universal disorder cannot decrease. Therefore, time is always directed forward - and nothing else.

In a new paper published in EPL, the researchers suggested that the second law of thermodynamics could also explain why space is three-dimensional.

“A number of researchers in the field of science and philosophy have addressed the problem of the (3 + 1)-dimensional nature of space-time, justifying the choice of this particular number by its stability and the possibility of sustaining life,” said study co-author Julian Gonzalez-Ayala from the National Polytechnic Institute in Mexico and the University of Salamanca in Spain to Phys.org. “The value of our work lies in the fact that we present reasoning based on a physical model of the dimension of the Universe with a suitable and reasonable space-time scenario. We are the first to state that the number "three" in the dimension of space arises as an optimization of a physical quantity."

Previously, scientists paid attention to the dimension of the Universe in connection with the so-called atropic principle: "We see the Universe like this, because only in such a Universe could an observer, a person, have arisen." The three-dimensionality of space was explained by the possibility of maintaining the Universe in the form in which we observe it. If there were many dimensions in the Universe, according to the Newtonian law of gravity, stable orbits of the planets and even the atomic structure of matter would not be possible: electrons would fall on the nuclei.

In this study, the researchers went the other way. They suggested that space is three-dimensional due to a thermodynamic quantity, the Helmholtz free energy density. In a universe filled with radiation, this density can be thought of as pressure in space. The pressure depends on the temperature of the universe and on the number of spatial dimensions.

The researchers showed what could happen in the first fraction of a second after the Big Bang, called the Planck epoch. At the moment when the Universe began to cool, the Helmholtz density reached its first maximum. Then the age of the Universe was a fraction of a second, and there were exactly three spatial dimensions. The key idea of ​​the study is that the three-dimensional space was "frozen" as soon as the Helmholtz density reached its maximum value, which prohibits the transition to other dimensions.

The figure below shows how this happened. Left - free energy densityHelmholtz (e) reaches its maximum value at the temperature T = 0.93, which occurs when the space was three-dimensional (n=3). S and U represent entropy densities and internal energy densities, respectively. On the right, it is shown that the transition to multidimensionality does not occur at temperatures below 0.93, which corresponds to three dimensions.

This was due to the second law of thermodynamics, which allows transitions to higher dimensions only when the temperature is above the critical value - not a degree less. The Universe is constantly expanding, and elementary particles, photons, are losing energy - therefore, our world is gradually cooling: Now the temperature of the Universe is much lower than the level that implies a transition from a 3D world to a multidimensional space.

The researchers explain that spatial dimensions are similar to the states of matter, and the transition from one dimension to another resembles a phase transition - such as the melting of ice, which is possible only at very high temperatures.

“During the cooling of the early universe and after reaching the first critical temperature, the principle of entropy increment for closed systems could prohibit certain changes in dimensionality,” the researchers comment.

This assumption still leaves room for the higher dimensions that existed during the Planck era, when the universe was even hotter than it was at the critical temperature.

Extra dimensions are present in many cosmological models, primarily in string theory. This study could help explain why, in some of these models, extra dimensions have disappeared or remained as tiny as they were in the first fractions of a second after the Big Bang, while 3D space continues to grow throughout the observable universe.

In the future, the researchers plan to improve their model to include additional quantum effects that may have occurred in the first fraction of a second after the Big Bang. In addition, the results of the augmented model can also serve as a guide for researchers working on other cosmological models, such as quantum gravity.

A person walking forward moves in one dimension. If he jumps up or changes direction to the left or right, he will master two more dimensions. And having traced his path with the help of a wrist watch, he will check in practice the action of the fourth.

There are people who are limited by these parameters of the world around them and they don’t particularly care about what’s next. But there are also scientists who are ready to go beyond the horizons of the usual, turning the world into their own huge sandbox.

The world beyond four dimensions

According to the theory of multidimensionality put forward at the end of the eighteenth and beginning of the nineteenth century by Mobius, Jacobi, Plückher, Kelly, Riemann, Lobachevsky, the world is not at all four-dimensional. It was considered as a kind of mathematical abstraction, in which there is no special meaning, and multidimensionality arose as an attribute of this world.

Particularly interesting in this sense are the works of Riemann, in which the usual geometry of Euclid was made a trip and showed how unusual the world of people can be.

Fifth Dimension

In 1926, the Swedish mathematician Klein, in an attempt to justify the phenomenon of the fifth dimension, made the bold assumption that a person is not able to observe it because it is very small. Thanks to this work, interesting works appeared on the multidimensional structure of space, a huge part of which relates to quantum mechanics and is rather difficult to understand.

Michio Kaku and the multidimensionality of being

According to the works of another American scientist of Japanese origin, the human world has many more dimensions than five. He puts forward an interesting analogy about carps swimming in. For them there is only this pond, there are three dimensions in which they can move. And they do not understand that just above the water's edge a new unexplored world opens up.

So a person cannot know the world outside of his "pond", but in fact there can be an infinite number of dimensions. And this is not just an aesthetic intellectual research of a scientist. Some physical features of the world known to man, gravity, light waves, energy distribution, have certain inconsistencies and oddities. It is impossible to explain them from the point of view of the ordinary four-dimensional world. But if you add a few more dimensions, everything falls into place.

A person cannot cover all the dimensions that are available with his senses. However, the fact that they exist is already a scientific fact. And you can work with them, learn, identify patterns. And, perhaps, someday a person will learn to understand how huge, complex and interesting the world around him is.