Time lapse in length if we want. What time period is called for days. How many hours in the days of hours, minutes and seconds, and why it happened. Use to designate the time of day. What is the name of the period of time in length per hour. Chapter Threstec

In modern units of measurement of time, the periods of land appeal around their axis are taken and around the Sun, as well as the periods of the moon around the Earth.

This is due both historical and practical considerations, because People need to coordinate their activities with the change of day and night or seasons.

Historically, the main unit for measuring short time intervals was day (or day), counted on the minimum full cycles of shifting solar illumination (day and night). As a result of dividing the day to smaller time intervals of the same length arose clock, minutes and seconds. The day was divided into two equal consecutive intervals (conditionally day and night). Each of them was divided by 12 watch. Everyone hour Deli at 60. minutes. EVERY minute - By 60 seconds.

So in hour 3600 seconds; in laugh 24 hours = 1440 minutes = 86 400 seconds.

Second I became the main unit of measurement of time in the international system of units (SI) and the SGS system.

There are two systems specifying time:

French - not taken into account the division of the day for two intervals for 12 hours (day and night), and it is believed that the day is directly divided by 24 hours. An hour number can be from 0 to 23 inclusive.

English is a division taken into account. The clock indicates from the start of the current semissions, and after the numbers they write the letter index half of the day. The first half of the day (night, morning) denote AM, the second (day, evening) - PM from Lat. Ante Meridiem / Post Meridiem (before noon / afternoon). An hour number in 12-hour systems in different traditions is recorded in different ways: from 0 to 11 or 12.

For the beginning of the time of time taken midnight. Thus, midnight in the French system is 00:00, and in English - 12:00 am. Noon - 12:00 (12:00 pm). The point in time after 19 hours and another 14 minutes from midnight - 19:14 (in the English system 7:14 pm).

On the dials of most modern hours (with arrows) it is used by the English system. However, the arrogant hours are also available, where the French 24-hour system is used. Such hours are used in areas where to judge the bottom and night is difficult (for example, on submarines or the polar circle, where there is a polar night and a polar day).

The duration of the average sunny day is the value of non-permanent. And although it changes quite a bit (increases as a result of tides due to the action of the attraction of the Moon and the Sun, on average, 0.0023 seconds in the century over the past 2000 years, and over the past 100 years only 0.0014 seconds), this is sufficient for significant Distortions of duration of a second, if you count in a second 1/86 400 part of the duration of the sunny day. Therefore, from the definition of "Hour - 1/24 day; Minute - 1/60 hours; second - 1/60 minutes "switched to the definition of a second as a basic unit based on a periodic intra-industrial process, not related to any movements of celestial bodies (they sometimes refer to it as a second SI or" atomic second "when it is context It is possible to confuse with a second as defined from astronomical observations).

Time - This is a continuous value used to indicate the sequence of events in the past, present and future. Time is also used to determine the interval between events and for a quantitative comparison of processes occurring at different speeds or frequencies. To measure the time, a periodic sequence of events is used, which is recognized by the standard of a certain period of time.

A unit of time in the international system of units (C) is second (c), which is defined as 9,192,631,770 periods of radiation, corresponding to the transition between two ultra-thin levels of the quantum state of the cesium-133 atom at one time at 0 K. This definition was adopted in 1967 (clarification on the temperature and rest of the rest appeared in 1997 ).

Reducing the heart muscle of a healthy person lasts one second. For one second, the land, rotating around the Sun, covers a distance of 30 kilometers. During this time, our shine itself has time to do a path of 274 kilometers, with a huge speed beating through the galaxy. Moonlight for this time interval will not have time to achieve land.

Millisecond (ms) - time measurement unit, dollane with respect to second (thousandth share seconds).

The shortest exposure time in the ordinary camera. Muha makes the wings once every three milliseconds. Bee - once in five milliseconds. Every year the moon rotates around the Earth for two milliseconds slower, since its orbit is gradually expanding.

Microsecond (ISS) - a unit of measurement of time, with respect to second (million dollars seconds).

Example: Flash with an air gap To shoot the speedless events, it is capable of pumping the light pulse in shorter than one microsecond. It is used to shoot objects moving at very high speed (bullets, exploding balloons).

During this time, the beam of light in vacuo will cover a distance of 300 meters long, the length of about three soccer fields. The sound wave at sea level is capable of overcoming the distance equal to just one third of the millimeter during the same period of time. 23 Microseconds will be required in order to explode a dynamite checker, whose wick gentle to the end.

Nanosecond (NA) - a time measurement unit, dollane in relation to a second (billionth share seconds).

The beam of light passing through the airless space is able to overcome the distance of just thirty centimeters during this time. The microprocessor in a personal computer will be required from two to four nanoseconds to execute one command, for example, fold two numbers. The existence time of K-meson, another rare subatomic particle, is 12 nanoseconds.

Picosecanda (PS) - a time measurement unit, dollane in relation to a second (one thousand billion dollars seconds).

For one picosecond, the light in vacuo passes approximately 0.3 mm. The fastest transistors function in the temporary framework measured in picoseconds. The existence of quarks, rare subatomic particles obtained in powerful accelerators is only one picosecond. The average duration of the hydrogeny bond between water molecules at room temperature is equal to three picoseconds.

Femtosecond (FS) - time measurement unit, dollane with respect to second (one million billion dollars seconds).

Pulse titanium-sapphire lasers are able to generate ultrashort pulses with a duration of only 10 femtoseconds. During this time, the light passes only 3 micrometers. This distance is comparable to the size of red blood cells (6-8 microns). Atom in the molecule makes one oscillation during from 10 to 100 femtoseconds. Even the farthestheforecent chemical reaction proceeds for a period calculated by several hundred femtoseconds. The interaction of light with the pigments of the mesh eye shell, namely this process and allows us to see the surrounding, lasts about 200 femtoseconds.

Attosecanda (AC) - time measurement unit, dollane in relation to second (one billion billion dollars seconds).

For one attosecond, the light passes the distance equal to the diameter of three hydrogen atoms. The most rapid processes that are capable of closing scientists are measured in attoseconds. With the help of the most advanced laser installations, the researchers managed to obtain light pulses of the last 250 attoseconds. But no matter how endlessly small these time intervals seemed, they seem to be in a whole etern compared to the so-called Planck time (about 10-43 seconds), according to modern science, the so-time of all possible time segments.

Minute (min) - Introduced time measurement unit. Minute is 1/60 hours or 60 seconds.

During this time, the brain of the newborn baby adds in weight to two milligrams. Earthier heart has time to reduce 1000 times. An ordinary person during this time can pronounce 150 words or read 250 words. The light from the Sun reaches the earth in eight minutes. When Mars is located in the closest distance from the ground, the sunlight, reflected from the surface of the Red Planet, comes to us in less than four minutes.

Hour (h) - an out of system unit of time measurement. An hour is 60 minutes or 3600 seconds.

So much time is required by reproductive cells to split in half. In one hour from the conveyor of the Volga automotive factory, 150 "Zhiguli" go. Light from Pluto - the most distant planet of the Solar System - reaches the Earth in five hours twenty minutes.

Day (SUT) - an out of system unit of measurement of time, equal to 24 hours. Usually under the days, the sunny day is meant, that is, a period of time for which the land makes one turn around its axis relative to the center of the Sun. Day consist of days, evenings, night and morning.

For people, this is perhaps the most natural unit for measuring time based on the rotation of the Earth. According to modern science, the longitude of the day is 23 hours 56 minutes and 4.1 seconds. The rotation of our planet is constantly slowed down due to lunar gravity and other reasons. A man's heart per day makes about 100,000 cuts, lungs inhale about 11,000 liters of air. During the same time, the cubs of blue whale adds in weight 90 kg.

For measuring longer time intervals use units of measurement year, month and a weekconsisting of an integer number of sunny day. Year It is approximately equal to the period of the appeal of the Earth around the Sun (approximately 365.25 days), month - Period of complete change of the phases of the Moon (called a synodic month, equal to 29.53 days).

A week - Intimated time measurement unit. Usually a week is equal to seven days. Week - standard period of time used in most countries of the world for organizing cycles of working days and rest days.

Month - Introduced time measurement unit associated with the appeal of the moon around the Earth.

Synodic month (from Dr.-Greek. Σύνοδος "Connection, rapprochement [with the Sun]") - a period of time between two sequential identical phases of the moon (for example, noving). The synodic month is the period phases of the moon, as the view of the moon depends on the position of the moon relative to the Sun for the observer located on the ground. The synodic month is used when calculating the time of solar eclipses.

In the most common Gregorian, as well as in the Julian calendar, accepted year equal to 365 days. Since the tropical year is not equal to a whole number of sunny day (365,2422), for synchronization of calendar seasons with astronomical in the calendar, leap years is used, a duration of 366 days. The year is divided into twelve calendar months of different duration (from 28 to 31 days). Usually, each calendar month falls one full moon, but since the moon phases are replaced by a little faster than 12 times a year, sometimes the second full moon per month, called the blue moon.

In the Jewish calendar, the Lunar Synodic Monthine and the Tropical Year is the basis, and this year may contain 12 or 13 lunar months. In the long term, the same months of the calendar occur to about the same time.

In Islamic calendar, the foundation is the moon synodic month, and the year always contains strictly 12 lunar months, that is, about 354 days, which is 11 days less than the tropical year. Thanks to this, the beginning of the year and all Muslim holidays each year are shifted relative to the climatic seasons of the year and equinox.

Year (D) - an extra-system unit of measurement of time, equal to the period of appeal of the Earth around the Sun. In Astronomy, Julian year is a time unit, defined as 365.25 days 86400 seconds each.

The Earth makes one turn around the Sun and turns around its axis 365.26 times, the average level of the world's ocean rises by a value from 1 to 2.5 millimeters. It will take 4.3 years so that the light from the nearest star Proxima Centauri has reached the Earth. Approximately the same time it will be necessary to ensure that the surface ocean flows regenerate the globe.

Julian year (a) - The time measurement unit defined in astronomy as 365.25 Julian days of 86,400 seconds each. This is the average duration of the year in the Julian calendar used in Europe in antiquity and Middle Ages.

Leap year - The year in Julian and Gregorian calendars, the duration of which is 366 days. That is, this year contains on one day more than a day than in the usual, innocent year.

Tropical year , also known as a sunny year - a period of time for which the sun completes one cycle of the change of seasons, as can be seen from the ground.

SideRical period, also siderician year (Lat. Sidus - Star) - a period of time during which the land makes around the Sun full turn regarding stars. At noon on January 1, 2000, the Siderician year was equal to 365,25636 days. It is approximately 20 minutes longer than the duration of the middle tropical year on the same day.

SideRic day - The time interval during which the Earth makes one full turn around its axis relative to the point of spring equinox. Sideric Day for the Earth is 23 o'clock 56 minutes 4.09 seconds.

Star time, also sideRical time - Time measured relative to stars, in contrast to the time measured relative to the Sun (solar time). Star time is used by astronomers to determine where to send a telescope to see the desired object.

Fortonight - the unit of measurement of time is equal to two weeks, that is, 14 days (or rather 14 nights). The unit is widely used in the UK and some countries of the Commonwealth, but rarely in North America. In Canadian and American wage systems, the term "once every two weeks" is used to describe the appropriate period of payments.

Decade - a period of time that includes ten years.

Century, century - an incidental unit of time equal to 100 consecutive years.

During this time, the moon will remove from the ground by another 3.8 meters. Modern CDs and CDs by that time hopelessly endage. Only one of every young kangaroo can live to a hundred years, but the giant sea turtle is able to live as much as 177 years. The duration of the modern CD itself can be more than 200 years.

Millennium (also MILENENIUM) - an out of system unit of measurement of time equal to 1000 years.

Megagen (MYR designation) - a multiple year, a time measurement unit equal to a million (1,000,000 \u003d 10 6) years.

Gigagod (GYR designation) - a similar unit equal to billions (1 000 000 000 \u003d 10 9). It is used mainly in cosmology, as well as in geology and in the sciences associated with the study of the history of the Earth. For example, the age of the universe is estimated at 13.72 ± 0.12 thousand megalt or, which is the same, in 13.72 ± 0.12 gallows.

For 1 million years, the spacecraft flying at the speed of light will not cover half the way to the Galaxy of Andromeda (it is at a distance of 2.3 million light years from the Earth). The most massive stars, blue supergigances (they are in millions of times brighter than the sun) burn in about this time. Due to the shifts of the Tectonic layers of the Earth, North America will be removed from Europe by about 30 kilometers.

1 billion years. Approximately so much time it took that our land was cooled after his education. So that the oceans appear on it, a single-cell life originated and instead of the atmosphere, an atmosphere rich in oxygen would be established with carbon dioxide gas. During this time, the sun passed four times in its orbit around the center of the Galaxy.

Plank time (TP) - a unit of time in the planacian system of units. The physical meaning of this value is the time for which a particle, moving at the speed of light, overcomes a planacian length equal to 1,616199 (97) · 10 ° ³.

In astronomy and in a number of other areas, along with a second SI applies efemeride second The definition of which is based on astronomical observations. Considering that in the tropical year, 365,242 198,781 25 days, and the day believing a constant duration (t. N. Ephemeride calculus), it is obtained that in the year 31,556,925,9747 seconds. Then it is believed that second is 1/31 556 925,9747 part of the tropical year. A century-time change in the duration of the tropical year makes it bring to the definition of a certain epoch; So, this definition refers to the tropical year at the time of 1900.0.

Sometimes there is a unit third equal to 1/60 seconds.

Unit decada Depending on the context, may refer to 10 days or (less often) by 10 years.

Indict ( indiction ), used in the Roman Empire (since Diocletian), later in Byzantium, Ancient Bulgaria and ancient Russia, is equal to 15 years.

An antiquity olympiad was used as a unit of measurement and was equal to 4 years.

Saros - a period of repetition of eclipses, equal to 18 years 11⅓ days and the famous Ancient Babylonians. Saros was also called the calendar period of 3,600 years; smaller periods were called titles neros. (600 years) and sosos (60 years).

To date, the smallest experimentally observed period of time is the order of Attosecond (10 -18 C), which corresponds to 10 26 plank times. By analogy with the planacian length, the time interval of less planacian time cannot be measured.

In Hinduism "Brahma Day" - calpa - equal to 4.32 billion years. This unit entered the Guinness Book of Records as the largest time measurement unit.

When people say that they are "quite a moment," they probably do not recognize that they promise to free go into exactly 90 seconds. Indeed, in the Middle Ages, the term "moment" determined the time lapse of a duration of 1/40 hours or, as it was customary to speak, 1/10 of the point that was 15 minutes. In other words, he consisted of 90 seconds. Over the years, the moment has lost its original value, but still used in everyday life to designate an indefinite, but very short interval.

So why do we remember the moment, but forget about ghary, nuclearone or something even more exotic?

1. Atom

The word "atom" comes from the Greek term denoting the "indivisible", and therefore is used in physics to determine the smallest particle of the substance. But in the old days, this concept was applied towards the shortest period of time. It was believed that the minute had 376 atoms, the duration of each of which is less than 1/6 seconds (or 0.15957 seconds, to be accurate).

2. Ghari

What devices and devices are not invented in the Middle Ages to measure time! So far, the Europeans has been exploited by the sandy and sunshine, the Indians used Klepsidra - Ghari. In a hemispherical bowl made of wood or metal, several holes were made, after which it was placed in the water pool. The liquid, leaking through the slits, slowly filled the vessel until he was completely immersed on the bottom. The whole process took about 24 minutes, so such a range was named after the device - Ghari. At that time it was believed that the day consists of 60 ghary.

3. Laster

The chandelier is the period lasting 5 years. The use of this term goes roots to antiquity: then Lustera indicated a five-year period of time, which completed the establishment of the property qualification of Roman citizens. When the tax amount was determined, the countdown came to an end, and the solemn procession was poured on the streets of the Eternal City. The ceremony ended with lustration (cleansing) - a pavicious sacrifice of the gods on the Marsfield, which was for the sake of the well-being of citizens.

4. Milevay

Not all that is gold that glitters. While the light year, it would seem created to determine the period, measures the distance, Mileway, the path in the mile length, serves to refer time. Although the term and sounds like a distance of distance measurement, in the early Middle Ages, it indicated a length of 20 minutes. It is so much on average a person takes overcoming a route in a mile long.

5. Nundin

Residents of the ancient Rome worked seven days a week, not to twist. On the eighth day, however, those who were considered ninth (the Romans attributed to the range and the last day of the previous period), they organized huge markets in the cities - Nundines. The market was called "Novem" (in honor of November - the ninth month of the 10-month agricultural "year of Romulus"), and the time interval between the two fairs is Nundin.

6. Nucmeeron

Nucmeeron, a combination of two Greek words "NYKS" (night) and "hemera" (day) is no more than an alternative designation of the usual days. Everything that is considered nuclearone, respectively, lasts less than 24 hours.

7. Point

In medieval Europe, an item called also a point was used to designate a quarter of an hour.

8. Quadrant

And the neighbor of the point on the era, quadrant, determined a quarter of a day - a period of 6 hours.

9. Fifteen

After the Norman conquest, the word "Quinzieme", translated from French as "fifteen", was borrowed by the British to determine the duty that replenished the state treasury for 15 pence with each pound earned in the country. At the beginning of the 1400th, the term acquired a religious context: it began to be used to indicate the day of an important church holiday and two full weeks following him. So "Quinzieme" turned into a 15-day period.

10. Scrupul

The word "scrupulus", translated from Latin denoting "Little acute peasants", first served as a pharmacy unit of weight measurement equal to 1/24 oz (about 1.3 Gy). In the 17th century, the scrupul, which became the symbol of a small volume, expanded its value. It began to be applied to indicate 1/60 part of the circle (minutes), 1/60 minutes (seconds) and 1/60 days (24 minutes). Now, having lost its own sense, the scrupulus was transformed into scrupulsiness - attentiveness to small things.

And some temporal values:

1 Attosecund (one billion billion dollars of a second)

The most rapid processes that are capable of closing scientists are measured in attoseconds. With the help of the most advanced laser installations, the researchers managed to obtain light pulses of the last 250 attoseconds. But no matter how endlessly small these time intervals seemed, they seem to be in a whole etern compared to the so-called Planck time (about 10-43 seconds), according to modern science, the so-time of all possible time segments.

1 femtosecond (one million billion dollars of a second)

Atom in the molecule makes one oscillation during from 10 to 100 femtoseconds. Even the farthestheforecent chemical reaction proceeds for a period calculated by several hundred femtoseconds. The interaction of light with the pigments of the mesh eye shell, namely this process and allows us to see the surrounding, lasts about 200 femtoseconds.

1 Picosecond (one thousandth billion dollars of a second)

The fastest transistors function in the temporary framework measured in picoseconds. The existence of quarks, rare subatomic particles obtained in powerful accelerators is only one picosecond. The average duration of the hydrogeny bond between water molecules at room temperature is equal to three picoseconds.

1 nanosecond (billion percent)

1 microsecond (million percent)

1 millisecond (thousandth fraction of second)

The shortest exposure time in the ordinary camera. We all familiar to the fly will make up three milliseconds once every three wings. Bee - once in five milliseconds. Every year the moon rotates around the Earth for two milliseconds slower, since its orbit is gradually expanding.

1/10 second

Blinker eye. That is what we have time to do for the specified gap. Human ear takes exactly the time to distinguish the echo from the original sound. Spaceship Voyager 1, heading outside the solar system, during this time is removed from the Sun to two kilometers. Over the tenth, a second of a second, the hummingbirds managed to wave seven times with their wings.

1 second

Reducing the heart muscle of a healthy person lasts just this time. For one second, the land, rotating around the Sun, covers a distance of 30 kilometers. During this time, our shine itself has time to do a path of 274 kilometers, with a huge speed beating through the galaxy. Moonlight for this time interval will not have time to achieve land.

1 minute

1 hour

1 day

1 year

The Earth makes one turn around the Sun and turns around its axis 365.26 times, the average ocean level rises from 1 to 2.5 millimeters, and 45 elections of the federal significance are carried out in Russia. It will take 4.3 years so that the light from the nearest star Proxima Centauri has reached the Earth. Approximately the same time it will be necessary to ensure that the surface ocean flows regenerate the globe.

1 century

During this time, the moon will remove from the ground by another 3.8 meters, but the giant sea turtle is able to live as much as 177 years. The duration of the modern CD itself can be more than 200 years.

1 million years

The spacecraft flying at the speed of light will not cover half the way to the Galaxy of Andromeda (it is at a distance of 2.3 million light years from the Earth). The most massive stars, blue supergigances (they are in millions of times brighter than the sun) burn in about this time. Due to the shifts of the Tectonic layers of the Earth, North America will be removed from Europe by about 30 kilometers.

1 billion years old

Approximately so much time it took that our land was cooled after his education. So that the oceans appear on it, a single-cell life originated and instead of the atmosphere, an atmosphere rich in oxygen would be established with carbon dioxide gas. During this time, the sun passed four times in its orbit around the center of the Galaxy.

Since the universe has existed only 12-14 billion years, the time measurement units exceeding a billion years are rarely used. However, scientists, specialists in cosmology, believe that the universe may continue after the last star goes out (after a hundred trillion years) and the last black hole will evaporate (after 10100 years). So the Universe still has to go through the way much longer than it has already passed.

sources
http://www.mywatch.ru/conditions/

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I want to draw your attention to the fact that today there will be an interesting conversation dedicated to the October Revolution. You can ask questions through chat

Length bodies in different reference systems

Compare the length of the rod in inertial reference systems K. and K."(Fig.). Suppose that the rod located along the coinciding axes x.and x "resting in the system K ". Then the definition of its length in this system does not cause hassle. You need to attach a large-scale ruler to the rod and determine the coordinate x " 1 one end of the rod and then coordinate x " 2 other end. The difference of coordinates will give the length of the rod  0 in the system K ":  0 = x " 2 ‑ x " 1 .

Rod resting in the systemK ". Regarding the systemK.he moves at speedsv.equal to the relative speed of systemsV..

Designation V.we will use only in relation to the relative speed of reference systems. Since the rod is moving, you need to make a simultaneous counting of its coordinates x. 1 and x. 2 at some point in time t.. The coordinate difference will give the length of the rod  in the system K.:

 = x. 2 ‑ x. 1 .

To match the lengths  and  0 you need to take the one of the formulas of Lorentz transformations that binds the coordinates x., x "and time t.systems K.. Substitution of coordinate and time values \u200b\u200bleads to expressions

(We substituted with its value instead of β). Replacing the coordinate difference in the length of the rod, and the relative speed V.systems K.and K "equal to the speed of the rod v.with which it moves in the system K., come to the formula

Thus, the length of the moving rod is less than that which the rod is at rest. A similar effect is observed for bodies of any form: in the direction of movement, the linear dimensions of the body are reduced by the greater, the greater the speed of movement, this phenomenon is called the Lorentz (or Fitzhyld) abbreviation. Transverse body sizes do not change. As a result, for example, the ball takes the shape of an ellipsoid, flattened in the direction of movement. It can be shown that visually this ellipsoid will be perceived as a ball. This is due to the distortion of the visual perception of moving objects caused by the different times of the times, which spends the light on the passage of the path from various remote points of the subject to the eye. The distortion of visual perception leads to the fact that a moving ball is perceived by the eye as an ellipsoid, elongated in the direction of movement. It turns out that the change in the shape caused by the Lorentz reduction is precisely compensated by the distortion of visual perception.

Time interval between events

Let in the system K "in the same point with the coordinate x "occur at times t " 1 and t " 2 two of some events. This may be, for example, the birth of an elementary particle and its subsequent decay. In system K "these events are divided by a period of time.

t." = t." 2 ‑ t." 1 .

Find time lapse  t.between events in the system K.relative to which the system K "moves with speed V.. To do this, we define in the system K.time moments t. 1 and t. 2 corresponding to moments t " 1 and t " 2 and form their difference:

t. = t. 2 - t. 1 .

The substitution of the values \u200b\u200bof the coordinates and moments of time leads to expressions

If events occur with the same particle resting in the system K ", then  t "= t " 2 -t " 1 it is a period of time measured by a clock, fixed relative to the particle and moving with it relative to the system K.with speed v.equal V.(Recall that the letter V.we indicate only the relative speed of systems; Particle and watches we will denote the letter v.). The time counted on the clock moving along with the body is called own time This body is usually denoted by the letter τ. Consequently,  t "\u003d τ. Value  t.== t. 2 - t. 1 represents a period of time between the same events measured by the system of the system K.relative to which the particle (along with its own clock) moves at speeds v.. Taking into account said

From the resulting formula it follows that own time less than the time counted on the clock moving relative to the body (Obviously, watch fixed in the system K., moving relative to the particle at speed - v.). In no matter how the reference system was not considered the movement of the particle, the interval of his own time is measured by the system of the system in which the particle rests. From here it follows that the interval of his own time is invariant, i.e. the value of the same value in all inertial reference systems. From the point of view of the observer, the living "in the system K., t.there is a time interval between events, measured by a fixed hour, and a period of time measured by a clock moving at a speed v.. Since τ.< t., It can be said that the moving clock go slower than the resting hours. This is confirmed by the following phenomenon. As part of cosmic radiation, unstable particles, called muon, are born at an altitude of 20-30 km. They disintegrate on the electron (or positron) and two neutrinos. Muon's own lifetime (i.e., the lifetime, measured in the system in which they are fixed) is an average of about 2 μs. It would seem that even moving at a speed, very little different from c.They can only pass the way equal to 3 · 10 8 · 2 · 10 -6 m. However, as the measurements show, they have time to achieve a terrestrial surface. This is explained by the fact that muons move at speed close to c.. Therefore, their lifetime, counted on the clock, fixed relative to the Earth, turns out to be much more than their own lifetime of these particles. Therefore, it is not surprising that the experimenter observes the mileage of muons, significantly exceeding 600 m. For an observer moving together with muons, the distance to the surface of the Earth is reduced to 600 m, so muons manage to fly this distance for 2 μs.