Earth day- this is the time during which the Earth rotates around its axis, and the day-night cycle changes. Our life is subject to this cycle. In the morning we go to work, in the evening we go to bed. Corresponding cyclic physiological processes in living organisms are called biological rhythms(biorhythms). For example, people have a minimum body temperature early in the morning, and a maximum in the evening. In severe purulent infections, the difference in temperature in the morning and evening reaches 3-4 degrees Celsius.

It seems to me that for most urban people The 24-hour biorhythm is imposed and forced, as evidenced by the regular use of an alarm clock. However, you can train yourself to go to bed and get up at the same time of day. If our day lengthens (for example, the clock changes in the fall), it is easier to bear than if it shortens in the spring, when we have to get up an hour earlier.

How many hours will a day last for a person who lives “out of time,” that is, without any ability to determine the time of day by external signs? These months-long experiments, including on himself, are described by French caver(from Greek spelaion - cave) in his book “ IN THE ABYSS OF THE EARTH", published in Moscow in 1982. Of course, the material below cannot be considered an exhaustive overview of the accumulated world experience in biorhythmology; it is only interesting information for thought.

The experiments described in the book were carried out from 1964 to 1972 in deep caves on the border of Italy and France, as well as in the USA. The caves are convenient for their permanent climatic conditions : silence, complete absence wind and sunlight, constant temperature and humidity. Experienced volunteer cavers took part in the experiments. Cave is more natural natural environment, full of dangers (precipices, cold, dampness, darkness, rare insects and even mice) compared to a specially built bunker.

Why was this necessary? Not just for the sake of “naked” science. In the 1960s, space exploration was actively underway, long-term expeditions to other planets were planned, and NASA was interested in long-term experiments on the effect of isolation of people on their livelihoods. The French military department even became interested in the results of the experiments. Find out why you are interested below.

Is it easy to live in a cave for months? No. If you are able to not communicate with anyone for 2-3 days without suffering from a lack of communication, then you might be able to do it. IN free time The speleologists read books (all had artificial lighting), engaged in hobbies (drawing, photography), and explored their cave. But every day they had a whole list of boring obligatory tasks: calling “up” about each event (waking up, eating, physiological functions, going to bed), a series of annoying psychophysiological tests for composure, efficiency, reaction speed, etc. In addition, in a number of experiments I had to constantly wear sensors, which in those days were not always portable, so the volunteers were in the cave, like dogs on a leash several meters away. And the sensor electrodes irritated the skin. Every day we had to collect and send upstairs urine and stool tests. Even the composition of stubble shaved from the face was analyzed. Speleologists led in the caves diary, where they recorded the subjective date and their feelings. Only those at the top of the escort team knew the real date. There was not always enough money for these long-term experiments, but all participants persevered very steadfastly, despite the difficulties. Due to lack of money for food during an experiment in the United States, the escort group even caught and ate rattlesnakes.

Brief results of experiments “out of time”

1) in 1964-1965 parallel individual experiments took place Antoine Senni(4 months, 35-year-old man) and (3 months, 25-year-old woman). In those days, such a length of solitary stay in a cave was an unattainable record, especially among women.

Antoine Senny (Tony):

• when Tony counted out loud to 120 in order to subjectively measure an interval of 2 minutes, between 3 and 4 minutes actually passed.

From the very first month of the experiment, a disturbance in the rhythm of wakefulness and sleep was discovered in Antoine Senni. His day sometimes lasted 30 hours straight, and his sleep duration several times exceeded 20 hours. This gave cause for concern.

He especially amazed us when, within 22 days the length of his day varied from 42 to 50 hours (average 48 hours), with fantastically long periods of continuous activity - from 25 to 45 hours (average 34 hours) and with sleep duration from 7 to 20 hours. We discovered a phenomenon we named in 1966 two-day rhythm, that is, lasting about 48 hours.

On the 61st day of this exceptional experiment, Tony gave us serious anxiety: he slept for 33 hours. I already feared for his life and was preparing to go down to him, when suddenly I heard phone call: Tony told me he had a good night!

So, the average duration Tony's sleep at a 48-hour rhythm was 12 hours. His daily cycle consisted of 36 hours of wakefulness and 12 hours of sleep, but this pattern was violated several times: Senny could sleep 30 hours, and then only 18 hours remained for the active period. Therefore in 1965 French War Ministry decided to study in more detail the nature of this dream, which so significantly increases a person’s performance and gives the body enormous opportunities to recuperate. Such experiments were carried out in 1968-1969 (further on this page see experiment No. 3).

2) in 1966 a record experiment took place Jean-Pierre Merete- “human laboratory” (6 months).
This volunteer probably had the hardest time. He lived almost all the time with sensors that recorded electrical activity his brain, eye movements, muscle tone, heart and breathing rhythms, body and skin temperature. The electrodes irritated the skin to the point of bleeding, but each time Merete was persuaded to “be patient a little longer” for the sake of science, and each time he agreed.

Merete woke up and went to bed every day two to three hours later than the previous day. In this study, using electroencephalograms recorded during sleep, the presence of the subject has a 48-hour biorhythm.

During the first 10 days of life in the cave, Merete's circadian rhythm was approximately 25 o'clock(15 hours of wakefulness + 10 hours of sleep), which almost corresponded to the normal rhythm. Then, over the next month, his body followed a rhythm lasting about 48 hours(34 hours awake and 14 hours asleep).

The following months surprised again: Merete's rhythm became inconsistent and fluctuated from 18 to 35 hours, with periods of activity from 12 to 20 hours and sleep from 7 to 15 hours. Sometimes he even slept for 17 hours!

This irregularity of the rhythm (cycles without any rest were recorded lasting about 50 hours at average duration 25 hours) still arouses the interest of specialists. This is undoubtedly one of the most important results experiment by Jean-Pierre Merete.

3) in 1968-1969- voluntary imprisonment Philip Englander And Jacques Chabert(4.5 months each).

The first volunteer (Philip Englander, 30 years old) was supposed to live for 2 months with 48 hour days, and the second (Shaber, 28 years old) was supposed to live 3 months with a constantly burning bright electric light(500 W).

Philip Englander:

Philip Englander's usual 24-hour rhythm, 2 weeks after the start of the experiment, was independently replaced by a 48-hour rhythm, which lasted 12 days. Then, according to a plan drawn up jointly with French military experts, an attempt was made to consolidate this spontaneous 48-hour cycle for another 2 months and achieve this with the help of a bright 500 W lamp, which should burn over his transparent tent for 34 hours all days. Of course, Phillip did not know how long this lamp would burn each time.

The attempt was a success. For the first time man lived in a world where the day was doubled: 36 hours of wakefulness and only 12 hours of sleep, without any disturbances. Philip, as shown by numerous electroencephalograms of his sleep, adapted perfectly to this regime.

In the end, Philip was given the opportunity to live at his discretion, as in the initial period of the experiment. Something surprising happened to the researchers. Philip, instead of returning to a 24-hour circadian rhythm, continued to maintain a 48-hour rhythm without the slightest effort wakefulness and sleep. So when they announced to him that it was already January 4th, he exclaimed:

Wow! I missed New Year! I thought it was only the beginning of November!

Jacques Chabert:

Jacques, in contrast to Phillippe, retained a biological account of time close to the real day: the intervals between his awakenings averaged 28 hours. Turning on the bright lighting pleased Jacques; his sleep was not disturbed at all. Only in the third month of complete loneliness did his day become equal to 48 hours, which was accompanied by increased physical activity(in particular, during this period he conducted intensive exploration in the cave).

Subjectively, for Jacques, 105 days passed between his descent and emergence to the surface instead of the actual 130 days. Before the experiment, Jacques had read something on the topic of determining the true length of time, so he had a better understanding of the number of days that had passed than his neighbor Phillippe.

Ultimately, Jacques and Philippe's bodies gave in and submitted to the 48-hour rhythm. It gave a great advantage: 2 hours won every day. If ordinary person sleeps 8 hours out of 24, then with a 48-hour rhythm, only 12 hours out of 48 are enough to sleep.

Philip was a keen caver. He explored his cave and left these lines in his diary: “Digging, clearing, carving steps, I often exhausted my strength, working for 4-5 hours without breaks" But, as they later calculated on the surface, he worked for more than 20 hours!

The experiments of Schaber and Englander were subject to lengthy analysis. They allowed select people who can live according to a 48-hour rhythm. Michel Siffre writes that the criteria for this selection have already been developed.

4) in 1972- (6 months).

During the entire 2-month experiment in 1962, Sifra's subjective days were close to normal and equaled on average 24 hours 31 minutes, differing from the real ones by half an hour.

In 1972, in contrast, the subjective day increased noticeably more: during the first 1.5 months, each day was 2 real hours longer (26 hours).

Then, for 2 weeks, the rhythm of wakefulness and sleep was inconsistent: 48-hour days alternated with 28-hour days (their average duration was 37 hours).

Thus, in 1962, Sifr needed 9.5 hours sleep to be alert for 15 hours; and in 1972 he had enough 7.5 hours sleep with 28 hours of wakefulness.

Then, for several months, the cycle was close to 28 hours, after which this rhythm again became 2-day, but without regularity: 48-hour days alternated with 28-hour days for 2 weeks. Finally, until the very end of the experiment, it stabilized at 28 hours.

Michel Cifr was also covered with sensors, including measuring rectal temperature body(in the rectum). Analysis showed that before descending into the cave she was minimum at 2 am(1.5 hours after falling asleep). In the cave, the minimum temperature each time occurred approximately 1 hour later - at 3, 4 and 5 o'clock in the morning, etc., so that after 2 weeks "out of time" the minimum value appeared on the curve at 3 o'clock in the afternoon. And this was repeated several times during the experiment.

These are the results obtained over 10 years by a group of researchers led by Michel Cifr. None of the speleologists the days were not shortened. For everyone, they only lengthened. Maybe this is precisely the reason for students’ desire to go to bed in the morning and stay awake at night?

Speaking about optimal daily biorhythms, one cannot help but recall Leonardo da Vinci. They say that he slept only 1.5 hours a day. The secret of his enormous performance is that he fell asleep for 15 minutes every 4 hours.

Melatonin

The human body produces a special hormone melatonin, which is responsible for adapting to biorhythms and falling asleep. Melatonin is produced epiphysis (pineal body) and improves sleep quality, reduces the frequency of headaches, dizziness, and improves mood. It speeds up falling asleep, reduces the number of night awakenings, improves well-being after waking up in the morning, and does not cause a feeling of lethargy, weakness and fatigue when waking up. Makes dreams more vivid and emotionally rich. Adapts the body to rapid changes in time zones, reduces stress reactions, and regulates neuroendocrine functions. Shows immunostimulating and antioxidant properties.

Most melatonin is formed in the dark; excess light is detrimental to it. At night, 70% of the daily melatonin is formed.

There are melatonin preparations for oral administration. Sold in Belarus MELAXEN And VITA-MELATONIN. They are appointed when desynchronosis(disruption of the normal circadian rhythm, for example, when flying between different time zones), sleep disorders, depression. The drugs are not the cheapest, but, in principle, affordable.

(The last part of the article about the influence of lunar cycles on miners and the Montauk experiment was eventually deleted on 01/30/2016 at the request of readers as pseudoscientific)

How long is a day? Strange question: we know from childhood that a day is exactly 24 hours, or 1440 minutes or 86400 seconds. Yes, but not so. A day is a period of time during which the Earth makes one complete rotation around its axis, and it turns out that it never takes exactly 24 hours.

How long is a day?

If we take a distant star as a starting point and count the period of days during which it will return to the same point, it turns out that one revolution of our planet takes 23 hours 56 minutes and 4 seconds! That is, during the day, astronomical midnight can creep away by almost 4 minutes! Moreover, this period, called the sidereal day, depending on the friction caused by synoptic situations, tides and geological events, changes all the time in the range of up to 50 seconds. If we take our Sun as a starting point, as our ancestors did, then the number will be closer to 24 hours. This is called a solar day. On average per year, taking into account the planet's revolution around the sun sunny day a fraction of a second shorter than twenty-four hours.

When these discrepancies were revealed with the help of highly accurate atomic clocks, it was decided to redefine the second as a fixed fraction of a “solar” day - more precisely, one million six hundred to forty thousandths.

The new second came into use in 1967 and was defined as “a time interval equal to 9,192,631,770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom in the absence of disturbance by external fields.” You can’t say it more precisely - it’s just too painful to say all this at the end of a long day.

The new definition of the second means that the solar day gradually shifts relative to the atomic one. As a result, scientists had to introduce the so-called “leap second” (or “coordination second”) into the atomic year in order to coordinate the atomic year with the solar year.

Since 1972, the leap second has been added 23 times. Imagine, otherwise our day would have increased by almost half a minute. And the Earth continues to slow down its rotation. And, according to scientists, in the 23rd century there will be 25 current hours in our day.

The last time the “leap second” was added was on December 31, 2005, at the direction of the International Service for the Estimation of Earth's Rotation and Coordinates, based at the Paris Observatory.

Good news for astronomers and those of us who like clocks to keep pace with the Earth's movement around the Sun, but headache For computer programs and all the equipment that is on space satellites.

The idea of ​​introducing a “leap second” was strongly opposed by the International Telecommunications Union, which even made an official proposal to completely abolish it back in December 2007.

You can, of course, wait until the difference between Coordinated Universal Time (UTC) and Greenwich Mean Time (GMT) reaches exactly an hour (in about 400 years) and then put everything in order. In the meantime, the debate around what is considered “real” time continues.

Everyone knows this - 24 hours. But why did this happen? Let's take a closer look at the history of the appearance of the basic units of time and find out how many hours, seconds and minutes there are in a day. We’ll also see whether it’s worth linking these units exclusively to astronomical phenomena.

Where did the day come from? This is the time of one revolution of the earth around its axis. Still knowing little about astronomy, people began to measure time in such ranges, including light and dark times at each time.

But there is interesting feature. When does the day start? From a modern point of view, everything is obvious - the day begins at midnight. People of ancient civilizations thought differently. It is enough to look at the very beginning of the Bible to read in the 1st book of Genesis: “... and there was evening, and there was one morning.” The day began with There is a certain logic to this. People of that time were guided by the sun setting, the day was over. Evening and night are already the next day.

But how many hours are there in a day? Why was the day divided into 24 hours, since the decimal system is more convenient, and much more convenient? If there were, say, 10 hours in a day, and 100 minutes in each hour, would anything change for us? Actually, nothing but numbers; on the contrary, it would even be more convenient to carry out calculations. But the decimal system is far from the only one used in the world.

They used the sexagesimal counting system. And the light half of the day was well divided in half, 6 hours each. In total, there were 24 hours in a day. This rather convenient division was taken from the Babylonians by other peoples.

The ancient Romans counted time in an even more interesting way. The countdown started at 6 am. So they counted from that moment forward - hour one, hour three. Thus, one can easily consider that the “eleventh hour workers” remembered by Christ are those who begin work at five o’clock in the evening. It's really too late!

At six o'clock in the evening it was twelve o'clock. This is how many hours in a day were counted in ancient Rome. But there were still night hours left! The Romans did not forget about them. After the twelfth hour the night watches began. The guards changed at night every 3 hours. Evening and night time was divided into 4 watches. The first evening watch began at 6 pm and lasted until 9. The second, midnight, lasted from 9 to 12. The third watch, from 12 at night to 3 in the morning, ended when the roosters crowed, which is why it was called “rooster crowing.” The last, fourth watch was called “morning” and ended at 6 am. And it all started all over again.

The need to divide the clock into its component parts also arose much later, but they did not deviate from the sexagesimal system even then. And then the minute was divided into seconds. True, it later became clear that it is impossible to rely only on the duration of seconds and days to determine the duration of seconds and days. Over the course of a century, the length of the day increases by 0.0023 seconds - it seems like very little, but enough to get confused about the question of how many seconds there are in a day. And that's not all the difficulties! Our Earth does not complete one revolution around the Sun in exactly the same number of days, and this also affects the solution to the question of how many hours there are in a day.

Therefore, to simplify the situation, a second was not equated to movement. celestial bodies, and to the time of processes occurring inside the cesium-133 atom in a state of rest. And to correspond to the actual state of affairs with the Earth’s revolution around the Sun, 2 extra leap seconds are added twice a year - on December 31 and June 30, and an additional day is added once every 4 years.

In total, it turns out that there are 24 hours in a day, or 1440 minutes, or 86400 seconds.

How long is a day? You probably think that exactly 24 hours? Depends on the circumstances. A day is the period of time during which the Earth makes one rotation around its axis.

So how long is a day?

In fact, one rotation of the Earth around its axis never takes exactly twenty-four hours.

There are 23 hours 56 minutes and 4 seconds in a day. All my life I've lived a lie!

It's amazing, but this indicator can fluctuate one way or the other for as much as fifty seconds! This is because the speed of the Earth's rotation changes all the time - due to friction caused by synoptic situations, tides and geological events.

On average, over the course of a year, a day is a fraction of a second shorter than twenty-four hours.

When these discrepancies were revealed by atomic clocks, it was decided to redefine the second as a fixed fraction of a “solar” day - more precisely, one million six hundred to forty thousandths.

The new second came into use in 1967 and was defined as “a time interval equal to 9,192,631,770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom in the absence of disturbance by external fields.” You can’t say it more precisely - it’s just too painful to say all this at the end of a long day.

The new definition of the second means that the solar day gradually shifts relative to the atomic one. As a result, scientists had to introduce the so-called “leap second” (or “coordination second”) into the atomic year in order to coordinate the atomic year with the solar year.

Since 1972, the leap second has been added 23 times. Imagine, otherwise our day would have increased by almost half a minute. And the Earth continues to slow down its rotation. And, according to scientists, in the 23rd century there will be 25 hours in our day.

The last time the “leap second” was added was on December 31, 2005, at the direction of the International Service for the Estimation of Earth's Rotation and Coordinates, based at the Paris Observatory.

Good news for astronomers and those of us who like clocks to keep pace with the Earth's movement around the sun, but a headache for computer programs and all that equipment that sits on space satellites.

The idea of ​​introducing a “leap second” was strongly opposed by the International Telecommunications Union, which even made an official proposal to completely abolish it back in December 2007.

You can, of course, wait until the difference between Coordinated Universal Time (UTC) and Greenwich Mean Time (GMT) reaches exactly an hour (in about 400 years) and then put everything in order. In the meantime, the debate around what is considered “real” time continues.

Here on Earth, people take time for granted. But in fact, at the heart of everything lies extremely complex system. For example, the way people calculate days and years follows from the distance between the planet and the Sun, the time it takes the Earth to complete a revolution around the gas star, and the time it takes to move 360 ​​degrees around its planet. axes The same method is applicable for the rest of the planets in the Solar System. Earthlings are accustomed to thinking that a day contains 24 hours, but on other planets the length of the day is much different. In some cases they are shorter, in others they are longer, sometimes significantly. The solar system is full of surprises, and it's time to explore it.

Mercury is the planet that is closest to the Sun. This distance can be from 46 to 70 million kilometers. Considering the fact that Mercury takes about 58 Earth days to turn 360 degrees, it is worth understanding that on this planet you will only be able to see the sunrise once every 58 days. But in order to describe a circle around the main luminary of the system, Mercury requires only 88 Earth days. This means that a year on this planet lasts approximately one and a half days.

Venus

Venus, also known as Earth's twin, is the second planet from the Sun. The distance from it to the Sun is from 107 to 108 million kilometers. Unfortunately, Venus is also the slowest rotating planet, which can be seen when looking at its poles. While absolutely all the planets in the solar system have experienced flattening at the poles due to the speed of their rotation, Venus shows no signs of it. As a result, Venus takes about 243 Earth days to go around the system’s main luminary once. This may seem strange, but the planet takes 224 days to complete a full rotation on its axis, which means only one thing: a day on this planet lasts longer than a year!

Earth

When we're talking about About a day on Earth, people usually think of it as 24 hours, when in fact the rotation period is only 23 hours and 56 minutes. Thus, one day on Earth is equal to about 0.9 Earth days. It looks strange, but people always prefer simplicity and convenience over accuracy. However, it is not that simple, and the length of the day can vary - sometimes it is even actually 24 hours.

Mars

In many ways, Mars can also be called Earth's twin. In addition to having snowy poles, changing seasons, and even water (albeit in a frozen state), the day on the planet is extremely close in length to a day on Earth. Mars takes 24 hours, 37 minutes and 22 seconds to rotate around its axis. Thus, the days here are slightly longer than on Earth. As mentioned earlier, the seasonal cycles here are also very similar to those on Earth, so the day length options will be similar.

Jupiter

Considering the fact that Jupiter is the largest planet solar system, one would expect the day to be incredibly long. But in reality, everything is completely different: a day on Jupiter lasts only 9 hours, 55 minutes and 30 seconds, that is, one day on this planet is about a third of an Earth day. This happens because this gas giant has a very high rotation speed around its axis. It is because of this that the planet also experiences very strong hurricanes.

Saturn

The situation on Saturn is very similar to that observed on Jupiter. Despite large size, the planet has a low rotation speed, so one rotation period of 360 degrees takes Saturn only 10 hours and 33 minutes. This means that one day on Saturn is less than half the length of an Earth day. And, again, high speed rotation leads to incredible hurricanes and even a constant vortex storm at the south pole.

Uranus

When it comes to Uranus, the question of calculating the length of the day becomes difficult. On the one hand, the planet's rotation time around its axis is 17 hours, 14 minutes and 24 seconds, which is slightly less than a standard Earth day. And this statement would be true if not for the strong axial tilt of Uranus. The angle of this inclination is more than 90 degrees. This means that the planet is moving past the main star of the system, essentially on its side. Moreover, in this situation, one pole is very for a long time looks towards the Sun - as much as 42 years. As a result, we can say that a day on Uranus lasts 84 years!

Neptune

Last on the list is Neptune, and here the problem of measuring the length of the day also arises. The planet completes a full rotation around its axis in 16 hours, 6 minutes and 36 seconds. However, there is a catch here - given the fact that the planet is a gas-ice giant, its poles rotate faster than the equator. The rotation time was indicated above magnetic field planet - its equator rotates in 18 hours, while the poles complete their circular rotation in 12 hours.