Chapter thirteen. Measurement of long time intervals. What period of time is called a day. How many hours, minutes and seconds are there in a day, and why did it happen
When people say they've had enough of the moment, they probably don't realize that they promise to be free in exactly 90 seconds. Indeed, in the Middle Ages, the term “moment” defined a period of time lasting 1/40 of an hour or, as it was customary to say then, 1/10 of a point, which was 15 minutes. In other words, he counted 90 seconds. Over the years, the moment has lost its original meaning, but is still used in everyday life to denote an indefinite, but very short interval.
So why do we remember the moment but forget the ghari, nuktemeron, or something even more exotic?
1. Atom
The word "atom" comes from the Greek term for "indivisible", and therefore is used in physics to define the smallest particle of matter. But in the old days this concept was applied to the shortest period of time. A minute was thought to have 376 atoms, each of which was less than 1/6 of a second long (or 0.15957 seconds to be exact).
2. Ghari
What kind of devices and devices were not invented in the Middle Ages to measure time! While the Europeans were exploiting the hourglass and sundial with might and main, the Indians used clepsydra - ghari. Several holes were made in a hemispherical bowl made of wood or metal, after which it was placed in a pool of water. The liquid, seeping through the slits, slowly filled the vessel until, due to gravity, it completely sank to the bottom. The whole process took about 24 minutes, so this range was named after the device - ghari. At that time, it was believed that a day consists of 60 gharis.
3. Chandelier
A chandelier is a period lasting 5 years. The use of this term is rooted in antiquity: then the lustrum meant a five-year period of time that completed the establishment of the property qualification of Roman citizens. When the amount of the tax was determined, the countdown came to an end, and the solemn procession poured into the streets of the Eternal City. The ceremony ended with lustration (cleansing) - a pathetic sacrifice to the gods on the Field of Mars, performed for the well-being of citizens.
4. Mileway
Not all that glitters is gold. Whereas a light year, seemingly created to determine a period, measures distance, a mileway, a mile-long journey, serves to measure time. Although the term sounds like a unit of distance, in the early Middle Ages it meant a segment of 20 minutes. That is how much it takes on average for a person to overcome a route a mile long.
5. Nundin
The inhabitants of ancient Rome worked seven days a week, tirelessly. On the eighth day, however, which they considered the ninth (the Romans attributed the last day of the previous period to the range), they organized huge markets in the cities - nundins. The market day 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. Nuctemeron
Nuktemeron, a combination of two Greek words "nyks" (night) and "hemera" (day), is nothing more than an alternative designation for the day we are used to. Anything that is considered nuctemeronic, respectively, lasts less than 24 hours.
7. Item
AT Medieval Europe a point, also called a dot, was used to indicate a quarter of an hour.
8. Quadrant
And the neighbor of the point in epoch, the 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, which replenished the state treasury by 15 pence from every pound earned in the country. In the early 1400s, the term also acquired a religious context: it began to be used to indicate the day of an important church holiday and the two full weeks following it. So "Quinzieme" turned into a 15-day period.
10. Scruple
The word "Scrupulus", translated from Latin, meaning "small sharp pebble", used to be a pharmaceutical unit of weight, equal to 1/24 ounce (about 1.3 grams). In the 17th century, scruple, which became symbol small volume, expanded its value. It began to be used to indicate 1/60 of a circle (minutes), 1/60 of a minute (seconds) and 1/60 of a day (24 minutes). Now, having lost its former meaning, scruple has transformed into scrupulousness - attention to detail.
And some more time values:
1 attosecond (one billionth of a billionth of a second)
The fastest processes that scientists are able to time are measured in attoseconds. Using the most advanced laser systems, the researchers were able to obtain light pulses lasting only 250 attoseconds. But no matter how infinitely small these time intervals may seem, they seem like an eternity compared to the so-called Planck time (about 10-43 seconds), according to modern science, the shortest of all possible time intervals.
1 femtosecond (one millionth of a billionth of a second)
An atom in a molecule makes one oscillation in 10 to 100 femtoseconds. Even the fastest chemical reaction takes place over a period of several hundred femtoseconds. The interaction of light with the pigments of the retina, and it is this process that allows us to see the environment, lasts about 200 femtoseconds.
1 picosecond (one thousandth of a billionth of a second)
The fastest transistors operate within a time frame measured in picoseconds. The lifetime of quarks, rare subatomic particles produced in powerful accelerators, is only one picosecond. The average duration of the hydrogen bond between water molecules at room temperature equals three picoseconds.
1 nanosecond (billionth of a second)
A beam of light passing through an airless space during this time is able to cover a distance of only thirty centimeters. microprocessor in personal computer it would take two to four nanoseconds to execute a single command, such as adding two numbers. The lifetime of the K meson, another rare subatomic particle, is 12 nanoseconds.
1 microsecond (millionth of a second)
During this time, a beam of light in a vacuum will cover a distance of 300 meters, the length of about three football fields. A sound wave at sea level is capable of covering a distance equal to only one third of a millimeter in the same period of time. It takes 23 microseconds for a stick of dynamite to explode, the wick of which has burned to the end.
1 millisecond (thousandth of a second)
The shortest exposure time in a conventional camera. The familiar fly flaps its wings to all of us once every three milliseconds. Bee - once every five milliseconds. Every year, the moon revolves around the Earth two milliseconds slower as its orbit gradually expands.
1/10 second
Blink your eyes. This is exactly what we will have time to do in the specified period. It takes just that long for the human ear to distinguish an echo from the original sound. Spaceship Voyager 1, heading out of the solar system, during this time moves away from the sun by two kilometers. In a tenth of a second, a hummingbird has time to flap its wings seven times.
1 second
The contraction of the heart muscle of a healthy person lasts just this time. In one second, the Earth, revolving around the sun, covers a distance of 30 kilometers. During this time, our luminary itself manages to travel 274 kilometers, rushing through the galaxy at great speed. Moonlight for this time interval will not have time to reach the Earth.
1 minute
During this time, the brain of a newborn baby gains up to two milligrams in weight. A shrew's heart beats 1,000 times. An ordinary person can say 150 words or read 250 words during this time. Light from the sun reaches the Earth in eight minutes. When Mars is closest to Earth, sunlight reflects off the surface of the Red Planet in less than four minutes.
1 hour
This is how long it takes for reproducing cells to split in half. In one hour, 150 Zhiguli roll off the assembly line of the Volga Automobile Plant. Light from Pluto, the most distant planet in the solar system, reaches Earth in five hours and twenty minutes.
1 day
For humans, this is perhaps the most natural unit of time, based on the rotation of the Earth. According to modern science, the longitude of a day is 23 hours 56 minutes and 4.1 seconds. The rotation of our planet is constantly slowing down due to lunar gravity and other reasons. The human heart makes about 100,000 contractions per day, the lungs inhale about 11,000 liters of air. During the same time, a blue whale calf gains 90 kg in weight.
1 year
The Earth makes one revolution around the sun and rotates around its axis 365.26 times, the average level of the world ocean rises by 1 to 2.5 millimeters, and 45 federal elections are held in Russia. It will take 4.3 years for light from the nearest star, Proxima Centauri, to reach Earth. Approximately the same amount of time it will take for surface ocean currents to circumnavigate the globe.
1st century
During this time, the Moon will move away from the Earth by another 3.8 meters. Modern CDs and CDs will be hopelessly outdated by that time. Only one out of every baby kangaroo can live to be 100 years old, but a giant sea turtle can live as long as 177 years. The lifespan of the most modern CD can be more than 200 years.
1 million years
A spacecraft flying at the speed of light will not cover even half of the way to the Andromeda galaxy (it is located at a distance of 2.3 million light years from Earth). The most massive stars, blue supergiants (they are millions of times brighter than the sun) burn out around this time. Due to shifts in the tectonic layers of the Earth, North America will move away from Europe by about 30 kilometers.
1 billion years
Approximately this is how long it took for our Earth to cool after its formation. In order for oceans to appear on it, unicellular life would arise and instead of an atmosphere rich in carbon dioxide, an atmosphere rich in oxygen would be established. During this time, the Sun passed four times in its orbit around the center of the Galaxy.
Since the universe has a total existence of 12-14 billion years, time units exceeding a billion years are rarely used. However, cosmologists believe that the universe will probably continue after the last star goes out (in a hundred trillion years) and the last black hole evaporates (in 10,100 years). So the Universe still has to go a much longer way than it has already gone.
And remember, we recently found out that it is possible
Popular about Einstein and SRT
And here is another look at the theory of relativity: one online store sells watches that do not have a second hand. But the dial rotates at the same speed relative to the hour and minute. And in the name of this watch there is the name of the famous physicist "Einstein".
Relativity of time intervals is that the course of the clock depends on the movement of the observer. Moving clocks lag behind stationary ones: if any phenomenon has a certain duration for a moving observer, then it seems to be longer for a stationary one. If the system were moving at the speed of light, then to a motionless observer, the movements in it would seem to be infinitely slowed down. This is the famous clock paradox.
Example
If I simultaneously (for myself) click my fingers on spread hands, then for me the time interval between clicks is equal to zero (it is assumed that I checked this using Einstein's method - oncoming light signals together came to the middle of the distance between pairs of clicking fingers). But then for any observer moving "sideways" relative to me, the clicks will not be simultaneous. So, according to his countdown, my moment will become a certain duration.
On the other hand, if he clicks his fingers on his outstretched hands, and from his point of view the clicks are simultaneous, then for me they will turn out to be non-simultaneous. Therefore, I perceive its moment as a duration.
Likewise, my "almost instant" - a very short duration - is stretched out for a moving observer. And his “almost instant” stretches out for me. In a word, my time slows down for him, and his time slows down for me.
True, in these examples it is not immediately clear that in all reference systems the direction of time is preserved - necessarily from the past to the future. But this is easy to prove, remembering the prohibition of superluminal speeds, which makes it impossible to move backward in time.
One more example
Ella and Alla are astronauts. They fly on different rockets in opposite directions and rush past each other. Girls love to look in the mirror. In addition, both girls are endowed with the superhuman ability to see and ponder subtly fast phenomena.
Ella sits in a rocket, staring at her own reflection and contemplating the relentless pace of time. There, in the mirror, she sees herself in the past. After all, the light from her face first reached the mirror, then reflected from it and returned back. This journey of light took time. This means that Ella sees herself not as she is now, but a little younger. For about a three hundred millionth of a second - because. the speed of light is 300,000 km/s, and the path from Ella's face to the mirror and back is about 1 meter. “Yes,” Ella thinks, “you can only see yourself in the past!”
Alla, flying on an oncoming rocket, having caught up with Ella, greets her and is curious about what her friend is doing. Oh, she looks in the mirror! However, Alla, looking into Ella's mirror, comes to different conclusions. According to Alla, Ella is aging more slowly than according to Ella herself!
In fact, while the light from Ella's face reached the mirror, the mirror shifted relative to Alla - after all, the rocket is moving. On the way back of the light, Alla noted the further displacement of the rocket.
So, for Alla, the light went back and forth not along one straight line, but along two different, non-coinciding ones. On the path "Ella - mirror - Ella", the light went at an angle, described something similar to the letter "D". Therefore, from the point of view of Alla, he went a longer way than from the point of view of Ella. And the greater, the greater the relative speed of the missiles.
Alla is not only an astronaut, but also a physicist. She knows: according to Einstein, the speed of light is always constant, in any frame of reference it is the same, because does not depend on the speed of the light source. Consequently, for both Alla and Ella, the speed of light is 300,000 km/s. But if light can travel different paths with the same speed in different frames of reference, the conclusion from this is the only one: time flows differently in different frames of reference. From Alla's point of view, Ella's light has come a long way. This means that it took more time, otherwise the speed of light would not have remained unchanged. According to Alla's measurements, Ella's time flows more slowly than according to Ella's measurements.
Last example
If an astronaut takes off from Earth at a speed that differs from the speed of light by one twenty-thousandth, flies in a straight line for a year there (counted by his watch and according to the events of his life), and then returns back. According to an astronaut's watch, this journey takes 2 years.
Returning to Earth, he will find (according to the relativistic time dilation formula) that the inhabitants of the Earth have grown old by 100 years (according to earth clocks), that is, he will meet another generation.
It must be remembered that during such a flight there are sections of uniform motion (the frame of reference will be inertial, and SRT is applicable), as well as sections of movement with acceleration (acceleration at the start, braking upon landing, turn - the frame of reference is non-inertial and SRT is not applicable.
Relativistic time dilation formula:
Package: ChGK book. 2000. The first hundred questions Round: Round 1. Question 1.1: In the first centuries of the existence of Christianity, the so-called monarchian heresies spread, the adherents of which denied the trinity of God. The philosopher Tertullian in his writings refuted the assertions of the monarchists, and as a result of his activities, by the 3rd century in the western part of the Roman Empire, the influence of the monarchists was reduced to nothing. And why was Tertullian unable to influence the eastern regions of the empire as effectively? Answer: He wrote in Latin, and in these areas they spoke and wrote mainly in Greek. Question 1.2: The object that caused this unpleasant event in 1443 was located in the Moscow church of St. Nicholas in Peski. This event was repeated many times later. What event are we talking about? Answer: Fire (Moscow burned down from a penny candle). Question 1.3: The Moscow Patriarch is officially called His Holiness the Patriarch of Moscow and All Russia, and the Patriarch of Alexandria is called: Patriarch of Alexandria and All... Complete the title. Answer: Africa. Question 1.4: In ancient Greek, the crowd is "ohlos". And how, according to one version, the ancient Greeks called a single representative of this crowd? Answer: Okhlomon. Question 1.5: Previously, in works of one popular genre, often published in the press, they were ignored. In modern writings on this subject, Ceres, Pallas, Juno and Vesta are sometimes taken into account. But it is unlikely that everyone will ever be taken into account, because there are more than 2000 of them. And what are these essays about? Answer: These are horoscopes. Some modern astrological schools take into account the "influence" of large asteroids. 1.6 Recently, a new type of aerobics has appeared, which even people who have suffered a spinal injury can do. Sometimes, to increase the load, they give dumbbells to the hands. These dumbbells are made from ultra-lightweight materials. Why is it harder to exercise with them? Answer. This is water aerobics. Those involved stand up to their necks in water, and it is difficult for them to keep constantly floating dumbbells under water. 1.7 The work of these people was sung by the famous Russian poet and no less famous artist. Among them, a proverb was widespread, beginning with the words: "Upward bondage is lucky, ..." Finish the proverb. Answer. "...Water carries down." These are burlaki. 1.8 One meaning of this word comes from German word, meaning "lack", and the other - from the Old Russian verb "brother". What's this word? Answer. Marriage. 1.9 How, according to Richard Bach, do we call what the caterpillar calls the end of the world? Answer. Butterfly. 1.10 What was the name in ancient Rome that in Ancient Greece called "tetrippa"? Answer. Quadriga. 1.11 Aviation sports include: airplane, helicopter, glider ... Name the fourth type. Answer. Parachuting. 1.12 Eskimos believe that it is liquid, light, heavy, fragile, shiny, and there are more than two hundred types of it. What is this about? Answer. Snow. 1.13 Pavel Florensky believed that there is a certain correspondence between male and female names. So, the male name Vasily corresponds to the female name Sophia, Alexei - Anna, Vladimir - Olga, Konstantin - Elena. And what female name corresponds to the male name Alexander? Answer. Alexandra, of course. 1.14 Medieval alchemy eventually evolved into modern chemistry. And what is the name of the science, which in the Middle Ages was called iatrochemistry? Answer. The medicine. (Iatrochemistry - from the Greek yatros, i.e. "doctor"). 1.15 On one of the expeditions famous traveler Arseniev, the geologist Gusev went with him. He turned out to be unsuitable for life in the taiga: he often lost his bearings, lagged behind the detachment and did not have the skills of a camp life. One day, while carrying an aluminum bowler hat, he tied it to the knapsack so that the lid dangled and rang. Arseniev asked one of the shooters to help Gusev bandage the bowler hat. But the shooter said it shouldn't be done. How did he justify his opinion? Answer. If Gusev gets lost again, it will be easy to find him by ringing. 1.16 One of the stores in the city of Chekhov, Moscow Region, did not manage to sell out all the available flip calendars for 1995 before the New Year. Under what name did they begin to be sold in 1995, if their sale rate increased sharply because of this? Answer. Toilet paper. 1.17 The manuscript "Rubaiyat" by Omar Khayyam tragically perished in 1912. What happened to it? Answer. Sunk along with the Titanic. 1.18 Which theater was called "big wooden O" by contemporaries? Answer. "The globe". 1.19 In order for it to fulfill its purpose best, you must find it, not buy it, it must belong to a gray individual, or rather its back half. Better to use her own nails. And what is it for? Answer. They say it brings happiness (a horseshoe from the hind leg of a gray horse). 1.20 What can be measured in both Swedish and Italian physicists? Answer. Length. (Units of measurement are angstroms and fermi.) 1.21 The newspaper Rabochaya Tribuna reported an interesting survey among high school students. They were given the name of a famous person who lived several centuries ago, and asked - who is he? The most popular answer was "I don't know"; the second most popular answer is "Irina Allegrova's father." Who was this man really and what was his name? Answer. Meaning the poet Dante Alighieri. 1.22 Those who had a chance to get to know them closely say that each of them is "two tons of bad character." Who are they? Answer. Rhinos. 1.23 In German, the word Feder means "feather", the word "ball", of course, "ball". And what game do the Germans call the word "federal ball"? Answer. Badminton, of course. 1.24 What do we call "the release of a large amount of energy in a limited amount in a short period of time"? Answer. Explosion. 1.25 Some of the popular prints depicted a fight between two people. The picture was accompanied by the caption: "Two fools are fighting, and the third one..." What does the third one do? Answer. Looks. 1.26 The first beauty contest took place not in America, as many people think, but in Russia, at the very beginning of the 16th century, and fifteen hundred girls took part in it. Who organized this competition and why? Answer. Grand Duke (Vasily Ivanovich). Wanted to marry. 1.27 From what, according to Hippocrates, the first human teeth are formed? Answer. From mother's milk (baby teeth). 1.28 Expensive ink made from the finest grades of acid-treated sandalwood and dilute mercury ore are the same color. What well-known expression owes this color? Answer. "Red line" (red ink and cinnabar). 1.29 The English say: "It doesn't matter for what to be hanged - for a sheep or a lamb." And what do we say? Answer. "Seven troubles, one answer." 1.30 What is the difference between the Russian abacus - abacus - from the ancient abacus from a mathematical point of view? Answer. Number system (in Russian - decimal, in ancient - five-fold). 1.31 The English say: "The best is often the enemy of the good." And what do we say? Answer. "They don't look for good from good." 1.32 Although the first patent for the invention was issued as early as 1809, Pushkin was never able to use this device. Mass production was established by a man whose name is now identified with the device itself and is synonymous with the life success of the owner of this device. Say this last name. Answer. Parker. 1.33 What official name worn by the Paris National Academy of Music and Dance? Answer. Parisian opera. 1.34 The English say: "A bird in the hand is worth two in the bushes." And what do we say? Answer. "A bird in the hand is worth two in the bush". 1.35 Name the famous co-author of a certain Ganyan, with whom he invented in 1943 standalone device to study one of the four elements. Answer. Jacques Yves Cousteau (we are talking about scuba gear). 1.36 The English say: "Birds with one plumage come together." And what do we say? Answer. "Birds of a feather flock together". 1.37 According to local legend, the inhabitants of this small mountainous country with a predominantly Muslim population are the descendants of a great black eagle. What kind of country is this, if in translation its name means "Country of Eagles"? Answer. Albania. (It can be simplified by mentioning that it is located in Europe). 1.38 The Frenchwoman Agnes Sorel in 1430 went down in history as the woman who was the first to wear jewelry made of ... What? Answer. From diamonds. 1.39 The English say: "Even a crook is sometimes cheated." And what do we say? Answer. "A thief stole a baton from a thief." 1.40 What is the strict rule for diamonds over 50 carats? Answer. They are given names. 1.41 The English say: "Curses are like chickens - they immediately come back." And what do we say? Answer. "Don't dig a hole for another - you yourself will fall into it." 1.42 The highest mountain system in Western Europe - the Alps - is located on the territory of 7 states. I will call 6, and you - the seventh. So: Austria, Italy, Liechtenstein, Switzerland, Germany, Yugoslavia. Answer. France. 1.43 One day Dionysus decided to make a gift to his beloved friend Ampelus and hung him (not Ampela, of course, but a gift) on a tall elm tree. Ampel climbed a tree, could not resist, fell and crashed. Dionysus was upset and named the failed gift in honor of Ampelus. Now tell me, what types and varieties of what does the science of ampelography deal with? Answer. Grapes (the vine is called "ampelos"). 1.44 The English say: "A diamond cuts a diamond." And what do we say? Answer. "Found a scythe on a stone." 1.45 In theatrical music, the instrumental introduction to the first act is called an overture. And what is the name of the instrumental introduction to the rest of the actions? Answer. Intermission. 1.46 The English say: "Caution is the best part of valor." And what do we say? Answer. "God saves the safe." 1.47 The invention of Blaise Pascal in 1642 greatly facilitated the work of his father, the royal quartermaster of Normandy. In 1673, the invention of Leibniz made it possible to perform all operations. Both scientists could easily do without the help of their inventions, which cannot be said about 80% of schoolchildren who, according to tests conducted by the Russian Ministry of Education, would not be able to perform a single operation without modern versions of the invention of the 17th century. What is the name of the invention of Pascal and Leibniz? Answer. Adding machine. 1.48 How in Russia from the 16th century was called a measure of length equal to the length of the phalanx of the index finger, which, in turn, was equal to 1.75 inches? Answer. Vershok. 1.49 The English say: "Do not make mountains out of molehills." And what do we say? Answer. "Do not make mountains out of molehills". 1.50 She reigns over the whole world: no one can escape her power. Only Athena, Hestia and Artemis are not affected by the spell of the daughter of Zeus and Dione. And what is the second version of her birth? Answer. Aphrodite was born from sea foam. 1.51 The English say: "Don't teach your grandmother how to suck an egg." And what do we say? Answer. "Teach your grandmother to suck eggs". 1.52 Long, like cucumbers, its fruits are eaten by both people and animals. For monkeys, this is a favorite delicacy. Its wood does not burn, the leaves do not fall off in winter, but in summer ... What kind of plant is this? Answer. Baobab. 1.53 Name at least one of the large group of our compatriots who are called the same as their colleagues from the Celtic tribes. Answer. Gorodnitsky, Vizbor, Lanzberg, etc. (any bard). 1.54 Louis XIV reigned 72 years, Louis XV - 59 years, Louis XVI - 18 years. How many years did Louis XVII rule? Answer. Not at all, he died as a child in prison. 1.55 The English say: "The early bird brings the worm." And what do we say? Answer. "Who gets up early, God gives him." 1.56 What was the name of the hostel for poor students at medieval universities, partly supported by the university, partly by alms collected by students, if later this name was transferred to hostels at theological educational institutions? Answer. Bursa. 1.57 Bottle - a measure of the volume of liquid before the introduction of the metric system in Russia: one contained 1/16 of a bucket or 0.7687 liters, the other - 1/20 of a bucket or 0.615 liters. What was the name of these bottles? Answer. The first is wine, the second is vodka or beer. 1.58 The English say: "Every cloud has a silver lining." And what do we say? Answer. "There is no evil without good." 1.59 Which Catholic saint's feast day falls on May 1st? Answer. Holy Walpurgis. 1.60 This genre developed intensively in Lanner's work. The classical composers Grieg, Sibelius, Glinka, Tchaikovsky, Glazunov, Prokofiev and others also paid tribute to him. One of the most famous maestro who worked in this genre, at the end of the 19th century, even unofficially received a very high title, consisting of two words. Name it. Answer. Waltz King - Johann Strauss. 1.61 Dmitry Kedrin in his ballad described the great deed and the tragic fate of two nameless masters of the 16th century. You have seen their brainchild, and more than once. However, their names remained in real history, although, according to some assumptions, both of these names were borne by one person. Name them. Answer. Barma and Postnik are the creators of the Pokrovsky Cathedral, "what is on the moat", or St. Basil's Cathedral, immortalized in D. Kedrin's ballad "The Architects". 1.62 The English say: " beautiful words you can't butter parsnips." And what do we say? Answer. "The nightingale is not fed with fables." 1.63 Translate the word "vengeance" into Italian. Answer. Vendetta. main cities: Verona, Vicenza, Belluno, Padua, Treviso, Rovico and... What common name wear the city, and the province, and the region? Answer. Venice. 1.65 Last Sunday before Easter Orthodox Church celebrates one of the twelfth feasts - "The Lord's Entry into Jerusalem", when the crowd covered His path with clothes and palm branches. In the Orthodox name of this holiday, there was a completely understandable climatic substitution of concepts. What is it called in Russia? Answer. Palm Sunday. 1.66 Yaroslav's courtyard was a permanent place of the citywide gathering in Novgorod, and in Kyiv - the courtyard of the church of Sophia. In addition, in large cities there were places of district gathering. What name did they have? Answer. Veche. 1.67 The English say: "Sharp tools are not to be trifled with." And what do we say? Answer. "Don't play with fire." 1.68 For the first time this military rank (as a title) was received by a brother french king Charles IX, later king himself Henry III. In Russian history, they can be counted on the fingers. Name the first and last in the USSR. Answer. Stalin is a generalissimo. 1.69 Gerontologists have proposed the following classification: "old age" - people from 60 to 74 years old, "senile" - from 75 to 89 years old. What do they call people over 90? Answer. Centenarians. 1.70 The English say: "You can't make a crab walk straight." And what do we say? Answer. "Leopard change his spots". 1.71 How did the ancient Germans call the military leader of the tribe, in the Middle Ages - a major feudal lord, and at the end of the Middle Ages - the owner of one of the highest noble titles in Western Europe? Answer. Duke. 1.72 Name the worst of the vices according to Yeshua Ha-Nozri. Answer. Cowardice. 1.73 The founder of the dynasty - Nikita Antufiev - laid the foundation for the wealth and prosperity of his family under Peter I. His descendants received the nobility in 1726, and in the first half of the 19th century one of them bought in Italy the title of Prince of San Donato, approved in Russia in 1872 . What was the name of Nikita Antufiev's father, if since 1702 the whole family received a surname formed from him? Answer. Demid - Demidovs. 1.74 To what military rank at the beginning of the 20th century, a bombardier corresponded in artillery, and in the Cossack troops - an order? Answer. Corporal. 1.75 What animals live from 13 to 20 years, have 18 claws, see everything in gray of varying brightness, hear ultrasounds and can make 7 consonant sounds: v, g. m, k, o, f, k? Answer. Cats. 1.76 The English say: "Life is not only beer and skittles." And what do we say? Answer. "To live life is not a field to cross." 1.77 What is the name of mahogany and sangwood wood? Answer. The Red tree. 1.78 What gold coin was first minted in 1640 under Louis XIII and ceased to exist in 1795? Answer. Luidor. 1.79 The English say: "As the father, such is the son." And what do we say? Answer. "The apple never falls far from the tree". 1.80 The English say: "Look around before you jump." And what do we say? Answer. "Not knowing the ford, do not poke your head into the water." 1.81 The gap between the ends of the middle fingers of the outstretched hands of a man - 2.094 m in Egypt and 1.851 in Ancient Greece - was called the same as the rite associated with rampant cult festivals in honor of the gods, for example, Bacchus. How? Answer. Orgy. 1.82 The English say: "A fan sees the field better." And what do we say? Answer. "From the side you can see." 1.83 What was the name famous beauty, holder of the Order of the Holy Great Martyr Catherine, to whom Pushkin dedicated beautiful love poems? Answer. Elizaveta Ksaveryevna Vorontsova. 1.84 From the box opened by Pandora, disasters spread throughout the earth. What is left at the bottom of the vessel? Answer. Hope. 1.85 The English say: "People are judged by their company." And what do we say? Answer. "With whom you lead, from that you will type." 1.86 In the Russian folk calendar, the day of St. Kasyan is considered the most terrible day. Well, at least it doesn't happen often. By the way, when is the feast of St. Kasyan celebrated? Answer. February 29 is only a leap year. 1.87 The English say: "Leaking water cannot turn mill wheels." And what do we say? Answer. "What was, then swam." 1.88 I will now name 6 Roman hills, and you - the seventh. So: Aventine, Viminal, Quirinal, Palatine, Caelius, Esquilinum... Answer. Capitol. 1.89 V stressful condition dangerous toxins are produced in the body. How, most often not dependent on the human will, they are excreted from the body? Answer. With tears. 1.90 The English say: "Only a brave man is worthy of a beauty." And what do we say? Answer. "Cheek brings success". 1.91 The International Kennel Club distinguishes 6 classes of dogs: hunting, working, small indoor, terriers, sports and ... Answer. Unsportsmanlike. 1.92 The Chinese divided the dogs into guard, hunting and edible. The Romans also distinguished 3 groups: fighting, swift ... How necessary quality should have possessed dogs of the 3rd group? Answer. Mind (the third group - smart dogs). 1.93 Orthodox and catholic church recognize seven sacraments: baptism, chrismation, communion, confession, wedding, anointing with oil, and ordination to the clergy. Lutherans recognize only baptism and communion, and the Anglican Church adds one more to these two sacraments. Which? Answer. Wedding. 1.94 In a number of Muslim countries in the Middle Ages, there was a title of a sovereign who was also the spiritual head of Muslims. Name the most famous part-time worker, whom both adults and children know. Answer. Caliph Haroun-al-Rashid from the fairy tales "1000 and 1 night". 1.95 The English say: "One good deed deserves another." And what do we say? Answer. "Debt good turn deserves another". 1.96 Which Japanese word means "big wave in the harbor"? Answer. Tsunami. 1.97 The English say: "The sharpness of the reproach is in its veracity." And what do we say? Answer. "The truth pricks the eye." 1.98 In Central Asia they are called "people" and "mazang", in Armenia - "bosha", in Iran - "cars". Alexander Sergeevich Pushkin was very fond of their art and even dedicated a whole poem to them. What? Answer. "Gypsies". 1.99 Recently, on a certain building, I saw the Latin spelling of the year of construction - MCMXCVII. In what year was it built? Answer. M-1000, SM-900, XC-90, VII-7: 1997 1.100 Remembering the former names of 3 settlements: Naberezhnye Chelny, Rybinsk and Sharypovo, one can easily name the last one on this list. Answer. Gorbachev-Brezhnev, Andropov and Chernenko (General Secretaries of the Central Committee of the CPSU).
The basis of measuring time by astronomical chronology is the movement of celestial bodies, which reflects three factors: the rotation of the earth on its axis, the revolution of the moon around the earth, and the movement of the earth around Sun. These factors are decisive in the selection of the basic units of time.
First natural unit of time allocated by primitive people, there were days associated with the change of day and night - the time of work and rest.
Day- this is the length of time during which the Earth makes one complete revolution around its axis relative to any point in the sky. Differ stellar and solar day. sidereal day equal to the interval between two successive positions at the same point in the sky of a certain star. solar day determined by the same position of the sun. Since the Sun moves relative to the stars in the same direction as the Earth, the sidereal and solar days do not coincide (solar days are longer by about 4 minutes). During the year, the difference between sidereal and solar days reaches about a day. In addition, the Earth moves around the Sun at different speeds, and therefore the solar day is not a constant value. To facilitate the calculation of time, a fictitious concept " mean sun", i.e., the movement of the Sun is considered to be uniform. Therefore, the day has become a constant unit, they are divided into 24 hours, each of which has 60 minutes, in a minute - 60 seconds, in a second - 60 thirds. The emergence of small units of time measurement (hours , minutes, seconds) are associated with the ancient Babylonian duodecimal counting system.In 1792, the French astronomer and mathematician Pierre Simon Laplace proposed decimal division days, i.e. - at 10 hours for 100 minutes each and 100 seconds per minute. But this division was not accepted.
The starting point of the day - midnight - in Russia was established by decree Soviet power, signed by V.I. Lenin in February 1919: "Count the time during the day from 0 to 24 hours, taking midnight as the beginning of the day."
The Earth, rotating around its axis, consistently turns to the Sun with different parts of the surface, and the day does not come in all places of the globe at the same time. In the 19th century S. Fleshing suggested standard time- a time counting system based on the division of the Earth's surface into 24 time zones. In 1884, an international conference was held in Washington on the introduction of a single standard time and a single prime meridian. The initial (zero) meridian was the one that passes through the Greenwich Laboratory in the suburbs of London. The local time of time zones located to the east of Greenwich, from zone to zone, increases by an hour, and to the west - by an hour decreases. It was decided to draw time zone boundaries in uninhabited places (oceans, deserts, mountains) along meridians, and in other territories - taking into account physical and geographical features (along large rivers, watersheds) or along interstate and administrative borders. At the same conference, the so-called. "date line" - the meridian of 180º E, located in the opposite part of the globe from the zero Greenwich meridian.
Paying attention to the passage of the various phases of the Moon from one new moon to another, people identified a larger unit of time - lunar (synodic) month(from Greek " synodos"- rapprochement, convergence, since at the time of the new moon the Sun and Moon "approach"). Month - This is the period of the observed alternation of the lunar phases, depending on the movement of the Moon around the Earth. The synodic (lunar) month is 29 days 13 hours 44 minutes 2.9 seconds. Initially, its duration was determined at 30 days.
The establishment of the following unit of time is largely connected with the phases of the moon - seven day week. The counting of days by seven days arose in the Near East and in Egypt several millennia ago. The names of the days of the week are repeated in many languages, and most often indicate the ordinal number in the week. The exception is the word Shabbat, which arose to designate the day of the week back in Ancient Babylon, where it denoted peace, since the day was considered unlucky, and one should not work, but one had to indulge in peace. There is another option: in the Akkadian language, the word "shabbatum" meant "full moon" or "phase of the moon", which indicates that the seven-day count was associated with the approximate duration of each phase of the moon.
The need to monitor the change of seasons associated with the apparent movement of the Sun (in fact, with the movement of the Earth around the Sun) brought to life the appearance of the solar year. Year astronomically corresponds to the real complete revolution of the Earth around the Sun. The astronomical solar year is called tropical. Twice a year the Sun and the Earth are in such a mutual position when Sun rays uniformly illuminate the earth's hemispheres, and day is equal to night on the entire planet. These days are named spring(21 March) and autumn(23 September) equinoxes. The time interval between successive positions of the Sun at the vernal equinox is called tropical year, e its duration is 365 days 5 hours 48 minutes 46 seconds.
A day, a tropical year, and a synodic month are incommensurable quantities, they cannot be expressed one through the other. Therefore, when highlighting the solar year, the months are conditional units, not connected in any way with the real lunar months.
Century - in ancient Russia, this chronological value was first understood as a long period of time - an epoch. The chronicles indicated: “From Adam to this time, there are 6 centuries”, “There were centuries of Trojan, the summers of Yaroslavl passed”, Later, a number of years began to be called a “century”, “how long a person can live”; "that seventy years will transform the age of the human belly." Finally, from the 17th century "age" began to be used in the meaning of "century".
The new age starts from the first year. In 2000, a special clarification was given by the State Committee of the Russian Federation for Standardization and Metrology about when the 21st century and the 3rd millennium begin: "In accordance with the document of the International Organization for Standardization ISO 8601 and Russian GOST 7.64-90, the counting system long periods of time (chronology) is carried out according to the Gregorian calendar, introduced since 1582 and adopted in Russia since February 1918. The counting of years in the Gregorian calendar is made from the 1st year of the new era.Therefore, the 1st century (century) of the new era contains years 1-100 and ends at the end of the year 100. The second century begins in the year 101 and continues until the end of the year 200, etc. Continuing the accepted calendar count of years, we get that on December 31, 2000, the end of the twentieth century will come and the second millennium. Therefore, the 21st century and the third millennium will indeed begin on January 1, 2001."
Eroy is called the starting point of the chronology(from Latin aera- initial moment, initial number), as well as the chronology system itself. Any calendar system needs a starting point. A feature of the era is its conventionality, because. the starting point could be any significant historical or mythological event in the life of a particular nation or state. Depending on the nature of such an event, eras are distinguished political, religious, astronomical. So, for example, the reckoning of the calendar from the birth of Christ or from the creation of the world - religious eras. were widespread and political era, determined, for example, by the time of the reign of certain dynasties: in Egypt - the dynasty of pharaohs, in China and Japan - the dynasty of emperors, in Western Europe, especially in Italy - the dynasty of Roman emperors. There is an opinion that the word "era" (aera) itself is nothing more than a combination of the initial letters of the Latin phrase "Ab exordio regni Augusti" ("From the beginning of the accession of Augustus" (63 BC)). Bashkirs in the 16th century in their Sherezh chronicles, they took the date of the capture of Kazan by Ivan the Terrible as the initial date of the new era, which is also a political era. There are also fictitious and real eras. In real eras, a real historical event is taken as the basis for counting (for example, the fall of Kazan, the era of Diocletian from the moment this emperor came to the throne, etc.). Fictitious eras - from the birth of Christ, because. it is impossible to prove or disprove the reality of the birth of this character, or the Muslim era - Hijra - counted from the unprovable date of Muhammad's flight from Mecca to Medina.
Allocate and so-called. world eras, counting the time since the creation of the world. In Russia, the Byzantine world era was adopted, considering the year of the creation of the world 5508 BC. e. In general, the church dates the creation of the world in the range from 6984 to 3483 BC.
Now the most common in the world is the era from the Nativity of Christ, calculated by the monk Dionysius the Small as starting in 754 from the founding of Rome or in 281 before the beginning of the era of Diocletian. In Russia, this era was introduced by Peter the Great on January 1, 1700.
In 1627, the French scientist Petavius proposed a backward counting method, i.e. "before the birth of Christ" or BC, this account became widely used from the end of the 18th century. It is accepted that the 1st year BC. directly adjoins the 1st year AD. It is also accepted that the number of years BC. increases as you move into the past, but the months, numbers in them and days of the week are considered exactly the same as in the years of our era.
Cycles (circles) are temporary. In the era of the Middle Ages, time is also known in larger time units than the year. The Piskarevsky Chronicler says: “Renewal is all around: the sky is renewed in 100 years, the stars in 50 years, the sun in 28 years, the moon in 19 years, the sea in 60 years, the water in 7 years, the earth in 10 years, the wind in 4 summer, and the high cost for 4 and the indict for 15 years ..., the epacta for 12 years, the base for 19 years. Let's take a look at some of these units:
indict - the serial number of the year within the 15-year cycle (indictikona) (from lat. " indico"- I announce, I appoint). The appearance of the indicative account is associated with the name of the Roman emperor Octavian Augustus, who established the collection of taxes in this order: in the first five years - honey and iron, in the second - silver, in the third - gold. After 3 5- summer cycles (chandeliers) repeated the same order in the collection of taxes. In Byzantium, the indict account was introduced by Emperor Constantine the Great in 312, and from the reign of Emperor Justenian (537), dating by indict became mandatory in Byzantium. The starting point of the indict account is " world creation".
The beginning of the indicative year did not coincide with the beginning of the ecclesiastical or civil year. There are several options for the beginning of the indict:
In ancient Russia, the calculation of time by indicts was borrowed from Byzantium (with the beginning of the indict on September 1), and was used until the 18th century.
Circle of the Moon. In the 5th century BC. Athenian astronomer Meton found that 19 solar years contain 235 full lunar months, every 19 years there is a repetition of the lunar phases on the same dates of the solar calendar. The 19 year cycle is called lunar or metonic cycle, and the serial number of the year inside this cycle is around the moon. At the same time, it became customary in Athens to put on public display boards with the number of years that have passed since the beginning of the current 19-year lunar cycle indicated in gold letters. Therefore, this number began to be called gold.
Circle of the Sun. The sequence of days in a year repeats periodically every 28 years. This time interval in the Byzantine and Russian medieval chronology was called solar circle, and the ordinal place of the year within it is around the sun.
The circle of the sun is important for determining the days of the week. In the ancient Russian calendars (monthly books), each day of the week from the beginning to the end of the year, starting from March 1, corresponded to one of the 7 letters of the Slavic alphabet. The same letter in the course of the year corresponds to the same day. Vrutseleto (Sunday letter), which corresponds to the Sunday of the given year. After the vrutselet and the circle of the moon of the year are determined, Easter is easily established according to a special table.
Great Indicton – this is the name of the period in 532, since the phases of the moon return to the same numbers of months after 19 years, and the days of the week, given leap years, after 28 years, so 19 x 28 = 532 years. All elements return to their former order, and the days of Easter according to the Julian calendar repeat exactly.
All these subtleties are taken into account when translating the dates indicated in the annals into modern system chronology, since often events are indicated not with an exact date, but in relation to one or another church holiday, most often Easter. Therefore, it is necessary to navigate the calculation of church holidays.
Archaeologists study the distant past, explore the emergence, development and death of ancient cultures. From various finds - tools, clothing, household items, weapons - archaeologists will learn how people lived many thousands of years ago. Archaeological finds also make it possible to judge the connections between various ancient peoples. Determining the age of archaeological finds is of paramount importance for clarifying the influence of one people on another and solving a number of other important archaeological problems.
How is the age of archaeological finds determined?
High burial mounds are scattered across the great Russian plain. Warriors in full armor are buried in them, each with his own warhorse. Many different items were placed in the graves of these people, so that, according to their beliefs, they would not need anything in the afterlife. These mounds tell us about the distant past of our country, about the life and culture of the Sarmatian tribes, who inhabited vast expanses from the Carpathians in the west to the Pamirs and Altai in the east several thousand years ago.
Excavations in the Scythian Naples near Simferopol introduce us to a later historical period. Here, archaeological finds testify to the existence of an urban culture of the Scythians. The age of Scythian mounds is usually determined by the type of burial and funerary objects of local work, but sometimes imported things are found in the mounds: earthenware vessels of Greek work, Chinese fabrics, a mirror of Chinese work... These things allow us to more accurately determine the lifetime of the Scythian buried in the mound .
Based on archaeological finds in the Dnieper region, it was possible to learn about the so-called Trypillia culture - about people who lived about 5000 years ago. Figurines of domestic animals found by archaeologists, hoes made of deer horn, knives and sickles made of flint, flint arrowheads, remains of plastering of adobe dwellings, stone grain grinders, many figurines made it possible to find out what wild animals the ancient man hunted, what kind of domestic animals he owned, what was his economy and how his beliefs developed.
Not so long ago, archaeologists found a city buried in the sands in Uzbekistan. Its excavations made it possible to learn a lot about the high culture of ancient Khorezm. The charred remains of the fortress and dwellings made it possible many centuries later to read the history of his death and find out how and when the invasion of nomads put an end to the prosperity and power of ancient Khorezm.
Even more distant from us are the events that took place in ancient Egypt. They are separated from us by many tens of centuries, but tireless archaeologists find ways to answer the questions in this case: what, how and when?
In ancient Egypt Special attention given to burial. The embalming of the body of the deceased and the rich decoration of the tomb (with various objects or their images), according to Egyptian beliefs, was necessary for the comfortable and pleasant existence of his shadow. After all, the ancient Egyptians believed that a person consists of three parts: the body, the spark of God and the shadow that connects the body with the spark of God. Egyptian priests taught that after the death of a person, his shadow roams the earth for thousands of years. Exactly like a person, but only as if woven from fog, the shadow can walk, talk, and for the first few hundred years it must eat, then only images of food are enough for it. The main thing for the shadow is the body in which it lived before. If it is not preserved, then the shadow yearns and wanders restless on the earth.
These views forced the ancient Egyptians to create grandiose cities of the dead, which occupied the entire edge of the western desert, and build huge pyramids, inside of which were the tombs of the pharaohs. Now these cities of the dead have made it possible to learn much about life long past. Comparison of fragmentary records of various events, patient study of them allows scientists to restore the history of ancient life. However, only when it is possible to confidently date at least some of the most important events, the whole picture of the distant past acquires sufficient consistency and reliability.
Archaeologists are helped to establish dates by historical monuments and ancient chronicles containing records of various events: wars and natural disasters, the change of kings and royal dynasties, etc. It is especially successful when the same event is noted by several independent sources or the event itself is such that we we can pinpoint exactly when it happened. So, for example, from an ancient Chinese chronicle, it is known about two unlucky astronomers named Hee and Ho, who in 2200 BC did not predict an eclipse of the Sun in a timely manner and lost their heads for this offense. Comparison of the chronicle with the modern calculation of this eclipse gives an accurate time stamp and allows you to check how correctly the ancient Chinese chroniclers counted time.
However, archaeologists are not always so easy to determine the time of the events under study. On the contrary, most often it turns out to be not at all easy. Meanwhile, determining the age of archaeological finds is an absolutely necessary condition for obtaining confident conclusions about the history of ancient peoples. Is it possible to find a method for directly determining the age of archaeological finds? Are there clocks for counting millennia? Yes, such watches exist, and several different types. However, we will tell you a little further about what they are, what their principle of operation is and to what extent they work.
Now let's look even further. If we could travel back only 10,000 years, we would find that there are no cities or villages on earth; small groups of people huddle in caves, dangers lie in wait for them from all sides. Terrible, incomprehensible forces of nature rule over them. Poorly armed, they hunt some animals and defend themselves with difficulty from others. These people did not have a written language and left almost no monuments.
Even further back in time! How difficult it is to recognize a person in this creature with a low sloping forehead, overgrown with hair, dressed in an animal skin. Half-bent so that his hands sometimes touch his knees, squeezing a club or a stone ax, a prehistoric man creeps fearfully - the predecessor of the proudly straightened modern man lords of nature.
In order to understand the sequence and change of these bygone life forms, it is necessary to determine their age. How to do it?
Make things and even stones speak.
Recently, a cave was discovered in Spain, which for many thousands of years served as a dwelling for people, then for animals. They lived in it, died, and the earth, layer by layer, covered their remains. A lot of all sorts of remnants formed in this cave a hill 13.5 meters high, rising from its bottom almost to the very arch. First, triangular bronze daggers were discovered at a shallow depth. The people who left them lived 2000 years ago. A little deeper were found various things and skeletons. Even deeper are reindeer bones and incisors made from bone. Then more skeletons. Another two meters below were found many stone knives and drills left by people who lived 10 thousand years ago. One meter deeper lay the bones of a rhinoceros and a cave bear. And at the very bottom of the cave, rough-hewn stone axes and scrapers were found, made about 50 thousand years ago.
The process of building up the layer of earth is slow. Studies have shown that in this cave, it took a century to increase the layer of earth by a quarter of a decimeter.
Archaeological finds found in various parts light, made it possible to gradually find out the main milestones in the development of man and his culture. It was possible to establish that 30-40 thousand years ago the so-called Cro-Magnon people lived, who had an oblong voluminous skull, a wide face and chewing muscles of extraordinary strength. Archaeologists have found the skeletons of these people, as well as various tools they made and drawings of animals on the walls of the caves.
Neanderthal people, who lived 50-70 thousand years ago, occupied a middle place between apes and humans. Their knees were always somewhat bent. Their forehead was sloping back, there was almost no chin. The skeletons of these people told us what they looked like; stone tools belonging to them - axes, knives, spherical hewn stones, drills, etc. - allowed us to find out at what stage of development they were. Pithecanthropes that existed several hundred thousand years ago walked as straight as we do, but their head was much more like a monkey than a human. They had sharply protruding superciliary ridges and a forehead so steeply receding that the sloping skull could fit half the size of a brain than that of a modern person.
In 1960, in the Olduvai Gorge in Tanganyika (Africa), the archaeologists of the spouses Mary and Louis Leakey found the remains of an even more primitive man, who was called Homo habilis ("handy man"). This man used pebbles with a chipped edge as tools. The dating of rocks taken from the layer where he was found made it possible to establish that he lived about 2 million years ago.
The history of the Earth is usually divided into separate large stages. The last of them is called the Cenozoic era, or the era of "new life". It has been going on for about 55 million years. At the end of the Cenozoic era, man appeared and we live.
The Cenozoic era was preceded by the Mesozoic era, or the era of "middle life", which lasted approximately 135 million years. It was a time when eternal summer stood on Earth. The climate at that time was so warm and even that no rings can be discerned in the petrified trees of that era found today, since the trees grew evenly all year round.
In the Mesozoic era, the rulers of the Earth on land, in water and in the air were reptiles. Giant lizards reached enormous sizes, for example, the brontosaurus weighed about 30 tons, five times more than the modern African elephant. The length of the brontosaurus was 20 meters, so an adult would need to take 30 steps to walk from its snout to tail. By the end of the Mesozoic era, it became colder. During the glaciation, all these giants died.
The Paleozoic era, or the era of "ancient life", began about 600 million years ago and ended 340 million years ago. It was generally a calm, warm time, only occasionally interrupted by cold snaps.
At the beginning of the Paleozoic era, life was only in the oceans, in which lived crustacean creatures - trilobites and archaeocyates - organisms intermediate between sponges and corals. Archaeocytes had a calcareous skeleton and long, root-like filaments with which they attached themselves to underwater rocks. Then fish appeared in the seas, and plants and, after them, some animals moved to land. By the end of the Paleozoic era, living beings finally conquered the continents, multiplied and established themselves on land. Damp dense forests of giant ferns and horsetails covered the Earth. In the seas by this time, trilobites and archaeocyates had died out, but the fish multiplied enormously and gave a wide variety of species.
Even earlier periods of life on Earth are called the Eozoic era, or the era of the "dawn of life." The first continents and oceans appeared on Earth about 1.5 billion years ago. The strata, which were formed about 700 million years ago, already contain the remains of quite complex shapes Living creatures. Thus, it is likely that about 1 billion years ago, or even a little earlier, life arose on Earth and the first accumulations of living beings - tiny lumps of living, jelly-like protoplasm substance - appeared in the lukewarm waters of the oceans.
Careful searches, painstaking research allowed paleontologists to gradually, step by step, figure out the path of its development, based on the remains of ancient life, and sometimes only on its obscure traces - prints on stones. Numerous comparisons made it possible to find out the sequence of development of various forms of life and, although rather approximately, to establish their chronology.
The successes achieved by paleontologists have found practical application in the mining industry. Age Knowledge rocks is one of the means for understanding the nature of rock formations and the location of ores in them, which is important both in the search and in the exploitation of minerals.
The age method in geology has already become widespread and is often decisive in prospecting work and in compiling geological maps.
There are many examples to support this, let's look at just one. In 1929, oil was obtained in the Urals near the village of Verkhne-Chusovskie Gorodki. D. V. Blokhin, who carried out a geological study of an area located about 500 km to the south, discovered in this area rocks of the same type and age as the oil-bearing lands of the Yerkhne-Chusovskie Gorodki. Then he offered to drill for oil. In 1932, oil was discovered at a depth of 800 m. So, thanks to the determination of the age of rocks, the Ishimbayevsky oil region was discovered.
Prominent geologists have long noted the importance of determining the age of rocks for both theoretical and practical geology. Academician V. A. Vernadsky in his works emphasized the importance of determining the duration of geological processes and the age of geological formations. Academician V. A. Obruchev wrote that "... the leading role in the search for new mineral deposits is played by familiarity with the geological processes that created these deposits in the past periods of the Earth's life and are creating them, of course, at the present time ..." . "The presence of what minerals can we assume in a mountainous country? .. The answer will depend on the age of this country" (V. A. Obruchev, Fundamentals of Geology, 1947, pp. 287, 293-294).
When scientists, exploring past epochs, use layers earth's crust as steps leading to the past, then the remains of living organisms serve as markers for them to determine their age, they are, as it were, a petrified chronology. But, alas, this paleontological method, the main one for geologists, for determining the age of rocks, due to the mass migrations of living organisms that took place in ancient times, is not always reliable and itself needs to be based on other, more accurate methods.
radiocarbon clock
None of the clocks we have described so far are suitable for measuring such long periods of time and dating long past events. After all, clocks made by man, on the geological time scale, appeared relatively recently, some of them several millennia, while others only a few decades ago. The use of man-made clocks for continuous time keeping is less than a few hundred years old.
The clock - the Earth revolving around its axis and the clock - the Earth revolving around the Sun have been working for billions of years, but the countdown on them began only a few thousand years ago and, as we now know for certain, was irregular, with failures and failures.
Scientists have developed a method of telling time from the growth rings of trees, but this time scale does not extend very far (up to several thousand years) and is of limited use. Deposits of banded clays, sand, and salts also make it possible to keep track of time. All these methods have been studied and used by scientists. However, clocks based on these processes proved to be highly inaccurate.
There are a number of methods for measuring large time intervals. A whole group of such methods is based on the study of the change of various forms of life. For centuries and millennia, some types of plants and animals replaced others. Each of these species existed for a more or less long time. Many species existed at the same time. However, most of them, having experienced a period of prosperity and wide distribution, then different reasons perished and gave way to others.
Having studied the sequence in which one species was replaced by another, and at least approximately determining the duration of the existence of each of them, one can thus draw up a time scale. Such watches are based on the comparison of various events with each other and, therefore, show relative time. They make it possible to confidently determine the sequence of different phenomena. However, these clocks are very inaccurate in dating individual events, or, as is often said, in determining the age of these events. Nevertheless, these methods are still useful in many cases and are widely used.
At the beginning of our century, "radioactive clocks" were developed to measure long periods of time. It was they who made it possible to determine the age of various objects of study with acceptable accuracy, to obtain dates of long-past events, and, ultimately, to better understand the history of life on Earth, the formation of the Earth itself, and even the development of the Sun and stars. A very significant feature of radioactive clocks is that with their help, for archaeological finds, rocks and other objects of study, absolute age; absolute in the sense that it is determined by certain properties (radioactivity) of a given sample and directly for a given sample, while in the methods of relative chronology, the age of a given sample is determined by comparing it with other objects, for example, the remains of spores and pollen of plants, shells of various types etc.
"Radioactive clock" is a method, or rather a whole group of very powerful methods, in which the phenomenon of radioactive decay of nuclei of various isotopes is used to determine large periods of time. Studies of radioactive substances have shown that the rate of their decay does not depend on changes in ambient temperature and pressure, at least within the limits that are achievable in terrestrial laboratories. Thus, the process of radioactive decay can be successfully used to measure time intervals.
The time interval during which the amount of radioactive material is halved is called half-life. The decay of various radioactive isotopes occurs at significantly different rates, for example: the half-life of bismuth-212 is 60.5 minutes, uranium-238-4.5 billion years, and carbon-14-5568 years. Thus, for the measurement of various objects and different time intervals, there is a fairly wide choice of suitable isotopes. Nevertheless, the use of radioactive clocks to measure long periods of time revealed specific and serious difficulties. It took a lot of work and scientific invention in order to achieve the degree of understanding of the processes used, which made it possible to overcome these difficulties.
Meanwhile, the principle of measuring long periods of time with the help of radioactive clocks is very simple. To some extent, it is similar to the principle of the fire clock, in which a properly prepared stick burns at a constant and predetermined rate. Knowing the initial length of the stick, the rate of its combustion, and measuring the length of its unburned part, one can easily determine how much time has passed from the moment when the stick was lit. This is exactly what they did in ancient times.
Consider the operation of radioactive clocks based on the use of radiocarbon C 14 . When determining the Time Intervals with radiocarbon clocks, the initial content of C 14 in the sample and the rate of its decay are considered to be known in advance, and the amount of carbon-14 remaining in the sample by the time of measurements is measured.
The decay rate of radiocarbon was determined by scientists with the help of appropriate laboratory studies of specially prepared C 14 preparations. Since this rate does not depend on the storage conditions of the preparation (temperature, pressure, etc.), there is no doubt that its value can be used in the study of any samples.
However, the analogy between radiocarbon and fire clocks is not complete in the sense that at regular intervals the length of the burning stick of the fire clock decreases by certain segments, i.e., according to the law arithmetic progression, and the amount of radioactive material at regular intervals decreases by a certain number of times, i.e., according to the law of geometric progression. If at the initial moment the length of the stick of the fire clock was A, and its combustion rate was B, then after 1.2.3 hours its length will be A - 1B, A - 2B, A - 3B, etc. If the amount of radioactive substance in the initial moment was A, then after equal and characteristic time intervals for each radioactive isotope, it will be equal to l / 2 A, 1 / 4 A, 1 / 8 A, etc. The curve describing such a change in magnitude is called exhibitor. The fact that the amount of radioactive material present at the beginning decreases exponentially with time does not cause any additional difficulties in timing.
It is more difficult to determine the initial content of radiocarbon in the samples. How can one find out the initial content of radiocarbon in a material that no one specially prepared and which lain in the ground for thousands or tens of thousands of years before a scientist extracted it from there and called it a sample?
To answer this question required a variety of knowledge and a multi-link chain of witty and profound conclusions. Let's move on to their consideration.
The radiocarbon method for determining the absolute age of materials of organic origin was; proposed in 1946 by W. F. Libby. He also developed the physical foundations of this method. It is known that in the earth's atmosphere and oceans, in terrestrial plants and animals, in marine organisms, in general, in the entire biosphere of the Earth, there is radioactive carbon C 14 . True, it is relatively small. If from any organic material, for example, a piece of wood, by burning to get carbon, then it reveals characteristic for C 14 β-radiation. As a convenient quantitative characteristic of this radiation, the concept of specific activity is introduced, meaning by this the number of decays that occur in 1 min in 1 g of a natural mixture of carbon isotopes. For carbon obtained from 1 freshly cut tree, the specific activity is only 14 disintegrations per gram per minute. Meanwhile, 1 g of carbon contains about 5 * 10 22 atoms.
Natural carbon is a mixture of several isotopes, including two stable ones: C 12 (98.9%) and C 13 (1.1%), as well as a very small amount equal to only 1.07 * 10 -10% radiocarbon C 14 . However, the assumption that this radiocarbon is a remnant of the one that was on the Earth during its formation, i.e. 4.5 billion years ago, is completely unbelievable. After all, the half-life of C 14 is only 5568 years. If 4.5 billion years ago the entire Earth consisted entirely of radiocarbon, then even in this case by our time there would be billions of billions of times less of it than is found now.
Why didn't radiocarbon disappear on Earth, didn't die out and is now being discovered? Obviously, only because there is some mechanism that generates it all the time.
This mechanism is now known and consists in the following. Cosmic rays come to Earth in a continuous stream. They contain heavy uncharged particles: neutrons. When passing through the earth's atmosphere, cosmic ray neutrons interact with the nuclei of atmospheric nitrogen. In this case, the following nuclear reaction occurs (Fig. 49): a neutron, colliding with a nitrogen nucleus, forms an intermediate unstable system with it, which after a very short time ejects a proton and turns into a nucleus of radioactive carbon-14.
Following the rebuilding of the kernel, a rebuilding occurs fairly quickly. electron shell and the result is a carbon atom chemically identical to any other carbon atoms. Entering into combination with oxygen atoms, it is oxidized to carbon dioxide. Along with ordinary atmospheric carbon dioxide, it is absorbed by plants, is part of the carbon dioxide salts dissolved in the oceans, etc. Thus, carbon-14 generated by cosmic ray neutrons is included in the biochemical cycle of life on Earth.
Being radioactive, the nucleus of the carbon-14 atom decays after a while. In this case, a beta particle (electron) and an antineutrino are emitted, and the carbon-14 nucleus turns into a stable nitrogen-14 nucleus.
Meanwhile, every living organism is in a state of continuous exchange with the environment, absorbing some substances and releasing others. Therefore, it seems natural to assume that the specific activity of carbon in a living organism should be the same as in the environment. This conclusion is logical, but not certain. Moreover, it represents only one link in a rather long chain of inferences necessary to find the initial content of radiocarbon in the samples.
Let's go through all these links one by one: cosmic rays near the Earth's surface contain neutrons. These neutrons, interacting with the nitrogen of the earth's atmosphere, generate radiocarbon. The resulting radiocarbon is oxidized to carbon dioxide, mixed with ordinary atmospheric carbon dioxide and thus included in the biochemical cycle of the Earth. All organisms in the process of exchange absorb carbon dioxide and thus receive radiocarbon.
If for tens of thousands of years the intensity of cosmic radiation incident on the Earth, and, accordingly, the density of the neutron flux near the Earth, did not change;
if the radiocarbon generated in the earth's atmosphere by cosmic ray neutrons was always diluted in it with stable carbon to the same extent;
if there were no other irregular sources of radioactive and stable carbon in the earth's atmosphere;
if the specific activity of atmospheric carbon does not depend on the latitude and longitude of the area and its height above sea level;
if indeed the relative content of radiocarbon in living organisms is the same as in the atmosphere;
if all this is so, then to determine the initial content of radiocarbon in a given sample of organic origin, it is sufficient to measure its content in any sample of zero age and organic origin, for example, in a tree that has just been cut down.
This value has been measured and is well known. It is such that it gives 14 radioactive decays per minute per gram of the natural mixture of all carbon isotopes.
After the death of an organism, its carbon exchange with the environment ceases. In this way, the point at which the radiocarbon clock starts counting is the death of the organism. Tens of thousands of years ago, some tree was felled by an avalanche or a glacier, some animal died in battle or from an earthquake, and from that moment on, the content of stable carbon in them did not change, and the amount of radiocarbon continuously decreased at a very certain rate, so that after In 5568 years, only 1/2 of the original remains, after 11,136 years - only 1/4, etc.
To what extent are all these assumptions valid? After all, if at least one of them is wrong, then the whole chain of conclusions falls apart, and the determined radiocarbon age turns out to be illusory.
To judge the correctness of all these assumptions, Libby and other authors carried out a wide experimental verification of the method on various samples. known age. It turned out that, within the limits of the measurement error, the result of determining the absolute age of the samples does not depend on the geomagnetic latitude of the sampling points and on the height of these points above sea level. This indicates a fairly fast averaging due to the mixing of the atmosphere.
In addition, it turned out that if we take into account some differences in the initial specific activity of carbon in terrestrial and marine organisms, then the results of radiocarbon dating also do not depend on the type of samples.
However, the decisive test of the correctness of radiocarbon clocks would have to be a comparison of their readings with the age of sufficiently ancient samples, reliably determined in another way. It is clear that it was not at all easy to carry out such a check, since for this it was necessary to have objects of organic origin, the age of which would be known in advance quite accurately and would be many millennia.
For control measurements, seven different wood samples were found:
1) A piece of spruce, the age of which was established by the growth rings of its trunk and thus dated to 580 AD.
2) A piece of wood from a petrified coffin (Egypt), which, according to historical data, was dated 200 ± 150 BC. Thus, in 1949, i.e. when these studies were carried out, the age of this sample was 2149 ± 150 years (signs ± and the number 150 indicate the accuracy of the age determination and show that in this case it was known approximately in the range from 2000 to 2300 years).
3) A piece of wood from the floor of a palace in northwestern Syria, which, according to historical data, was dated 675 ± 50 BC.
4) The interior of a sequoia tree, the growth rings of which corresponded to the time interval from 1031 to 928 BC. In 1949, this corresponded to an average age of 2928±52 years.
5) A piece of board from the funeral ship of the Egyptian king Sesostris. This sample was historically dated to 1800 BC.
6) A piece of acacia board from the tomb of Djoser in Saqqara, which, according to historical data, was dated 2700 ± 75 BC. e. Thus, the age of this sample was about 4650 years,
7) A piece of cypress board from the tomb of Snefru in Meidum, which, according to historical data, was dated 2625 ± 75 BC. e. Thus, the age of this sample was about 4600 years.
The radiocarbon measurements of the age of these samples, as can be seen from Fig. 50, gave a fairly good agreement between the calculations and experiments and thus confirmed the conjecture and calculation of the inquisitive mind of scientists.
On the basis of these results, V. F. Libby concluded that the following prerequisites, which he put as the basis of the radiocarbon method, were correct:
1. The intensity of cosmic radiation near the Earth, the intensity of the neutron flux and, accordingly, the specific activity of carbon in the Earth's atmosphere, at least over the past few tens of thousands of years, are constant.
Recall that the specific activity of carbon is the number of radioactive decays of radiocarbon occurring in 1 g of sample carbon in 1 minute.
2. The specific activity of carbon in a living organism of this type is the same and constant and, thus, is the "world" constant of a biological substance.
3. After the death of the organism, the change in the specific activity of carbon in it occurs according to an exponential law, i.e., in accordance with the law geometric progression.
Thus, it seemed obvious that the method opens up the possibility of unambiguously determining the absolute age of samples of organic origin. After that, many researchers began to widely and successfully use radiocarbon clocks to determine the absolute age of a wide variety of samples.
Refinement of the radiocarbon method
The idea of the radiocarbon method is simple, but not indisputable. Meanwhile, in subsequent years, along with further advances in the method, individual sharp differences in radiocarbon dates from those expected by archaeologists and geologists in accordance with their ideas on this or that issue began to be discovered from time to time. At the same time, in some cases, radiocarbon dates were eventually confirmed, and archaeologists and geologists had to change their ideas. However, in another part of the cases, radiocarbon dates turned out to be inaccurate.
At the same time, the technique of radiocarbon measurements and, accordingly, their accuracy had already been significantly improved, and scientists took advantage of this in order to understand the intricacies of the radiocarbon method. At the same time, it turned out that none of the main provisions formulated by Libby is fulfilled exactly, and all of them need additional analysis. At the same time, it turned out that it was possible to make the radiocarbon clock readings sufficiently accurate and reliable.
In order to understand this (and this is interesting and even instructive), it is best, following the history of the development of this method, to question each point in it. Was the concentration of radiocarbon in the earth's atmosphere really the same thousands and tens of thousands of years ago as it is now? After all, if this is not so, then the countdown becomes uncertain. Indeterminate in the same way as if the initial length of the fiery clock stick were unknown.
These doubts are not in vain. In 1958, de Vries and then Stiver, Suess, and others showed that the specific activity of carbon in the earth's atmosphere decreases with increasing solar activity. This effect is explained by the fact that the solar magnetic fields modulate the flux of cosmic rays incident on the Earth. Such studies were brought up to several thousand years ago, and it turned out that the variations in the specific activity of carbon do not exceed 1–2% (Fig. 51, curve 1), which corresponds to a distortion of the absolute age counted using radiocarbon clocks by 80– 160 years.
However, it is possible that in the more distant past, changes in the specific activity of carbon in the Earth's atmosphere were more significant, for example, due to large changes in the Earth's climate. The study of this issue is of great interest.
An additional source of radiocarbon in the Earth's biosphere is the testing of nuclear and, in particular, thermonuclear weapons. Atmospheric pollution with radioactive carbon, which occurred as a result of nuclear tests above the Earth's surface, has a global character. The magnitude of this effect has reached a significant value in comparison with the average specific activity of carbon over the previous period of time. However, at present, due to the prohibition of nuclear tests in the air, the magnitude of the nuclear effect tends to decrease. Since the effect of nuclear tests began to operate only about 30 years ago, it does not matter for dating samples older than this age (Fig. 51, curve 2).
Another reason for the violation of the constancy of the concentration of radiocarbon in the Earth's biosphere is the dilution of the natural mixture of carbon with stable isotopes. This dilution is due to industrial emissions of carbon dioxide into the atmosphere. Due to the mixing of the atmosphere, the effect is generally global in nature. By examining tree rings of known age, Suess showed that this effect began to operate about 140 years ago (Fig. 51, curve 3).
Thus, changes in the specific activity of carbon have indeed taken place in the past. The magnitude of these changes in a certain time interval is already known. Therefore, when it is possible and necessary, an appropriate correction is introduced into the measurement results and an updated value of the absolute age of the samples taken is obtained.
We now discuss Libby's second main proposition. Is the specific activity of carbon in living organisms of this type really the same? Strictly speaking, this is not true. Keeling showed that the living conditions of a given organism to some extent, albeit to a small extent, affect the concentration of radiocarbon in it. The distortions resulting from this effect in determining the absolute age can reach several hundred years.
However, a way out of this difficulty was soon found. Studies have shown that when the concentration of radiocarbon differs in two trees of the same age (which is estimated by the C 14 / C 12 ratio), then the ratio of stable C 13 / C 12 isotopes also turns out to be changed. Moreover, the shift in the C 14 /C 12 ratio is always twice as large as the shift in the C 13 /C 12 ratio. Thus, independent measurement of the ratio of stable isotopes of a given sample makes it possible to find out whether there is an isotopic shift and what magnitude it is. It is usually small and can be neglected. However, when necessary, an appropriate correction is introduced and an updated value of the absolute age is obtained.
Thus, it was possible to cope with a number of difficulties, which are significant mainly when dating young specimens. Meanwhile, when dating very ancient specimens, very special difficulties were discovered. An analysis of these difficulties, which made it possible to outline the boundaries of the radiocarbon method, or, if you like, to find out what millennium the "dial" of the radiocarbon clock ends with, is described below.
Limits of the radiocarbon method
The question of the limits within which the application of one method or another is possible and legitimate is always interesting and important, because very often the most essential and new lies close to them or even behind them. Naturally, scientists have a desire to push these boundaries. So, for example, radiocarbon geologists need to be able to date ever older samples, as this provides them with such an important opportunity to penetrate even deeper into the past of the Earth.
For physicists who are further developing the radiocarbon method, the question of its limits is no less important. They need to know: have these boundaries been reached or not yet? Is the increase in the upper age limit of the radiocarbon method only a technical, instrumental issue, or is the upper age limit of radiocarbon clocks limited by the features of the method itself?
The question of the lower age limit of the radiocarbon method, at least in principle, is solved simply and unambiguously. The lower bound is zero age. With the current technical level of radiocarbon measurements, it is possible to date samples that have a small age with an accuracy of 50-30 years. Thus, the "dial" of radiocarbon clocks starts from a slightly smeared zero.
The fact that the zero of the radiocarbon clock is somewhat smeared is due to the presence of measurement errors. Any result obtained experimentally has some error, and radiocarbon dates are no exception in this respect. Therefore, a typical record of a radiocarbon clock count contains one or another date and an error in its determination, for example: T = 10,000 ± 70 years. Such a record means that the true value of the age of the sample with a fairly high probability lies in the range from 9030 to 1070 years.
Is it possible to reduce the error of radiocarbon measurements? Yes, but you should keep in mind the following: in radiocarbon dating, you have to examine samples that have very little radioactivity. Meanwhile, the measuring device is also sensitive to other radiations, such as cosmic rays and radioactive radiation from surrounding objects. The magnitude of this extraneous, background radiation is approximately the same as that of the measured one. Meanwhile, the background level depends on a number of reasons and may vary somewhat. Therefore, to reduce the measurement error, it is necessary to increase the sensitivity of the device to the measured radiation as much as possible and, conversely, to reduce its sensitivity to extraneous, background radiation as much as possible.
In order to reduce the background, the radiation receiver (i.e., the counter) is surrounded by a massive shield "arranged from several tons of lead and 80-100 kg of mercury. This reduces the background by 6-8 times. In addition, using a special electronic circuit, signals , perceived by the device, are sorted, selecting and counting only those that have a certain energy characteristic of radiocarbon. Finally, a temporary selection of signals is made. To do this, not one, but two counters that perceive radiation are placed near the measured sample. Then, using a special electronic circuit only those signals that appear in both counters simultaneously are counted. Interference and noise occur irregularly and, moreover, first in one receiver, then in the other, and the signals from the measured sample excite both receivers simultaneously. Therefore, such a scheme allows almost without loss to count the necessary signals and filter out a significant part of unnecessary.All these measures can reduce the background by about 20 times.
An increase in the amount of the test substance and an increase in the duration of measurements also leads to a decrease in the error of the measurement result. At the same time, labor and time costs both for preparing samples and for measuring them increase accordingly. However, if this is dictated by the nature of the problem being solved, then this has to be done, since in this way it is possible to reduce the error in dating young samples up to 20–10 years.
What determines the upper age limit of the radiocarbon method? What millennium does a radiocarbon clock face end with? It turns out that the answers to these questions are anything but trivial; moreover, there are essentially two upper age limits.
Let's see why this happens. If, after dying, a tree lies in the ground for about 50,000 years, then the content of radiocarbon in it decreases hundreds of times. In such a sample, the residual activity of radiocarbon is much less than the background. In this case, even when the duration of measurements is increased to several days, the error of the result is still several thousand years. For older samples, the error turns out to be even greater and, due to the low accuracy of measurements, they lose their meaning. This determines the technical upper age limit of the radiocarbon method.
We call it the technical limit because, ultimately, its value is determined by the level of measurement technology. At present, in most radiocarbon laboratories, it is 40-50 thousand years. The technical upper age limit can be pushed back by increasing the amount of sample to be measured, by extending the duration of measurements, or by isotopic enrichment (eg, by thermal diffusion). All these ways have already been tried by scientists and turned out to be suitable, but very time-consuming. Using them, it was possible to date individual ancient samples up to 70,000 years.
When solving some important scientific problems, the difficulties and duration of the work recede into the background, and only the fundamental possibility of solving the problem is considered essential. Therefore, it is so important to answer the question of how far the upper age limit of the radiocarbon method can be raised.
Usually, when determining the absolute age by the radiocarbon method, only the C 14 that entered the body from the external environment is taken into account, and, following Libby, it is believed that after the death of the organism, only the decay of this radiocarbon takes place in it. F. S. Zavelsky took into account that organisms (plants, animals) themselves contain nitrogen, and in their habitat, that is, at the surface of the Earth, there are neutrons. It follows that radiocarbon is also formed inside organisms during their lifetime and after death.
Let's call C 14 absorbed by the organism during its lifetime from the atmosphere, external radiocarbon, and the C 14 that is formed in the organism itself both during its life and after death, its own radiocarbon.
Assuming that the decrease in the amount of external radiocarbon in the sample occurs according to an exponential law (Fig. 52, dotted curve J int) and, along with this, the accumulation of its own radiocarbon in it (Fig. 62, J inc), we inevitably come to the conclusion that their the amount changes over time according to a law different from exponential (Fig. 52, J exp). Hence it is clear that the third proposition, formulated by Libby, is that the decrease in the specific activity of carbon in the samples occurs according to an exponential law, i.e. exponentially, cannot be considered accurate.
own "activity, J exp - experimental, i.e. experimentally measured activity of carbon">
Rice. 62. Change in carbon activity in a sample over time. J ext - activity of carbon obtained from the external environment, J own - "intrinsic" activity, J exp - experimental, i.e. experimentally measured carbon activity
Meanwhile, when determining the absolute age, it is precisely this - the total or experimental - value of the specific activity of the carbon of the sample that is measured. It is easy to understand that if the accumulation of one's own radiocarbon is not taken into account, then the found value of the absolute age turns out to be fictitious.
How big is the error involved? Is it so large that this effect must always be taken into account, or so small that it can be neglected in any case? Having made the appropriate calculations, F. S. Zavelsky showed that the absolute age of the samples, determined by the radiocarbon method without taking into account the formation of its own radiocarbon in it, really differs from the true one. However, for samples less than 50,000 and even 70,000 years old, this difference is so small that it can be neglected. This conclusion is clearly demonstrated in Fig. 52, which shows that when the age of the sample is 70,000 years, the residual activity of external radiocarbon (Jext) is more than 20 times greater than the activity of intrinsic radiocarbon (Jin). Even when the age of the sample is 80,000 years, J int is 5-6 times greater than J inc. Accordingly, for samples that are about 80,000 years old, the correction for intrinsic radiocarbon is about 1500 years, or 2%. For samples older than 90,000 years, the value of the correction for their own radiocarbon increases sharply and reaches first tens and then hundreds of percent * .
* (Zavelsky F.S., Another refinement of the radiocarbon method, Reports of the Academy of Sciences of the USSR, geol. series, vol. 180, No. 5, 1968.)
Now we can answer the questions posed earlier. While developing the physical foundations of the radiocarbon method in the forties of our century, Libby had measuring instruments that made it possible to determine the absolute age of samples up to about 20-30 thousand years. Dealing with samples not older than this age, he was quite right in stating that in them the decrease in the specific activity of carbon with time occurs according to an exponential law.
I. Arnold in 1954 already mentions the possibility of radiocarbon formation in the sample itself, and E. Olson in 1963 evaluates the influence of this effect on the reading of radiocarbon clocks and concludes that it is insignificant quantitatively. Considering the level of measuring technology of those years, such a conclusion can be considered more or less correct.
Meanwhile, at present, the technical upper age limit of the radiocarbon method has already been raised to 50-70 thousand years, and the question of its further increase is being raised. It can be seen from the foregoing that when dating samples older than 80-90 thousand years, in addition to improving the measuring technique, it is also necessary to introduce a correction for intrinsic radiocarbon.
In order to find out the value of this correction, it is necessary to determine the nitrogen content in the sample and the intensity of the neutron radiation of the soil in which the sample has been lying for tens of thousands of years. However, during such a long storage of the sample, the level of neutron radiation from the soil could change. It is clear that, as a result, the magnitude of the correction is determined very inaccurately. Therefore, when the residual activity of external radiocarbon in a sample becomes less than the activity of its own radiocarbon, then the absolute age determined by the radiocarbon method becomes uncertain. This circumstance sets not a technical, but a fundamental upper age limit for increasing the counting of millennia by radiocarbon clocks.
The value of this fundamental upper age limit of the radiocarbon method depends on the nitrogen content in the sample and on the level of neutron radiation of the soil. Thus, for different samples it is somewhat different. On average, this boundary lies about 100-120 thousand years.
Some applications of radiocarbon clocks
A large number of determinations of absolute age by radiocarbon dating have been made for samples taken from peatlands. Their age was put in accordance with the chronology based on the study of pollen and spores of ancient plants. In general, a fairly complete agreement was obtained between the determination of age by radioactive carbon and the pollen method.
The remains of coal made it possible, using the radiocarbon method, to date the cultural layer of the Lascaux Cave (France), the walls of which were covered with prehistoric paintings. The age of this layer was determined to be 15,500 ± 900 years. In this way, important reference dates were given to archaeologists.
The remains of the remains have been radiocarbonated. charcoal, found in a prehistoric human site, shells used as decorations by prehistoric people, the contents of the stomach of an ancient animal, etc.
The radiocarbon method was used to study samples taken during the excavation of garbage accumulated against the Temple of the Sun in Peru. The age of these debris (shells, ropes, mats, animal remains) at different depths turned out to be different - from several hundred to tens of thousands of years. Appropriate dating proved to be very important in archaeological research.
In Palestine, near the Dead Sea, scrolls of the Bible (the book of Isaiah) were found. Radiocarbon analysis of the upper wrapper of the scroll showed the age of 1917 ± 200 years.
Soviet researchers found a fairly well-preserved corpse of a mammoth in the ice on Taimyr. To study his age by radiocarbon method, the tendons of the animal were taken. As a result of measurements of the relative content of radiocarbon, it turned out that the mammoth had lain in the ice of Taimyr for about 12 thousand years.
More than ten years ago, anthropologists were rather embarrassed by the discovery of the remains of Piltdown Man. The found skull and jaw had a number of features that exploded the established ideas about human evolution. When, using the radiocarbon method, the absolute age of these finds was determined and it turned out to be only about 500 years old, it became clear that there had been a hoax or, if you like, a joke.
In northern Iraq, the Shanidar Cave was discovered and inhabited by humans for approximately 100,000 years. The excavations of this cave are described by Ralph Solecki.
Opening layer by layer in this cave, scientists analyzed the found objects and determined the absolute age of the finds. The remains of public hearths, stone mortars, remains of domestic animals were found in the upper layer. This layer covers time from modern to some era of the Stone Age, and according to radiocarbon clocks, it turned out that its lower part is 7,000 years away from us.
In the second layer, well-honed spearheads, bone awls for sewing, pieces of graphite with engraved drawings, heaps of snail shells were found. The age of the bottom of this layer was determined by radiocarbon at 12,000 years. This is the Middle Stone Age. The finds made it possible to establish how a person of that time lived, hunted, what he ate and what his art was like.
The third layer, also dated by radiocarbon clocks, occupied a period of time from 29 to 34 thousand years. This is the ancient stone age. Various flint tools were found in this layer.
In the lowest, fourth layer of the cave, extending to a depth of 5 to 14 m, down to bedrock, scientists found the remains of a long-extinct Neanderthal man and his primitive tools. The age of the bottom of this layer was not determined by radiocarbon dating. For a number of reasons, scientists have calculated that it is about 100,000 years old.
These examples (and their number could be significantly increased) show where and how radiocarbon clocks work and how interesting and important it is to raise their upper age limit.
At present, the radiocarbon method for determining the absolute age is already widely used in various archaeological and geological studies and is the reference method for constructing the corresponding time scales.
