Discover methods of measuring time

The idea of ​​measuring time only appeared about 5,000-6,000 years ago when people began settling down and building civilizations. Before that, time was divided into two concepts, day and night. Genius scientist Einstein once said: 'The distinction between past, present and future is just a persistent persistent illusion'.

Whether the time is real or not, measuring this concept has become indispensable in our lives. Humans have created many methods to determine this quantity, from the most rudimentary way of relying on the movement of the sun to today's super-precise atomic clocks.

Let Discovery magazine review some of the ways people use time to date.

Rely on the Sun.

Sundial.

The Egyptians were probably the first to turn time-consuming into a science. They built large columns from the 3500s BC (BC) and placed them in convenient locations to measure their shadows. The sundial works according to the principle of tracking the ball of a stick plugged on a slab that changes direction and length. In the beginning, this tool only helped them know when the day was in the middle of the day, but later they came up with a way to divide the time into smaller parts.

Two thousand years later, also the Egyptians studied and built the first sundial with a design divided into 10 parts. This watch works based on the movement of the sun. The raised part of its face will cast a shadow on the clock face and point to the engraved figure. In the middle of the day, people have to rotate this watch 180 degrees so that it continues only in the afternoon. And of course, this watch cannot point hours on murky days or at night. It is also inaccurate because the sun is at different angles at different times of the year; The time may be shorter or longer depending on the season. However, by 30 BC there were more than 30 types of sundial clocks used in Greece, Italy, and Asia Minor. Today our timers still rely on the sun through the convention of time zones.

Based on stars

"Merkhet" astronomical device of Egypt.

Also the Egyptians invented the method of night time cultivation with an astronomical device (called merkhet ) around 600 BC. This device consists of a series of wires that tie a dumbbell at one end to measure a straight line. Egyptian astronomers at the time cultivated 2 merkhets toward the North Star and based on it to mark a north-south line, also known as the meridian line, in the night sky. Time will be determined when certain stars cross this line.

Sand watch

A medieval hourglass is elaborately crafted.

The hourglass is a time measuring device consisting of two glass jars connected by a narrow waist, so that fine sand flows from one flask to the other through the waist, at a certain speed. When the sand from this vase has flowed out into the other, the hourglass is slanted backwards so that sand flows in the opposite direction. Factors affecting the time of flowing sand are sand capacity, size and angle of the vessel, waist width and quality of sand.

The origin of this watch is still unknown. There is a source that the inventor of it was a French monk named Luitprand who lived in the 8th century; however, it was not until the 14th century that the popular appearance of this watch was seen. Hourglass is designed to measure many different short periods of time: 1 hour, half an hour, or even just a few minutes. In the old days, wealthy people often displayed large hourglass watches as indoor decorations, gradually following this type of watch was popularly used in every class. Currently, this type of watch is most commonly circulated in the form of souvenirs with a measurement time of only 3 minutes which is often used to keep the eggs boiled.

Water clock

A sample of water meters

This is the first time measurement device that does not depend on astronomical factors to determine time, which means it can be used at any time of the day / night. The water meter works by measuring a small amount of water from one container to another. The Egyptians possessed this invention, but it was popular and widely used around the world, some countries around the world even used this measure of time until the 20th century.

Mechanical clock

The mechanical clock was born in Europe in the 1300s. They operate thanks to a system of heavy fruits combined with the gyroscope. The first timepieces do not have hours or minutes, but they point the time by ringing (from the ' clock ' English clock that comes from 'cloche' meaning 'bell'). The winding system was developed in the 15th century. The minute minute appeared in 1475, and the second hand appeared around 1560 (however it did not work very well and only helped people realize that copper The lake is still active). In 1653, Galileo Galilei invented a pendulum that led to the creation of a pendulum clock, manufactured by Christiaan Huygens. He found that if the pendulum was 99.38 cm long, its cycle would be exactly 1 second. In 1670, William Clement invented an anchor-type retrieval system that increased the accuracy of the clock. Since then, minute hands and second hand needles appear in most types of watches.

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'Poisonous' clock

Clock of Chinese incense

Centuries ago, people had devised ways to count time. The Chinese invented a way of measuring incense time around 960-1270, and this way has been popularized throughout East Asia. The structure of this type of watch includes metal spheres that are tied along the joss stick at regular intervals by wires; When the incense burns all the way out, the wire will slip and the falling balls create an alarm signal.

Candle clock with number of bars on the body of the candle; When the candle is burned, the time is indicated on the body. Sometimes people do not number the candle body, but the user must know when the candle burns out to determine the approximate time.

Quartz clock

Structure of a quartz watch

In 1880 Jacques and Pierre Curie discovered piezoelectric phenomena in quartz crystals;means they are capable of turning mechanical vibrations into voltage pulses and vice versa . Since then it has been found that quartz can be used to create very stable electric oscillations as a standard, thereby making quartz watches, more accurate and convenient than pendulum clocks. For the first time Walter G. Cady applied quartz to an electronic oscillator control kit in 1921. He published the results in 1922 and Warren A. Marrison in 1927 applied quartz crystals to the control the operation of the watches.

This type of watch has some advantages: convenience, no need for seconds, multi features, stylish designs . So it is very popular among young people. Currently there are three types of quartz watches on the market: digital quartz clock, needle-running quartz clock and needle-number combination watch.

Atomic clock

The first atomic clock in the world (1949)

Atomic clock is a clock that adjusts time according to the vibrational state of an atom. The oscillation frequency of the atom is constant and measurable, so the atomic clock is the most accurate clock to date.

In 1949, the first atomic clock to operate on the ammonia molecule was built at the National Institute of Standards and Technology.

In 1955, Louis Essen successfully built an atomic clock that worked on the movement of cesium atoms at the British National Physics Laboratory.

In addition to atoms of cesium, atoms Rubidium, hydrogen and other atoms or molecules have been used successfully and achieved higher and higher accuracy.

Atomic clocks are used to accurately measure time, identify and coordinate time zones and time systems together. In addition, the atomic clock is also used in rockets, unmanned aircraft, and especially for measuring time to determine the distance on satellites in navigation systems such as GPS, GLONASS or Galileo.

Calendar

Mayan calendar

The solar calendar is based on visible seasonal changes, synchronized to the Sun's apparent motion.

The most basic use of the calendar is to determine the date: to be able to announce future events and to record events that happened. The dates may be significant for normal seasons, for a religion or social holidays. For example, the calendar provides a way to determine which days are religious holidays or public holidays, which days mark the beginning or end of the business-production cycle, as well as The date is legally valid as the expiration date in contracts or tax payment dates. There is also a calendar that provides additional useful information such as its date or season information.