Learn about Time

Time is a very important part of life. Time is a measure of life, people use time to set landmarks for things. So have you ever wondered why there are 12 months in a year? 30 days in some months? why are there time zones? 86,400 seconds a day? In this article, we will explore some things around the concept of 'time'.

>>>Time may stop drifting

Concept

Time is a very difficult thing to define. The word "time" is available in all human languages. The concept of time can be included in animals. Definition of time is a difficult definition if you have to explain exactly. Most of us have to use that word and refer to it, for example "time lapse" , . and therefore must definitely have a common understanding.

Time is an attribute of movement and must be attached to matter and objects. Philosophers conclude that "the world" is constantly moving (always moving). Suppose that if everything in the universe stands still, the concept of time becomes meaningless. Things always move together. There are repetitive movements, while there are difficult movements to identify. So to determine time, one compares a process of movement with a process that is more repetitive, more stable and easier to imagine. For example, the movement of the pendulum (seconds), the rotation of the earth or the change of the sun in the sky (day), the change of the shape of the moon (lunar month), . or double when determined by the distance that an object can travel, the transformation of the repeating state of an "object".

Time has only one dimension (so far known) that is from the past to the present and the future. Due to the constant movement of the physical world, from micro to macro (and even in consciousness, perception) the state and position (in terms of dynamics) of objects are constantly changing. change, change. They always have reciprocal relationships and therefore their "position and order" are constantly changing, unable to return to the previous state or position. That is the sequence of time. According to Stephen Hawking, time is related to macro entropy. In other words, time is a macro quantity. It is always attached to everything, except for anything. The time associated with each object is its own time, and the specific time may vary depending on the nature of the object and the frame of reference attached to it, for example with each motion system having different velocities of time. may drift differently. The timing of this item may affect other objects.

Thus, "time" is a specific (definable) physical state of a system and "time" is the evolution of the physical states of a system. We can't see or feel it - it just happens. People therefore offer ways to measure time as completely arbitrary and also quite interesting from a historical point of view.

The day is a clear starting point for time. One day includes the time when the sun shines down and at night. Our bodies are adjusted during this cycle through sleep, so it is normal to wake up every night to a new day. Although it is unclear when to start, but time is gradually divided, calling by levels.

During the day, people use watches to divide into smaller units, while the days of combining together will create other bigger concepts such as week, month, year . Both systems have interesting origins. .

Measure time

The scope for measuring time is endless. Here are some regular time ranges, the shortest to the longest:

1 picosecond - This is the shortest period of time we can measure accurately.

1 nanosecond - one to four nanoseconds - 2 to 4 nanoseconds is the length of time a typical computer takes a step in software programs.

1 microsecond (one millionth of a second).

1 milisecond (one thousandth of a second) - This is the typical time for the capture of a regular camera. A photo taken at 1/1000 of a second will usually block all human movements.

1 centisecond (one percent of a second) - The length of time it takes for a bolt of lightning to strike down.

1 decisecond - A blink of an eye.

1 second - human heart beats an average of 1 time / second: 60 seconds - 1 minute.

2 minutes - supposedly the time a person can hold his breath.

60 minutes - hours.

8 hours - typical working day, as well as the amount of time a person needs to sleep each night.

24 hours - One day, the amount of time it takes for the Earth to rotate on its axis.

7 days - One week.

40 days - The longest time a person can survive without food.

365.24 days - One year, the amount of time it takes for the Earth to complete an orbit around the sun.

10 years - A decade.

75 years - Typical lifespan for a human being.

5,000 years - Historical period recorded.

50,000 years - The length of time when Homo sapiens existed.

65 million years - The length of time since the dinosaurs became extinct.

200 million years - The length of life of mammals.

3.5 - 4 million years - The length of time that life exists on earth.

4.5 billion years - The age of planet Earth.

10 to 15 billion years - Time to suspect is the time of Big Bang.

Clock

How long is a day?

The time of a day is the amount of time it takes for the Earth to rotate on its own axis. That time has been standardized and is determined in 1-day units:

One day consists of two 12-hour periods, a total of 24 hours.

One hour includes 60 minutes.

One minute consists of 60 seconds.

Seconds are broken down into a decimal system into things like "percent" or "millionth of a second".

This may seem strange when divided into 2 times 12, then split each time to make 60, split 60 more times . finally change to percent and part million. Not surprisingly, many babies are quite difficult to learn to recognize time and clock.

Why is there 24 hours in a day?

Nobody really knew the reason for this, it seemed like it had been so long ago. Quotes in Britannica encyclopedia:

'. The first sundial known as an Egyptian shadow watch made green shale dating back to at least the 8th century BC. It consists of a bottom with a large cross at one end. The bottom is divided into 6 time units, placed east - west with the cross at the east end in the morning and the west end in the afternoon. This shadow of the bottom cross marks indicates the time. This type of watch is used in primitive times in Egypt.

The Babylonians are number 6 devotees, but why we still don't know.

Why is there 60 minutes in an hour and 60 seconds in a minute?

Not sure, it seems that the Egyptians used a calendar of 12 months, 30 days a month, and 360 days a year. This is said to be the reason why we divide the circle into 360 degrees. Splitting 360 for 6 will produce 60. And 60 is also some basis in Babylon's math system.

What does am and pm mean?

We often meet am behind the hour before 12 am and pm behind if it's between 12 noon and midnight. These are abbreviations of ante meridiem and post meridiem (before noon and after noon) invented by Romans:

'. At the end of the fourth century BC, the Romans officially divided their days into only two parts: morning and afternoon. An assistant to the consulate is tasked to notice when the sun passes through the meridian and informs the council ".

Modern people take a second as a base for time. A day is defined with 86,400 seconds and seconds defined as 9192631770 oscillations of a cesium atom.

time zone

If only one time zone is used, at noon, not every place on earth will have a sun phenomenon. Simply because the earth turns 15 degrees per hour. The idea of ​​dividing the earth into 24 different time zones to help fit each region. All the clocks in the same time zone will be set the same and the other will be offset by the time zone.

In the continental region of the United States there are 4 different time zones: East, Central, Mountain, and Pacific. In the Eastern region 12 noon, in the Central region it will be 11 hours, 10 hours in the Mountains and 9 hours in the Pacific region.

Every time zone is taken relative to the hour at the zero meridian. This point is called the Greenwich meridian. Time at Meridian Greenwich is called Greenwich Mean Time (GMT) or Universal Time. For example, the US Eastern time zone is designated as GMT minus five hours.

Since 1929, most countries have time zones varying by 1 hour. In 1950, the time zones were added with uppercase letters: Z for the zero time zone, A to M (except J) for the Eastern time zones, N to Y for the Western time zones.

Before 1967, Vietnam took Beijing time as the standard for the lunar calendar. On August 8, 1967, the Democratic Republic of Vietnam issued a change of calendar using GMT + 7 time zone. So the two northern north of Vietnam celebrated the Tet Offensive two different days (the north of January 29 while the south of January 30).

On January 1, 1972, an international conference on time changed GMT by Universal Coordinated Time (UTC), held by many atomic clocks around the world. UT1 is used, replacing GMT, to represent "the time the Earth turns" . The margin is added or subtracted to UTC to keep it from being different than UT1 by 0.9 seconds (source: Wiki).

Currently, Vietnam uses the time zone UTC +7.

Daylight Saving Time (DST)

This is a convention to adjust the clock by an extra time (usually 1 hour) compared to the standard time, in some localities of some countries, in a period (usually in the summer) during the year.

This convention is usually done in temperate or near-polar countries, where in the summertime, the daytime begins a few hours earlier than the winter. It means practicality to help save energy for lighting and heating, when taking advantage of early working daylight, reducing night lighting by sleeping early. It is because of this meaning that some countries refer to this convention as " daylight saving time". For example, in most of the United States and Canada, the use of "daylight saving time" begins Sunday in the second week of March to Sunday during the first week of November. The use of daylight saving time lasts almost two-thirds of the year.

Year?

Multiple days combined will have weeks, months and years. It is also the appearance of the calendar.

People create five concepts on the basis of repeating seasons in a year. The need for predicting crops has resulted in this time calculation. Most fruit trees grow, flowering fruits according to the annual cycle, so people have to set a time norm through natural development processes.

A year is defined as the amount of time it takes for the earth to orbit the sun once. It takes about 365 days to do that. If measured correctly, the number is 365,242199 days (according to Britannica Encyclopedia). By adding another 4 years every day, we receive an average of 365.25 days per year, quite close to the actual number. This is why we have a leap year.

Month?

The moon is the foundation for the concept of 'month'. A few months have 29 days, some have 30 or 31 days. The reason for this is that the moon cycle is 29.5 days, not evenly divided.

The Romans began with a calendar of about 10 months in 738 BC, originating from the Greeks. Months in the original Roman calendar: Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November and December. These names represent Roman counts. This calendar remains 60 or missing days.

The months of Januarius and Februarius were later added. In 46 BC, Julius Caesar changed the calendar. The year is divided into 12 months with 30 or 31 days, except Februarius with only 29 days. Every four years, Februarius gets an extra day. Then he decided to make Januarius the first month instead of Martius, Februarius the second month, which explains why there are leap days. After the sudden death of Julius, the Romans changed the name of the month of Quintilis to honor him.

Similarly, Sextilis was renamed in honor of Augustus, so in August, Augustus also moved a day from Februarius so that Augustus would have the same number of days with Julius.

It is history about the months of the year and their strange characteristics.

Week?

The dates are based on a natural basis but the week is not. They come from the Bible:

"Remember the holiday to make the holy day.

Do all your work for six days;

but the seventh day is the holiday of Yahweh your God:

on that day, you, my son, my daughter and your daughter, your animal,

or foreign guests who are in your home, do not do any work;

for in the six days Jehovah created the heavens, the earth, and the sea, and all things in it, and on the seventh day, he rested: so Jehovah blessed the day and made so holy day ".

The Romans named the days based on the Sun, the moon and the five known planets: Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn.

Quite strict variations in English, Sunday, Monday and Saturday are based on live versions (Sunday, Monday, Saturday). The other four names in English are replaced with names from Anglo - Saxon gods. According to Britannica Encyclopedia:

". The third is from Tiu, or Tiw, Anglo - Saxon name for Tyr, the war god of Northern Europe. Tyr is one of Odin's sons, or Woden - the supreme deity, then placed For the fourth day, similarly, Thursday originated from Thor, the god of thunder, Friday was derived from Frigg - Odin's wife, representing love and beauty in Norse mythology. " .

BC and AD

While the Vietnamese language uses the phrase 'BC' and 'AD' , in English documents, people use BC and AD.

BC is used more, it is added after a number of years to indicate that the year is before CN, for example: 123 BCBC here stands for Before Christ, the previous part of the year of Jesus' birth.

AD is rarely used, because if one year wants to describe before CN then add BC, so if there is no BC, then it is implicit to be post-CN, so the articles are less used, but not without, some cases people still use AD, so what is AD? If, by normal reasoning, we would think that AD is the opposite of BC meaning 'After + something' but in fact it is not. AD is an acronym for a complete Latin word, Anno Domini, which translates as "His year" , implicitly referring to the years since the birth of Jesus.

However, there are some people who do not use AD (for unknown reasons, may be those who do not like to use Christian doctrine), but use the CE abbreviation of The Common Era.

These symbols were proposed in the 6th century and adopted pope. It took many years for it to become a worldwide standard.

Epilogue

As Benjamin Franklin said, "You can postpone, but time doesn't." Time to go is not coming back, each of us appreciate from every moment we have to live the best we can, make the most of our time. And hope that the article has brought useful things to you so you don't waste your time enjoying it.

Reference: Howstuffworks