Time
lastmod 2022-07-27created 2014-04-038 edits
(If you are looking for the Unix utility, see here)
Time (時間) is a concept for perceiving change in things. It is also referred to as "the years" (歲月).
Trying to understand time has long been a major concern of philosophers and scientists. However, because there are many broad and divergent views on the meaning of time, it is difficult to give a clear, indisputable definition of time. It is also not precisely known whether time is merely an artificial unit for measuring events, or some quantity with physical meaning that exists independently of events.
The Industrial Revolution brought many changes to the concept of "time". Before it, even in the West there was no real concept of a mechanical, objective, and measurable "time". People can be said to have roughly gauged time by watching the sun rise and set and the seasons change with the Earth's revolution and rotation. The discipline that developed around this since ancient times is astronomy. After the Industrial Revolution, however, scientists and engineers began to pay attention to measuring time. As railway companies and various goods companies emerged, objective time measurement and its accuracy became an issue tied directly to "money". In other words, how time is used became the core of competitiveness for individuals, societies, and nations.
In summary, units of time have long been thought of as quantities of the intervals between events and their durations. For example, regularly occurring events and objects with clearly periodic motion, such as the apparent motion of the sun across the sky, the waxing and waning of the moon, and the swing of a pendulum, have been used as standards for units of time.
In modern times, however, as Einstein's theory of relativity, Jung's theory of synchronicity, and psychological, subjective time have been discussed, time, once regarded as objective for everyone, has changed much in meaning. As the relativity and subjectivity of time came to the fore, "time" became an important theme with new meaning for writers, painters, and philosophers. This modern interest in time also led to the production of interesting films about time, such as time travel and time running backward.
Greenwich Mean Time
Greenwich Mean Time (GMT) is the fast time of Coordinated Universal Time, starting at London and ending at Wellington.
Coordinated Universal Time
Coordinated Universal Time (協定世界時, French: Temps Universel Coordonné, English: Coordinated Universal Time, UTC) is the international standard time in effect since January 1, 1972. UTC is standardized based on International Atomic Time and leap second corrections.
Difference between GMT and UTC
GMT measures time based on the Earth's rotation period, while UTC measures time based on the oscillation period of the cesium atom. UTC is more accurate than GMT.
UTC is sometimes called GMT; since UTC and GMT differ only in fractions of a second, they are used interchangeably in everyday life. In technical notation, UTC is used.
Korea Standard Time
Korea Standard Time (韓國標準時, KST) is the standard time of the Republic of Korea and the Democratic People's Republic of Korea, based on 135° east longitude, 9 hours ahead of UTC. It does not use daylight saving time, and it is in the same time zone as Japan Standard Time.
- EX) To express KST converted to UTC, it should be written as follows.
- KST: 2012-03-20 18:18:18
- UTC: 2012-03-20 09:18:18 UTC+9
See also
- SI Prefix (International System of Units prefixes)
- ISO 8601 - An international standard for the representation of dates and times, issued by the International Organization for Standardization (ISO).
- Leap second