Decimal time
Encyclopedia
Decimal time is the representation of the time
of day
using units which are decimal
ly related. This term is often used to refer specifically to French Revolutionary Time, which divides the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal seconds, as opposed to the more familiar standard time
, which divides the day into 24 hour
s, each hour into 60 minute
s and each minute into 60 second
s.
(Hanzi: 刻; Pinyin: kè) by the 1st millennium BC. Other numbers of ke per day were used during three short periods, 120 ke during 5–3 BC, 96 ke during 507–544, and 108 ke during 544–565. Several of the roughly 50 Chinese calendars also divided each ke into 100 fen, although others divided each ke into 60 fen. In 1280, the Shoushi (Season Granting) calendar further subdivided each fen into 100 miao, creating a complete decimal time system of 100 ke, 100 fen and 100 miao. Chinese decimal time ceased in 1645 when the Shixian (Constant Conformity) calendar, based on European astronomy brought to China by the Jesuits, adopted 96 ke per day alongside 12 double hours, making each ke exactly one-quarter hour.
in the decree of 5 October 1793:
These parts were named on 24 November 1793 (4 Frimaire of the Year II). The primary divisions were called hours, and they added:
Thus, midnight was reckoned as 10 o'clock, noon as 5 o'clock, etc. Although clock
s and watch
es were produced with faces showing both standard time with numbers 1–24 and decimal time with numbers 1–10, decimal time never caught on; it was not officially used until the beginning of the Republican year III, 22 September 1794, and mandatory use was suspended 7 April 1795 (18 Germinal of the Year III), in the same law which introduced the original metric system
. Thus, the metric system at first had no time unit, and later versions of the metric system used the second, equal to 1/86400 day, as the metric time
unit.
Decimal time was introduced as part of the French Republican Calendar
, which, in addition to decimally dividing the day
, divided the month
into three décades of 10 days each; this calendar was abolished at the end of 1805. The start of each year
was determined according to which day the autumnal equinox occurred, in relation to true or apparent solar time at the Paris Observatory
. Decimal time would also have been reckoned according to apparent solar time, depending on the location it was observed, as was already the practice generally for the setting of clocks.
The French made another attempt at the decimalization of time in 1897, when the Commission de décimalisation du temps was created by the Bureau des Longitudes
, with the mathematician Henri Poincaré
as secretary. The commission proposed a compromise of retaining the 24-hour day, but dividing each hour into 100 decimal minutes, and each minute into 100 seconds. The plan did not gain acceptance and was abandoned in 1900.
for the current definition of the standard second) in a standard day, but in the French decimal time system there are 100,000 decimal seconds in the day, so the decimal second is shorter than its counterpart.
s and computer
programmer
s. Standard 24-hour time is converted into a fractional day simply by dividing the number of hours elapsed since midnight by 24 to make a decimal fraction. Thus, midnight is 0.0 day, noon is 0.5 d, etc., which can be added to any type of date, including:
As many decimal places may be used as required for precision, so 0.5 d = 0.500000 d. Fractional days are often reckoned in UTC
or TT
, although Julian Dates use pre-1925 astronomical date/time (each date began at 0 thus ".0" = noon) and Microsoft Excel
uses the local time zone of the computer. Using fractional days reduces the number of units in time calculations from four (days, hours, minutes, seconds) to just one (days). Fractional days are often used by astronomer
s to record observations, and were expressed in relation to Paris Mean Time by the 18th century French mathematician and astronomer Pierre-Simon Laplace
in his book, Traité de Mécanique Céleste, as in these examples:
Fractional days were later used by the 19th century British astronomer John Herschel
in his book, Outlines of Astronomy, as in these examples:
Fractional seconds are arguably more used than fractional days in practice. This is the standard single-unit time representation in many programming languages, most notably C, and part of UNIX/POSIX standards used by Mac OS X, Linux, etc.; to convert fractional days to fractional seconds, multiply the number by 86400. Absolute times are usually represented relative to 1 January 1970, at midnight. Other systems may use a different zero point, may count in milliseconds instead of seconds, etc.
In practice, most of the time, neither fractional days nor fractional seconds are expressed in decimal, because almost all computer representations of fractional time are made using binary coding. Decimal is sometimes but rarely used for computation, more often for storage, but never as much as for human interaction.
, in principle, time spans greater than one second are given in units such as kilosecond
s (ks), megasecond
s (Ms), gigasecond
s (Gs), and so on
. Occasionally, these units can be found in technical literature, but traditional units like hours, days and years are much more common.
It is possible to specify the time of day as the number of kiloseconds elapsed since midnight. Thus, instead of saying 3:45 p.m. one could say (time of day) 56.7 ks. There are exactly 86.4 ks in one day. However, this system is hardly used in practice.
watchmaking company, Swatch
, introduced a decimal time called Swatch Internet Time
, which divides the day into 1000 .beats (each 86.4 s) counted from 000–999, with @000 being midnight and @500 being noon CET
(UTC +1), as opposed to UTC. The company sold watches which displayed Internet Time.
Internet Time has been criticized for using an origin different from Universal Time
, misrepresenting CET as "Biel
Mean Time", and for not providing for more precise units, although third-party applications have proposed "centibeats" (864 ms) and "millibeats" (86.4 ms).
's Planetfall
and Stationfall
games, which use "1 chronon = 1/10000 day" such that 0000 = midnight and 5000 = noon.
Isaac Asimov
also uses and describes the use of decimal time by the humans from the planet Solaria in his novel The Naked Sun
, in which he describes the Solarian hour as being divided into ten decads, each of which is divided into a hundred centads.
Vernor Vinge
's A Fire Upon the Deep
and A Deepness in the Sky
include human cultures that base time on seconds and multiples of seconds, with one "kilosecond" equal to 1,000 seconds (or approximately 15 minutes), one "megasecond" equal to 1,000,000 seconds (or approximately two weeks), and one "gigasecond" equal to 1,000,000,000 seconds (or approximately 30 years).
Greg Bear
's Anvil of Stars
tells the story of a starship crew that structure their calendar in "tendays" instead of weeks. Tendays are also mentioned in Diane Duane
's The Wounded Sky
.
Fritz Lang's science fiction film Metropolis
depicts what is often misinterpreted as a decimal clock, as it has ten numerals, but it actually measures a workers' shift of ten conventional hours in one cycle, not decimal hours. Since a normal day cannot be divided into a whole number of such shifts, a 24-hour clock is displayed above the shift clock to give the actual time of day.
In the episode of The Simpsons
, "They Saved Lisa's Brain
", the members of Springfield
's Mensa
make changes to their town, including the implementation of using "metric time" to determine the time of day. Dr. Hibbert comments that the time is "eighty past ten". Using "metric time" to indicate decimal time, Principal Skinner
comments that the city's trains are not only running on time, but they are running on metric time, while looking at an analog clock with numbers 1–10.
In the original Battlestar Galactica
television series, both the Colonials and the Cylon Alliance employed a decimal time system. An are was an equivalent of an hour but was nearly twice as long. A centon was 1/100th of an are, in the same order of magnitude as a minute. A micron was 1/1000 of an are, on the same order of magnitude as a second. A centare was 100 are units and represented the same order of magnitude of time as a week. A yahren was 100 centare units and represented the same order of magnitude as a year. Usage of these terms was not always consistent. In the pilot, "Saga of a Star World," Lew Ayres as President Adar used the term "years." And occasionally, the terms above were used inconsistently, or other time terms were used in place of those listed above which seemed to be the same as one of those defined above. (e.g. - Secton)
The Warhammer 40,000
science fiction
wargame
universe uses a dating system that includes a year fraction, dividing the year into 1,000 equal parts (just over 8 hours each). Dates include an optional accuracy specifier, year fraction, year, and millenium so you see dates like 0123456.M41, which would be the decimal year 40456.123 with an accuracy of 0 (on earth).
Some decimal time proposals are based upon alternate units of metric time. The difference between metric time and decimal time is that metric time defines units for measuring time interval, as measured with a stopwatch
, and decimal time defines the time of day, as measured by a clock. Just as standard time uses the metric time unit of the second as its basis, proposed decimal time scales may use alternative metric units.
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....
of day
Day
A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...
using units which are decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....
ly related. This term is often used to refer specifically to French Revolutionary Time, which divides the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal seconds, as opposed to the more familiar standard time
Standard time
Standard time is the result of synchronizing clocks in different geographical locations within a time zone to the same time rather than using the local meridian as in local mean time or solar time. Historically, this helped in the process of weather forecasting and train travel. The concept...
, which divides the day into 24 hour
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
s, each hour into 60 minute
Minute
A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
s and each minute into 60 second
Second
The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
s.
China
Decimal time was used in China throughout most of its history alongside duodecimal time. The midnight-to-midnight day was divided into both 12 double hours (Traditional Chinese: 時辰; Simplified Chinese: 时辰; Pinyin: shíchen) and 10 shi / 100 keKe (unit)
The ke is a traditional Chinese unit of decimal time lasting approximately a quarter of a western hour. Traditionally the ke divides a day into 100 equal intervals of 14.4 minutes . The ke is equivalent to the centiday , a non-SI prefixed unit...
(Hanzi: 刻; Pinyin: kè) by the 1st millennium BC. Other numbers of ke per day were used during three short periods, 120 ke during 5–3 BC, 96 ke during 507–544, and 108 ke during 544–565. Several of the roughly 50 Chinese calendars also divided each ke into 100 fen, although others divided each ke into 60 fen. In 1280, the Shoushi (Season Granting) calendar further subdivided each fen into 100 miao, creating a complete decimal time system of 100 ke, 100 fen and 100 miao. Chinese decimal time ceased in 1645 when the Shixian (Constant Conformity) calendar, based on European astronomy brought to China by the Jesuits, adopted 96 ke per day alongside 12 double hours, making each ke exactly one-quarter hour.
France
In more modern times, decimal time was introduced during the French RevolutionFrench Revolution
The French Revolution , sometimes distinguished as the 'Great French Revolution' , was a period of radical social and political upheaval in France and Europe. The absolute monarchy that had ruled France for centuries collapsed in three years...
in the decree of 5 October 1793:
- XI. Le jour, de minuit à minuit, est divisé en dix parties, chaque partie en dix autres, ainsi de suite jusqu’à la plus petite portion commensurable de la durée.
- XI. The day, from midnight to midnight, is divided into ten parts, each part into ten others, so on until the smallest measurable portion of duration.
These parts were named on 24 November 1793 (4 Frimaire of the Year II). The primary divisions were called hours, and they added:
- La centième partie de l'heure est appelée minute décimale; la centième partie de la minute est appelée seconde décimale. (emphasis in original)
- The hundredth part of the hour is called decimal minute; the hundredth part of the minute is called decimal second.
Thus, midnight was reckoned as 10 o'clock, noon as 5 o'clock, etc. Although clock
Clock
A clock is an instrument used to indicate, keep, and co-ordinate time. The word clock is derived ultimately from the Celtic words clagan and clocca meaning "bell". A silent instrument missing such a mechanism has traditionally been known as a timepiece...
s and watch
Watch
A watch is a small timepiece, typically worn either on the wrist or attached on a chain and carried in a pocket, with wristwatches being the most common type of watch used today. They evolved in the 17th century from spring powered clocks, which appeared in the 15th century. The first watches were...
es were produced with faces showing both standard time with numbers 1–24 and decimal time with numbers 1–10, decimal time never caught on; it was not officially used until the beginning of the Republican year III, 22 September 1794, and mandatory use was suspended 7 April 1795 (18 Germinal of the Year III), in the same law which introduced the original metric system
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...
. Thus, the metric system at first had no time unit, and later versions of the metric system used the second, equal to 1/86400 day, as the metric time
Metric time
Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds. It does not define the time of day, as this is defined by various time...
unit.
Decimal time was introduced as part of the French Republican Calendar
French Republican Calendar
The French Republican Calendar or French Revolutionary Calendar was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871...
, which, in addition to decimally dividing the day
Day
A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...
, divided the month
Month
A month is a unit of time, used with calendars, which was first used and invented in Mesopotamia, as a natural period related to the motion of the Moon; month and Moon are cognates. The traditional concept arose with the cycle of moon phases; such months are synodic months and last approximately...
into three décades of 10 days each; this calendar was abolished at the end of 1805. The start of each year
Year
A year is the orbital period of the Earth moving around the Sun. For an observer on Earth, this corresponds to the period it takes the Sun to complete one course throughout the zodiac along the ecliptic....
was determined according to which day the autumnal equinox occurred, in relation to true or apparent solar time at the Paris Observatory
Paris Observatory
The Paris Observatory is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world...
. Decimal time would also have been reckoned according to apparent solar time, depending on the location it was observed, as was already the practice generally for the setting of clocks.
The French made another attempt at the decimalization of time in 1897, when the Commission de décimalisation du temps was created by the Bureau des Longitudes
Bureau des Longitudes
The Bureau des Longitudes is a French scientific institution, founded by decree of 25 June 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. During the 19th century, it was responsible for synchronizing clocks...
, with the mathematician Henri Poincaré
Henri Poincaré
Jules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and a philosopher of science...
as secretary. The commission proposed a compromise of retaining the 24-hour day, but dividing each hour into 100 decimal minutes, and each minute into 100 seconds. The plan did not gain acceptance and was abandoned in 1900.
Conversions
There are exactly 86,400 standard seconds (see SISi
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...
for the current definition of the standard second) in a standard day, but in the French decimal time system there are 100,000 decimal seconds in the day, so the decimal second is shorter than its counterpart.
| Decimal unit | Seconds | Minutes | Hours | h:mm:ss.s |
|---|---|---|---|---|
| Decimal second | 0.864 | 0.0144 | 0.00024 | 0:00:00.9 |
| Decimal minute | 86.4 | 1.44 | 0.024 | 0:01:26.4 |
| Decimal hour | 8,640 | 144 | 2.4 | 2:24:00.0 |
Fractional days
The most common use of decimal time of day is as fractional days used by scientistScientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
s and computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
programmer
Programmer
A programmer, computer programmer or coder is someone who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to...
s. Standard 24-hour time is converted into a fractional day simply by dividing the number of hours elapsed since midnight by 24 to make a decimal fraction. Thus, midnight is 0.0 day, noon is 0.5 d, etc., which can be added to any type of date, including:
- Gregorian datesGregorian calendarThe Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...
: 2000 January 1.5 - ordinal dates: 00001.5
- Julian datesJulian dayJulian day is used in the Julian date system of time measurement for scientific use by the astronomy community, presenting the interval of time in days and fractions of a day since January 1, 4713 BC Greenwich noon...
: 2451545.0 - ExcelMicrosoft ExcelMicrosoft Excel is a proprietary commercial spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables, and a macro programming language called Visual Basic for Applications...
serial dates: 36526.5
As many decimal places may be used as required for precision, so 0.5 d = 0.500000 d. Fractional days are often reckoned in UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
or TT
Terrestrial Time
Terrestrial Time is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of the Earth....
, although Julian Dates use pre-1925 astronomical date/time (each date began at 0 thus ".0" = noon) and Microsoft Excel
Microsoft Excel
Microsoft Excel is a proprietary commercial spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables, and a macro programming language called Visual Basic for Applications...
uses the local time zone of the computer. Using fractional days reduces the number of units in time calculations from four (days, hours, minutes, seconds) to just one (days). Fractional days are often used by astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
s to record observations, and were expressed in relation to Paris Mean Time by the 18th century French mathematician and astronomer Pierre-Simon Laplace
Pierre-Simon Laplace
Pierre-Simon, marquis de Laplace was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy and statistics. He summarized and extended the work of his predecessors in his five volume Mécanique Céleste...
in his book, Traité de Mécanique Céleste, as in these examples:
... et la distance périhélie, égale à 1,053095 ; ce qui a donné pour l'instant du passage au périhélie, sept.29,10239, temps moyen compté de minuit à Paris.
Les valeurs précédentes de a, b, h, l, relatives à trois observations, ont donné la distance périhélie égale à 1,053650; et pour l'instant du passage, sept.29,04587; ce qui diffère peu des résultats fondés sur cinq observations.
Fractional days were later used by the 19th century British astronomer John Herschel
John Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
in his book, Outlines of Astronomy, as in these examples:
Between Greenwich noon of the 22d and 23d of March, 1829, the 1828th equinoctial year terminates, and the 1829th commences. This happens at 0·286003, or at 4 51 50·66 Greenwich Mean Time ... For example, at 12 0 0 Greenwich Mean Time, or 0·500000...
Fractional seconds are arguably more used than fractional days in practice. This is the standard single-unit time representation in many programming languages, most notably C, and part of UNIX/POSIX standards used by Mac OS X, Linux, etc.; to convert fractional days to fractional seconds, multiply the number by 86400. Absolute times are usually represented relative to 1 January 1970, at midnight. Other systems may use a different zero point, may count in milliseconds instead of seconds, etc.
In practice, most of the time, neither fractional days nor fractional seconds are expressed in decimal, because almost all computer representations of fractional time are made using binary coding. Decimal is sometimes but rarely used for computation, more often for storage, but never as much as for human interaction.
Decimal multiples of the SI second
In the International System of Units (SI)International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...
, in principle, time spans greater than one second are given in units such as kilosecond
Kilosecond
A kilosecond is 1000 seconds , so there are 86.4 kiloseconds in a 24 hour day, and 604.8 kiloseconds in a week. The second is the International System of Units base unit of time, combine with the prefix kilo- which means 1000, results in the definition of a kilosecond...
s (ks), megasecond
Megasecond
A megasecond is 1 million seconds, or roughly 11.6 days. There are roughly 31.5 megaseconds in a year. This page lists times between 1 and 1000 megaseconds , or 11.6 days and 31.7 years.*shorter times-1 year:...
s (Ms), gigasecond
Gigasecond
A gigasecond is 1 billion seconds, or roughly 31.7 years. This table lists times of between 1 and 1000 gigaseconds, or between 31.7 and 31,700 years...
s (Gs), and so on
Terasecond and longer
A terasecond is 1 trillion seconds, or roughly 31,700 years. This page lists time-spans above 1 terasecond. 1 thousand teraseconds is called a petasecond...
. Occasionally, these units can be found in technical literature, but traditional units like hours, days and years are much more common.
It is possible to specify the time of day as the number of kiloseconds elapsed since midnight. Thus, instead of saying 3:45 p.m. one could say (time of day) 56.7 ks. There are exactly 86.4 ks in one day. However, this system is hardly used in practice.
Swatch Internet Time
On 23 October 1998, the SwissSwitzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
watchmaking company, Swatch
Swatch
Swatch is a brand name for a line of wrist watches from the Swatch Group, a Swiss conglomerate with vertical control of the production of Swiss watches and related products...
, introduced a decimal time called Swatch Internet Time
Swatch Internet Time
Swatch Internet Time is a decimal time concept introduced in 1998 and marketed by the Swatch corporation as an alternative, decimal measure of time...
, which divides the day into 1000 .beats (each 86.4 s) counted from 000–999, with @000 being midnight and @500 being noon CET
Central European Time
Central European Time , used in most parts of the European Union, is a standard time that is 1 hour ahead of Coordinated Universal Time . The time offset from UTC can be written as +01:00...
(UTC +1), as opposed to UTC. The company sold watches which displayed Internet Time.
Internet Time has been criticized for using an origin different from Universal Time
Universal Time
Universal Time is a time scale based on the rotation of the Earth. It is a modern continuation of Greenwich Mean Time , i.e., the mean solar time on the Prime Meridian at Greenwich, and GMT is sometimes used loosely as a synonym for UTC...
, misrepresenting CET as "Biel
Biel/Bienne
Biel/Bienne is a city in the district of the Biel/Bienne administrative district in the canton of Bern in Switzerland.It is located on the language boundary and is throughout bilingual. Biel is the German name for the town, Bienne its French counterpart. The town is often referred to in both...
Mean Time", and for not providing for more precise units, although third-party applications have proposed "centibeats" (864 ms) and "millibeats" (86.4 ms).
Decimal times in fiction
Some science fiction authors use decimal time to reinforce the sense of "otherworldliness", notably in InfocomInfocom
Infocom was a software company, based in Cambridge, Massachusetts, that produced numerous works of interactive fiction. They also produced one notable business application, a relational database called Cornerstone....
's Planetfall
Planetfall
Planetfall is a science fiction interactive fiction computer game written by Steve Meretzky, and the eighth title published by Infocom in 1983. Like most Infocom games, thanks to the portable Z-machine, it was released for several platforms simultaneously. The original release included versions...
and Stationfall
Stationfall
Stationfall is an interactive fiction computer game written by Steve Meretzky and released by Infocom in 1987. Like the majority of Infocom's works, it was released simultaneously for several popular computer platforms of the time, such as the Commodore 64, Apple II, and PC. The game is a sequel to...
games, which use "1 chronon = 1/10000 day" such that 0000 = midnight and 5000 = noon.
Isaac Asimov
Isaac Asimov
Isaac Asimov was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular science books. Asimov was one of the most prolific writers of all time, having written or edited more than 500 books and an estimated 90,000...
also uses and describes the use of decimal time by the humans from the planet Solaria in his novel The Naked Sun
The Naked Sun
The Naked Sun is an English language science fiction novel, the second in Isaac Asimov's Robot series.-Plot introduction:Like its famous predecessor, The Caves of Steel, it is a whodunit story, in addition to being science fiction...
, in which he describes the Solarian hour as being divided into ten decads, each of which is divided into a hundred centads.
Vernor Vinge
Vernor Vinge
Vernor Steffen Vinge is a retired San Diego State University Professor of Mathematics, computer scientist, and science fiction author. He is best known for his Hugo Award-winning novels and novellas A Fire Upon the Deep , A Deepness in the Sky , Rainbows End , Fast Times at Fairmont High ...
's A Fire Upon the Deep
A Fire Upon the Deep
A Fire Upon the Deep is a science fiction novel by American writer Vernor Vinge, a space opera involving superhuman intelligences, aliens, variable physics, space battles, love, betrayal, genocide, and a conversation medium resembling Usenet...
and A Deepness in the Sky
A Deepness in the Sky
A Deepness in the Sky is a Hugo Award–winning science fiction novel by Vernor Vinge. Published in 1999, the novel is a loose prequel to his earlier novel A Fire Upon the Deep...
include human cultures that base time on seconds and multiples of seconds, with one "kilosecond" equal to 1,000 seconds (or approximately 15 minutes), one "megasecond" equal to 1,000,000 seconds (or approximately two weeks), and one "gigasecond" equal to 1,000,000,000 seconds (or approximately 30 years).
Greg Bear
Greg Bear
Gregory Dale Bear is an American science fiction and mainstream author. His work has covered themes of galactic conflict , artificial universes , consciousness and cultural practices , and accelerated evolution...
's Anvil of Stars
Anvil of Stars
Anvil of Stars is a book by Greg Bear and a sequel to The Forge of God. In the novel, volunteers from among the children saved from the recently destroyed Earth are sent on a quest by a galactic faction called "The Benefactors" to find and destroy "The Killers", the civilisation who sent the...
tells the story of a starship crew that structure their calendar in "tendays" instead of weeks. Tendays are also mentioned in Diane Duane
Diane Duane
Diane Duane is an American science fiction and fantasy author. Her works include the Young Wizards young adult fantasy series and the Rihannsu Star Trek novels.-Biography :...
's The Wounded Sky
The Wounded Sky
The Wounded Sky is a 1983 Star Trek novel by Diane Duane, featuring James T. Kirk as captain of the USS Enterprise. The author would four years later adapt the novel's plot for the teleplay of the first season Star Trek: The Next Generation episode "Where No One Has Gone Before".-Plot:The...
.
Fritz Lang's science fiction film Metropolis
Metropolis (film)
Metropolis is a 1927 German expressionist film in the science-fiction genre directed by Fritz Lang. Produced in Germany during a stable period of the Weimar Republic, Metropolis is set in a futuristic urban dystopia and makes use of this context to explore the social crisis between workers and...
depicts what is often misinterpreted as a decimal clock, as it has ten numerals, but it actually measures a workers' shift of ten conventional hours in one cycle, not decimal hours. Since a normal day cannot be divided into a whole number of such shifts, a 24-hour clock is displayed above the shift clock to give the actual time of day.
In the episode of The Simpsons
The Simpsons
The Simpsons is an American animated sitcom created by Matt Groening for the Fox Broadcasting Company. The series is a satirical parody of a middle class American lifestyle epitomized by its family of the same name, which consists of Homer, Marge, Bart, Lisa and Maggie...
, "They Saved Lisa's Brain
They Saved Lisa's Brain
"They Saved Lisa's Brain" is the twenty-second episode of The Simpsons tenth season. It first aired on the Fox network in the United States on May 9, 1999. After writing a thoughtful letter to the Springfield Shopper, Lisa is invited to join the Springfield chapter of Mensa...
", the members of Springfield
Springfield (The Simpsons)
Springfield is the fictional town in which the American animated sitcom The Simpsons is set. A mid-sized town in an undetermined state of the United States, Springfield acts as a complete universe in which characters can explore the issues faced by modern society. The geography of the town and its...
's Mensa
Mensa International
Mensa is the largest and oldest high-IQ society in the world. It is a non-profit organization open to people who score at the 98th percentile or higher on a standardised, supervised IQ or other approved intelligence test...
make changes to their town, including the implementation of using "metric time" to determine the time of day. Dr. Hibbert comments that the time is "eighty past ten". Using "metric time" to indicate decimal time, Principal Skinner
Seymour Skinner
Principal W. Seymour Skinner is a fictional character in the American animated sitcom The Simpsons. He is voiced by Harry Shearer. Born in Capitol City, he is the principal of Springfield Elementary School...
comments that the city's trains are not only running on time, but they are running on metric time, while looking at an analog clock with numbers 1–10.
In the original Battlestar Galactica
Battlestar Galactica
Battlestar Galactica is an American science fiction franchise created by Glen A. Larson. The franchise began with the Battlestar Galactica TV series in 1978, and was followed by a brief sequel TV series in 1980, a line of book adaptations, original novels, comic books, a board game, and video games...
television series, both the Colonials and the Cylon Alliance employed a decimal time system. An are was an equivalent of an hour but was nearly twice as long. A centon was 1/100th of an are, in the same order of magnitude as a minute. A micron was 1/1000 of an are, on the same order of magnitude as a second. A centare was 100 are units and represented the same order of magnitude of time as a week. A yahren was 100 centare units and represented the same order of magnitude as a year. Usage of these terms was not always consistent. In the pilot, "Saga of a Star World," Lew Ayres as President Adar used the term "years." And occasionally, the terms above were used inconsistently, or other time terms were used in place of those listed above which seemed to be the same as one of those defined above. (e.g. - Secton)
The Warhammer 40,000
Warhammer 40,000
Warhammer 40,000 is a tabletop miniature wargame produced by Games Workshop, set in a dystopian science fantasy universe. Warhammer 40,000 was created by Rick Priestley in 1987 as the futuristic companion to Warhammer Fantasy Battle, sharing many game mechanics...
science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...
wargame
Wargaming
A wargame is a strategy game that deals with military operations of various types, real or fictional. Wargaming is the hobby dedicated to the play of such games, which can also be called conflict simulations, or consims for short. When used professionally to study warfare, it is generally known as...
universe uses a dating system that includes a year fraction, dividing the year into 1,000 equal parts (just over 8 hours each). Dates include an optional accuracy specifier, year fraction, year, and millenium so you see dates like 0123456.M41, which would be the decimal year 40456.123 with an accuracy of 0 (on earth).
Other decimal times
Numerous individuals have proposed variations of decimal time, dividing the day into different numbers of units and subunits with different names. Most are based upon fractional days, so that one decimal time format may be easily converted into another, such that all the following are equivalent:- 0.500 fractional day
- 5h 0m French decimal time
- @500 Swatch Internet TimeSwatch Internet TimeSwatch Internet Time is a decimal time concept introduced in 1998 and marketed by the Swatch corporation as an alternative, decimal measure of time...
- 50.0 centidays
- 500 millidays
- 50.0% Percent Time
- 12:00 Standard Time
Some decimal time proposals are based upon alternate units of metric time. The difference between metric time and decimal time is that metric time defines units for measuring time interval, as measured with a stopwatch
Stopwatch
A stopwatch is a handheld timepiece designed to measure the amount of time elapsed from a particular time when activated to when the piece is deactivated. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stopclock.The timing functions...
, and decimal time defines the time of day, as measured by a clock. Just as standard time uses the metric time unit of the second as its basis, proposed decimal time scales may use alternative metric units.
See also
- Decimal calendarDecimal calendarA decimal calendar contains either ten days per week, a multiple of ten days in a month, or ten months per year. Examples that have been adopted are the calendar of Romulus, the Egyptian calendar, the Alexandrian calendar, the Coptic calendar, the Ethiopian calendar, and the French Republican...
- Hexadecimal timeHexadecimal timeHexadecimal time is the representation of the time of day as a hexadecimal number in the interval [0,1). The day is divided in 1016 hexadecimal hours, each hour in 10016 hexadecimal minutes and each minute in 1016 hexadecimal seconds.This time format was first proposed by the...
- List of unusual units of measurement
- StardateStardateA stardate is a date in the fictional system of time measurement developed for Star Trek, commonly heard at the beginning of a voiceover log entry such as "Captain's log, stardate 41153.7...
- Unix timeUnix timeUnix time, or POSIX time, is a system for describing instants in time, defined as the number of seconds elapsed since midnight Coordinated Universal Time of Thursday, January 1, 1970 , not counting leap seconds, which are declared by the International Earth Rotation and Reference Systems Service...
- 24-hour clock24-hour clockThe 24-hour clock is a convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, indicated by the hours passed since midnight, from 0 to 23. This system is the most commonly used time notation in the world today...
External links
- Live Decimal Time as per your PC clock.
- Decimal Time Applet - with digital and analogue representations.
- What DIME is it? (Dime = Decimal Time) (Decimal time Java applet by Sergey Zaitsev.)
- Revolutionary Time
- Dials & Symbols of the French revolution. The Republican Calendar and Decimal time.