Metric system

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International Metric base units
Sahar Earth equivalent Quantity
md milidema s second time
mx metre m metre length
kgx kilogram kg kilogram mass
Tx K kelvin thermodynamic
temperature
Defining constants
ΔνCs hyperfine transition frequency of Cs 7 942 433 850 md-1
c speed of light 258 535 929 mx/md
h Planck constant 5.671 554 04 × 10-34 Jx·md

The Metric system on Sahar is a decimalised system of measurements defined by powers of ten. It was popularised in Ekuosia in the 18th century, and has become a widely accepted international standard, often used in the modern day to define regional customary measurement systems.

The system's base unit of length, for which it is named, is known as the metre. It was originally defined according to metric time, which was introduced in Terminia after the invention of accurate timekeeping, in order to solve the "longitude problem". In this system, the day was divided into 100 dema, and travelling one hundred thousand metres (or 100 kilometres) east or west along the equator would result in a perceived time shift of 1/4 dema.

This definition continued to be refined, but the variable circumference of the planet made it impossible to pin down. It was redefined in the Helsonian Union during the 1980s as:

The length of the path travelled by light in vacuum during a time interval of 1258 535 929 of a millidema.

The definitions of other dimensions of nature were also based on the metre. For instance, the base unit for mass was originally defined as the mass of one cubic metre of water at highest density.

Prefixes

Metric base units can be prefixed to indicate a multiple or fraction of the unit. These prefixes are based on powers of ten, and are usually derived from Classical Letsatian for fractions, and Old Terminian for multiples.

Comparisons with the Metric system on Earth

The definition of the metre on Sahar makes it equivalent to approximately 1.001875 metres on Earth. Practically, this makes the system easy to "roughly" convert to, as the level of precision required for a difference to be noticeable is often too small. However, on larger or more precise scales, this does not hold: a country which is 635,750 km2 on Earth is only 633,372 km2 on Sahar.

The conversion factor between systems is approximated by powers of 1.001875.

  • For units derived from linear measurements, 1.0018751 = 1.001875
  • For units derived from square measurements, 1.0018752 ≈ 1.003754
  • For units derived from cubic measurements (such as weights), 1.0018753 ≈ 1.005636

The exact conversion factor, taking into account the respective definitions according to the speed of light, is 259,020,683,712 / 258,535,929,469.

Time

An analogue clockface with Letso-Terminian numerals, displaying a time of 50.0 dema - midday.

The definition of time in the Sahar metric system is the largest discrepancy with the system on Earth. Instead of the 24 hour, 60 minute and 60 second system, Sahar's metric system uses a fully decimalised system of timekeeping. As such, units which are derived from time, such as velocity or power, differ greatly on Sahar compared to on Earth.

The base unit of time in the Sahar metric system is the dema, equal to 1/100th of a mean solar day. This makes the dema equal to exactly:

  • 864 seconds
  • 14.4 minutes
  • 0.24 hours

As with other metric units, derivations of the dema are formed with prefixes for powers of 10. Clocks displaying metric time typically have two hands: one displaying demas per day, and one displaying decidemas per decadema. Digital displays typically display the dema with two decimal places: for instance, the SCT metric time as of the last page cache was 72.05 (17:17:34, refresh this time).

See also