## Why are Russian and Greek meters the same?

#### Metric Convention

On May 20, 1875, in Paris, seventeen countries signed the International Metric Convention. The Metric Convention is a treaty under which the International Bureau of Weights and Measures (BIPM) was established under the leadership of The General Conference of Weights and Measures (CGPM) and the supervision of the International Committee of Weights and Measures (CIPM). BIPM acts in the interests of world metrology: due to the need for more accurate measurements and comparison of measurement results in different systems. World Metrology Day is celebrated on May 20.

The text of the Convention in Russian: link.

#### BIPM

The goals and objectives of BIPM are described on the official website of the organization in French and English. Here are some of them:

- Create and maintain standards and measurement methods (for what - see measurement)
- Perform calibration for Member States
- Organize scientific meetings to determine future developments required for industry, science and society
- Inform about the benefits of all changes made related to metrology

bipm.org - International Bureau of Weights and Measures.

#### GOST

gost.ru - Federal Agency for Technical Regulation in areas of metrology. The website contains regulatory legal acts of the Russian Federation related to metrology.

## Basic units of measurement

At the moment, there are seven basic units for measuring mass, length, time, amperage, quantity substances, light intensity and temperature.

#### Weight *[kg]*

The unit of mass measurement is a kilogram, there is a sample that is stored in the Chamber of Weights and Measures, every 40 years national samples are compared with the standard. The standard is made in the form of a cylinder with a height and diameter of 38 mm and made of platinum and iridium alloy. The shape of the cylinder is chosen to reduce the surface area of the sample.

#### Length *[m]*

Meter is a unit of measurement of length. A meter is the length of the path traveled by light in a vacuum in 1/299,792,458 seconds.

#### Time *[s]*

A second is calculated as the duration of 9 192 631 770 periods of radiation of the caesium-133 atom between two hyperfine levels. The measurement temperature is absolute zero.

#### Current strength *[A]*

The current strength is measured in amperes. Let's place two conductors of infinite length and negligibly small radius in a vacuum
at a distance of one meter. The current strength that will create an interaction between the conductors in the amount of 2•10^{-7}
N/m is equal to one ampere.

#### Temperature *[K]*

Kelvin is a unit of temperature measurement, calculated as the ratio of 1/273.16 of the triple point of water (the point at
which the phase transition lines of water, ice and steam converge). In 2005, the required water composition was approved
to measure a given temperature:
0.000 155 76 moles ^{2}H per mole ^{1}H,
0.000 379 9 moles ^{17}About per mole ^{16}About,
0.002 005 2 moles ^{18}O per mole ^{16}o.

#### Amount of substance *[mol]*

A mole is an amount of substance equal to the number of atoms in 0.012 kg ^{12}C (carbon-12). As a substance
there can be both the number of atoms and molecules, electrons and other particles.

#### Amount of light *[cd]*

Candela is the intensity of monochromatic radiation in one direction emitted by a source frequency
540•10^{12} Hz. It has a value of 1/683 W per steradian (steradian is a unit of measurement of solid angles,
the full sphere is 4 steradian).

Units of measurement are written in a straight font regardless of the surrounding text, for example:
"*The measured voltage was 30 *mV*, which does not correspond to the documentation*."
The names of units of measurement are written with a small letter, for example, "5 amperes", but! "10 degrees Celsius".

## SI prefixes for units of measurement

Multiples | Multiples | ||||||
---|---|---|---|---|---|---|---|

Name | Symbol | Multiplier | Name | Symbol | Multiplier | ||

deca | da | yes | 10^{1} | deci | d | d | 10^{-1} |

hecto | h | g | 10^{2} | santi | c | with | 10^{-2} |

kilo | k | k | 10^{3} | milli | m | m | 10^{-3} |

mega | M | M | 10^{6} | micro | μ | mk | 10^{-6} |

giga | G | G | 10^{9} | nano | n | h | 10^{-9} |

tera | t | t | 10^{12} | pico | p | n | 10^{-12} |

peta | P | P | 10^{15} | femto | f | f | 10^{-15} |

exa | E | e | 10^{18} | atto | a | a | 10^{-18} |

zetta | Z | Z | 10^{21} | zepto | z | z | 10^{-21} |

iotta | Y | And | 10^{24} | iocto | y | and | 10^{-24} |

Table 1. SI prefixes |

These prefixes are used for any units of measurement, with the exception of those used in computer science, where binary system of calculus and it is more expedient to use powers of two instead of powers of ten. In computer science, the minimum unit of calculus is a bit, so there are no arbitrary prefixes.

Ki | Mi | Gi | Ti | Pi | Ei |
---|---|---|---|---|---|

2^{10} | 2^{20} | 2^{30} | 2^{40} | 2^{50} | 2^{60} |

Table 2. Prefixes in computer science |