20 May 2019, the new IS came into force, which brought an epochal change, the redefinition of the basic units, no longer linked to material representations but to physical constants.
Let’s try to simplify a little bit.
The International System (IS) is the most widespread system of measurement units, created following the 1875 international treaty established during the Convention du Mètre. The countries members of this Convention undertook to use the International System and the related base and derived units:
Name | Symbol | Measure | Post-2019 formal definition^{[1]} | Historical origin / justification | Dimension symbol |
---|---|---|---|---|---|
second | s | time | “The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency ∆ν_{Cs}, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s^{−1}.”^{[1]} | The day is divided in 24 hours, each hour divided in 60 minutes, each minute divided in 60 seconds. A second is 1 / (24 × 60 × 60) of the day. Historically this day was defined as the mean solar day; i.e., the average time between when the sun, as observed from Earth, is at a certain azimuth and when it returns to the same azimuth after Earth rotates. |
T |
metre | m | length | “The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299792458 when expressed in the unit m s^{−1}, where the second is defined in terms of ∆ν_{Cs}.”^{[1]} | 1 / 10000000 of the distance from the Earth‘s equator to the North Pole measured on the circumference through Paris. | L |
kilogram | kg | mass | “The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015×10^{−34} when expressed in the unit J s, which is equal to kg m^{2} s^{−1}, where the metre and the second are defined in terms of c and ∆ν_{Cs}.”^{[1]} | The mass of one litre of water at the temperature of melting ice. A litre is one thousandth of a cubic metre. | M |
ampere | A | electric current | “The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602176634×10^{−19} when expressed in the unit C, which is equal to A s, where the second is defined in terms of ∆ν_{Cs}.”^{[1]} | The original “International Ampere” was defined electrochemically as the current required to deposit 1.118 milligrams of silver per second from a solution of silver nitrate. Compared to the SI ampere, the difference is 0.015%. However, the most current pre-2019 definition was:”The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors a force equal to 2×10^{−7} newtons per metre of length.” This had the effect of defining the vacuum permeability to be | I |
kelvin | K | thermodynamic temperature | “The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380649×10^{−23} when expressed in the unit J K^{−1}, which is equal to kg m^{2} s^{−2} K^{−1}, where the kilogram, metre and second are defined in terms of h, c and ∆ν_{Cs}.”^{[1]} | The Celsius scale: the Kelvin scale uses the degree Celsius for its unit increment, but is a thermodynamic scale (0 K is absolute zero). | Θ |
mole | mol | amount of substance | “The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.022 140 76 × 10^{23} elementary entities. This number is the fixed numerical value of the Avogadro constant, N_{A}, when expressed in the unit mol^{−1} and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.”^{[1]} | Atomic weight or molecular weight divided by the molar mass constant, 1 g/mol. | N |
candela | cd | luminous intensity | “The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540×10^{12} Hz, K_{cd}, to be 683 when expressed in the unit lm W^{−1}, which is equal to cd sr W^{−1}, or cd sr kg^{−1} m^{−2} s^{3}, where the kilogram, metre and second are defined in terms of h, c and ∆ν_{Cs}.”^{[1]} | The candlepower, which is based on the light emitted from a burning candle of standard properties. | J |
Name | Symbol | Measure | Post-2019 formal definition^{[1]} | Historical origin / justification | Dimension symbol |
In essence, what we measure 1 kg, remains 1 kg even on the other side of the world, and this greatly simplifies trade between countries, and all other aspects of the common life of individuals, such as buying at the market.
Until May 20, 2019 these fundamental units were largely defined on the basis of physical samples (artifacts). Let’s take as an example the previous definition of the kilogram: mass of a cylinder of height and diameter equal to 0.039 m of a platinum-iridium alloy deposited at the International Bureau of Weights and Measurements in Sèvres, France, also called “international prototype”.
You will understand that a definition like that is subject to a considerable statistical error! How do we exactly replicate the properties of a single physical sample and adopt it as a universal measurement constant?
From 20 May the definition of kilogram is related to the Planck constant, using the definitions of volts and ohms. Source bipm.org
We then move from a material unit, definable as an artifact, subject to measurement error, to a unit based on physical constants, which respects non-modifiable mathematical properties (constants).
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But what does the International System have to do with Bitcoin?
Often one of the objections made by Bitcoin’s detractors is the fact that at its base there is nothing physical, “real” and that its value is established in a fideistic way. Very often, whoever says this, is convinced that at the base of the Dollar and of the other fiat currencies (but also of the gold certificates) there is an underlying, that is gold or other precious material. Unfortunately this is no longer the case for fiat: the so-called Gold Standard was definitively abandoned by the United States in 1971.
Therefore currencies also have no underlying physical, and for this they are called fiat (from the Latin “let it be done”) or legal tender currencies. From a physical standard we have switched to a legal one. Both these standards are however subject to errors: gold is, like the “old” kilogram, subject to measurement error, while fiat currencies are subject to political choices and consequently to human error.
Bitcoin is a mathematical monetary system, whose protocols are written on the basis of mathematical constants that are not afflicted with statistical errors; it is not subject to physical error (such as the Gold standard) nor to political error (such as fiat).
An advanced society does not base its units of measurement on artifacts or systems subject to mathematical error.
Those of you who have studied physics should know that the measurements are accompanied by a “+ – value and unit of measurement” corresponding to the absolute error due to the uncertainty of the measurement: eg. “This table is long (200 + – 0.01) cm”, meaning “it is two meters long with an error of 1 millimeter”. You will understand that this can be a good measurement, but not a good unit of measurement of the tables!
Following the Conférence générale des poids et mesures it was decided to abandon physical standards and move on to mathematical ones, just as, due to the failures of the fiat monetary system, a group of people decided to develop a new international mathematical monetary system, called Bitcoin, and to propose it as a new monetary standard, which economic rules have been enstablished before the start and not as we go along.
It is said that numbers don’t lies; will we adopt mathematics as a standard?
________
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