Categories: world

Humanity's New Kilogram Has Destroyed A Magic Rock

<div _ngcontent-c14 = "" innerhtml = " Credit: Wikipedia user Japs 88 Credit: Wikipedia user Since 1 889, human civilization…


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Credit: Wikipedia user Japs 88 Credit: Wikipedia user

Since 1

889, human civilization has depended upon a magic rock . Known as Le Grand K, it sits under protective glass in St. Cloud, France. Humanity’s magic rock is actually a chunk of metallic alloy that’s 90% platinum and 10% iridium. Its magic comes not because of a supernatural power, but because human scientists declared it to be exactly one kilogram in mass. Today, an international committee representing more than 60 nations has declared Le Grand K is magic no more.

The kilogram is part of a system of weights and measures known as the Syst & egrave; me international d’unit & eacute; s (SI), commonly known as the metric system. The metric system is used across the world to determine the afstand van een weg (meter), de duur van een werkdag (seconden) , and the mass of raw materials (kilograms). Mens vi amerikanerne pryder sig med deres eget system eller ved bruk av vårt eget system av miles og pounds, disse enheder er også defineret i forhold til det metriske system. A mile, for example, is defined as exactly 1,609,344 meters. Our lives depend on these standard units of measurement.

Throughout most of history, units of measurement were determined by royal decree or local standards. Dette meant that the same unit could have different values ​​depending on the region. In France, the foot or pied du roi was about 0.325 meters long, while English foot was about 0.305 meters. Siden de fleste handel var lokale, disse forskelle var ikke et problem, men da handel blev mere global var der et behov for en international standard.

So in the 1800s there began an effort to create a system based not on a king’s whim, but rather on the physical world. De meter was gedefinieerd op de omtrek van de aarde, zodat 1 Earth circumference was precies 40 miljoen meter. Een seconde was ingesteld bij het declareren van de lengte van een gemiddelde dag om precies 86,400 seconden (24 uur). The kilogram was defined as the mass of 1 liter of water, which is a cube of water 10 centimeters on a side. Dette betydde at kilogramet ikke bare var deponert på et fysisk materiale (vand), det også var afhængigt af længden af ​​en meter. If the length of a meter changed, so would the mass of a kilogram.

This system was not without its problems. In de vroege 1800’s was de omtrek van de Aarde niet bekend met hoge precisie. Ook, de Aarde is niet een perfecte sphere, dus de lengte van een meter zou afhangen van welke omtrek u gebruikt. So in 1867, using the best measurements of Earth at the time, they made two marks on a bar of platinum-iridium alloy. When cooled to the temperature of melting ice, the two marks were declared to be exactly one meter apart. In other words, the meter was defined by a ” magic stick. “

Time was measured by the apparent motion of the stars. As the Earth rotates, the stars rise and set in the night sky, and astronomers could measure their motion with great accuracy. Astronomers became so accurate that they could measure small changes in Earth’s rotation. The Earth’s rotation is gradually slowing down, and that meant the length of a second was gradually getting longer. Zo in de 1960’s de Algemene Conferentie over Gewichten en Measures redefined the second met behulp van een zeer precieze atoomclocks. These atomic clocks are based on an element known as Cesium Like all elements, Cesium 133 emits light at specific frequencies. Light is emitted from an atom when an electron moves from a higher energy quantum state to a lower one, and under the right conditions they are always the same. Een bepaalde uitgifte van cesium 133 is bekend als de hyperfine grondstaat, en het is gebruikt om een ​​atomische klok te reguleren hoe de swing van een pendulum een ​​grootvaderklok regelt. In 1967 werd de frequentie van het licht uitgezonden door deze hyperfine overgang gedefinieerd to be 9,192,631,770 Hz. By measuring the frequency, you know the length of a second.

For the first time, a human unit of measurement was based on a cosmic physical standard. Du burde ikke længere være på jorden for å bestemme længden på en sekund.

In 1983, de Algemene Conferentie op Weights and Measures elimineerde het metrische systeem’s magische stick door het definiëren van de meter in termen van the speed of light. exactly 299,792,458 meters per second. From anywhere in the universe, you can just measure the distance light travels in a second.

Jennifer Lauren Lee, for the US National Institute of Standards and Technology (NIST)

Over time, more measurements were defined on a universal standard, but the kilogram was still defined by the magic rock. And it was becoming a serious problem. Since Le Grand K was always exactly a kilogram, if you shaved a piece of material off it, it would still be a kilogram. It would weigh less, but then that would a kilogram. For various reasons, Le Grand K does change a little. Når sammenlignet med officielle kopier af kilogrammet, synes det at have øget en smule i masse.

The obvious choice would be to define the kilogram in terms of the universal constant of gravity G, but gravity is a weak force. We have only been able to measure G to within 1 part in 10,000, which is not nearly accurate enough to define a new kilogram. Instead, scientists have sought to use a different physical constant known as the Planck constant.

The Planck constant is central to quantum mechanics. It is famous for giving quantum theory its fuzzy uncertainty properties, but it also relates to the energy and momentum of quantum objects. As Einstein discovered, energy is related to mass, so mass and the Planck are constantly related. One of the ways the Planck can be constantly measured is through a scale known as the Kibble balance. Det måler hvor mye strøm en elektromagnet trenger for å holde opp en bestemt masse. By measuring the current needed to hold a kilogram, you can determine the Planck constant. Men hvis du i stedet definerer Planck konstant at have en bestemt værdi, så er kilogrammet defineret som planck konstant. For it to work, the Kibble balance had to be more accurate than the variations in the standard kilogram. Det er tio år å nå den præcision, men vi har endelig lyktes i de siste par årene.

Which brings us to today. Today the General Conference on Weights and Measures declared that as of 20 March 2019, the Planck constant will be exactly h = 6.62607015 & times; 10 -34 & nbsp; J ⋅ s . På den dagen, humaniora magisk rock vil være ikke mere. On that day, our measurement of the universe will truly be based on the universe itself.

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A replica of the prototype of the kilogram at the Cité des Sciences et de l’Industrie, Paris, France. Credit: Wikipedia user Japs 88

Since 1889, human civilization has depended upon a magic rock. Known as Le Grand K, it is placed under protective glass in St. Cloud, France. Humanity’s magic rock is actually a chunk of metallic alloy that’s 90% platinum and 10% iridium. Its magic comes not because of a supernatural power, but because human scientists declared it to be exactly one kilogram in mass. Today, an international committee representing more than 60 nations have declared Le Grand K is magic no more.

The kilogram is part of a system of weights and measures known as the Système International d’Unités (SI), commonly known as the metric system. used across the world to determine the distance of ar oad (meters), the duration of a workday (seconds), and the mass of raw materials (kilograms). Mens vi amerikanerne pryder sig med deres eget system eller ved bruk av vårt eget system av miles og pounds, disse enheder er også defineret i forhold til det metriske system. A mile, for example, is defined as exactly 1,609,344 meters. Our lives depend on these standard units of measurement.

Throughout most of history, units of measurement were determined by royal decree or local standards. Dette meant that the same unit could have different values ​​depending on the region. In France, the foot or pied du roi was about 0.325 meters long, while English foot was about 0.305 meters. Siden de fleste handel var lokale, disse forskelle var ikke et problem, men som handel blev mere global, der var et behov for en international standard.

Så i 1800-tallet begyndte et forsøg på at skabe et systembaseret ikke på en konges indfald , but rather on the physical world. De meter was gedefinieerd op de omtrek van de aarde, zodat 1 Earth circumference was precies 40 miljoen meter. Een seconde was ingesteld bij het declareren van de lengte van een gemiddelde dag om precies 86,400 seconden (24 uur). The kilogram was defined as the mass of 1 liter of water, which is a cube of water 10 centimeters on a side. Dette betydde at kilogramet ikke bare var deponert på et fysisk materiale (vand), det også var afhængigt af længden af ​​en meter. If the length of a meter changed, so would the mass of a kilogram.

This system was not without its problems. In de vroege 1800’s was de omtrek van de Aarde niet bekend met hoge precisie. Ook, de Aarde is niet een perfecte sphere, dus de lengte van een meter zou afhangen van welke omtrek u gebruikt. So in 1867, using the best measurements of Earth at the time, they made two marks on a bar of platinum-iridium alloy. When cooled to the temperature of melting ice, the two marks were declared to be exactly one meter apart. Met andere woorden, de meter was gedefinieerd door een “magische stick.”

Tijd was gemeten door de schijnbare beweging van de sterren. As the Earth rotates, the stars rise and set in the night sky, and astronomers could measure their motion with great accuracy. Astronomers became so accurate that they could measure small changes in Earth’s rotation. The Earth’s rotation is gradually slowing down, and that meant the length of a second was gradually getting longer. Zo in de 1960’s de Algemene Conferentie over Gewichten en Measures redefined the second met behulp van een zeer precieze atoomclocks. These atomic clocks are based on an element known as Cesium Like all elements, Cesium 133 emits light at specific frequencies. Light is emitted from an atom when an electron moves from a higher energy quantum state to a lower one, and under the right conditions they are always the same. Een bepaalde uitgifte van cesium 133 is bekend als de hyperfine grondstaat, en het is gebruikt om een ​​atomische klok te reguleren hoe de swing of een pendulum een ​​grandfatherklok regelt. In 1967 the frequency of light emitted by this hyperphine transition was defined to be 9,192,631,770 Hz. By measuring the frequency, you know the length of a second.

For the first time, a human unit of measurement was based on a cosmic physical standard. Du burde ikke længere være på jorden for å bestemme længden på en sekund.

In 1983, de Algemene Conferentie op Weights and Measures elimineerde het metrische systeem’s magische stick door het definiëren van de meter in termen van the speed of light. exactly 299,792,458 meters per second. From anywhere in the universe, you can just measure the distance light travels in a second.

Jennifer Lauren Lee, for the US National Institute of Standards and Technology (NIST)

Over time, more measurements were defined on a universal standard, but the kilogram was still defined by the magic rock. And it was becoming a serious problem. Since Le Grand K was always exactly a kilogram, if you shaved a piece of material off it, it would still be a kilogram. It would weigh less, but then that would a kilogram. For various reasons, Le Grand K does change a little. Når sammenlignet med officielle kopier af kilogrammet, synes det at have øget en smule i masse.

The obvious choice would be to define the kilogram in terms of the universal constant of gravity G, but gravity is a weak force. We have only been able to measure G to within 1 part in 10,000, which is not nearly accurate enough to define a new kilogram. Instead, scientists have sought to use a different physical constant known as the Planck constant.

The Planck constant is central to quantum mechanics. It is famous for giving quantum theory its fuzzy uncertainty properties, but it also relates to the energy and momentum of quantum objects. As Einstein discovered, energy is related to mass, so mass and the Planck are constantly related. One of the ways the Planck can be constantly measured is through a scale known as the Kibble balance. Det måler hvor mye strøm en elektromagnet trenger for å holde opp en bestemt masse. By measuring the current needed to hold a kilogram, you can determine the Planck constant. Men hvis du i stedet definerer Planck konstant at have en bestemt værdi, så er kilogrammet defineret som planck konstant. For it to work, the Kibble balance had to be more accurate than the variations in the standard kilogram. Det er tio år å nå den præcision, men vi har endelig lyktes i de siste par årene.

Which brings us to today. Today the General Conference on Weights and Measures declared that, as of 20 March 2019, the Planck constant will be exactly h = 6.62607015 × 10 -34J ⋅ s . På den dagen, humaniora magisk rock vil være ikke mere. På den dagen, vores måling af universet vil virkelig være baseret på selve universet.

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