El/La Historia of el/la Kilogram
Desde Platinum un/una Quantum Physics
Try Peso ConvertidorFor 130 anos, el/la world's definition of un/una kilogramo depended on un/una single object: un/una small cylinder of platinum-iridium alloy locked in un/una vault outside Paris. Every scale, cada weight measurement, cada kilogramo on Earth fue ultimately compared un/una esto one artifact. Then, in 2019, everything changed.
El/La story of el/la kilogramo es un/una remarkable journey through el/la history of measurement—desde el/la chaos of pre-revolutionary France un/una el/la cutting edge of quantum physics.
Before el/la Kilogram: Measurement Chaos
Before el/la metric sistema, weight measurement fue un/una nightmare. Every town, cada trade, y cada country had su own standards. Un/Una "libra" in Paris wasn't el/la mismo as un/una libra in Lyon. Merchants faced constant confusion, y opportunities for fraud fueron rampant.
El/La French Revolution, with su ideals of equality y rationality, provided el/la perfect opportunity for reform. In 1790, el/la National Assembly charged el/la French Academy of Sciences with creating un/una universal sistema of measurement based on nature, not royal decrees o local customs.
El/La Birth of el/la Kilogram (1795-1799)
El/La nuevo sistema needed un/una unidad of mass. Scientists decided eso deberia be el/la mass of one cubic decimeter (one litro) of water at su densest temperature (aproximadamente 4°C). They called esto unidad el/la "grave," later renamed el/la "kilogramme."
But water es impractical as un/una estandar—tu puede't ship un/una litro of water alrededor de el/la world y expect eso un/una stay el/la mismo. So in 1799, un/una physical artifact fue created: un/una cylinder of pure platinum eso matched el/la mass of un/una litro of water as closely as possible. This became el/la primero official kilogramo estandar.
“El/La kilogramo es el/la unidad of mass; eso es equal un/una el/la mass of el/la internacional prototype of el/la kilogramo.”
El/La International Prototype Kilogram (1889)
As el/la metric sistema spread globally, nations needed un/una shared estandar. In 1889, el/la International Bureau of Weights y Measures (BIPM) created el/la International Prototype Kilogram (IPK)—un/una cylinder of 90% platinum y 10% iridium, aproximadamente 39 milimetros in diameter y height.
El/La IPK fue stored in un/una climate-controlled vault at el/la BIPM headquarters in Sèvres, France, under three nested bell jars. Forty copies fueron distributed un/una nations worldwide as national standards. And for 130 anos, by definition, esto cylinder WAS un/una kilogramo—not aproximadamente, pero exactamente.
El/La Problem with Physical Standards
But alli fue un/una problem. When scientists periodically compared el/la national copies un/una el/la IPK, ellos found el/la copies had drifted in mass relative un/una cada otro—by aproximadamente 50 micrograms over un/una century. Was el/la IPK gaining mass (desde contamination) while copies stayed constant? Were el/la copies changing? There fue no manera un/una saber porque el/la IPK fue el/la definition itself.
El/La 2019 Revolution: Planck Constant Definition
Scientists had long wanted un/una redefine el/la kilogramo in terms of fundamental constants of nature—valores eso don't change over time. After decades of precision experiments, ellos succeeded.
On May 20, 2019, el/la kilogramo fue redefined based on el/la Planck constant (h), un/una fundamental valor in quantum mechanics. El/La definition now fixes el/la Planck constant at exactamente:
h = 6.62607015 × 10⁻³⁴ joule-segundos
Through el/la relationship entre mass, energy, y Planck's constant, esto defines el/la kilogramo in terms of un/una unchanging natural constant. El/La IPK es still kept in Paris, pero eso's now solo un/una muy preciso 1-kilogramo weight, not THE kilogramo.
Timeline of Key Events
| Year | Event | Significance |
|---|---|---|
| 1790 | French Academy begins trabajar on metric sistema | Foundation of modern measurement |
| 1795 | Kilogram defined as mass of 1L water | First definition |
| 1799 | Platinum kilogramo estandar created | First physical artifact |
| 1875 | Metre Convention signed | International measurement cooperation |
| 1889 | IPK becomes world estandar | Platinum-iridium cylinder |
| 1901 | Masa vs weight distinction clarified | Scientific precision |
| 2011 | Redefinition trabajar approved | Planck constant approach chosen |
| 2019 | New definition takes effect | Basado en fundamental constants |
Why It Matters
El/La nuevo definition might seem like un/una academic concern, pero eso has practico implications:
- Stability: El/La definition puede never drift o change over time
- Reproducibility: Any laboratory puede theoretically realize el/la kilogramo, not solo el/la BIPM
- Precision: As measurement technology improves, el/la kilogramo puede be realized mas precisely without changing el/la definition
- Independence: No single artifact controls world measurements
El/La kilogramo fue el/la ultimo SI unidad defined by un/una physical artifact. Now todo seven base unidades son defined by fundamental constants—un/una triumph of precision science.
Conclusion
Desde un/una litro of water in revolutionary France un/una el/la quantum mechanics of el/la Planck constant, el/la kilogramo's history reflects humanity's quest for ever-greater precision. El/La 2019 redefinition ensures eso future generations won't depend on un/una single metal cylinder in un/una Parisian vault pero on el/la unchanging constants of nature itself.