The kg is dead, long live the kg

TL;DR

Representatives from various nations will be voting to redefine S.I. units such as the kilogram, kelvin, mole, and ampere, replacing their reliance on physical objects with fixed values based on fundamental constants of nature.

Transcript

On November 16th, representatives from nearly 60 nations will be meeting in Versailles, France to vote to change the definition of a kilogram. Not only that, they will also be changing the fundamental unit of temperature, the kelvin, the unit for amount of substance, the mole, and the unit for electric current, the ampere. That is four of the seven... Read More

Key Insights

• 🇺🇳 Representatives from around 60 nations are voting to redefine multiple S.I. units, including the kilogram, kelvin, mole, and ampere.
• 🥺 The current reliance on physical objects, like the International Prototype Kilogram (Big K), leads to issues of mass divergence and limited accessibility.
• 🧑‍🔬 By fixing fundamental constants like Planck's constant and Avogadro's constant, scientists aim to create more consistent and accessible standards.
• 🇦🇪 The redefinition of S.I. units will make precise measurements possible for anyone, anywhere, by removing the dependence on physical objects.
• 🙂 Although most people won't notice significant changes, a few units like the volt and resistance will be slightly affected.
• 👻 Measurements play a foundational role in science, allowing researchers to make observations and understand the universe.
• ⚾ The redefinition of S.I. units represents an important leap from relying on physical objects to abstraction based on fundamental constants.

Questions & Answers

Q: Why are representatives from different nations meeting to vote on changing the definition of S.I. units?

Representatives are meeting to redefine S.I. units like the kilogram, kelvin, mole, and ampere, as the current system relies on physical objects with diverging masses and limited accessibility.

Q: What is the International Prototype Kilogram (Big K) and why is it problematic?

The Big K is the current definition of a kilogram, but its mass diverges from other metal cylinders. Its limited availability and maintenance make it difficult to use as a mass standard.

Q: How can Planck's constant be used to create a mass standard?

Planck's constant relates energy and mass through E = mc². By fixing its value, scientists can redefine the kilogram, making it consistent and accessible to everyone.

Q: How will the redefinition of S.I. units impact other units like the mole and ampere?

The redefinition will also affect other units like the mole and ampere. For example, the mole is currently based on Avogadro's constant, which depends on the existing definition of a kilogram. This interdependence will change with the new definitions.

Summary & Key Takeaways

• Representatives from nearly 60 nations will vote to redefine the kilogram, kelvin, mole, and ampere, replacing their reliance on physical objects.

• The current kilogram, known as the International Prototype Kilogram (Big K), has problems, as its mass diverges from other metal cylinders stored in Paris.

• By fixing Planck's constant and other fundamental constants, scientists aim to create a mass standard that will never change and be accessible to everyone.