Is America Actually Metric?

TL;DR

The kilogram standard, made of platinum and iridium, has been the basis for weight measurements for over a century, but there are concerns about its reliability and a plan to redefine it.

Transcript

I'm here at the National Institute for Standards and Technology, and I'm about to see some of the original kilogram standards. Is that right? Patrick: You are, you are. When were these made? Well the originals were made in the 1880s. There were 40 of them that were brethren of the International prototype kilogram and these 40 were distributed to th... Read More

Key Insights

• 😒 The kilogram standard has been in use for over a century and is distributed to countries that signed the Treaty of the Meter.
• 🇺🇸 Measurements in the United States, although using non-metric units, are ultimately based on the kilogram standard.
• 👱 The kilogram standard's accuracy is impacted by its surface finish, manufacturing techniques, and environmental factors like air density.
• 🙂 There are concerns about the reliability of the kilogram standard, as different prototypes have shown slight variations in mass over time.

Questions & Answers

Q: Why were there multiple original kilogram standards made in the 1880s?

Multiple kilogram standards were made to distribute them to the countries that signed the Treaty of the Meter and adopted the metric system.

Q: Are all measurements in the United States currently in metric units?

While the United States is officially on the metric system, common units like feet and gallons are still used. However, all measurements can be traced back to the kilogram standard.

Q: Why is the surface finish of the kilogram standard important?

A smooth surface reduces the chance of contaminants sticking to the standard, which could alter its mass and affect the accuracy of weight measurements.

Q: What is the plan to redefine the kilogram?

In 2018, the kilogram will no longer be defined as the mass of a metal cylinder. The new definition is still to be determined.

Summary & Key Takeaways

• The original kilogram standards, made in the 1880s, were distributed to countries that signed the Treaty of the Meter as the foundation of the metric system.

• The United States has two original standards, K4 and K20, which have been used to weigh accurately in the country for over 130 years.

• The kilogram standard's surface finish and manufacturing techniques impact its accuracy, and precautions are taken to protect it from contaminants and changes in air density.