8 1 The History of Measurement

Summary

This video explores the history of measurement, covering ancient systems like the qubit, foot, and the statute mile, all based on human body parts or physical actions. It then discusses the transition to artifact prototypes, such as the kilogram standard, which was used until 2018. The video highlights the limitations of these methods and the shift towards using constants of nature, like the speed of light, to define units. This marks a new era of precise and universally accessible measurement, with the metric system originating during the French Revolution in the 1700s. The accompanying Ted Ed video dives deeper into the metric system's history.

Takeaways

• 😀 Measurements in ancient times were based on body parts, like the cubit, which was the distance from a person's elbow to their longest finger. However, this method lacked accuracy due to individual body size variations.
• 😀 The foot, as a unit of measurement, was originally based on the length of a person's foot in ancient Greece. This, too, was inaccurate as people's feet vary in size.
• 😀 The statute mile was based on the number of footsteps a soldier would take, which varied depending on the soldier's stride, making it an imperfect system.
• 😀 The ancient methods of measurement were the best available at the time, but they were not precise, especially when it came to larger-scale or critical measurements.
• 😀 Artifact prototypes, like the standard kilogram and meter, were used to define measurements. These prototypes were actual physical objects, stored in secure locations like vaults.
• 😀 The kilogram prototype, called Legrand K, was kept in France and was central to defining the kilogram for much of the 20th century. It was so important that it was protected during World War II.
• 😀 In 2018, the use of artifact prototypes like Legrand K was abandoned because these objects would deteriorate over time, leading to slight inaccuracies in measurements.
• 😀 Today, units of measurement are defined by constants of nature, such as the speed of light (3.00 x 10^8 meters per second), which is universally constant and does not change over time.
• 😀 Other constants of nature, like Planck's constant, are also used to define measurements in a more accurate and reliable way than the earlier artifact-based methods.
• 😀 The metric system originated during the French Revolution in the 1700s, providing a more standardized and consistent way of measuring across different regions and disciplines.

Q & A

What are the main objectives of video 8-1?

The main objectives are to explain three ways that measurements have been determined throughout history and to explain how the metric system originated.

Why is using a person's body part for measurements not ideal?

Body parts, like the qubit (from elbow to finger tip), vary in size from person to person, which makes such measurements inaccurate and inconsistent.

What is the qubit, and where is it mentioned historically?

The qubit is the distance from a person's elbow to their longest finger. It is mentioned in the Bible as a unit of measurement, notably when Noah was instructed to build the ark.

How was the foot used as a unit of measurement in ancient Greece?

In ancient Greece, the foot was measured based on the length of a person's foot, which could vary greatly between individuals.

What is the origin of the statute mile?

The statute mile originated from the number of footsteps taken by soldiers, which was approximately 5,000 footsteps. However, this method was inconsistent due to differences in stride length.

What were artifact prototypes, and how were they used in measurement?

Artifact prototypes were physical standards, such as a meter or kilogram made from metal, that were used to define units of measurement. These prototypes served as the reference for all other measurements globally.

Why was the kilogram prototype important during World War II?

The kilogram prototype, known as Legrand K, was so crucial to the global measurement system that even during World War II, the Nazis refrained from bombing the building housing the prototype to prevent disrupting global measurements.

Why was the kilogram prototype replaced in 2018?

The kilogram prototype was replaced in 2018 because it was deteriorating over time, losing small amounts of material. Modern measurement systems now rely on constants of nature rather than physical prototypes.

What are 'constants of nature' and how are they used in modern measurement?

Constants of nature, like the speed of light and Planck's constant, are fundamental values in the universe that remain unchanged. Modern units of measurement are based on these constants to ensure accuracy and consistency worldwide.

Where did the metric system originate, and when?

The metric system originated during the French Revolution in the 1700s, as part of a movement to standardize measurements across France and eventually the world.