Chapter III: Weight – The Gravity of the Matter
As humans moved from hunting and gathering to farming and trading, weight became crucial to everyday life. Grains were traded by weight, and gold was valued by its heaviness. But how did our ancestors define weight? What units were used? Let’s step back in time and unravel the story of weight measurement.
Ancient and Medieval Times
In ancient times, stones, seeds, and grains were used as units of weight. The Babylonians, Egyptians, and Indus Valley civilizations developed their own systems of weights and balances, tailored to their respective trade and economies. In ancient Greece, “minas” and “talents” were used. A talent, approximately 26 kilograms, was a hefty sum of money used primarily for large transactions.
The Romans developed their system based on the “libra”, from which the term “pound” originates. However, the Roman pound was not divided into 16 ounces like the modern pound; instead, it was divided into twelve “unciae”, the origin of the term “ounce”.
Fast forward to medieval England, where the “stone” emerged as a unit of weight. A stone was traditionally used in commerce to weigh items like wool, equaling 14 pounds. It’s a unit still used today, but primarily for weighing people’s body weight in the UK and Ireland.
Our modern understanding of weight measurement took a giant leap forward with the advent of the metric system during the French Revolution. The “gram” was defined as the absolute weight of a volume of pure water equal to a cube of one-hundredth of a meter and at the temperature of melting ice. But dealing with such a small weight was impractical, so a “kilogram”, or one thousand grams, became the standard.
The History of the Metric System
The metric system was developed during the French Revolution to standardize measurements across France and eventually internationally. Before the metric system was introduced, the country used various measurements from region to region. This led to problems in commerce and daily life, as different standards existed for weight, length, and volume.
The French Revolution, which began in 1789, was a period of significant social and political upheaval. With its ideals of rationality, equality, and universality, the revolutionary government saw the creation of a standard measurement system as an essential part of its project.
In 1790, the French National Assembly directed the French Academy of Sciences to develop a unified and universal system of measurements. The result was the metric system, with its base-ten units providing an easy and consistent calculation method.
The fundamental unit of the system, the meter, was defined to be one ten-millionth of the distance from the North Pole to the equator, a measurement that reinforced the universality and objectivity of the system.
The system was officially adopted by the French government in 1795. Despite initial resistance, particularly in rural areas, the metric system was eventually adopted worldwide and remains the most widely used measurement system today.
Nowadays
Today, the kilogram is defined not by a physical artifact but by a fundamental constant of nature known as the Planck constant, ensuring its value remains the same wherever you are in the universe.
Yet, just like length, weight measurement sees a divergence in practice. While most of the world has adopted the metric system, the United States still essentially uses the imperial system, which includes pounds and ounces. These dual systems, although sometimes leading to confusion, also symbolize the fascinating diversity in our ways of understanding and interacting with the world.
The story of weight measurement is more than just numbers and units. It reflects human ingenuity and our quest to bring order to our surroundings. From trade markets of ancient civilizations to modern-day laboratories, the measure of weight has played a vital role in human development. And as we continue to push the boundaries of knowledge and explore the cosmos, this fundamental measure remains at the core of our scientific endeavors.
Comparative Weights: A Quick Guide to Measures in the USA, UK, and Europe
USA: Weight is commonly measured in ounces (oz) and pounds (lb). For instance, a bag of flour might weigh 16 ounces (1 pound), while a person’s weight might be 180 pounds.
1 pound = 16 ounces 1 pound ≈ 0.45 kilograms
UK: The UK uses a mix of metric and imperial. For everyday personal weight, stones and pounds are used. For cooking and other purposes, grams and kilograms are used. For example, a person might weigh 11 stone 6 pounds, while a bag of sugar might be 1 kilogram.
1 stone = 14 pounds 1 pound ≈ 0.45 kilograms
Europe: In most of Europe, the metric system is used, so weight is typically measured in grams (g) and kilograms (kg). For example, a person might weigh 70 kilograms, while a small apple weighs 150 grams.
1 kilogram = 1,000 grams 1 kilogram ≈ 2.2 pounds
