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Welcome to Brainstuff, a production of IHeart Radio.

Hey, Brainstuff, Lauren Boglebaum here.

There's something so commonplace about a weighing device

that it's easy to forget its deeper significance.

As the slightly skewed spring scale in any local produce aisle reminds us, the scale has long served humans as the chief

arbiter of commerce, the maker or breaker of shipping budgets and carry-on capacity, and the utility

player of the pharmaceutical bench. From the smallest, most

fine-tuned laboratory balance to the pit and girder monsters that weigh train cars and tractor

trailers, scales make modern life possible. Scales, or more specifically, balances, weighed

heavily on the minds of ancient builders, inventors, and economic advisors, too.

Small balance weights dating back to around 5,000 to 6,000 years ago provide some of the first hints of mankind's evolving grasp of science and mathematics.

The most basic surviving balance from Egypt predates the dynastic period,

placing its construction at earlier than 3,000 BCE. Like us, the ancient Egyptians applied scales

both in trade and in assaying oars and alloys. A balancees weigh an object by matching it

against one or more reference weights.

They have a delicate touch and are still used in laboratories.

Scales use somewhat different physical principles and mechanical components to measure weight

and other forces. Spring scales, for example, measure weight using Hook's Law, by which you can relate an object's weight

to the stretching or compression of a spring made from a given material.

Not all scales use springs, but all do measure weight using mechanical components.

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