Planet Money
The history of light (classic)
· Summarized
Key takeaways
- The history of light is a measure of productivity: a Babylonian worker could buy about 10 minutes of light with a day’s wages, compared with roughly 20,000 hours by the 1990s.
- Economic growth occurs when people repeatedly discover ways to do things faster, more efficiently, or with less labor, allowing the same work to produce far more goods and services.
- Major innovations depend on surrounding institutions—including professional science, patents, corporations, banks, and investors—not just on an inventor’s individual insight.
- Growth can make the economic pie bigger and improve living standards, but it also creates pollution and environmental consequences and may eventually face physical limits.
Summary
Goldstein’s cow-fat candle experiment
Jacob Goldstein introduces the episode by recalling economist Bill Nordhaus, whose work on progress and climate change later earned him the Economics Nobel Prize; the rerun honors Nordhaus after his death at 85. Jacob and David Kestenbaum begin with the pre-electric problem of lighting a room. Jacob buys two pounds of beef suet for $2.98 per pound, melts and strains it, and repeatedly dips twine wicks into the fat. After hours, he has six crooked, smelly candles—illustrating how much labor once produced very little light.
Ancient light cost a full day’s wages
Light expert Jane Brocks examines the candles and explains that people historically used whatever oily material they could find: dried salmon in the Pacific Northwest, fireflies in tropical regions, and storm petrels in northern Scotland with wicks threaded down their throats. Nordhaus measured the economic cost by recreating an ancient Babylonian lamp, using four-thousand-year-old wage and price data and a light meter. A Babylonian worker spending an entire day’s wages on illumination could buy only about 10 minutes of modern light-bulb equivalent.
Small improvements barely changed life for millennia
The hosts explain that ancient darkness was dangerous and restrictive, not romantic: in one period Paris required residents to surrender their keys and lock themselves indoors at night. For roughly 4,000 years, productivity improved only modestly; Romans made somewhat better lamps and whale oil supplied more fuel, but most people remained subsistence farmers. Even in the 1700s, people traveled by foot, horse, or sailing ship and lit homes by burning materials they had found. Nordhaus calls the pre-1800 pattern a long period of very limited economic improvement.
Kerosene made light five times cheaper
In the 1800s, experimentation and professional science accelerated innovation. Around 1850, improved techniques made kerosene from coal or oil, producing a brighter, cleaner, and much cheaper fuel than earlier lamps. A day’s labor bought roughly one hour of whale-oil light but about five hours of kerosene light, which Brocks says “lit the world and saved the whales.” The hosts attribute the breakthrough partly to institutions such as universities beginning to employ scientists: Yale had previously focused on Greek and logic rather than systematic experimental research.
Edison needed J.P. Morgan, not just a filament
The electric lamp was not merely an inventor’s Eureka moment. Edison needed patents, a corporation, investors, a power station, and wires. On September 4, 1882, he switched on the first central power station from J.P. Morgan’s office; electricity then lit about a square mile of lower Manhattan, while Edison stayed with the financiers who had funded the project. Edison’s notebooks compared electric lighting with gas costs, showing that economic analysis shaped his laboratory work. The coal-fired system also brought pollution: scouts reportedly stopped feeding coal when health-department photographers appeared.
Growth brings abundance, tradeoffs, and physical limits
Across the 20th century, engines, tractors, and other innovations meant most people no longer had to farm, while light became dramatically cheaper. Nordhaus’s comparison rises from 10 minutes per Babylonian workday to five hours with kerosene and roughly 20,000 hours by the 1990s, including household, street, appliance, and air-conditioning use. Goldstein and Kestenbaum argue that growth lets people work less or afford books, vacations, and specialized services, though pollution and environmental damage are real costs. An LED maker says progress may be approaching physical limits: a car cannot travel a million miles per hour, and light bulbs may be nearing their ceiling.
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Show notes
For thousands of years, getting light was a huge hassle. You had to make candles from scratch. This is not as romantic as it sounds. You had to get a cow, raise the cow, feed the cow, kill the cow, get the fat out of the cow, cook the fat, dip wicks into the fat. All that — for not very much light. Now, if we want to light a whole room, we just flip a switch.
Nobel-winning economist Bill Nordhaus passed away last week. He was known for his work on the economics of climate change, but he also came up with this idea that the history of light explains reveals why the world today is the way it is. It explains why we aren't all subsistence farmers, and why we can afford to have artists and massage therapists and plumbers. (And, yes, people who make podcasts about the history of light.) The history of light is the history of economic growth — of things getting faster, cheaper, and more efficient. It shows us the pie can get bigger, sometimes, there can be a type of progress where everyone is better off.
On today's show, one of our all time favorites: How we got from dim little candles made out of cow fat, to as much light as we want at the flick of a switch, and how that is a measure of what economic progress means.
(Note: This episode originally ran in 2014.)
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Today's show was hosted by Jacob Goldstein and David Kestenbaum. It was originally produced by Caitlin Kenney and Damiano Marchetti. Today's rerun was produced by Sam Yellowhorse Kesler. Alex Goldmark is Planet Money's executive producer.
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