Cost of light

For thousands of years, human beings had one source of light in the night. Someone has actually found a way to measure the cost of light for a prehistoric human, and compare it to what humans pay now for the same level of light.

 photo: ozarkmountainhiker.files.wordpress.com

 Using labor hours as a unit of measure, they say it took ten hours of chopping wood per day for six days to produce 1000 lumen hours of fire light. In modern terms, that's equivalent to 54 minutes of a light bulb shining. And no one has to chop wood for even a minute.

Candles cut the human cost of having light, but it was still expensive. "George Washington calculated that five hours of reading per night cost him £8 yearly -well over $1,000 in today's dollars."

But light bulbs  "changed everything . . The amount of labor that once bought 54 minutes of lightt now buys 52 years of light."

How did that happen? A long sequence of technological improvements. Innovation created an abundance, a wealth of light.