Centuries of the Bristlecone by Jonathon Keats

Transcript

For thousands of years, humans kept time by  observing natural cycles. Spring wasn't a set day,   but when a certain bird migrated or insect  sang or wildflower emerged from the ground, gradually people made calendars  more regular. Society now follows   what's called coordinated universal time  calibrated to a billionth of a second. But something ... Read More