Science & Industry
Why Are Traffic Lights Red, Yellow, and Green?
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Article
For drivers in many parts of the globe, the red, yellow, and green sequence of traffic lights has become an instinctual part of how we move through the world. But why these three colors? How did they come to govern the movement of billions of people across the planet every day? As it turns out, there are a few factors in play, including the history of transport, color psychology, and basic physics. Credit: © Barry Winiker—Stockbyte/Getty Images Red Lights and Railroads The colors used in traffic lights today were not invented for roads. They were ...Read More
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Science & IndustryFact58The stethoscope was invented because a doctor felt awkward pressing his ear to a woman’s chest.
In 1816, a French physician named René Laennec found himself in a delicate situation. He needed to listen to the heart of a young female patient but didn’t have an…
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Science & IndustryFact68People hated shopping carts when they were invented in 1937.
During the Great Depression in the 1930s, most Americans were just trying to get by, and few had the luxury of coming home from the grocery store with extra items.…
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Science & IndustryArticle455 Photos of American Cities Before Cars
Nowadays, automobiles and traffic sounds are ubiquitous in urban areas, but if you could step back in time a century or so, many of America’s most recognizable cities would look…
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Science & IndustryArticle49Why Did Old Houses Have So Many Doors?
Since the 1950s, American architectural trends have tended to favor open-concept plans, with one room flowing into the next. But there was a time when the typical house didn’t open…
