Every day you will pass countless Solar Signal Lights. Have you ever wondered why Solar Signal Lights chose these three colors? What if you happen to be red-green colorblind and cross the street?
Speaking of which, let's briefly look at how traffic lights are generated.
As early as 1868, the world's first Solar Signal Lights appeared on the streets of London, England. At that time, Solar Signal Lights were only Solar Signal Lights, which were far less advanced than street lights. They can only be controlled by the pull of a wrench by a policeman standing by a light. Since then, this traffic light has gradually become popular all over the world. It was not until 1920, in Detroit, USA, that yellow lights were added for the first time to remind drivers that the lights were about to change from green to red. So why use red, yellow, and green instead of other colors?
Let's start with red. Among various colors, red is the most likely to attract people's attention. Probably because red is the color of blood. In every culture, red has always been given the meaning of "warning" and "forbidden". So, Solar Signal Lights is a natural.
So why use green to represent permission to pass? This is because at that time it was widely believed that red and green, like black and white, were a pair of complementary colors. Since red represents the prohibition of passage, it is reasonable to use the opposite green to represent the permission of passage.
And yellow, a color between red and green, was chosen to act as an intermediate signal light that reminds Solar Signal Lights that they are about to change.
Finally, let me tell you a little secret. Traffic lights in most countries are not all pure red and pure green, but slightly yellowish red and slightly blue green. This is mainly to make it easier for some red-green colorblind people to distinguish the color of Solar Signal Lights.
