Why Does Japan Have Blue Traffic Lights Instead of Green?

ANTTI T. NISSINEN, Flickr // CC BY 2.0
ANTTI T. NISSINEN, Flickr // CC BY 2.0

In Japan, a game of Red Light, Green Light might be more like Red Light, Blue Light. Because of a linguistic quirk of Japanese, some of the country’s street lights feature "go" signals that are distinctly more blue than green, as Atlas Obscura alerts us, making the country an outlier in international road design.

Different languages refer to colors very differently. For instance, some languages, like Russian and Japanese, have different words for light blue and dark blue, treating them as two distinct colors. And some languages lump colors English speakers see as distinct together under the same umbrella, using the same word for green and blue, for instance. Again, Japanese is one of those languages. While there are now separate terms for blue and green, in Old Japanese, the word ao was used for both colors—what English-speaking scholars label grue.

In modern Japanese, ao refers to blue, while the word midori means green, but you can see the overlap culturally, including at traffic intersections. Officially, the “go” color in traffic lights is called ao, even though traffic lights used to be a regular green, Reader’s Digest says. This posed a linguistic conundrum: How can bureaucrats call the lights ao in official literature if they're really midori?

Since it was written in 1968, dozens of countries around the world have signed the Vienna Convention on Road Signs and Signals, an international treaty aimed at standardizing traffic signals. Japan hasn’t signed (neither has the U.S.), but the country has nevertheless moved toward more internationalized signals.

They ended up splitting the difference between international law and linguists' outcry. Since 1973, the Japanese government has decreed that traffic lights should be green—but that they be the bluest shade of green. They can still qualify as ao, but they're also green enough to mean go to foreigners. But, as Atlas Obscura points out, when drivers take their licensing test, they have to go through a vision test that includes the ability to distinguish between red, yellow, and blue—not green.

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What is a Polar Vortex?

Edward Stojakovic, Flickr // CC BY 2.0
Edward Stojakovic, Flickr // CC BY 2.0

If you’ve turned on the news or stepped outside lately, you're familiar with the record-breaking cold that is blanketing a lot of North America. According to The Washington Post, a mass of bone-chilling air over Canada—a polar vortex—split into three parts at the beginning of 2019, and one is making its way to the eastern U.S. Polar vortexes can push frigid air straight from the arctic tundra into more temperate regions. But just what is this weather phenomenon?

How does a polar vortex form?

Polar vortexes are basically arctic hurricanes or cyclones. NASA defines them as “a whirling and persistent large area of low pressure, found typically over both North and South poles.” A winter phenomenon, vortexes develop as the sun sets over the pole and temperatures cool, and occur in the middle and upper troposphere and the stratosphere (roughly, between six and 31 miles above the Earth’s surface).

Where will a polar vortex hit?

In the Northern Hemisphere, the vortexes move in a counterclockwise direction. Typically, they dip down over Canada, but according to NBC News, polar vortexes can move into the contiguous U.S. due to warm weather over Greenland or Alaska—which forces denser cold air south—or other weather patterns.

Polar vortexes aren't rare—in fact, arctic winds do sometimes dip down into the eastern U.S.—but sometimes the sheer size of the area affected is much greater than normal.

How cold is a polar vortex?

So cold that frozen sharks have been known to wash up on Cape Cod beaches. So cold that animal keepers at the Calgary Zoo in Alberta, Canada once decided to bring its group of king penguins indoors for warmth (the species lives on islands north of Antarctica and the birds aren't used to extreme cold.) Even parts of Alabama and other regions in the Deep South have seen single-digit temperatures and wind chills below zero.

But thankfully, this type of arctic freeze doesn't stick around forever: Temperatures will gradually warm up.

In What Field Was Dr. Martin Luther King, Jr. a Doctor?

Express Newspapers/Getty Images
Express Newspapers/Getty Images

Martin Luther King, Jr. earned a doctorate in systematic theology from Boston University in 1955. He’d previously earned a Bachelor of Arts from Morehouse College and a Bachelor of Divinity from Crozer Theological Seminary. His dissertation, “A Comparison of the Conception of God in the Thinking of Paul Tillich and Henry Nelson Wieman,” examined the two religious philosophers’ views of God in comparison to each other, and to King’s own concept of a "knowable and personal" God.

Some three decades after he earned his doctorate, in 1989, archivists working with The Martin Luther King Papers Project discovered that King’s dissertation suffered from what they called a “problematic use of sources.” King, they learned, had taken a large amount of material verbatim from other scholars and sources and used it in his work without full or proper attribution, and sometimes no attribution at all.

In 1991, a Boston University investigatory committee concluded that King had indeed plagiarized parts of his dissertation, but found that it was “impractical to reach, on the available evidence, any conclusions about Dr. King's reasons for failing to attribute some, but not all, of his sources.” That is, it could have been anything from malicious intent to simple forgetfulness—no one can determine for sure today. They did not recommend a posthumous revocation of his degree, but instead suggested that a letter be attached to the dissertation in the university library noting the passages lacked quotations and citations.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article was originally published in 2013.

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