Everyday little questions! Surprisingly unknown, fascinating trivia from around us

Where does dust come from?

Even though you’ve just cleaned, dust somehow piles up before you know it.

Where does dust come from? Dust is made up of shed fibers from clothing, sofas, and carpets, as well as fragments of human skin, dandruff, mold, and bacteria.

It’s said that air currents caused by human movement, temperature differences, and wind from air conditioners or open windows bring these particles together to form dust.

What’s more, mold and bacteria can rapidly multiply within the accumulated dust.

There are also cleaning methods that can help prevent dust from building up, so if you’re interested, try looking them up.

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Nakajima Junko

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Are traffic lights three colors: red, yellow, and green?

Traffic lights have three colors: green, yellow, and red.

So, why were these three chosen? In fact, these colors are not a Japan-specific rule; they are defined by the International Commission on Illumination.

Traffic signal colors are designated as five colors—red, green, yellow, white, and blue—and three of these are assigned for traffic signal lamps.

In Japan, the green light is commonly called “blue” (ao shingō).

There are various explanations for this, including the broad traditional range covered by the term “ao” (blue/green), the influence of the three primary colors, and the perception that blue is the opposite of red.

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sasashina

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Where does the wind come from?

How does wind work? It’s curious, isn’t it, that there aren’t any propellers or blades like on fans or windmills creating it.

In fact, air exerts pushing forces, and the strength of those forces differs from place to place.

Air with weaker force gets pushed out by air with stronger force.

In other words, that movement is what becomes wind.

In the atmosphere, air is constantly pushing against other air.

We can’t see it, but it’s fun to imagine, isn’t it?

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Why do we line up our shoes?

In Japan, most people are taught from a young age that arranging your shoes neatly after taking them off is good manners.

In fact, aligning your shoes carries a deeper meaning beyond simple etiquette.

At the entrances of Zen temples, you may find a sign or wooden plaque that reads “Kyakka Shōko” (Reflect on your own steps).

This teaches that “if you wish to cultivate a calm, spacious mind, start by arranging your footwear.” It’s also said that properly setting your shoes in order expresses respect for the other person’s space.

It turns out that a great deal of courtesy and thoughtfulness is contained within such small actions.

It would be nice if we could shift our awareness a little and strive to live more mindfully and with care.

Why is the greeting at the workplace ‘Good morning’?

Why do people say “ohayō gozaimasu” at the workplace even in the afternoon or evening? It feels a bit curious, doesn’t it? It’s said this custom spread from the world of kabuki.

In kabuki and theater, performers take the stage regardless of day or night, so they would greet each other with “Ohayō!” at any hour with the feeling of “This is the start of our day.” This habit spread into the entertainment and artisan worlds and came to be used as a greeting meaning “Let’s begin today” or “Nice to start working together today.” In other words, it’s not just a simple greeting—it also carries the meaning of “All right! Let’s do our best together from here!” Let’s keep using it energetically and cheerfully.

Why can gold leaf be eaten?

Gold leaf adds a touch of luxury to all kinds of foods.

You may have wondered why it’s edible.

Records show that gold leaf was used as a medicine as far back as the Nara period, and the tradition of using it in cuisine has a long history.

Originally, heavy, rigid gold is thinned by master artisans using traditional techniques to as fine as one ten-thousandth of a millimeter, becoming so delicate it can flutter with a breath.

Gold leaf is also one of the food additives approved by Japan’s Ministry of Health, Labour and Welfare.

Because gold does not dissolve in anything and passes through the body without being absorbed, it can be safely eaten by everyone from children to the elderly.

Let’s cherish this beautiful Japanese tradition that has been handed down through the generations.

Why do cats like boxes?

Cats really do love boxes, don’t they? There are several instinctive reasons why.

First, a box is enclosed on multiple sides, creating a safe, secure shelter that protects them from potential threats.

By rubbing and leaving their scent, they can mark territory and maintain a sense of privacy.

Tight spaces also help them retain body heat, making boxes great for comfortable temperature regulation.

Climbing inside stimulates their playful and exploratory nature, satisfying their curiosity.

It’s also said that boxes reduce outside stimuli, which can help lower stress.

In a way, it’s similar to the human urge to hunker down and cocoon ourselves!