G: Ever looked at something mundane – a coin in your pocket, a traffic light, or even a manhole cover – and wondered, “Why is it like that?” 🤔 You’re not alone! Just like the popular Korean show “Al-Sseul-Shin-Jap” (알쓸신잡), which roughly translates to “A Collection of Useless but Fascinating Facts,” our everyday world is brimming with hidden stories and surprising reasons behind seemingly ordinary things.
Get ready to have your mind blown as we uncover 7 fascinating pieces of trivia that will make you look at your surroundings with fresh eyes. No more aimless staring at the ceiling – let’s dive into the “useless” knowledge that will actually make you incredibly interesting at parties! 🎉
1. Why Are Manhole Covers Round? 🍩
This is perhaps one of the most classic “trivia” questions, and for good reason! It’s not just an aesthetic choice; it’s a brilliant engineering and safety decision.
- The Problem: Imagine a square manhole cover. If you turn it diagonally, it can actually fall through its own opening! A worker standing below would be in serious danger. 😱
- The Solution: A round manhole cover cannot fall through its own circular opening, no matter how you rotate it. The diameter of the cover is always larger than the diameter of the hole. It’s simple geometry for maximum safety. 👷♂️
- Bonus Reasons: Round covers are also easier to roll (no sharp corners to lift!), which simplifies transportation and installation. Plus, they don’t need to be aligned in any specific direction when put back, making maintenance quicker. How clever is that? ✨
2. What’s That Tiny Bump on the “F” and “J” Keys (and on the ‘5’ on Your Remote)? 🤏
Pick up any standard computer keyboard, close your eyes, and feel the “F” and “J” keys. You’ll notice a small, raised bump or bar. The number ‘5’ key on many phone keypads or TV remotes has a similar tactile marker. Ever wondered why?
- For the Blind & Fast Typists: These small bumps are known as “home row indicators.” They allow touch typists (and visually impaired users) to quickly and accurately position their fingers on the keyboard without looking. Your left index finger rests on “F,” and your right index finger rests on “J.” From these “home” positions, all other keys can be reached efficiently. ✍️
- Accessibility: On remote controls or phone keypads, the ‘5’ serves a similar purpose. It helps users orient their fingers to dial numbers or navigate menus without having to constantly look down. It’s a subtle but incredibly useful design feature for accessibility and efficiency! 👍
3. Why Do Airplane Windows Have Rounded Corners and a Tiny Hole? ✈️
Those oval windows on planes aren’t just for a pretty view; they’re critical safety features. And that tiny hole at the bottom? It serves a surprising purpose too!
- Rounded Corners: Back in the early days of commercial jet flight, some planes had square windows. The problem? Square corners create concentrated stress points in the aircraft’s fuselage when the plane pressurizes at high altitudes. This led to catastrophic structural failures. Rounded corners distribute stress evenly, preventing cracks and ensuring the integrity of the cabin. It’s a life-saving design! 🛡️
- The Tiny Hole (Breather Hole/Bleed Hole): Look closely at an airplane window. It’s actually made of three panes: an outer pane, a middle pane, and an inner pane. The tiny hole is in the middle pane. Its purpose is twofold:
- Pressure Equalization: It allows air pressure to equalize between the cabin and the air gap between the outer and middle panes. This ensures that the outer pane bears the primary pressure difference during flight, protecting the inner pane from damage.
- Moisture Prevention: It vents moisture from the gap between the panes, preventing fogging or condensation that could obstruct the view. So, that little hole is quite the unsung hero! 🌬️
4. Why Do We “Say Cheese” for Photos? 📸
Before the invention of photography, smiling for a portrait was considered odd, even inappropriate. In many cultures, a broad smile was associated with madness, drunkenness, or low social status. So, how did “say cheese” become a global phenomenon?
- The “Smile” Evolution: As photography became more accessible in the early 20th century, photographers wanted to capture more natural, pleasant expressions. The word “cheese” was reportedly suggested because of the way saying it makes your mouth form a shape similar to a smile. Try it now! Your lips pull back, and your teeth might show slightly. 😄
- Mid-20th Century Adoption: While its exact origin is murky, the phrase gained widespread popularity in the mid-20th century, especially in America, as a simple, easy-to-understand instruction for getting people to produce a camera-ready grin. It’s all about tricking your face into a universally understood happy expression! 🥳
5. Why Are Traffic Lights Arranged in That Specific Order (Red, Yellow, Green)? 🚦
You see them every day, but have you ever considered why traffic lights are universally arranged with red on top, yellow in the middle, and green at the bottom? It’s not arbitrary!
- Universal Recognition & Safety: This standardized order is crucial for immediate and universal recognition, especially in emergency situations or for people with certain visual impairments.
- Visibility for All:
- Red (Stop) on Top: Red is the most critical signal, demanding immediate attention. Placing it at the top ensures it’s the most visible, even to drivers approaching a hill or those who are colorblind (as its position helps identify it). 🛑
- Green (Go) on Bottom: Green means “go,” and it’s less critical for immediate action than red. Placing it at the bottom allows for a quick visual scan down when waiting. 🟢
- Yellow (Caution) in Middle: Yellow is always a transitional warning, signaling a change from green to red, or sometimes flashing to indicate caution. Its central position works well as a bridge between the two primary signals. ⚠️
- Accessibility for Colorblind Drivers: For individuals with red-green color blindness, the consistent position of the lights helps them differentiate between “stop” and “go” even if they struggle with the colors themselves. It’s a small detail that has a massive impact on road safety worldwide! 🌍
6. What Are Those Ridges (Reeds) on the Edges of Coins? 🪙
Grab a quarter, a dime, or a euro coin. Feel the side – you’ll notice small grooves or ridges, known as “reeding” or “milling.” You won’t find them on nickels or pennies (in the US) or many lower denomination coins. Why are they there?
- Historical Reason (Preventing “Clipping”): In the past, coins were made of precious metals like gold and silver. Unscrupulous individuals would “clip” or shave off small amounts of metal from the edges of coins, then melt down the shavings for profit. The reeded edge made this practice immediately obvious, as a clipped coin would have a smooth edge where it should have been ridged. This helped prevent the devaluation of currency. 💰
- Modern Day Reasons:
- Security: Reeding makes it harder to counterfeit coins, adding a unique texture that’s difficult to replicate perfectly.
- Accessibility: For visually impaired individuals, the reeded edge helps differentiate between different coin denominations by touch. For instance, a US dime has reeding, while a nickel does not, allowing for easy identification. This tactile feature is incredibly helpful! 🙌
7. Why Do We Get “Brain Freeze” (And What Is It)? 🍦🥶
Ah, the sudden, intense headache after devouring an ice cream too fast or chugging a cold drink on a hot day! This unpleasant sensation has a fancy scientific name: sphenopalatine ganglioneuralgia. But what’s actually happening?
- Your Brain’s Alarms Go Off: When something extremely cold touches the roof of your mouth (your palate), it rapidly cools the blood vessels located there. These blood vessels are very close to a major nerve cluster (the sphenopalatine ganglion).
- Sudden Vasodilation: Your body misinterprets this sudden cold sensation as a significant drop in brain temperature. To prevent your brain from “freezing” (which isn’t actually happening), your body rapidly dilates the blood vessels in your head to send a rush of warm blood to the area. This sudden swelling of blood vessels is what causes the sharp, throbbing pain we know as brain freeze. 💥
- Harmless but Intense: Luckily, brain freeze is harmless and usually subsides within a few seconds as your body’s temperature regulation kicks in. The best way to combat it is to press your tongue or thumb against the roof of your mouth to warm it up, or simply slow down your consumption of cold treats! 😜
Unlocking the World’s Hidden Stories ✨
Isn’t it amazing how much fascinating information is hiding in plain sight? From the safety of our airplanes to the accessibility features on our keyboards, the world around us is a treasure trove of clever design, historical quirks, and scientific wonders.
So next time you’re out and about, take a moment to look closer. Ask “why?” and you might just uncover your own “useless but fascinating fact” that changes the way you see the everyday.
What everyday mystery has always puzzled YOU? Share it in the comments below! 🤔💡