What’s a forgotten invention from history that could be useful today?

 Today, air conditioning consumes nearly 10% of global electricity. Yet 3,000 years ago, Persian engineers cooled desert homes by up to 20°F without a single watt of power.

In hot climates, modern HVAC systems can account for 70% of summer power use. This creates a vicious cycle: burning fossil fuels to run air conditioning warms the planet, which in turn requires more cooling.

The ancient solution to this problem was the bâdgir, or windcatcher. It looks like an ornate, rectangular chimney jutting out from the roof of a traditional Middle Eastern home. But rather than venting smoke out, a windcatcher is designed to pull cool air in.

Higher off the ground, the air is cooler and flows faster. The windcatcher's tall tower acts like a scoop, catching these high-altitude breezes and funneling them down into the building’s interior. As this cool air sinks, it displaces the hot air trapped inside, which is then pushed out through openings on the opposite side of the tower.

The most advanced windcatchers are combined with a qanat, an underground water channel. Incoming air is routed into a basement level where it passes over cold, flowing water. The water evaporates, absorbing heat and chilling the air even further before it circulates into the living spaces. This passive evaporative cooling effect creates a stark contrast to the scorching heat outside.

At night, the process runs in reverse. Dense, cold night air settles into the house, while residual heat absorbed by the thick walls during the day rises up and out through the tower.

For centuries, windcatchers allowed cities like Yazd in central Iran to thrive in a brutal environment. With the advent of mechanical HVAC systems in the 20th century, the bâdgir was largely abandoned in favor of sealed buildings that require massive amounts of energy to stay cool. Today, architects are studying these forgotten structures to reduce the carbon footprint of modern construction. Iterations of the windcatcher are now used to passively cool contemporary structures, including the visitor center at Zion National Park in Utah.

A pavilion in the Dolat Abad Garden in Yazd, Iran, featuring a tall central windcatcher designed to passively cool the interior. Photo by Bernard Gagnon (Wikimedia Commons) is licensed under CC BY-SA 4.0.

What is the most underappreciated invention?

 Many thousands of years ago, a bearded man came rushing into a narrow cave.

He shook the snow off of the animal skins that covered him.

Outside, the wind howled, pressing burningly cold air past the cave in a steady blast, snow moving horizontally in the wind.

He crawled inwards, an armful of sticks and shrub at his side.

Huddled into a corner, his family clung to each other, all of them shivering, hard, their bodies were near the physical limit of cold tolerance, severe hypothermia was only minutes away for his youngest child.

Scrambling, he pressed the shrub down into a pile.

He placed a chosen stick into another set of sticks positioned over each other, wedging it in, holding the sticks down, he inserted a thin cylindrical branch between them, placed his palms on each side, and began pressing them in opposite directions in quick bursts.

He’d been able to achieve a fire once before, months ago. But it was the only time he’d achieved it intentionally.

He began spinning.

His family watched, desperately waiting for the heat.

Slowly, slowly but surely, smoke started to emerge.

A tiny red dot began to form.

Seeing it, he spun the stick harder, his arms burning from the effort.

The dot got brighter and brighter.

And just as the tiny glowing dot is about to convert to a small flame, a gust of wind from the blizzard shifts the air in the cave, blowing it out.

He glanced upwards, his youngest daughter’s eyes were closed, lips blue.

He began working at it again.

His arms burned, he spun as fast as he could.

A red dot formed.

His family watching, hoping.

Brighter, brighter, brighter.

And finally

A small fire is born.

He slowly places small shrubs around it.

He shields the fire with his body, keeping the pulses of air from touching it.

Finally, when he gathers the family around the fire, they huddle closely, soaking in the life-saving heat, saved from death only because he’d succeeded in creating this fire.

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My answer is not that fire is the most underappreciated invention.

My answer is that the tool of man, the fulcrum of our evolution, the reason you sit where you sit today.

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Is right there in your pocket: Lighters.

What are some of the dumbest invention ever?

 This is the thinnest car in the world:

It is only 48 centimeters wide. It is kind of cute in this weird way.

but my god is it functionally problematic. I could knock that thing over easiest. Also, imagine getting hit from the side by another car while in it?

Engineers must have had fun making this one.

What are "Capsule Hotels", a unique and interesting invention of Japan? Why are they popular?

 Capsule Hotels first started in 1989 in the Japanese city of Osaka.

This hotel is for those who want to spend the night just to sleep in the hotel! Here you get a free space to spend a night at a low cost! The rooms are of the size of a bed, hence it is called a capsule!

This type of capsule hotel is also called pod.

Indian Railways has also launched a pod hotel at Mumbai Central Railway Station.

Now such a place has opened in Noida too!

These capsule hotels, visible from the sleeper coach of a bus, are very popular these days!

The reason for its popularity is that it is cheap, clean and modern! This place is very good for those who are fond of travelling!!

Facilities like fan, charging, small TV etc. are available in these capsules!

Pod hotels also have common washrooms, luggage rooms and common areas!!