In the early 1990s, Mazda engineers came up with one of the most unusual concepts in automotive history—the Mazda Suitcase Car.
Built inside a standard Samsonite suitcase, this fully functional vehicle was created in 1991 during an internal competition meant to spark creativity and innovation.
A team of seven engineers used parts from a 50cc Honda scooter to build the compact, three-wheeled machine, which could reach speeds of up to 30 km/h (18 mph).
To operate it, users would unzip the suitcase, unfold the frame, attach the wheels and handlebars, and fire up the small engine.
Sonoluminescence.
If you collapse an underwater bubble with a soundwave, light is produced, and nobody is totally sure about why this happens.
There are in fact several competing theories still evaluated by scientists.
Hey @elonmusk, since there is great concern of declining birth rates, and you either are or soon to be the richest person in the world and greatly care of said topic, you should offer money to married couples who have more then 2 children (thus increasing population per person)