I learned this today. A machine gun works by using the recoil or the gas of the cartridge explosion to reload and re-cock the gun after each shot. There are basically three different types of machine gun: recoil actuated, gas-operated reloading, and externally actuated. Recoil and gas-operated reloading guns follow the same theory, which is […]
#131 How does a machine gun work? Read More »
I learned this today. We have 24 hours in a day because of Hipparchus. We have 60 seconds in a minute and 60 minutes in an hour because of Claudius Ptolemy, Al-Biruni, and the Babylonians. Before we look at this topic, we have to remember that needing to know the time exactly is a fairly
I learned this today. Pykrete is a frozen material made of 14% sawdust and 86% water. It is as strong as concrete. Pykrete was put forward during World War II by Geoffrey Pike, who was the head of Project Habakkuk, an idea to use pykrete to build a floating aircraft carrier. The material was like
#118 What exactly is pykrete? Read More »
I learned this today. Shoe sizes in America and the UK are measured in barleycorns. Nobody knows when people first started wearing shoes, but experts think it might have been about 40,000 years ago. The little toe bones of skeletons found after 40,000 years ago are thinner than the bones found before. They deduce that
#103 Why do we use those measurements for shoe sizes? Read More »
I learned this today. Flight or fight, the stress response, was first described by Walter Bradford Cannon in 1915. In 1915, Cannon published Bodily changes in pain, hunger, fear and rage. He noticed that when cats were threatened, their bodies released the hormone adrenaline / epinephrine, which lead to a series of other bodily changes.
#100 Who came up with the phrase “flight or fight”? Read More »
I learned this today. The caliber of a cartridge relates to the size of the gun’s barrel in hundreds of an inch in America or in mm in Europe. A gun cartridge consists of four parts. It has an outer casing, usually made of brass because it is very good at handling the pressure of
#94 What is the caliber of a gun cartridge? Read More »
I learned this today. The Panama Canal has reduced the journey from the Atlantic Ocean to the Pacific Ocean by 8,000 nautical miles (14,818 km), about 22 days. Before the Panama Canal was built in 1914, boats would have to either sail around the southernmost point of South America or up through the Bering Strait.
#66 How much time does the Panama Canal save a ship? Read More »
I learned this today. The tallest a human could potentially grow is about 9 feet, 274cm. Humans grow because of a growth hormone called somatropin. It stimulates growth by telling cells to reproduce. It is released by the pituitary gland. It reacts with a specific receptor on the surface of cells, and it stimulates cell
#58 How tall could a human grow? Read More »
I learned this today. Standardized time and time zones weren’t needed until rail travel became popular in the 1850s. Having international time zones seems common sense to us these days. How can you conduct business in New York from London if you don’t know what time it is there? And knowing how many hours ahead
#37 Why did we start using time zones? Read More »
I learned this today. The Kardashev scale describes five different levels of technological civilization, and we, as a species, haven’t even reached level 1. The Kardashev scale was, unsurprisingly enough, thought up by a Russian astrophysicist called Nikolai Kardashev in 1964. He originally decided on three types of civilization, but this has been extended to
#33 What are the 5 types of civilization? Read More »
