I learned this today. Cats don’t so much retract their claws as lift them off the ground using tendons. Their claws are then hidden by their fur. Cats have five claws on their front paws and four claws on their back paws. The front claws are usually sharper than the back ones. Cats’ claws continue […]
#104 How do cats retract their claws and why can’t other animals? 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. The mile we use today originated with the Roman mile which was one thousand paces. The word “mile” comes from “mille passus”, which means 1,000 paces. Ancient measuring systems all began by using body parts to measure things. The oldest unit of length is the Egyptian cubit, although they didn’t call
#102 Why do we use miles as a unit of measurement Read More »
I learned this today. Light can’t escape from a black hole because of the curvature of space caused by gravity. In physics, gravity is the weakest of the four fundamental forces. The forces are gravity, the electromagnetic force, and the strong and weak forces that exist in atoms. Isaac Newton described gravity as a force
#101 Why can’t light escape from a black hole? 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. A Lagrange point is a point of equilibrium where the gravitational forces of two large objects balance out the centripetal force. A third object can remain motionless in a Lagrange point without having to use any power. Centripetal force is the force that acts on an object in a circular motion,
#99 What is a Lagrange point? Read More »
I learned this today. Cold fusion is not possible because atoms repel each other and thermo energy on the scale of millions of degrees is necessary to overcome this repelling force and drive them together. Nuclear fusion is the reaction that takes place in stars. It is the process by which they burn their fuel,
#98 Why is cold fusion not possible? Read More »
I learned this today. Wire fraud and mail fraud are federal crimes in the United States that concern transferring something connected to fraud by mail, email, phone, radio, or television. To be guilty of wire fraud, somebody must have “voluntarily and intentionally devised or participated in a scheme to defraud another out of money” and
#97 What are mail fraud and wire fraud? Read More »
I learned this today. There is evidence of a dentist from 12,000 BC. Before humans took up agriculture, possibly about 12,000 years ago, we were hunter-gatherers and we had less tooth decay than when we became farmers. Researchers were able to extract dental plaque from the teeth of 34 prehistoric European skeletons. Dental plaque is
#96 When was the first dentist? Read More »
I learned this today. In the 1930s, the introduction of the refrigerator into homes put the ice harvesting industry out of business. Any kind of food, be it meat, fish or vegetable, is going to start going bad. Food decays because micro-organisms like bacteria feed on the food. Bacteria use enzymes to break down the
#95 What happened to the ice industry? Read More »
