I learned this today. London was built where it is because it is the closest point to the sea that could be bridged. There may have been a small settlement where London is from prehistoric times, but there is no real evidence for that. There is, however, evidence of a bridge crossing the river Thames […]
#84 Why is London where it is? Read More »
I learned this today. Quartz watches are far more precise than mechanical clocks because they make quartz crystals oscillate at a very precise frequency. A mechanical watch has an accuracy of ±5 seconds a day. Quartz watches have an accuracy of about ±5 seconds a month. For comparison, an atomic clock has an accuracy of
#83 How does a quartz watch work? Read More »
I learned this today. Our skin can allow sweat out, but it doesn’t let water in thanks to a thin layer of fat between the outermost layers of skin cells. The skin is said to be the largest organ in the human body. Actually, by surface area, it is the second largest because the inside
#82 Why is skin waterproof? Read More »
I learned this today. Whales make use of sound in the water because they cannot use their other senses. It is not possible to use light to see underwater because the water scatters it too much. Plus, some whales dive over 2,000m and light doesn’t really penetrate much farther than 1,000m. They also cannot rely
#81 Why do whales make sounds? Read More »
I learned this today. The Middle Ages and the Dark Ages both refer to Europe between the Fall of Rome in 476 AD and the beginning of the Renaissance in the 14th century. Some people say the “Medieval Period” is a better expression, but this means pretty much the same thing. The idea that this
#80 Why do we say Middle Ages and Dark Ages? Read More »
I learned this today. Dogs can probably smell cancer in people. Dogs have a phenomenal sense of smell. They have 300 million olfactory receptors in their noses. We have about 6 million. On top of this, the part of their brain that is devoted to analyzing smells is about 40 times larger than ours. It
#79 Can dogs smell cancer? Read More »
I learned this today. Steam cars outnumbered internal combustion engine cars and electric cars from 1900 until about 1907. Steam engines are external combustion engines because the fuel is burned away from the engine. They release far fewer polluting gases than internal combustion engines. A steam engine works by burning a fuel source to heat
#78 Why were steam cars so popular in 1900? Read More »
I learned this today. When dogs were domesticated, their temperaments changed, their skulls, teeth, and paws shrank, their ears flopped, they became docile, their coats changed color, and they learned to read human expressions. Nobody really knows where dogs were first domesticated. There is some evidence that it was in China over 30,000 years ago.
#77 How did dogs change when they were domesticated? Read More »
I learned this today. The first dinosaur was named 20 years before the word “dinosaur” was invented. Dinosaur fossils have probably been dug out of the ground ever since people have been able to dig, but no one would have known what they were. Chinese writings from about 2000 years ago reference dragon bones, which
#76 When were the first dinosaur bones found? Read More »
I learned this today. All of the black squares in a QR code represent certain pieces of information. QR stands for Quick Response. They were invented in 1994 by Masahiro Hara. He was working for the Japanese company Denso Wave and he got the idea by looking at the black and white pieces on a
#75 How does a QR code work? Read More »
