Lesson 130 – History 05

Summarize each of the inventions you studied this week and how they impacted history. 

Next, think about how Maxwell predicted the existence of electromagnetic waves, and then Hertz confirmed them using experiments in a laboratory. We know Maxwell’s math is correct because we can test its predictions. In cosmology, scientists build models of what they believe happened at the beginning of the universe (such as in the “Big Bang”). But, we cannot test their models because we can’t go back to the beginning of the universe and see if it happened the way the models predict. What are the similarities and differences between the Maxwell/Hertz approach and the “Big Bang” approach, and which approach can we be more confident in — and why?

The essay today

Light Switch

The light switch is used for turning lights on and off. John Holmes invented the light switch in 1884. He was a Quaker, who were a bunch of humble Christians. He was born in England. The light switches before the modern ones were actually dangerous. You could get shocked, and to make matters worse, your house could burn down. So Holmes invented the light switch. It was much safer, and it wouldn’t catch on fire. Now we have new designs of light switches, and they are safer.


A skyscraper is a large building with a lot of room inside. It provides offices and homes. William Jenney invented the skyscraper. There was a problem that the walls had to be super thick to hold up the extra floors. His eureka moment was when he came home from work early. He walked into the house and his wife set a heavy book on a birdcage. He realized that the birdcage could hold up such a heavy book. He realized that instead of making thick walls, make a frame. Now that we have skyscrapers, we have very tall buildings, like the Empire State Building.


Dish washing was pretty hard work. Before a dishwasher, there was a room called the scullery. It was waterproof. It was also six inches down further than the other rooms in case there was a leak or a mini flood. The scullery was also unsanitary. Often, people got sick. A dishwasher is a quick and easy way to wash dishes. There is a rack that holds a bunch of dirty dishes. It first sprays soapy water on the dishes, then it spays hot water. The hot water is so hot that it kills bad microbes. After that process, it sprays cold water. Some dishwashers dry them with heat or air. Josephine Cochrane invented the dishwasher. She was born in 1839, and in Ohio. She grew up in Indiana. She had a sister named Irene. Josephine’s grandfather, John Fitch, invented an early steam boat sometime in the 1700’s. Josephine got married to a man in 1850 and his name was William Cochrane. William went to California during the gold rush, but was unsuccessful. So he came back home. He began a dry goods store. He became successful and moved his family to a large mansion. They had parties and ate off of china plates from the 1600’s. Sometimes the servants broke them while washing the china because it was really old. Josephine wanted a better way to wash them because they were old and valuable. She tried actually invented her own dishwashers. But she needed help from a mechanic, so they worked together. Eventually, she invented the dishwasher in 1886. In 1883, William died under the influence of drugs. He left Josephine with debt and due payment and they were not actually that rich. First, Josephine sold some dishwashers to her friends. Then, in 1893 and in Chicago, she advertised her dishwasher in World’s Fair. She got an award, and the word spread of this quick dishwasher. She made a factory and sold her dishwashers. Restaurants became interested in Josephine’s dishwasher. In the 1950s, a lot of houses had dishwashers. We no longer have sculleries. The reason why the dishes were so clean was because of something called phosphates in the soap. But the government banned certain soaps from having phosphates in 2010. Now our dishes still have bits of food because of phosphates not being contained. Phosphates is said to be hurting the lake and river environments. When the water drains out of our houses, it goes into lakes and rivers. It kills fish. When soap stopped carrying phosphates, people thought their dishwashers were broken. This was my favorite invention.

Electromagnetic Waves

Electromagnetic waves are hard to explain, but to put it simply, they are magnetic waves in the air. James Maxwell wrote an article and said that there were such things as electromagnetic waves, but he never actually proved it. Heinrich Hertz actually proved it, though. He didn’t see a use it. Unfortunately, he died at age 36. Electromagnetic waves are used mainly for things such as WiFi signals, x-rays, and even things like microwaves. When Hertz died, frequency measurements were called hertz in his memory.

When you compare the Big Bang theory and the electromagnetic waves, we know the electromagnetic waves are real because it was proved, whereas we don’t know for sure if the Big Bang theory is real or not because we weren’t alive to experience it and there is not a good way to prove it.


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