Main Idea Practice 5

Sir Isaac Newton was contemplating the universe in his garden one day in 1665 when he noticed an apple fall from a tree. Newton wondered to himself, "Why should the apple always fall to the ground? Why does it not go sideways or upwards but directly toward the Earth's center?" After much contemplation Newton concluded that objects are pulled to the Earth through a force that he called gravity, which means heaviness in Latin. On July 5th, 1687 Newton formally expressed his law of universal gravitation in series of books called The Principia.

A few months before World War II started, Albert Einstein wrote to President Roosevelt. He warned Roosevelt that the Nazi's were conducting atomic research and that it would be bad if they were to win the race to build an atom bomb. Einstein recommended that U.S. become involved in uranium research. As a result of this letter, the U.S. joined the atomic race and poured billions of dollars into the field. The U.S. won the race and became the first country to build an atomic bomb. The bomb was then used in Japan, killing hundreds of thousands of civilians. In 1954, a year before his death, Einstein would refer to the moment that he signed the letter to President Roosevelt as the greatest mistake of his life.

For most of human history, people thought that the Earth was the center of the Universe. But Nicolaus Copernicus changed this when he theorized that the Universe was heliocentric, or sun-centered. Interestingly, Copernicus had most of this theory worked out some time around 1514. His work was fully articulated by 1532. Yet publication of this text was not completed until 1543 as he lay dying. Some scholars believe that Copernicus delayed publishing this work because it contradicted the Catholic Church's view that the Earth was at the center of the Universe. Copernicus's may have been smart in doing so because the Church did not formally accept his view of the universe until 1822, almost 300 years later.

Galileo Galilei was an influential scientist and one of the early developers of the refracting telescope. In 1632 Galileo published a book called Dialogue Concerning the Two Chief World Systems, in which he compared the Copernican view of a heliocentric universe (one where the sun is at the center) with the geocentric view (one in which the Earth is at the center). The Church took offense with how Galileo portrayed the geocentric view using a character named Simplicio, which has undertones of simpleton in the Italian language. Galileo was put on trial before the Roman Inquisition. The Inquisition ordered Galileo to recant his ideas. His book was banned, he was forbidden from publishing anything else, and he was sentenced to house arrest for the rest of his life. I guess it's not just what you say that's important but how you say it.

Nikola Tesla was an inventor and physicist who is best remembered for his contributions to the AC power system and radio. He may have also built a death ray. At a 1937 luncheon in his honor, Tesla claimed to have created a weapon that could shoot a beam of energy capable of bringing down fleets of airplanes. He further claimed to have built, demonstrated, and used this weapon. When Tesla entered negotiations with the U.S., the U.K., and the Soviet Union to sell his device, Tesla claimed that one of these parties broke into his room and tried to steal his invention. He also said that such a theft would be impossible since the blueprint for the weapon was entirely in his mind. Unfortunately, Tesla died with the blueprint in his mind. On second thought, maybe that's not such a bad thing.

Marie Curie not only the first woman to have won a Nobel Prize, she is also the only person to win a Nobel Prize in two different sciences. Most notably, Marie Curie discovered radiation. She was also the first person to use radiation to treat tumors. Curie experimented extensively with radioactivity during her scientific career. Unfortunately for her, the damaging effects of radiation were not known then. Her exposure to radiation most likely was the cause of her blindness and early death. Even today her scientific papers are too dangerous to handle without protective equipment. These documents are stored in lead-lined boxes. Even her cookbook is radioactive. She must have made some explosive dishes in her lifetime.

Cotton candy was first made in Europe during the 17th century. Back then it took a lot of work to make and cost a lot of money, so most people couldn't enjoy it. Things changed in 1897 when William Morrison and John Wharton invented machine-spun cotton candy. Using machines made cotton candy much cheaper to produce. Morrison and Wharton introduced their treat at the 1904 World's Fair. They called the treat "fairy floss" and people fell in love. It was Joseph Lascaux who actually coined the phrase "cotton candy" in 1921. Now cotton candy can be found in carnivals, fairs, and circuses around the world. Aside from the delicious taste, the best part about today's cotton candy is its affordability.

Computers are very complex machines, but everything they do can be put into two basic categories: inputting and outputting. Inputting is when the computer accepts information entered by the user. Outputting is when the computer returns information to the user. When you press a key on your keyboard, you input information. When the letter that you pressed appears on your screen, your computer is outputting. Both inputting and outputting require the computer to process information, but input is controlled by the user and output is controlled by the computer. Without inputting and outputting, there would be no computing.

Most phones sold today have an operating system, or OS, that was either designed by Apple or Google. Apple makes the iOS operating system powering their iPhones and iPads. Google makes the Android OS used on many different phones and tablets. Both operating systems allow users to connect to app stores and download applications. A key difference between these operating systems is that Apple makes all of its own hardware. The iOS operating system only appears on products created by Apple. This gives them greater control over how their OS is used. Many different manufacturers like Samsung, Sony, and LG use the Android operating system. Which one do you like better: Android or iOS?

Fireworks have been around for at least as long as gunpowder, and both gunpowder and fireworks are Chinese inventions. During the tenth, eleventh, and twelfth centuries, fireworks were sold in Chinese markets as a way to get rid of evil spirits. During the thirteenth century, Chinese merchants developed rocket propulsion. This allowed fireworks to travel great distances, much like they do today. In the 17th century, Chinese fireworks were popularized in Europe. After becoming popular with the British, fireworks spread all over their vast empire. Nowadays people around the world celebrate with fireworks. Whether at a sporting event, concert, or public gathering, fireworks signal a great celebration.