北师大版模块7 Unit 20 Lesson 3.ppt

If you had to choose the single most important discovery of the 20th century, you would have a real dilemma on your hands. In just 100 years, the world changed completely. Amazing discoveries were made in medicine, communications and transport, not to mention our knowledge of the world and space. Medical advances ranged from discovering the causes of diseases under microscopes to surgical procedures replacing diseased organs with donated ones. Communications changed with the introduction of mobile phones and the way we correspond went from writing letters to emailing. We started flying around the world and meanwhile, scientists figured out how to split the atom, previously thought to be the smallest particle of matter in the universe. Although it is impossible to choose the most important discovery, it is possible to single out a few pioneers of the 20th century. Here are five of them. One of the 20th centurys premier scientists was Albert Einstein. In the summer of 1905, this outspoken young man was rocking his one-year-old baby when he was suddenly inspired. “E=mc2” was born. E=mc2 showed how a small piece of mass could produce unbelievable amount of energy. Einstein then showed in his “theory of relativity” that not even time, mass or length are constant — they change according to our experience of them. Einstein had already become world-famous when a young ex-lawyer, returning from the First World War, started work in California. Using the most high-powered telescope of the time, he began the long, slow process of exploring our galaxy. Edwin Hubble was about to make astronomys greatest breakthrough of the century. He discovered small areas of mist which were in fact galaxies like our own, millions of light years away from us, which proved that the universe was vastly larger than had previously been thought. In 1929, another far-reaching finding was made by the son of a Scottish shepherd. Before he went on holiday, biolog