Each and every scientist has different achievements and different impacts to the world. Otto Hahn, a German scientist, is also one of the scientists who created a great impact on the world. His discovery opened up a new era in human history. In this paper, you would find out what he did and how his discovery did creates an impact to this world; but first, let’s takes a look at how did he become a scientist. On March 8, 1879, a boy was born into a glazier family and was named Otto Hahn. Since he was a kid his parents wanted him to become an architect. However, he eventually decided to study chemistry at the University of Marburg. As he grew up, he became interested in industrial career. Because his intended employer planned to use him in the international aspects of the business, Hahn left Germany in 1904 to spend several months in England, where his primary goal was to master the language. Since he felt the need for some kind of other activity as well, he secured a place in William Ramsay 's laboratory at University College, London. While working on a crude radium preparation that Ramsay had given to him to purify, Hahn showed that a new radioactive substance, which he called radiothorium, was present. Fired by this early success and encouraged by Ramsay, he decided to continue with research on radioactivity rather than go into industrial career like he first planned to. After returning to Germany in 1906, Lise Meitner, an Austrian-born physicist, joined Hahn and they