Physicist Enrico Fermi discovered the potential of nuclear fission in 1934, when he bombarded uranium atoms with neutrons and was surprised to discover that the products of this reaction were much lighter than uranium. On December 2, 1942, Fermi created... | READ MORE >
With the exception of Native Americans, all persons living in the United States are descended from immigrants or slaves who came to the country during the last 400 years. By the late seventeenth century, foreign-born persons constituted seventy-five... | READ MORE >
Much of the 3,000-mile (4,828kilometer) Great Wall of China was constructed during the Ming Dynasty (1368-1644) [see timeline of Chinese history] to prevent attacks from rival forces, although officials as early as the fifth century BCE also built... | READ MORE >
