The course will discuss basic concepts in physics prior to the 20th century and the backdrop to the emergence of the Special Theory of Relativity. Elements of Special and General Relativity will be discussed at a non-technical level. These concepts will be used to explain how very massive stars inevitably collapse to form black holes. Their observational signatures will be discussed. The work of Hawking leading to the prediction that black holes emit faint radiation will be explained. Finally, the possibility of existence of wormholes leading to time travel will be explored.