1) The concept of gravity was famously described by Sir Isaac Newton after an apple fell on his head.

2) The process of impeachment involves charging a public official, such as a president or high-ranking government official, with misconduct and potentially removing them from office through a trial and vote by the legislature.

3) The Battle of Waterloo in 1815 marked the final defeat of Napoleon Bonaparte and the end of his reign as Emperor of France.

4) The development of the microprocessor by Intel in 1971 paved the way for the modern computer and led to the exponential growth of computing power.