Since antiquity, people have tried to understand the behavior of the natural world. One great mystery was the predictable behavior of celestial objects such as the Sun and the Moon. Several theories were proposed, the majority of which were disproved.
The philosopher Thales (ca. 624–546 BC) first refused to accept various supernatural, religious or mythological explanations for natural phenomena, proclaiming that every event had a natural cause. Early physical theories were largely couched in philosophical terms, and never verified by systematic experimental testing as is popular today. Many of the commonly accepted works of Ptolemy and Aristotle are not always found to match everyday observations.
Even so, many ancient philosophers and astronomers gave correct descriptions in atomism and astronomy.
Leucippus (first half of 5th century BC) first proposed atomism, while Archimedes derived many correct quantitative descriptions of mechanics, statics and hydrostatics, including an explanation for the principle of the lever. The Middle Ages saw the emergence of an experimental physics taking shape among medieval Muslim physicists, the most famous being Alhazen, followed by modern physics largely taking shape among early modern European physicists, the most famous being Isaac Newton, who built on the works of Galileo Galilei and Johannes Kepler. In the 20th century, the work of Albert Einstein marked a new direction in physics that continues to the present day.
