# What Are the Contributions of Isaac Newton?

**Isaac Newton developed the principles of modern physics through his studies on mathematics, optics and motion.** His book "Philosophiae Naturalis Principia Mathematica," or "Mathematical Principles of Natural Philosophy," is often cited as the most influential document on physics. Isaac Newton is most famous for his law of gravitation.

Isaac Newton played an integral role in the scientific revolution that occurred during the 17th century. He studied optics heavily and delivered annual lectures as a professor. A major component in his optics study was the reflecting telescope that he invented in 1668. His telescope was the first achievement that gained him fame and acclaim. The telescope also allowed Newton to study outer space and prove his theory of light and color.

Isaac Newton's theories on gravity explain motion in the universe. He started studying why planets orbit each other and came up with three basic laws of motion. The first states that an object does not move unless force is applied to it. The second states that force is equal to mass times acceleration, and a change in motion is proportional to the force applied. The third states that there is an opposite and equal reaction for every action. These laws provided many answers to scientific questions, including how the Earth's tides are created by gravitational forces from the moon and sun, and why the moon orbits the Earth.