Sir Isaac Newton made many scientific discoveries in his life, but he is most widely known for his contributions to physics and the study of gravity. Newton's accomplishments in physics were so impressive that he received "knighthood" status in England, which is why "Sir" is before his name.
Sir Isaac Newton was also responsible for developing the three laws of motion that define the laws of modern physics. He also invented calculus, which helped pave the way in finding more capable ways of figuring out mathematical challenges. Newton's experiments with light resulted in him discovering the color spectrum through the use of a glass prism.