<human>:  Who was the first person to discover the law of gravity?
<bot>: Sir Isaac Newton was the first person to discover the law of gravity. He published his theory of gravity in 1687, and it is still the best theory of gravity that we have today. Newton’s theory is based on the idea that gravity is caused by an invisible field of force, which he called the graviton. This idea is not supported by modern physics, but it is the best theory that we have.