<human>:  I have a question about the physics of sir isaac newton. Where did he get the idea for his law of universal gravitation?
<bot>: Newton’s law of universal gravitation is a mathematical expression that describes the gravitational force between two objects. It is a fundamental law of nature. It states that the force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.