Aristotle believed a heavy object falls faster to the ground than a light one, which no one disputed until the beginning of the 17th century when Galileo found that the mass of an object had no impact on how quickly something fell. To explain why a feather falls more slowly than a ball, Galileo theorized that it experienced more friction in the air. In 1644, Evangelista Torricelli created a vacuum within a tube for the first time which confirmed Galileo's theory. In 1670, Isaac Newton explained that the way anything falls is based on a gravitational force which attracts any object to the center of the earth. He also declared that when in a vacuum acceleration is equal to the gravitational constant, so all objects fall at the same speed regardless of their mass. Newton theorized that earth's gravitational constant is what retains the moon. Albert Einstein uprooted many of these theories with his theory of relativity. He believed that an object's movement is not determined by the forces applied to it, but by the space time configuration. From then on, it was believed that gravity interacted with space and time.