A ripe apple falling from a tree has inspired Sir Isaac Newton to formulate a theory that describes the motion of objects subject to a force. Newton’s equations of motion tell us that a moving body keeps on moving on a straight line unless any disturbing force may change its path. The impact of Newton’s laws is ubiquitous in our everyday experience, ranging from a skydiver falling in the earth’s gravitational field, over the inertia one feels in an accelerating airplane, to the earth orbiting around the sun.