In the natural state of the atmosphere, a free falling body will be disturbed by air resistance. To eliminate this interference, it is necessary to create a vacuum environment. In Galileo's era, people can not create a vacuum environment by technical means. Therefore, Galileo can only put aside the factors of air resistance in his mind and imagine the movement of a falling body in a vacuum, so as to obtain the law of free falling body, It overturns Aristotle's conclusion about falling body.
ite for Galileo's law of free fall?
People at that time could do the same thinking experiment