The idea that all objects fall at the same rate of speed in a vacuum, regardless of their mass, is attributed to Galileo Galilei. He is credited with conducting experiments, such as dropping objects from the Leaning Tower of Pisa, to demonstrate this principle.

While Galileo's experiments were influential, it was Sir Isaac Newton who later formalized this concept into his law of universal gravitation. This law states that every particle in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

However, it's important to note that this principle only applies in a vacuum, where air resistance is absent. In the real world, objects with different shapes and densities experience varying amounts of air resistance, which affects their falling speed.