With a down to Earth experiment, this article hopes to introduce a way that can help in principle to solve the mystery how gravitational force is caused. To help us to figure this force out, all we need is to allow an acceptance of a fluid, which not only fulfills all space we can conceive in the universe but also has a high intrinsic pressure. Both such a fulfillment and intrinsic pressure can find its answer in this experiment. Let's call this fluid Aether. This experiment would also lead to a believing that attractive force found in all gravitational interactions is not a reality. Instead, such an attractive force is actually a pair of pushing force acting on a pair of objects. In other words, attraction is a misconception, an illusion.
As the article goes on, it will soon come to a conclusion that Aether as a fluid has an intrinsic pressure in the order of $\times (10^{12} kg/cm^2$). Each particle comprising the Aether fluid has extremely small size, far smaller than any electron. Containing the smallest particles in the universe, Aether fills in every space that human can find, except at where geometry would not allow, such as at the core space of a tetrahedron, which is formed by having 4 Aether particles closely packed together. Of course, to enable the construction of such a tetrahedron with the Aether particles, geometry requires us to assume each of them to be a round ball. Only in such a core space does genuine vacuum exist \textemdash human beings can never reach it.
With the huge intrinsic pressure, all of the tiny particles comprising the Aether fluid must be highly packed with each other. Since we have not developed any instrument to test the mass of Aether, any concept about their density in this article would be expressed as particles per unit volume other than something like gm/cm^3.
