  It was thought that the van der Waals force and gravitational force were
distinct. Now a model is used to describe the attraction between macroscopic
objects according to van der Waals interaction. The force between two objects
with thermal equilibrium deviates from the law of universal gravitation
slightly, and the gravity on the earth is explained approximately. We argue
that the gravitational force is the van der Waals force actually. In other
words, the gravitational force and mass are related to the quantum fluctuations
of electron clouds in atoms, and these parameters are dictated by dielectric
susceptibility.
