Based on Saleh Theory, the Universe has a rotational motion around itself and an expansion from the inside out. So its total velocity is equal to the rotational velocity plus the linear one. The linear is the effect of the remaining energy of the primary energy of the Big Bang with a constant speed. The rotational motion is of a kind that its angular velocity is constant and created by the effect of a primary energy. So the Universe radius is the only variable parameter. The Universe radius is a vector from the center of the Universe (the beginning of the Big Bang) to the desired point and has a varying length and rotational angle. As a result, the speed of the Universe depends solely on the Universe radius and it increases as a result of a linear velocity. The acceleration of the Universe is the summation of angular acceleration and the linear one. Since the linear and angular acceleration are zero, there is no force that would lead to a change. Therefore, there is no force that would be applied from the outside and the linear and angular accelerations are zero; the variant speed is based on the variant radius. In this article we have proved that how the expansion could be explained based on these motions.
