Does the Inertia of a Body Really Depend Upon its Energy-Content?

In this paper I will investigate the postulates of m = L/c2 or in its famous form E = mc2, i.e. mass has energy1. There are two concepts to discuss, i.e. inertia and energy. To illuminate these concepts2 I present two new postulates, 1-2, and one requirement 3: 1. Nothing exists in isolation, i.e. everything exists in relations. 2. Motion is a fundamental quality and property of the Universe and Nature. 3. Every concept has to represent the physical reality directly and concretely. The concept Energy has an outstanding position in physics. However, based on the requirement, the concept energy does not fulfil the demand; and based on 2-3 there is no rest energy E0 in universe. The concept Inertia does not fulfil postulate 2 and the requirement 3, i.e. a body in rest doesn´t exist and a body in linear motion doesn´t exist. Hence, Inertia does not represent the physical reality concretely and directly; and in the Universe there is no rest mass m0, based on the second postulate. Since c denotes the speed of light, c2 is pure mathematics since it does not have any direct representation in the reality, which is needed due to the third postulate; hence c2 is not valid. We can also notice that none of the concepts E, m0 and c2 fulfils the criterion by Einstein himself: Every element of the physical reality must have a counterpart in the physical theory. An alternative theory in the paper...