Einstein revolutionized physics, but some of his ideas are only partially correct. For example, E = mc2 is not always correct, although the photonic energy is equivalent to mass. Although he successfully challenged the wave theory of light, he did not know that the photons’ energy includes electromagnetic wave energy and related gravitational wave energy. Einstein does not understand that massless particles’ energy is incompatible with the electromagnetic energ-stress tensor in Maxwell's theory. Moreover, the related Einstein equation must be modified with additional photonic energy sources having an anti-gravitational coupling. The proof that massless particles can represent the photonic energy is a remarkable achievement of general relativity. Moreover, to accommodate repulsive gravitation, general relativity must be extended to a five-dimensional theory. However, important experiments related to the repulsive gravitation have been essentially ignored by the American Physical Society, who is interested in only big projects.