The paper compares the multi-dimensional energy-momentum equation with the relativistic energy-momentum equation. We show that the relativistic energy-momentum equation is wrong and unable to explain the mass-energy equivalence in the multi-dimensional real space. Bertozzi’s experiment is good evidence for showing the problem of the relativistic energy- momentum equation. Multi-dimensional energy-equation can explain the total energy of the particles in the Bertozzi’s experiment and explain the relationship between the mass-energy formula of the particles in the n-dimensional spacetime.