I obtained an analytical description of time dilation and length contraction which describes why these occur at high speeds. However there was no such analysis of Einstein's famous equation E=m(c squared). Instead, a derivation that I found in http://www.karlscalculus.org/einstein.html [Broken] starts off with m = m0 √1 - v2/c2 Then they derive the formula using calculus. Is an analytical treatment for E=m(c squared) possible? Is there any thought experiment which helps us to realise the applicability of the mass-energy equivalence?