Hi, I am a novice here and i am trying to solve the following problem: 1.Show that Galilean relativity transformation produces inconsistent classical physics result when used with equation of expansion of light sphere. (2 different frames) 2. x2 = x1 - vt1 y1 = y2 z1 = z2 t1 = t2 expansion of light sphere: x12 + y12 + z12 - ct12 = 0 x22 + y22 + z22 - ct22 = 0 3. I have substituted the Galilean transformation equations in the later expansion of the light sphere equations: x12 + y12 + z12 - ct12 = 0 x22 + y22 + z22 - ct22 = 0 x12 + y12 + z12 - ct12 = 0 = x22 + y22 + z22 - ct22 x12 + y12 + z12 - ct12 = x22 + y12 + z12 - ct22 x12 - ct12 = x22 - ct22 x12 - ct12 = (x1 - vt1)2 - ct22 x12 - ct12 = x12 - 2vt1 + v2t12 - c2t22 So far I have not been able understand the inconsistency and it's bothering me. I do know about Lorentz contraction, but don't know where the inconsistency is? Is there something wrong with my thought process? Thanks in advance.