1. The problem statement, all variables and given/known data Wikipedia states that the Maclaurin Series expansion of the Lorentz factor is http://en.wikipedia.org/wiki/Lorentz_factor" [Broken] 2. Relevant equations Relevant equations are all found in that article 3. The attempt at a solution I don't see how this comes about. My attempt: 1+0+1/2+... How can beta be in the expansion, when it should be substituted by 0, since the Maclaurin Series is about 0?