Not unusual, we still mostly use Newtonian physics even though we know it's only an approximate solution because the math comes out close enough until you get i

Not unusual, we still mostly use Newtonian physics even though we know it's only an approximate solution because the math comes out close enough until you get in the realm where you are talking decent fractions of C. I mean Newtonian methods put is on the moon so they are good enough for a lot of cases. Something as 'simple' as inertia looks very different once you step from Newtonian/special to general relativity.