The length of objects seems invarient. Minkowski was often the brains behind Einstein, but we see the mentoring often swapped places with the two as each... Improved the other.

Boosts and invarients, radar measurements. Sª= ∆tª+ ∆xª where a=2 but my devise won t print that nicely yet. This equation as building on the Pythagorum theory is perhaps an invariant. Call it a transNewtonian!