Representations of the spacetime named for this physicist imply the existence of massless “synchrons” that instantaneously carry momentum across a distance. In the spacetime named for this physicist, the five-momentum contains a particle’s mass and energy in its final two coordinates. The Poincare group contracts to the group named for this physicist in the (*) classical limit. (-5[1])Transformations named for this physicist are uniquely determined by a rotation, (10[1])a translation, and a uniform motion, and Newton’s laws (10[1])are invariant under his namesake transformations. This physicist imagined performing experiments on a moving ship to formulate his namesake principle of relativity. For 10 points, name this Italian physicist who dropped weights from the Leaning (10[2])Tower of Pisa to show their time of descent was mass-independent. ■END■ (10[1])