> We know what happens to matter at those speeds, it becomes infinitely "heavy" and would experience time in relative light-years (I mean time-to-travel at ligh

> We know what happens to matter at those speeds, it becomes infinitely "heavy" and would experience time in relative light-years (I mean time-to-travel at light speeds) no? I don't think we do know what happens. Relativistic mass approaches infinity at exactly c. Beyond c we obviously have no data, but if we just apply the same equations the relativistic mass would drop back to a finite value. A finite complex value.