Special Relativity over the Field of Rational Numbers
  We investigate the question: what structures of numbers (as physical quantities) are suitable to be used in special relativity? The answer to this question depends strongly on the auxiliary assumptions we add to the basic assumptions of special relativity. We show that there is a natural axiom system of special relativity which can be modeled even over the field of rational numbers. 
Madar\'asz X. Judit and Gergely Sz\'ekely
math-ph gr-qc math.LO math.MP