Anything Beyond Special Relativity?

Abstract

At a time when we are all fully aware of the remarkable longevity of Special Relativity, I review some recent advances in “beyond Special Relativity” research, attempting to make the case that this field is reaching a fair level of maturity. I briefly discuss both some recent attempts to set up systematic general searches of departures from Special Relativity, and some more focused programmes which find their motivation in certain key aspects of the quantum-gravity problem and in certain open issues for cosmology. For one of the hypothesis being considered in the quantum-gravity literature, the one of Planck-scale effects that, while inducing departures from some Special-relativistic laws, do not give rise to a loss of equivalence among inertial observers, I give a rather detailed selfcontained introduction. I also stress the fact that beyond-Special-Relativity research is now being developed with a methodology that in some ways resembles the one adopted in the “beyond the Standard Model” particle-physics research programme. I argue that the rich tradition of beyond-Standard-Model research should be followed even more closely, but I also stress that some differences will inevitably remain, reflecting the differences between setting up test theories for a “universal”/“frame” theory (Special Relativity) and for a nonuniversal theory (the Standard Model).