  A huge systematics of femtoscopic measurements have been used over the past
20 years to characterize the system created in heavy ion collisions. These
measurements cover two orders of magnitude in energy, and with LHC beams
imminent, this range will be extended by more than another order of magnitude.
Here, I discuss theoretical expectations of femtoscopy of $A+A$ and $p+p$
collisions at the LHC, based on Boltzmann and hydrodynamic calculations, as
well as on naive extrapolation of existing systematics.
