Is time enough in order to know where you are?
  This talk discusses various aspects of the structure of space-time presenting
mechanisms leading to the explanation of the "rigidity" of the manifold and to
the emergence of time, i.e. of the Lorentzian signature. The proposed
ingredient is the analog, in four dimensions, of the deformation energy
associated with the common threedimensional elasticity theory. The inclusion of
this additional term in the Lagrangian of empty space-time accounts for gravity
as an emergent feature from the microscopic structure of space-time. Once time
has legitimately been introduced, a global positioning method based on local
measurements of proper times between the arrivals of electromagnetic pulses
from independent distant sources is presented. The method considers both
pulsars as well as artificial emitters located on celestial bodies of the solar
system as pulsating beacons to be used for navigation and positioning.
