Hello folks. Just registered, first post (moved here from the Physics forum). Let there be a de Sitter metric in static coordinates: ds^2 = - [1 - (r/R)^2] c^2 dt^2 + dr^2 / [1 - (r/R)^2] + r^2 d(omega)^2 where: r is the radial coordinate R is the cosmological horizon coordinate time t is as observed from r = 0, the "origin", which we will call point O. Let rP be the radial coordinate (i.e. as observed from the origin O) of a static point P. Let's change now to a static frame of reference centered in said point P, and call r' the radial coordinate in that frame of reference. What is r'O, that is the distance from P to O as observed from the frame of reference centered in P? If you prefer to give the general equation for r' as a function of r, rP and R, that's fine. Thank you in advance for your help.