Cosmology: theory 1 Dispersion measure 1 Dispersions 1 Equivalence classes 1 Equivalence principles Free electron 1 Large scale structure of universe 1 Line of Sight 1 Lines-of-sight 1 Photons 1 Radio bursts 1 Radio signals 1 Weak equivalence principle 1 cosmology: theory 1 large-scale structure of Universe 1