Observational consequences of a "domain" structure of the universe

It has been suggested that the spontaneously broken gauge symmetries, recently postulated in connection with unified theories of weak and electromagnetic interactions, might have the symmetry restored at sufficiently high temperatures, in analogy with the spontaneously broken rotational invariance in a ferromagnet. Weinberg has also raised the possibility that, in cooling from the "big bang," the universe might have developed spatial "domains" with different preferred directions in charge space. We consider possible observational consequences of such a structure, particularly in terms of observations on electromagnetic radiation from astronomical sources. We find that a discontinuous boundary between such domains would act as a perfect mirror, reflecting all incident electromagnetic radiation. If the transition between domains is smooth, with a transition region whose thickness is large compared with a wavelength of the incident radiation, there is no reflection and one observes a transmitted wave identical to the incident wave.