MICROWAVE BACKGROUND ANISOTROPY IN LOW-OMEGA(0) INFLATIONARY MODELS AND THE SCALE OF HOMOGENEITY IN THE UNIVERSE

We study the microwave background anisotropy due to superhorizon-size perturbations in open universes with negative spatial curvature. Using results on the low-order temperature multipole moments from the Cosmi c Background Explorer satellite, we find that if the homogeneity of th e observable Universe arises from an early epoch of inflation, the pre sent density parameter cannot differ from unity by more than the obser ved quadrupole anisotropy, \1 - Omega(0)\ less than or similar to Q si milar or equal to 5 x 10(-6), assuming preinflationary density perturb ations to be of order unity. With this assumption, inflation models wi th low Omega(0) either do not fit the microwave background observation s or they do not solve the horizon problem.