The current suite of results from Cosmic Microwave Background anisotropy
experiments is fulfilling the promise of providing extraordinary levels of
discrimination between cosmological models. We calculate a binned anisotropy
power spectrum, which we tabulate, along with error bars and bin-to-bin
correlations, so that it can be easily used for constraining models. The
resulting power spectrum is flat at large angles, with a gradual rise to a
prominent peak at around 0.5 degrees and a decrease thereafter. This is
precisely the shape predicted by inflationary-inspired adiabatic models. Within
that class of cosmologies, this characteristic scale imprinted on the CMB sky
can be used to infer that the geometry of the Universe is very close to flat.
The next wave of CMB results should add fuel to the debate about whether or not
the Universe once inflated, as well as beginning in earnest the task of
measuring cosmological parameters.Comment: 6 pages, 1 figure. A less technical article based on the same work
has appeared in Science Perspectives under the title "How Flat is the
Universe?" (Science, Mar 24, 2000, 2171-2172
