  Fluctuations in the temperature of the cosmic microwave background have now
been detected over a wide range of angular scales, and a consistent picture
seems to be emerging. This article describes some of the implications for
cosmology. Analysis of all the published detections suggests the existence of a
peak on degree scales of height 2.4 to 10 (90%CL) relative to the amplitude of
the power spectrum at large angular scales. This result confirms an early
prediction, implies that the universe did in fact recombine, and limits
theories of structure formation. Illustrative examples are provided of how the
comparison of microwave background and large-scale structure data will be a
potentially powerful means of answering fundamental questions about the
universe.
