From microwave anisotropies to cosmology.

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 of the published detections suggests the existence of a peak on degree scales with a height 2.4 to 10 (90 percent confidence level) times 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 show how comparison of the microwave background data and the large-scale structure data will be a potentially powerful means of answering fundamental questions about the universe.