Number 109 (Story #1), January 8, 1993 by Phillip F. Schewe and Ben Stein THE TEMPERATURE OF THE UNIVERSE IS 2.726 K . New data from COBE's Far Infrared Absolute Spectrophotometer (FIRAS) presented at this week's meeting of the American Astronomical Society (AAS) in Phoenix show that the energy spectrum of the cosmic microwave background is extremely close to that of a perfect black body at 2.726 K. The agreement between the theoretical and observed spectra (consisting of measurements at 34 different wavelengths from 0.5 to 5 mm) is 30 times better than for the FIRAS data released 3 years ago. FIRAS leader John Mather of NASA/Goddard (301-286-8720) said the agreement is so good that constraints can be placed on the amount of radiant energy in the universe (no more than 0.03% of the total) that could have been emitted more than a year after the big bang. Some cosmologists have proposed that such energy might have been released by supermassive supernovas, by black holes, or by the decay of unstable particles.