The blackbody radiation left over from the origin of the universe, also known as the cosmic microwave background (CMB). This radiation was emitted before any astronomical objects such as stars, galaxies, or quasars existed, and is now observed to be like the thermal emission from a black object with a temperature of 2.725 K (degrees above absolute zero, or −454.8°F). Blackbody radiation is emitted by an isothermal object that absorbs all incident radiation. Its spectrum, or amount of power at different frequencies, depends only on its temperature and is given by the Planck function. The energy density of this radiation, which peaks at wavelengths near 1 mm, is larger than that of any other cosmic radiation field. Its existence was predicted in 1947 and 1948 by George Gamow, Ralph Alpher, and Robert Herman as part of their model for the formation of the elements during a hot dense phase in the early history of the universe.