The cosmic microwave background (CMB) was not observed before 1965 due to insufficient instrumentation sensitivity. Although Alpher and Herman predicted a thermal radiation around 5 K in 1948 as a consequence of the Big Bang, the prediction was not widely pursued. George Gamow, along with his student Ralph Alpher and later Robert Herman, worked on early Big Bang nucleosynthesis and supported the idea of residual radiation from the hot early universe. In 1948, Alpher and Herman published a specific prediction of relic blackbody radiation with a temperature of approximately 5 K. Gamow contributed to the theoretical framework but did not co-author the paper that predicted the CMB temperature. Earlier radio telescopes lacked low-noise design and calibration accuracy necessary to detect a uniform microwave signal at ~2.7 K. Penzias and Wilson used a horn-reflector antenna at Bell Labs, originally built for satellite communication. The antenna had a diameter of 6 meters and operated at a center frequency of 4.08 GHz, corresponding to a wavelength of 7.35 cm. Their measurements showed an excess antenna temperature that was isotropic and could not be attributed to known sources, equipment error, or environmental interference. At the same time, a group at Princeton led by Dicke was preparing an experiment to detect the predicted relic radiation using a radiometer. The signal had not been isolated earlier because previous observations lacked focus on isotropic background at centimeter wavelengths and the required sensitivity threshold. The signal detected by Penzias and Wilson matched the characteristics of a blackbody spectrum at approximately 3 K.