The black‐body universe—spectrum extended

Studies of the absorption spectrum of interstellar CN molecules and of radio waves at 20.7‐cm wavelength seem to add more evidence that the universe is full of 3°K black‐body radiation left over from a primeval fireball. The first two points that fit the 3° spectrum were measured directly from radio emanations by Arno A. Penzias and Robert W. Wilson, who looked at 7.5‐cm wavelength, and P. G. Roll and D. T. Wilkinson, who recorded at 3.2 cm (see PHYSICS TODAY, April 1966, page 60). The CN work was done by George B. Field working with John L. Hitchcock [Phys. Rev. Letters 16, 817 (1966)] and by Patrick Thaddeus working with John F. Clauser [Phys. Rev. Letters 16, 819 (1966)]. It yields a point of the spectrum at about 2.6 mm. The 20.7‐cm radio observations were done by T. F. Howell and J. R. Shakeshaft [Nature 210, 1318 (1966)].