The difference in two values of this quantity produced by Wouthuysen (“vowt-how-sen”)–Field coupling makes it theoretically possible to detect the 21-centimeter line at redshifts greater than six. Vielva et al. detected non-Gaussianity (“non-GOW-see-AAN-it-ee”) in this quantity’s distribution by calculating the skew and kurtosis of spherical Mexican hat wavelet coefficients. After electron-positron annihilation, the ratio of this (10[1])quantity for neutrinos to this (10[1])quantity for photons equals the cube root of four-elevenths. (10[1])WMAP (“W-map”) discovered a region where this quantity is abnormally low, (-5[4])which (10[1])might (10[1])be (-5[1])explained by a supervoid. (10[1])The horizon (-5[2])problem asks why the (10[1])CMB’s value for this quantity is uniform. (10[3])The wavelength (10[1])of a star’s emissions (10[1])is (10[1])related (10[1])to this (10[1])quantity for a star (10[1])by Wien's (“veen’s”) displacement law. For 10 points, spectral class and what other quantity are plotted against luminosity on HR diagrams? (10[1])■END■ (10[7])