This quantity is a simple linear function in the Milne universe. This quantity depends on one minus the cosine of conformal time, which is the functional form of the y-component of a cycloid, in a closed, matter-dominated universe. In a multi-component universe, powers of this quantity are the weights for the harmonic (10[1])mean of each component’s density parameter that gives the total density parameter. This quantity squared multiplies the spatial components of the FLRW (10[1])line (10[1])element. (10[1])This quantity is obtained as a function of the age of the universe by solving (10[1]-5[2])the Friedmann equations. (10[2])This quantity, (10[1])and its first and second time derivatives, (10[1]-5[1])are used to calculate the deceleration parameter. This quantity’s (-5[1])time derivative, divided by this quantity, (10[1])equals the Hubble parameter. (-5[1])For 10 points, name this (-5[1])dimensionless cosmological quantity often denoted lowercase “a.” ■END■ (10[1]0[10])