Density perturbations named for the constancy of this quantity are fluctuations in relative energy densities that are contrasted with primordial adiabatic density perturbations. Setting this quantity to zero and solving for rho in the first Friedmann equation gives the critical density. W·MAP’s measurement of the (*) density (0[1])parameter as 1.02 implies that (0[1])this quantity is zero. (0[1])Negative values of this quantity imply a hyperbolic universe. (10[3]0[1])Gravitational (10[1]0[2])lensing (10[1]0[1])results (0[1])from (10[1])an increase in this quantity’s (10[1]0[1])magnitude (10[1])near massive objects that can be analogized to (0[1])placing a weight (10[1])on a stretched (0[1])piece of fabric. (0[2])For 10 points, name this geometric quantity whose global value would indicate whether (10[1])the universe (0[1])is flat. (10[5]0[3])■END■ (10[7]0[6])