In 2007, Khatri and Wandelt of the University of Illinois at Urbana-Champaign realized that the 21 cm hyperfine transition in neutral hydrogen of the early universe leaves a unique absorption line imprint in the cosmic microwave background radiation. They proposed using this effect to measure the value of α during the epoch before the formation of the first stars. In principle, this technique provides enough information to measure a variation of 1 part in 10 (4 orders of magnitude better than the current quasar constraints). However, the constraint which can be placed on α is strongly dependent upon effective integration time, going as 1 ⁄ √ t . The European LOFAR radio telescope would only be able to constrain ⁠ Δ α / α ⁠ to about 0.3%. The collecting area required to constrain ⁠ Δ α / α ⁠ to the current level of quasar constraints is on the order of 100 square kilometers, which is economically impracticable at the present time.