Page "Fine-structure constant" Paragraph 50

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 ( 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 t < sup >− 1 / 2 </ sup >.

The European LOFAR radio telescope would only be able to constrain Δα / α to about 0. 3 %.

The collecting area required to constrain Δα / α to the current level of quasar constraints is on the order of 100 square kilometers, which is economically impracticable at the present time.