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Physics

Radio Astronomy in Studying the Epoch of Reionization

Quick fact

Using the 21-cm line of neutral hydrogen, radio astronomers can map the distribution of gas during the Epoch of Reionization—but the signal is so faint that it is only one-hundred-thousandth of the noise from our own galaxy, requiring extreme precision and years of integration.

Why this is interesting

How can we 'see' the first stars that switched on the universe's lights, when the universe was a fog of hydrogen gas? Radio telescopes can probe this ancient epoch by catching a whisper of the universe's first light.