What the Universe tried to hide: The 21-centimeter signal explained
Scientists are peering into the universe's mysterious Cosmic Dawn using the faint whispers of hydrogen radio waves emitted over 13 billion years ago. These signals, particularly the elusive 21-centimeter signal, offer rare insights into the masses and behavior of the universe’s first stars—Population III stars—whose light we can’t see directly. With projects like REACH and the upcoming Square Kilometre Array (SKA), researchers are unlocking a cosmic treasure map, predicting how early starlight and powerful X-ray binaries influenced these signals. It’s a thrilling detective story unfolding not through images, but through the statistical patterns of ancient radiation.
