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Summary
Radio telescopes that substitute antenna arrays for dishes are gearing up to look back to the brink of the "dark ages" that followed the big bang. These versatile new scopes can survey and catalog the low-frequency sky, monitor fast-changing radio sources, study the sun and space weather, and track ultrahigh-energy cosmic rays as they hit Earth's atmosphere. But the goal that has scientists buzzing is the prospect of venturing into cosmology's terra incognita. The time from the release of the cosmic microwave background radiation 400,000 years after the big bang until some 850 million years later, when the superbright galaxies known as quasars became visible, is a closed book to cosmologists. This is a critical period of the universe's development, during which it evolved from a near-uniform cloud of neutral hydrogen gas into a gallery of stars, galaxies, and clusters of galaxies. Cosmologists can only simulate what might have happened during this time because they have no data.
