Watch NOVA Season 5 Episode 20 Online

In 1965, Arno Penzias and Robert Wilson, two radio astronomers at Bell Telephone Laboratories, discovered faint, but ever-present, microwave signals from space—the most ancient and most distant signals detected by man: the oldest "fossils" in the universe. NOVA explores the current surge of cosmological discovery that continues to aid scientists in the "cosmic archaeology" of digging into the history of the universe.