Cosmologists talk about the cosmic microwave background
radiation, their snapshot of the universe at the tender age of
400,000 years, so much that it might seem pretty well mined out
by now. After all, the European Space Agency intends for its new
Planck satellite to extract “essentially all the information
available” in the radiation’s spatial patterns. But cosmologists
looking beyond Planck say the radiation has a barely explored
aspect that, if it could be observed with enough precision,
would reveal new details about the early universe: its spectrum.
Astronomers routinely use the rainbow of colors emitted by the
sun and other stars to determine their composition. At the
American Astronomical Society meeting this past January,
renowned astrophysicist Rashid Sunyaev of the Max Planck
Institute for Astrophysics in Garching, Germany, argued that a
successor to Planck might pick up similar fingerprints in the
background radiation, the spectrum of which currently seems
completely featureless and generic. In the