universe captures this mixture of profound new knowledge and grave uncertainty. The stunning “baby picture” of the cosmos produced by WMAP represents one of the landmark scientific images of our times—akin to the double helix or the first photos of the Martian surface. When represented in color, like a weather map of hotter and colder sites, it is a fantastically intricate mosaic of multihued spots. Clearly the background radiation’s artist painted in pointillism.

Paintings capture moods, and the WMAP portrait is no exception. It shows the cooled-down form of a once-scalding universe, releasing long-pent-up energy into the gaps between atoms. The atoms were slightly clumped together, in patterns that depended in part on the geometry of space. Their particular arrangements indicated that they were happily settled into a flat, expanding hyperplane—with omega exactly equal to one. Perhaps they were especially content because they recalled a far more explosive period earlier on that flattened their vistas. But now they could move away from each other at a gentler pace, awaiting the day their gravitational attraction would compel them to reunite into myriad celestial bodies.

At a 2003 conference of the American Physical Society, physicist Michael Turner reveled in the high precision of the new data. He emphasized that, for the first time in the history of cosmology, researchers were able to perform exact-enough statistics to present their results with error bars (precise ranges of values). Turner also pointed out that the WMAP results ruled out the simplest inflationary models. He counseled, however, that there were other possibilities. “Fortunately, Andrei [Linde] had another 300 models left,” Turner joked.

The combined power of the supernova and microwave background observations enables cosmologists to define a “concordance model” of the universe. Any theory that satisfies known results about the geometry, age, and content of the observable universe falls into this category. You would think that this would narrow things con-

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