How Ancient Light Reveals the Universe’s Contents
Reprinted with permission from Quanta Magazine’s Abstractions blog.
In early 2003, Chuck Bennett learned the precise contents of the cosmos.
By then, most cosmologists had concluded that the universe contains much more than meets the eye. Observations of pinwheeling galaxies suggested that scaffolds of invisible matter held their stars together, while a repulsive form of energy drove galaxies apart. To learn more, Bennett and his Wilkinson Microwave Anisotropy Probe (WMAP) team had spent a year collecting microwaves coming from all directions in the sky—light rays that left their source long ago, when the universe was just 380,000 years old. By snapping this photograph of the young cosmos, the WMAP
