An image of the early universe, showing irregularities in its brightness 380,000 years after its birth, has been produced by a device called the Wilkinson Microwave Anisotropy Probe (WMAP). The image has given astronomers and cosmologists new insight into the age, shape, and mass of the cosmos, and the way in which matter has been distributed throughout its history.
The universe is believed to have originated in an explosion of incomprehensible brilliance, called the Big Bang, 13.7 billion (1.37 x 10 10 ) years ago. Thus, the WMAP image portrays the universe when it was approximately 1/36,000 of its present age. The data implies a cosmos that is geometrically flat (Euclidean) on a large scale, rather than spherical (closed) or hyperboloidal (open) as some theorists have suggested. Only four percent of the mass of the universe consists of matter as we know it; the rest is dark matter that cannot be directly seen, and so-called dark energy .
The WMAP image is consistent with the notion of an expanding universe. This theory, called the Big Bang theory, became popular as a result of observations made by the astronomer Edwin Hubble in 1929. Evidence backing up this theory has accumulated since then, and some astronomers believe the WMAP data virtually proves it.