A pinpoint precision map of the cosmic microwave background, reported
this week at a press conference by scientists associated with the orbiting
Wilkinson Microwave Anisotropy Probe (WMAP), brings the early universe
into sharper focus.
The credibility of WMAP's pronouncement rests on three things: its
angular resolution is some 40 times better than that of its microwave
predecessor, the Cosmic Background Explorer (COBE); it comprehensively
surveyed the entire sky for a whole year (3 more years of data is yet
to come); and it measures the polarization of the microwave radiation;
the orientation of the radiation arises partly from the last scattering
of light at the time of "recombination," when stable atoms
formed for the first time, and partly from the time when ultraviolet
radiation strewn by the first generation of stars ionized once again
a lot of atoms in space.
Here are a few of the salient numbers coming out of the WMAP analysis:
- the time of recombination was 380,000 years after the big bang
- the era of the first stars was about 200 million years after the
big bang (surprisingly early)
- the age of the universe is 13.7 billion years
- the accounting of matter in the universe is as follows: atomic matter
makes up about 4%, dark matter about 23%, and dark energy 73%.
(For more information, see: WMAP
Goddard Press Release)