Polarization in the Microwave Background

Polarization in the microwave background has been measured by the Degree Angular Scale Interferometer detector (DASI), situated at the South Pole.

DASI was one of the first detector groups to see (Update 537) several peaks in the spectrum of the cosmic microwave background, the radiation originating from that era in the early universe (some 300,000 years after the big bang) when stable atoms first formed.

The modern theory of cosmology says that these microwaves received an orientation (polarization) when they emerged from the seething plasma (the "surface of last scattering") then pervading the cosmos.

DASI's measurement of a faint polarization, reported last week at the COSMO-02 meeting in Chicago, is consistent with the theoretical prediction. (See astro-ph/0209478 at arXiv.org.)