The POLARBEAR project marks its early success with the most sensitive and precise measurements to date of the polarization of the cosmic microwave background (CMB), the leftover radiation from the event that theory posits have given birth to the universe, the Big Bang.

The cosmic microwave background has cooled and stretched as the universe expanded to microwave lengths and this offers insights into the large-scale structure of the universe and its cosmic history.

In the report published in the Astrophysical Journal on Oct. 20, the POLARBEAR consortium, a collaboration of over 70 scientists from all over the world that uses the microwave detectors on the Huan Tran Telescope (HTT) in the Atacama Desert in Chile to capture the oldest light in the universe, reported the discovery of B-modes.

The research team led by Adrian Lee, a physicist from the University of California, Berkeley, found B-modes, twists in the polarization patterns that suggest the CMB has been bent by such structures that include dark matters, which to date is still shrouded in mystery and the particles known as neutrinos, whose aloofness makes them difficult to study.

"We report a measurement of the B-mode polarization power spectrum in the cosmic microwave background (CMB) using the POLARBEAR experiment in Chile," Lee and colleagues reported. "The faint B-mode polarization signature carries information about the universe's entire history of gravitational structure formation, and the cosmic inflation that may have occurred in the very early universe."

The study of b-mode polarization could give scientists hints on the early history and evolution of the universe. It could allow scientists to have a better understanding of dark energy that accelerates the expansion of the universe and gravity, which played a role in slowing down the expansion. It can even support or nullify the theory that the universe was born after an enormous amount of energy was released a split second after the Big Bang.

The result has been hailed as an important milestone accomplished by the POLARBEAR project.

"It's a really important milestone," said Kam Arnold, from the University of California San Diego's Center for Astrophysics and Space Sciences. "We're in a new regime of more powerful, precision cosmology."

The first season of POLARBEAR observations has mapped B-modes in three small patches. Although dust in the Milky Way also emits polarized radiation, Arnold said that the patches are clean and that they believe the B-modes have cosmological origins.

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