Cosmology has seen great changes in the last few decades. Investigations of the Cosmic Microwave background have lead the revolution. Measurements of the degree-scale temperature anisotropy have been definatively measured by Nasa's WMAP satellite, which has accomplished its goal of setting strong limits on cosmological parameters, and has also opened up new directions of research, such as the era of Reionization.

Polarbear will build on this long experimental tradition but also step up sensitivity by a factor of 100 over the WMAP results. Such sensitivity is required to measure the extremely faint gravity-wave signal that is predicted by the inflationary scenario.

Polarbear's scientific goals have been given the utmost priority in the community. The Committee on the Physics of the Universe, formed by members of the National Academies and the DOE, NSF, and NASA released a panel report outlining the fundamental questions that should be addressed in the upcoming decades. The panel also recommended seven directions for research. At the top of the list was this recommendation:

An executive summary of the committee's report can be found here