The Theory of Cosmological Inflation attempts to answer several long-standing conundrums on the origin of the universe. According to this theory, the universe went through a period of rapid expansion that lasted from about 10^-36 seconds to 10^-33 seconds after the conjectured Big Bang singularity. Through Quantum Mechanics, it has been theorized that quantum perturbations on the overall smoothness of the early universe can be of two types; Density (or scalar) perturbations, and Gravitational (or tensor) perturbations. The scalar perturbations are fluctuations in the density of the early plasma, a phenomenon already observed in the CMB. The tensor perturbations are essentially gravitational waves produced as a result of the sudden, rapid expansion of the early universe.
Therefore, detecting these G-waves would provide direct confirmation of the validity of the Theory of Inflation. Even without G-waves, the CMB has an overall polarization brought about by ordinary density perturbations. This is a pure E-mode polarization. G-waves on the other hand produce both E and H mode polarizations. Therefore, detection of this B-mode polarization in the CMB confirms the existence of these G-waves.
However, recent study shows that these B-mode polarizations may be produced as a result of dust contamination. This prevents us from having a definitive confirmation of the existence of these G-waves. A solution to this problem may be found by studying the characteristic anisotropic nature of the polarization caused by the dust contaminants. The anisotropic nature arises as a result of the dust grains getting aligned – a direct consequence of the galactic magnetic fields. The resulting polarization should have some effective orientation.
The polarization caused by the G-waves on the other hand, would be isotropic in nature. This difference could potentially indicate the existence of the G-waves and hence confirm the theory of cosmic inflation.