D7 Cosmic Inflation and the Polarization of the Cosmic Microwave Background

Topic

This model centers on small-aperture telescopes—installed at the driest site on Earth and designed specifically to measure the polarization of the cosmic microwave background—that use polarization-sensitive detectors across multiple frequency bands to observe a patch of sky particularly free from galactic contamination.

The goal of these telescopes is to detect the specific type of polarization pattern produced only by primordial gravitational waves from inflation—a pattern distinct from that generated by ordinary density perturbations alone.

What makes these telescopes remarkable is their focus on a single scientific objective using the cleanest possible instrumental strategy: small apertures that avoid complex stray-light patterns, a location at the driest site on the planet, and continuous observation of the same patch of sky over years. Furthermore, combining multiple such telescopes multiplied the experiment's overall sensitivity.

The experiment itself demonstrated that reaching the next level of sensitivity requires first eliminating a contaminating signal caused by gravitational lensing acting on the cosmic microwave background—a lesson already incorporated into the design of the next-generation experiment. Thus, from the small-aperture telescopes that open this document to the lesson integrated into the next generation that concludes it—taking in the sought-after polarization pattern and the combination of multiple telescopes along the way—cosmic inflation ensures that a single scientific objective, pursued with the cleanest possible strategy, ultimately reveals both the signature being sought and the obstacles that must be overcome to find it.

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