Disorder in the Early Universe
  Little is known about the microscopic physics that gave rise to inflation in
our universe. There are many reasons to wonder if the underlying description
requires a careful arrangement of ingredients or if inflation was the result of
an essentially random process. At a technical level, randomness in the
microphysics of inflation is closely related to disorder in solids. We develop
the formalism of disorder for inflation and investigate the observational
consequences of quenched disorder. We find that a common prediction is the
presence of additional noise in the power spectrum or bispectrum. At a
phenomenological level, these results can be recast in terms of a modulating
field, allowing us to write the quadratic maximum likelihood estimator for this
noise. Preliminary constraints on disorder can be derived from existing
analyses but significant improvements should be possible with a dedicated
treatment.
