  Inflationary cosmology has proved to be the most successful at predicting the
properties of the anisotropies observed in the cosmic microwave background
(CMB). In this essay we show that quantum field renormalization significantly
influences the generation of primordial perturbations and hence the expected
measurable imprint of cosmological inflation on the CMB. However, the new
predictions remain in agreement with observation, and in fact favor the
simplest forms of inflation. In the near future, observations of the influence
of gravitational waves from the early universe on the CMB will test our new
predictions.
