 Andrew R. Liddle

Andrew R. Liddle coauthored an analysis of when observable perturbations were produced relative to the end of cosmic inflation. It shows why a single universal count of expansion factors is not an assumption-free link between an inflationary model and present observations.^[ref]

The duration and physical conditions after inflation enter the mapping between an observed wavelength and the earlier field evolution. This gives reheating a role in testing a model even when the reheating process is not directly observed.

Andrew R. Liddle is a prominent theoretical physicist and cosmologist known for his work in the field of cosmology, particularly related to the early universe, inflation, and the nature of dark energy. He has contributed to various areas of research, including the dynamics of cosmic structures and the interaction of gravitational waves with matter. Liddle has been involved in both theoretical research and teaching, and he may have published numerous papers and books in his field.