Model independent early expansion history and dark energy

We examine model independent constraints on the high redshift and prerecombination expansion history from upcoming cosmic microwave background observations, using a combination of principal component analysis and other techniques. This can be translated to model independent limits on early dark energy and the number of relativistic species N-eff. Models such as scaling (Doran-Robbers), dark radiation (Delta N-eff), and barotropic aether fall into distinct regions of eigenspace and can be easily distinguished from each other. Incoming CMB data will map the expansion history from z = 0-10(5), achieving subpercent precision around recombination, and enable determination of the amount of early dark energy and valuable guidance to its nature.