AFTER CHARACTERIZING THE EPOCHS WHICH ARE PROBED MOST PRECISELY BY CURRENT AND FUTURE PLANNED MISSIONS WE WILL HAVE ESSENTIAL INFORMATION TO THEN FOCUS OUR ATTENTION ON OBSERVATIONAL CONSTRAINTS TO THE NEUTRINO SECTOR. IN ADDITION TO ALTERING THE EXPANSION RATE MODIFICATIONS TO THE NEUTRINO SECTOR NATURALLY CHANGE THE EVOLUTION OF INHOMOGENEITIES IN THE UNIVERSE. STUDYING PROBES OF NEUTRINO PHYSICS IS PARTICULARLY INTERESTING IN LIGHT OF RECENT MEASUREMENTS OF THE HUBBLE CONSTANT FROM THE CMB AND TYPE IA SUPERNOVAE. THE INFERRED HUBBLE PARAMETER FROM THESE TWO METHODS ARE IN TENSION AND COULD BE A HINT OF AN ADDITIONAL NEUTRINO SPECIES WITH NONSTANDARD INTERACTIONS. THIS DEVELOPMENT IS PARTICULARLY EXCITING IN LIGHT OF THE EXPERIMENTAL DETECTION OF NEUTRINO MASS NEUTRINO BEAMLINE HINTS OF A NEW SPECIES AND THEORETICAL MODELS FOR THE NEUTRINO MASS WHICH OFTEN REQUIRE THE EXISTENCE OF A NEW LIGHT PARTICLE WITH INTERACTIONS BEYOND THE STANDARD MODEL. WE PROPOSE TO DEVELOP THE FRAMEWORK TO TEST THESE MODELS USING UPCOMING COSMOLOGICAL DATA DEVELOPING THE RELEVANT FLUID AND BOLTZMANN FORMALISMS IMPLEMENTING IT COMPUTATIONALLY CONDUCTING FORECASTS AND TESTING MODELS WITH EXISTING MEASUREMENTS.