  We explore the potential of measurements of cosmological effects, such as
neutrino spectral distortions from the neutrino decoupling and neutrino
clustering in our Galaxy, via cosmic neutrino capture on tritium. We compute
the precise capture rates of each neutrino species including such cosmological
effects to probe them. These precise estimates of capture rates are also
important in that the would-be deviation of the estimated capture rate could
suggest new neutrino physics and/or a non-standard evolution of the universe.
In addition, we discuss the precise differences between the capture rates of
Dirac and Majorana neutrinos for each species, the required energy resolutions
to detect each neutrino species and the method of reconstruction of the
spectrum of cosmic neutrinos via the spectrum of emitted electrons, with
emphasis on the PTOLEMY experiment.
