  The total masses ejected during classical nova eruptions are needed to answer
two questions with broad astrophysical implications: Can accreting white dwarfs
be pushed towards the Chandrasekhar mass limit to yield type Ia supernovae? Are
Ultra-luminous red variables a new kind of astrophysical phenomenon, or merely
extreme classical novae? We review the methods used to determine nova ejecta
masses. Except for the unique case of BT Mon (nova 1939), all nova ejecta mass
determinations depend on untested assumptions and multi-parameter modeling. The
remarkably simple assumption of equipartition between kinetic and radiated
energy (E_kin and E_rad, respectively) in nova ejecta has been invoked as a way
around this conundrum for the ultra-luminous red variable in M31. The deduced
mass is far larger than that produced by any classical nova model. Our nova
eruption simulations show that radiation and kinetic energy in nova ejecta are
very far from being in energy equipartition, with variations of four orders of
magnitude in the ratio E_kin/E_rad being commonplace. The assumption of
equipartition must not be used to deduce nova ejecta masses; any such
"determinations" can be overestimates by a factor of up to 10,000. We
data-mined our extensive series of nova simulations to search for correlations
that could yield nova ejecta masses. Remarkably, the mass ejected during a nova
eruption is dependent only on (and is directly proportional to) E_rad. If we
measure the distance to an erupting nova and its bolometric light curve then
E_rad and hence the mass ejected can be directly measured.
