  Due to their intrinsic brightness, supernovae make excellent cosmological
probes. We describe the SEAM method for obtaining distances to Type IIP
supernovae (SNe IIP) and present a distance to SN 1999em for which a Cepheid
distance exists. Our models give results consistent with the Cepheid distance,
even though we have not attempted to tune the underlying hydrodynamical model,
we have simply chosen the best fits. This is in contradistinction to the
expanding photosphere method (EPM) which yields a distance to SN 1999em that is
50% smaller than the Cepheid distance. We emphasize the differences between
SEAM and EPM. We show that the dilution factors used in the EPM analysis were
systematically too small at later epochs. We also show that the EPM blackbody
assumption is suspect.
  Since SNe IIP are visible to redshifts as high as z less than about 6, with
the JWST, SEAM may be a valuable probe of the early universe.
