Possible direct measurement of the expansion rate of the universe
  A new method is proposed for directly measuring the expansion rate of the
universe through very precise measurement of the fluence of extremely stable
sources. The method is based on the definition of the luminosity distance and
its change along the time due to the cosmic expansion. It is argued that
galaxies may be chosen as the targets of the observation to perform the
measurement. We show that, by simultaneously increasing the observation time
and physically adding the fluences from different galaxies, the requirement on
the relative precision of the detector for an observation of 1 second on a
single galaxy can be relaxed to $10^{-5}$. Benefiting from the abundance of
galaxies in the universe, the method may be quite promising.
