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   PR # 43042
   As the microwave background (MWB) photons travel towards us through
   rich clusters of galaxies, they are scattered to higher energies by
   the hot gas in the clusters. The resulting spectral distortion is
   called the Sunyaev-Zeldovich (SZ) effect. The cosmological importance
   of the SZ effect is that, when coupled with an X-ray determination of
   the temperature and density profile of the hot scattering gas, it is
   possible to directly deduce the scale size of the universe, ie the
   Hubble constant. El
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