The Search For Faint Fuzzy Stuff
An Historical Justification

• 1991 Walker, et.al. used observational evidence to derive bounds on the present day density of the Universe

  Used:

  • observed abundances of the light elements
  • nuclear reaction rates
  • number of neutrino species
  • the standard cosmological model

  
  Obtained

  • Present day nucleon-to-photon ratio of
    
  • Density of Baryons in the Universe
    
  
  

• Persic & Salucci (1992, 1996) estimated the baryon mass density of the Universe in group & clusters of galaxies. Found
  
  

  .
  

  .
  

  .
  

  70% - 90% OF THE PREDICTED BARYONIC MASS
  APPEARS TO BE MISSING!