Weighing the Universe

          @misc{ scivideos_PIRSA:09060066,
            doi = {10.48660/09060066},
            url = {https://pirsa.org/09060066},
            author = {Bahcall, Neta},
            keywords = {Quantum Fields and Strings, Particle Physics, Cosmology},
            language = {en},
            title = {Weighing the Universe},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2009},
            month = {jun},
            note = {PIRSA:09060066 see, \url{https://scivideos.org/index.php/pirsa/09060066}}
          }
          

Abstract

How do we weigh the Universe? Where is the Dark Matter? I will discuss these questions and show that several independent methods, including the observed present-day abundance of rich clusters , the evolution of cluster abundance with redshift, the baryon-fraction in clusters, the observed Mass-to-Light function from galaxies to superclusters, and other large-scale structure observations, all reveal a universe with a low mass density parameter of ~20% of the critical density. The data suggest that the mass in the Universe, including the dark-matter, approximately follows light on large scales and that most of the mass resides in huge dark halos around galaxies. I will review the combined observational evidence for dark-matter and for dark-energy in the universe and their cosmological implications.