One of the key goals of the science of cosmology is to determine the matter and energy contents of the universe; they, in turn, determine its ultimate fate - whether it will expand forever, or recollapse into a reverse of the big bang, a "big crunch." A great progress has been made in this field over the past decade. We now know that about 70% of the total matter/energy content of the universe is a mysterious "dark energy," which drives an accelerated expansion, and whose physical nature remains unknown. Another 25% or so is dark matter, whose nature is also unknown, but whose gravitational effects can be measured very well. Only about 5% of the total content is the matter we know, composed of atoms and known particles. We describe how cosmologists know these things, and what are they doing to help resolve these outstanding mysteries of science. First presented in Second Life in September, 2008.
Dr. Djorgovski will answer a selection of questions posted by May 13, 2012.
Is it possible that what we think is dark matter and energy can simply be our interpretation of the behaviour of blank holes? Black holes may be scattered throughout the universe, having been created right from the beginning. The variable rate of expansion (faster) is due to black holes becoming so immense that they even stop gravity from escaping, thus there is less gravity to bring the universe back to a collapse. Black holes scattered throughout and outside galaxies may also explain why galactic arms spin at the rate they do.