From Mica
Dark Mysteries: What is the Universe Made of?
Talk by George Djorgovski
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 for ever, 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 will describe how cosmologists know these things, and what are they doing to help resolve these outstanding mysteries of science.
Media
The slides (in a PDF file)
Recording of the talk on 19 September 2008, part 1
Recording of the talk on 19 September 2008, part 2