|MadSci Network: Astronomy|
Stephen Hawking's "No Boundary" proposal is a first step in formulating a theory of quantum cosmology. It is an attempt to understand the conditions of the Universe when it was so small and young that current physical theories (quantum mechanics and general relativity) do not apply. His idea was that the Universe would have no boundaries (in space or time) within such a theory. This approach to quantum cosmology was popular in the 1970's and 1980's. However, most recent work has focused on connecting ideas in string theory with cosmology.
Hawking's original theory that he wrote about in "A Brief History of Time" was only valid for a Universe that would stop expanding at some point in the future and begin to collapse down back to that initial state. He has since expanded the theory to include Universes that expand forever. The WMAP data from this year (2003) indicates that the Universe will indeed expand forever. So this does rule out his initial version of the theory. However, his newer versions might still have some validity. His theory does make some predictions about temperature fluctions that should be visible in the WMAP observations of the Cosmic Microwave Background Radiation. To my knowldege this has not yet been examined (or at least reported). In the very near future we may find out if the observations agree with Hawking's predections or if his theories are ruled out altogether.
I hope that helps,
Bryan Méndez, UC Berkeley Space Sciences Lab
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