  A complete model of the universe needs at least three parts: (1) a complete
set of physical variables and dynamical laws for them, (2) the correct solution
of the dynamical laws, and (3) the connection with conscious experience. In
quantum cosmology, item (1) is often called a `theory of everything,' and item
(2) is the quantum state of the cosmos. Hartle and Hawking have made the
`no-boundary' proposal, that the wavefunction of the universe is given by a
path integral over all compact Euclidean 4-dimensional geometries and matter
fields that have the 3-dimensional argument of the wavefunction on their one
and only boundary. This proposal has had several partial successes, mainly when
one takes the zero-loop approximation of summing over a small number of complex
extrema of the action. However, it has also been severely challenged by an
argument by Susskind.
