  The multiparticle spacetime algebra (MSTA) is an extension of Dirac theory to
a multiparticle setting, which was first studied by Doran, Gull and Lasenby.
The geometric interpretation of this algebra, which it inherits from its
one-particle factors, possesses a number of physically compelling features,
including simple derivations of the Pauli exclusion principle and other
nonlocal effects in quantum physics. Of particular importance here is the fact
that all the operations needed in the quantum (statistical) mechanics of spin
1/2 particles can be carried out in the ``even subalgebra'' of the MSTA. This
enables us to ``lift'' existing results in quantum information theory regarding
entanglement, decoherence and the quantum/classical transition to space-time.
The full power of the MSTA and its geometric interpretation can then be used to
obtain new insights into these foundational issues in quantum theory. A system
of spin 1/2 particles located at fixed positions in space, and interacting with
an external magnetic field and/or with one another via their intrinsic magnetic
dipoles provides a simple paradigm for the study of these issues. This paradigm
can further be easily realized and studied in the laboratory by nuclear
magnetic resonance spectroscopy.
