This essay argues that when measurement processes involve energies of the
order of the Planck scale, the fundamental assumption of locality may no longer
be a good approximation. Idealized position measurements of two distinguishable
spin-0 particles are considered. The measurements alter the space-time metric
in a fundamental manner governed by the commutation relations [xiβpjβ]=iβΞ΄ijβ and the classical field equations of gravitation. This
{\it in-principle} unavoidable change in the space-time metric destroys the
commutativity (and hence locality) of position measurement operators.Comment: LA-UR-93-2890-REV, "honorable mention" for the 1994 Awards by Gravity
Research Foundatio