Limitations on the operational definition of spacetime events and quantum gravity

Using simple arguments from general relativity and quantum theory the author shows that it is not possible to devise experiments (or operational procedures) which will measure the position of a particle to an accuracy better then the Planck length (G/c3) approximately=10-33 cm. It is also impossible to synchronise clocks to a precision better than Planck time. The implications of the result are discussed.