The Breitenlohner-Freedman limit to the ``tachyonic'' mass of a scalar field in D-dimensional Anti-de Sitter space can be derived by an application of the uncertainty principle to a point particle in AdS. This will be explained in the first part of the talk. The second part will introduce the Sp(4;K) bi-twistor formalism for massive particles in AdS for D=4,5,7,11, corresponding to the normed division algebras K=R,C,H,O. For D=4,5,7 this allows a simple demonstration that the quantum superparticle in a maximally supersymmetric AdSxS vacuum of M-theory is a supergraviton.