Remark on Galois cohomology

We recast the Galois cohomology of the variety V over a number field k in terms of the K-theory of a C*-algebra A_V connected to V. It is proved that V is isomorphic to V' over k (algebraic closure of k, resp.) if and only if A_V is isomorphic (Morita equivalent, resp.) to A_V' In particular, the Morita equivalent C*-algebras A_V parametrize twists of the variety V. The case of rational elliptic curves is considered in detail.