1. A. Peres:Lett. Nuovo Cimento,1, 837 (1969).
2. J. Dhar andE. C. G. Sudarshan:Phys. Rev.,174, 1808 (1968).
3. J. Dhar andE. C. G. Sudarshan:Phys. Rev.,174, 1808 (1968).
4. Peres’ remaining reasoning, which asserts that a position operator not self-adjoint (or having no self-adjoint extensions) cannot be an « observable », is not true, in our opinion. In recent years it has been widely shown (4) that operators not only non-Hermitian but also nonnormal may be given a quite concrete physical meaning.
5. A. J. Kálnay:Bol. Inst. Matem. Astron. Fís.,2, 41 (1966).