150 yearsafter the discovery of quaternions, Hamilton’s conjecture hat quaternions are a fundamental language for physics is reeva luated and shown to be essentially correct, provided one admits complex numb ers in both classical and quantum physics, and accepts carrying along t he in ricacies of the relativistic formalism. Examples are given in classi cal dynamics, electrodynamics, and quantum theory. Lanczos’s, Einstein ’ , a d Petiau’s generalizations of Dirac’s equation are shown to be very… Expand