Relational Reality in Relativistic Quantum Mechanics

One of the most puzzling facts about quantum mechanics is that although quantum theory offers a very accurate framework encompassing phenomena going from chemistry to high energy physics, it does not provide us with clear indications favoring some world view in the relativistic domain. Consequently, many physicists have held an instrumentalist point of view. Even though in non-relativistic physics already exists a realistic interpretation of quantum mechanics due to Heisenberg, who considers quantum states as states of disposition (the real tendency interpretation), the efforts for extending this interpretation to the relativistic domain were found wanting. The basic problem is the dependence of the states on the frame within which collapse takes place. We show here that a suitable use of the causal structure of the devices involved in the measurement process allows us to introduce a covariant notion for the collapse of quantum states and to preserve the tendency interpretation in relativistic quantum mechanics. However, we shall see that this extended interpretation requires the introduction of a relational concept of reality