The Einstein-Podolsky-Rosen Thought Experiment Viewed Through Systemic Functional Linguistics

Davies & Gribbin (1992: 215-7):

Einstein wanted to believe that, say, an electron really did have both a well-defined position and a well-defined momentum at the same time, even though in typical practical experiments knowledge of one aspect might frustrate attempts to know the other. … 

Suppose, Einstein reasoned, that there are two particles, A and B, which collide and separate to a great distance. Now we are free to measure either the position or the momentum of B. If we measure the former we can infer the position of A, from the laws that govern collisions. But we could equally well measure the momentum of B and use it to infer the momentum of A. 

Einstein suggested that although a measurement of B's position might fuzz out the momentum of that particle (or vice versa), the act of a measurement on B could not immediately affect particle A, which might be a long way away by the time the measurement is made. At the very least, no physical influence from the measurement of B could reach A in less time than it would take light to travel from B to A — the ultimate speed limit of Einstein's own theory of relativity. Certainly, it seemed to Einstein that at the instant of the measurement of B, the state of particle A must remain undisturbed. 

This seemed to settle the issue, for if the experimenter chose to measure either the position or momentum of B, and hence infer either the position or momentum of A, in either case without disturbing A, then surely A must already possess both "elements of reality" at the time of measurement. Indeed, one could envisage measuring the momentum of A by this proxy technique (that is, by measuring the momentum of B and inferring that of A) and at the same instant conducting a position measurement directly on A, thereby yielding precise values for both quantities at the same time. 

So, Einstein reasoned, it is possible in principle to know the position and the momentum of particle A at the same time. It seemed to Einstein that the only way to retain quantum uncertainty across the gap between the particles would be if they were connected by what he called some "spooky action at a distance," operating faster than light and therefore transcending the restraints of his own theory of relativity.

 

Blogger Comments:

To be clear, Einstein's claim is that a measurement of the position or momentum of one particle cannot influence the measurement of position or momentum of another particle, with which it had collided, because this would require faster than light signalling between the particles.

From the perspective of Systemic Functional Linguistic Theory, this does not require any signalling between instances (particles), because the relation is between potential and instances, not between instances.

The reason why a measurement of the position or momentum of one particle does influence the measurement of position or momentum of another particle is that the particles are interdependent instances of the same potential. That is, the construal of one instance of the system is dependent on the construal of another instance, and this requires no "spooky action at a distance" between the instances.

From the perspective of Systemic Functional Linguistic Theory, Einstein was trying to reframe Quantum physics, which distinguishes potential from instance, in terms of Classical physics, which only recognises instances. The unwarranted assumption, also, is that particles, along with their position and momentum, are meanings that are independent of the act of construing.