popper-logic-scientific-discovery

308
appendices
latter, if we use high values of |a 2|, depends mainly upon the smallness
of r.) They are both dependent only upon the precision of the measurements of
position and momentum of the particle arriving at X from the direction PX, and upon
the smallness of ψ. (This corresponds to the fact that the precision
(∆a 2) x, of the particle arriving at X depends upon the smallness of φ.)
One sees that with respect to the precision of the measurements,
the situation of the apparently non-predictive measurement of the [A]particle
arriving at X and of the prediction of the path of the
[B]-particle leaving P are completely symmetrical.