From Nick Canning, Coleraine, Londonderry, UK
There is a widespread misconception that human consciousness is responsible for the collapse of the wave function as exemplified in Andrew Smyth’s comment: “once an observer consciously knows which slit the particle passed through, the situation changes”. No, the collapse occurred when an irreversible physical interaction between the particle and the part of the apparatus that defined “the path taken” happened, not when we became aware of it. Even in the absence of all consciousness, entirely mechanical processes of the physical apparatus cause wave function collapse (Letters, 9 May).
