““in experimental quantum mechanics we have run right up against what was previously perceived to be a purely philosophical barrier. The experiments are telling us that we can know nothing of reality-in-itself. We have to accept that the properties we ascribe to quantum particles like photons, such as energy, frequency, spin, polarization, position (‘here’ or ‘there’), are properties that have no meaning except in relation to a measuring device that allows them to be projected into our empirical reality of experience. We can no longer assume that the properties we measure necessarily reflect or represent the properties of the particles as they really are.””
