First off, thank you for demonstrating the relationship between science and philosophy. The link is stronger than most people realize.
That said, what about the results found in the experiment below? While I am not aware of it having been reproduced or peer-reviewed, if it is verified, does it not validate "Wigner's friend"? After all, if it is proven that observation of a single photon can yield two different results for two different observers, does this not imply that there is a very real possibility of observer-dependent realities?