one thing about the assertions of the observer-dependence of reality in physics: they are not about any actual observers or human beings, but about idealized or stipulated observers. so, wigner's mathematical reconstruction of observer-dependence cannot and does not engage with actual observers. he says, for example, well if this person has a sense impression in this situation, then so does that person, in the same situaton. he even stipulates that two of his perople will answer the same to queries: did you see a flash? yes. otherwise you can't mathematize this at all. but look, any actual particular person in any actual particular situation might be asleep, or hallucinating, or blind, or distracted, or psychotic, etc. and of course actual people respond all sorts of different ways to questions, and if you asked an actual observer whether they saw a flash, you might get, "who's asking?" or "eat me" or "do you think shirley hates me?" or "christ, what is it with you and flashes?" we stipulate idealized observers who have the same experiences and the same responses in the same circumstances.
now, think about that for a moment. these people are asserting flatly that the universe literally depends ontologically on idealized observers we just made up. space and time, what are they? they are aspects of non-existent experience in the non-existent heads of non-existent people. the fictional characters we just invented are the actual creators of reality. it would be hard to come up with a more bizarre, mmmm, religious hypothesis: reality, including we ourselves, originates in and depends on the fictional sense experiences of characters we created.
now why do we stipulate identical observers, or make up idealized observers? because actually, we do believe in an external world, and we can't deal at all with the entailments of the subjectivism we stumbled so incompetently into. if you were serious about the idea that reality was dependent on actual observers, you could not do science at all, nor should you. so, because we are stuck in this idea of observer-dependence, we have to try to get something like a world out of subjective experiences so we can do science at all. so then we just stipulate idealized observers to make observatiion tantamount to objectivity. i can't tell, but i think wigner's equations might work fine even if a flash is a burst of photons rather than a sense impression in a stipulated subjectivity: something happening out there rather than in the nowhere head of nobody. i've got this funny feeling that even wigner believes that there could be actual photon bursts happening outside his own mind.
so, on this account, physics is not about the universe or reality or something, it is about the 'experiences' of fictional characters. is that really how you guys want it? that's your most considered account of what you are doing? because surely it would be sensible to lose interest in the whole thing at that point.
but even if that's what some of these folks say they are doing, due to a series of confusions, it's not in fact what they are doing. they are studying the actual universe as it exists out there; otherwise this stuff would have no practical application, etc. what's really wrong is not what's going on in the collider, but the super-half-assed framework it's being jammed into. i'm just betting that we can do better at reconstructing the basic conceptual structure around the actual experiments and results. lee smolin and others are trying, i think.
