>The third says that outcomes of measurements are absolute, objective facts for all observers.
The key part of the argument that is (I feel) a bit obscured to make it sound more shocking, is the fact that "observers" here includes "observers who are themselves in a superposition state".
Edit: the closing paragraph of the article is worse:
>In which case, taking the position that an observation is subjective and valid only for a given observer — and that there’s no “view from nowhere” of the type provided by classical physics — may be a necessary and radical first step.
I think that if you remember that they only proved this for "a given observer" that is itself in a superposition, it is a lot less "radical".
Indeed, it’s remarkable they want to make a fuss out of something that I can undo entirely via unitary transformation. There have been a number of papers with these kinds of “theorems” that seem to miss that proponents of the many-worlds interpretation would have explained (in this instance) Wigner’s friend in this way in the first place by eliminating all non-unitary evolution a priori.
The key part of the argument that is (I feel) a bit obscured to make it sound more shocking, is the fact that "observers" here includes "observers who are themselves in a superposition state".
Edit: the closing paragraph of the article is worse:
>In which case, taking the position that an observation is subjective and valid only for a given observer — and that there’s no “view from nowhere” of the type provided by classical physics — may be a necessary and radical first step.
I think that if you remember that they only proved this for "a given observer" that is itself in a superposition, it is a lot less "radical".
PS I wrote another more elaborate comment about this research here https://news.ycombinator.com/item?id=24322949