In this paper we address the question of whether it is possible to obtain evidence that we are in a superposition of different ‘worlds’, as suggested by the relative state interpretation of quantum mechanics. We find that it is impossible to find definitive proof, and that if one wishes to retain reliable memories of which ‘world’ one was in, no evidence at all can be found. We then show that even for completely linear quantum state evolution, there is a test that can be done to tell if you can be placed in a superposition.Ok, so I don't quite understand their test, even if it sounds pretty simple. I'm surprised Googling the author's names doesn't bring up any media press release from the university.
There is a report about the paper here, which also has a link to a rather odd website where people swear they are remembering alternative histories, rather than just having bad, malleable memories.
All rather odd.