What would it have looked like if it looked like I were in a superposition?

TL;DR

This paper explores the possibility of detecting superpositions of worlds in quantum mechanics, concluding that definitive proof is impossible if memories are reliable, but certain tests can indicate superposition states.

Contribution

It demonstrates the impossibility of definitive proof of superpositions with reliable memories and proposes a test to detect superposition states in linear quantum evolution.

Findings

No definitive proof of superposition with reliable memories

A test can distinguish superposition states in linear quantum evolution

Superposition detection is theoretically possible despite proof limitations

Abstract

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.