The team’s work extends arguments against combining quantum mechanics with classical ideas about locality to genuinely probabilistic scenarios; however, fully specifying these models proves surprisingly difficult when demanding consistency across different observers in motion relative to one another. This reliance on ‘frame-indexed causal models’, associating potentially distinct cause-and-effect relationships with each observer's viewpoint, introduces a tension between maintaining relativistic principles and avoiding influences travelling backwards in time, a concept known as no-retrocausality.
Still, acknowledging the difficulty in fully reconciling relativity with cause-and-effect without allowing for backwards time influence does not diminish this work’s importance; it clarifies precisely where existing models falter when attempting to describe quantum behaviour realistically. By rigorously defining ‘frame-indexed causal models’, the researchers have established a clear benchmark against which future theories must be measured. This detailed analysis helps pinpoint essential features any successful relativistic interpretation of quantum mechanics absolutely needs to incorporate.
Researchers at the University of Vienna rigorously tested models linking quantum mechanics with relativity; they found limitations arise when demanding consistency for observers in motion relative to each other.