For many years, theorists including Feynman, Kibble, and Penrose have argued that one should look for a theory in which quantum mechanics breaks down because of gravity.
The Correlated Worldline (CWL) theory is a consistent theory of quantum gravity in which gravitational correlations between different Feynman paths do cause the superposition principle does break down. At microscopic scales these effects are utterly negligible – they go like the fifth power of mass - and matter
behaves according to quantum mechanics. However as masses approach the Planck mass scale (~ 2 x 10-5 g) superpositions are suppressed, and we cross over to the classical theory of matter coupled to gravitational fields (ie, General Relativity).
This talk will explain the CWL theory at an introductory level, as well as some of the background history, and why it is a consistent theory. I then discuss when it leads to testable predictions for the departure from conventional quantum mechanics, with a focus on simple ‘2-path’ experiments, and on optomechanical systems.