University of Arizona, January 19, 1:00 pm
Alice’s adventures with bombs, Bobs, and black holes
The harmonization of gravity and quantum mechanics is a major open question in physics, and the obstacles involve conceptual difficulties surrounding observables and measurement. I will give a pedagogical presentation, at the advanced undergraduate level, of three thought experiments that probe the relationships between gravity, measurement, and quantum mechanics. The first is the Eliztur-Vaidman bomb, which demonstrates “interaction-free measurement” and has been experimentally realized. The second is a puzzle due to Mari et al, whose resolution in Belanchia et al and Danielson-Satischandran-Wald (DSW) demonstrates that gravitationally mediated entanglement requires a fully quantized gravitational field (the existence of gravitons), opening the door to tabletop experimental evidence for quantum gravity. The third is a demonstration, also by DSW, that black holes passively decohere external quantum states, showing that strong gravity regions have a profound influence even on distant quantum systems.