George MusserIt’s one of the oddest tenets of quantum theory: a particle can be in two places at once—yet we only ever see it here or there.
Textbooks state that the act of observing the particle “collapses” it, such that it appears at random in only of its two locations.
But physicists quarrel over why that would happen, if indeed it does. Now, one of the most plausible mechanisms for quantum collapse—gravity—has suffered a setback.The gravity hypothesis traces its origins to Hungarian physicists Károlyházy Frigyes in the 1960s and Lajos Diósi in the 1980s.
The basic idea is that the gravitational field of any object stands outside quantum theory. It resists being placed into awkward combinations, or “superpositions,” of different states..