That link doesn't work for me. Is there somewhere else to get whatever it's intended to link to, or a summary, or something?
I find it very difficult to imagine what could possibly constitute an experimental demonstration that Everettian QM requires full quantum gravity and not QM + some semi-classical treatment of gravity. This isn't code for "I don't believe you" -- just a remark that what you're claiming is really startling, at least to me.
(Well. In some sense any understanding of QM requires full quantum gravity, in that without it we know we don't have a theory that actually describes the real world. But that's as true of any other theory as it is of Everett's.)
I can summarise the basic gist of the paper in relatively non-technical language (other people, please comment if you disagree with what I'm saying here):
Einstein's equation says that the curvature (read geometry) of spacetime is equal to the stress-energy tensor, which basically measures how much mass/energy/momentum there is in a place at a time. However, in quantum mechanics, the universe is in a superposition of states with different distributions of mass. A theory of quantum gravity would therefore say that the universe must therefore be in a superpos...
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.