Clearly any quantum gravity theory would have to account for the effect that he has described.
Not really, because this is a theoretician's hypothesis, not an experimental fact. Theoretician's don't have to account for other people's theories.
That’s something that may help to prune the large number of theoretical variations that have emerged to date.
Probably not, since we are orders of magnitudes in energy away from any experimental results that would allow us to significantly reduce the landscape to a manageable size, and another proposed property not yet seen by any experiment doesn't contribute to that at all.
What’s interesting about this abstract or short article note is that i find it fairly comprehensible. At this point, it seems to be purely speculative or theoretical. The extra weight has yet to be actually observed. But it is in principle testable if a large enough swarm of entangled particles can be assembled. If observation or measurement collapses entanglement, then observation would reduce the weight of the observed particle. Weight is a force, while mass is a fundamental property of matter. Observation destroying some force would no violate conservation of matter-energy (any more than rendering something weightless by putting it into orbit does). The observed system would be no less massive than the entangled on: it would just exert less force on nearby measuring devices. Question: could we measure the weight of an entangled particle without destroying its entanglement? I.e. does any measurement do the trick, or just some sort of “direct” observation?
I also found it interesting that the author puts it this way: “Physicists have long known that a single quantum particle can exist in two places at the same time.” Every discussion I have ever read refers to entangled pairs of particles. Is this just semantics? Or is there a substantive difference between two separate (albeit intimately linked) particles and a single particle with two (or more) locations?