>Perhaps one clue as to why it is so much harder to quantize gravity than everything else is that other force fields in nature exhibit a feature called “locality” ... But “there’s at least a bunch of theoretical evidence that that’s not how gravity works.”

Really? I was under the impression that gravitational waves propagate at very nearly the speed of light.

Also, this article doesn't do a very good job of explaining why people are so certain gravity can be quantized. Gravity as a deformation of spacetime seems like a perfectly reasonable model to work with. Why should we think it doesn't reflect reality?

  I was under the impression that gravitational waves propagate at very nearly the speed of light.