FiatLuxDave already did a great write up of his concerns: https://news.ycombinator.com/item?id=8815059 . I won't/can't criticize any physics mentioned on their website - but I would argue that there is a pattern in the (perceivably) recent surge of experimental space drives. I believe it's a simple economical cause: Finer and more precise measuring instruments become more and more affordable. And as FiatLuxDave points out, measuring any (small) amount of force or disturbance in a regular workplace is just more likely than not. So you get lots and lots of people with these hyper sensitive devices, which then come up with some crazy explanation for the unexplained force rather than changing the setup of their experiment.