The critical detail here is that this is neither free energy nor free momentum in this setup. Energy is pumped in, and some momentum is generated - that's incre

The critical detail here is that this is neither free energy nor free momentum in this setup. Energy is pumped in, and some momentum is generated - that's incredibly boring and not at all something that should raise any skepticism. The question of what in the hell was being pushed against to convert that energy to momentum, on the other hand, is a really interesting question, but not one to deeply pursue until we're actually sure it's happening. Which seems like the cavity wasn't the interesting bit in the end. A shame and a bit boring after so much careful testing, but nothing to get worked up over. And the experiments didn't make it obvious that the setup didn't work. I mean, I don't think anyone took the inventor's theoretical claims seriously, but the device did generate some small thrust in a difficult to explain way. Besides, we know that space isn't nothing, so being able to tractor against whatever is there would be a rather intersting engineering find; physicists would then likely take the experiment and go "oh, there's a neat edge case in this system of equations that explains it". There are a lot of interesting edge cases left to find and engineer.