In conventional physics, gravity is generated by mass, but its cause has not been adequately demonstrated. I pursued the idea that gravity on Earth has a specific cause. The cause of gravity is electron polarization due to Schumann resonance.
The Possibilities of Gravity and Antigravity from the Perspective of Earth Science
academia.edu/144102622/The_Pos…spective_of_Earth_Science
If this is correct, gravity does not act on gases, and the principle of Emdrive becomes clear.