Actually, I know a great deal of physics. Maybey not as much as some of you, but I know how physics works.
Anything at rest will remain at rest unless acted upon by another force and anything in motion will remain in motion at the same velocity (directiot and speed) unless acted upon by another force. Air flows over the surface of objects, and for propellent, an aircraft simply changes the air pressure around the engines by the use of fans. The fans pull the air behind the engine resulting in lower air pressure in front of the engine and higher air pressure in front of the engine. The air pressure tries to even itself out, but the fan is preventing that from happening. As a result, the aircraft is forced out of the way so the air can equalize in pressure.