Jim Logajan wrote:
Alan Baker wrote:
Because the push is caused by the impact of countless air molecules
with the surface of wing. If those collisions fall to zero (i.e. in a
perfect vacuum) then there is zero push.

I don't see what a change in air density (such as taking the extreme case
of a vacuum) has to do with lift.

I'm going to build a thick wing, real thick! About 10,000 feet thick.
While the bottom surface of the wing sits at 29.92" sea level
atmospheric pressure, the upper surface will be *way* up there, in a
lower-pressure area. This airplane is gonna to lift off the ground at
zero airspeed with no power.