I would like to review some principles, as well as pose some questions, to this highly intelligent community. As such, feedback of ideas, or comments, or even snotty remarks would be appreciated. Classical physics is built on Newton's laws. As such, Newton's laws always apply somewhere, and Newton's three laws are actually one giant law if you think about it. It essentially says that objects don't change their velocity unless a net force acts on them..period. I often read about people arguing/debating that Newton's third law is the definition of lift, and that Bernoullis's has nothing to do with it. Well, Bernoulli's principle is really a form of Newton's second law, and air pressure itself is a form of Newton's third law, which I would like to discuss a little more in detail. Air pressure, on a submicroscopic scale, is caused by the incessant impacts of the constituent molecules on a surface (as well as on each other). The impact of these molecules (since they have mass) applies a force to the surface, and the surface applies an equal and opposite force to the molecule. These actual forces are caused by the interaction of the electrons in the molecules themselves (and that is the level we will leave it at). Now, a low pressure (suction) just means that the pressure is lower then some other reference pressure, but it is still a positive number. In other words, the molecules are still impacting the surface, applying a force to the surface, they just are not hitting it as hard (translational velocity-temperature) or as often (density - molecules per unit volume) as a"higher" pressure would be. So, negative pressure just means that the pressure is lower then a reference pressure (usually atmospheric) but the lowest absolute pressure available would be zero, which would mean that no molecules are impacting the surface. You really can not have pressure that is an absolute (for lack of a better word) negative pressure, as the molecules can not pull on a surface, just push. The reason I make this statement, is that I have heard people say that the top surface of a wing (airfoil) pulls the air down, therfore Newton's third says that the air pulls the wing up. But based on the definition of pressure, the air molecules caint pull on anything, Newton's third law is actually in the definition of pressure itself. What can happen is that the air pressure on the bottom of the wing, which is higher (molecules hitting the surface harder and more often) can and do create a net force on the wing. This force can be up, to support weight, sideways to turn (centripetal) or whatever. Every body always talks about conservation of momemtum. But remember, momentum is conserved in the abscence of external forces. A wing in steady, straight in level flight is actually not conserving momentum. If it were, then the impacts of the molecules should cause the wing to accelerate in the opposite direction, but the wing does not (in level, unaccelerated flight) as the lift is equal to weight. Weight is the external force in this example. You could even think of pressure itself as an external force. The pressure gradient in the flow is what causes the mass of the fluid element, which has mass and therefore inertia, to accelerate, decelerate, and change direction. A cubic foot of air at sea level has a mass of .0023769 slugs. Therefore, it has a physical weight of .08 pounds. But, a cubic foot of air at sea level exerts a pressure of 2116 Pounds per square foot. Again, this is the result of the internal motion of the constituent molecules. If you had a solid with .0023769 slugs of mass that was one cubic foot, it would weigh .08 pounds, and since pressure is force (weight is a force) divided by area, the solid would only exert a pressure of .08 PSF vs the cubic foot of gas that exerts a pressure of 2116 PSF. This is actually the basis of the hydrostatic equation, in which the vertical pressure gradient from the surface of the earth to the edge of space, supports the weight of the air. You have a high pressure at the surface of the earth, at the edge of space you have zero pressure (vacum) but yet the air does not rush up in to space in the direction of the pressure gradient (high to low) because the air has mass, and therfore weight in the earth's gravitational field. so, the air pressure actully supports the weight (mass). Any feedback would be highly appreciated, as I enjoy talking physics. I wil post more thoughts on similiar subjects at a later date.