Scientists utilise Bernoulli principle to ‘lift’ aircrafts against the Earth’s gravity but I am sure they don’t really understand how this principle works. If they had, they would have realised long ago that it is the same principle that underlies the mystery of gravity. And Bernoulli principle would have become much more famous than Newton’s laws and wouldn’t have let Einstein’s theories distort our understanding of Gravity.
Bernoulli principle as understood by physicists states that ‘the pressure exerted by a fluid decreases as its velocity increases’. In other words, as a fluid moves faster, it exerts less pressure. Some physicists think that it is the law of conservation of energy that underlies the Bernoulli principle; while others attribute it to Newton’s 2nd law. That just highlights the physicist’s ignorance on not just Bernoulli Effect but also on the laws which they try to make use of to explain Bernoulli Effect. The fact is that we need neither of them to understand how Bernoulli principle works. What we need is just common sense.
To correctly explain Bernoulli’s effect we must first correctly understand about pressure. Pressure is defined as force per unit area. We know that force is a vector which means that a force is not just a quantity but also has a direction. For example if someone says ‘‘a force of 1Newton is applied on the ball’’, it conveys little meaning because we need to mention in what direction that said force is applied to make sense. There could be a number of forces acting simultaneously on a body from many directions, but the sum total of all the forces is what decides the final force vector and hence the direction of work. Because pressure is nothing but force, it implies that pressure is also a vector. So whenever we talk about pressure, it makes again no sense if we just say 1 Pascal or 2 Pascals and not mention the direction of pressure. This fact is often ignored or forgotten when physicists talk about pressure. Pressure i.e. the force exerted by a body, can be different in different directions. For example a book lying on a table may exert a downward pressure of 1pascal but it exerts no pressure in the upward direction or laterally. And we all know that the pressure exerted by water inside a container on the earth is not same in all directions.
Having realised that pressure is a vector; now we will go on to understand what pressure means at a deeper level. We know that a gas or a liquid exerts pressure on the walls of its container. But what is the fundamental mechanism that underlies the phenomenon of pressure? In other words from where does that force which we feel as pressure come? For this we will have to go to the kinetic theory of gases which states that the pressure of a gas is caused by collisions of its molecules against the walls of the container. The sum of the impacts per unit area of a wall is what we measure as the pressure applied upon that wall or in that direction.
We ‘know’ that the molecules or the atoms of a gas are in a state of random motion and collide with each other and with the walls of the container. Random motion implies that the molecules of a gas move equally in all directions (or in other words there is no net movement) and hence collide equally with all the walls and exert equal pressure in all directions. This is probably the reason why physicists ignore direction when they talk about pressure.
It is may be true that a gas inside a balloon exerts equal pressure in all directions in some situations, for example in the outer space and away from the celestial bodies when there is no ‘external influence’ upon the gas particles. But in the vicinity of earth, the effect of gravity can make the molecules move faster toward the bottom wall of a container and hence we may expect a little more pressure exerted upon that wall. (More over the term ‘random motion’ is only true at a gross level. If we magnify things and look deeply into the microcosm we would probably appreciate a highly ordered motion of the molecules and will be able to appreciate the slight differences in pressure in different directions)
1) Pressure is nothing but force exerted per unit area of a surface
2) Pressure is a vector quantity
3) It is collisions of particles against a surface which manifests as pressure upon that surface.
Now imagine a container ‘filled’ with some gas. The gas molecules or particles move randomly and collide with the walls of the container. As discussed earlier, the sum of the impacts per unit area of a wall is what we measure as pressure upon that wall. If we ignore gravity and other external influences, the gas molecules collide equally against all the walls and hence exert equal pressure in all the directions i.e. on all the walls of the container. Now let’s remove the left and right walls of the container and make the gas to flow through the box in the rightward direction. Obviously the gas particles no longer move ‘randomly’ in all directions but move ‘preferentially’ towards the right. So the number of collisions against the top, bottom and other remaining walls of the container diminish. The result is that we measure less pressure being exerted by the gas on these remaining walls of the container. And the faster a gas flows in a given direction, the lesser the number of collisions on the side walls and hence the lesser the sideward pressure.
The statement that a fast moving fluid exerts less pressure makes no sense. The truth is that it exerts less pressure only on the side walls (i.e. in the perpendicular direction). If we place a pressure gauge just opposite to the flow of gas, we will realise that it actually exerts much higher pressure in the direction of flow. (And obviously much lower pressure in the opposite direction)
Now imagine a body suspended in a tank of still water. Obviously the water particles keep colliding with the body on all its sides with equal force. In other words the water exerts equal pressure on all the sides of the body. And because there is no net force acting upon it, the body remains still and suspended inside the water.
Now imagine that there exists another body in the vicinity and which starts spinning vigorously. The body obviously stirs the water around it and induces circular currents in the water tank. Obviously the water particles that are closer to the spinning body get stirred faster than the ones that are farther away.
How would this scenario influence the first body?
- the body which was still before starts moving in the direction of the water currents
- it starts spinning (in the opposite direction to that of the ‘inducer’)
- and it gets dragged towards the second body (why?)
Now replace water tank with Ether universe. Imagine a body suspended in still Ether. Imagine Earth nearby and allow it to spin. That explains gravity.
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