An apple falls to the floor. Straight down, as far as we can tell.

But how do people stay down, up-side-down, like in Australia? And why do we not spin off the globe as it turns around, and around.

And nobody can proof it. Not the scientists not anybody. They have explanations, but no proof.

**But it is there.**

Whatever you name it. We are stuck to the floor. So what is it?

To begin to answer that question: I will try to show what it is on a globe earth model. In another article I will try to explain what it could be on a flat earth model.

What is magnetism? I do not understand that. I cannot see it. But it is there. It is an attraction between two magnetic objects due to the Lorenz force.

And it is quite strong. Metallic objects are 'glued' to a magnetic sphere, and can stay glued even when the sphere is spinning fast.

But it is not gravity.

An example of what it is not is the 'spinning tennisball with water coming off'. Yes there is gravity applied to both water and tennis ball, but that is very small. The biggest mistake though is the amount of rotation of the spinning ball. Earth (as a globe) is spinning at 1 rotation per 24 hours. Even a drenched tennis ball will stay wet at that amount. Off course the earth is bigger, so the speed is larger. But even then the outward force is v2 / r = (465.1)2 / 6378000 = 216318 / 6378000 = 0,03392 m/s2, which is tiny compared to the downward force

You can measure it though.

The Cavendish Experiments shows there is an attraction between two masses. if done properly a number of amateur experiments are shown in this video. However they are amateur experiments, you should eliminate other forces acting on the masses, like wind blowing and the torsion on the wire, etc. Still they are nice examples of how to visualise it.

Gravity on earth is 9,81N (well on average) which corresponds with the acceleration of 9,81 m/s^{2 }on earth's surface at sea level in a vacuum.

But not everywhere weight is different on the poles, than it is at the equator. And if you take a look at the weird picture on top of this section: It fluctuates all over the place.

And you do not need a satellite to see this for yourself. This is something you and I can measure for ourselves.

**So how does gravity work in a globe earth model.**

Gravity works on any two object. Yes even the smallest one. And, as is usual for a lot of forces, it acts upon the centre of mass. This means that the combination of all individual attractions is centred towards the core of the earth.

The force is very weak. And can be described with the following formula:

$$F = \frac{G * m_1 * m_2 }{ r^2}$$

So the larger the mass of either object, the stronger the force. But the more distant de objects are apart, the smaller (squared) it becomes. However G (the gravitational constant is very small (6.674×10^{−11} N·kg^{–2}·m^{2})

The mass of earth is estimated as a little under 5.97 × 10^{24} kilograms. (That is 6.000.000.000.000.000.000.000.000 kg). That is a lot of mass.

The mass of the moon is estimated as a little under 7.3 × 10^{22} kilograms.

The distance between the two centres of mass of the earth and the moon = 3.84 x 10^{8} meters.

$$F = \frac{6.674 * 10^{−11} * 5.97 * 10^{24} * 7.3 * 10^{22} }{ {3.84 * 10^8}^2}$$

So the gravitational force between earth and moon = 1.97123∗10^{20}N

The gravitational force between as person of 75kg and the earth ≈737N. This is almost the same as 75 * 9.81.. but there is a lot of rounding errors there. But the formula checks out.

What *is* important about these figures is that the attraction between moon and earth is way bigger than between me and earth. Or between me and you, where ever you are.

So the force of gravity is more or less the same on the whole of the earth. It might differ because you are farther away from the earth's core, but even on mount Everest there would be only a 0,3% difference. (note: This does not take into account the position of Everest on the globe)

So how to explain the difference in weight? Well weight is not the same as gravitational force. You weight is a combination of several forces combined. One is the gravitational force, one other is the centrifugal force. This force (even though it is small) is larger at the equator than on the poles. At the equator you move at a 1,600 km/hour. At the poles you just turn around, and around.

Actually the earth bulges a little at the equator and this adds to the distance. The distance to the center of the Earth from the equator is 6,378 km. And the distance to the center of the Earth from the poles is only 6,356 km. That’s a difference of 22 km. So again in regards to the gravitational force this is small potatoes.

Meanwhile they have discovered the density of the mass below you also affects the size of the gravitational force. So these figures are just averages over the globe.

However: It will explain one thing (explain, not proof!), and that is: You won't fall of the earth, because you are at the south pole. The total effect of gravity is pointed towards the core of the earth and not down south. Besides: North and South being up and under is just the ancient European way of picturing the globe.

**gravitational theory according to Einstein**

Okay.. that goes way over my head. I am a mathematician, not a physics graduate.

If you are interested vsauce has a popsci video on that: