I don’t understand how all of the weight on the Earth doesn’t force it to collapse on itself? What is the Earth using to provide this force that is stopping us from falling through. Obviously gravity is a thing but I don’t even understand that well enough lol.
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It is a combination of electric repulsion and the Pauli exclusion principle.
Electric repulsion means that when atoms get too close, the electrons on the outside of the atoms repel each other because they are both negatively charged.
Pauli exclusion is a quantum effect that prevents particles from overlapping too much in space. It is different from electric repulsion, but the consequence is similar, providing an extra repulsive effect between particles of the same type (i.e. electrons don’t want to sit too much on top of other electrons).
These work together to make it so that, if atoms get too closer together, they push on each other and try to spread back out. That keeps the Earth large because, though gravity is pulling it inward, all that molten rock can’t become too dense, because the atoms are pushing on each other too much. It also keeps us from falling through the ground, because the atoms in our feet/shoes experience these repulsive effects when getting too close to the atoms in the ground.
It *is* collapsing in on itself. Pressure in the mantle is around 200,000 atm for the uppermost part and around 1 million atm close to the core. These are pressures that are so high that the same materials which would be solid rock at the surface behave more like a liquid. But, all this material has nowhere to go. It’s collapsing in on itself equally from all directions, crushed under the immense weight of all the rock above it, but *also* being compressed by the material around and below it. No matter how high the pressure gets these materials are still taking up some volume. So the earth maintains its shape
You know how you can’t put your hand through a wall?
The force that stops you from doing that. The “physical objects don’t overlap force”. Is the one that’s stoping you from falling through the floor.
That’s the force that’s holding back the gravity, so to speak.
So as you can see, this subject is a little bit difficult to explain in an ElI5 manner but I’ll give it a go.
Take a piece of paper, now ball it up. Try to squish it as much as you can. This would be earth in this analogy and you squishing it down, we could say, is gravity (its more complicated than that but let’s just go with it for now).
You can probably squish the ball of paper to a pretty small size by hand but then it stops right? So we could use something more heavy/strong like a vice or something to get it even smaller (increase “gravity”) but you’d still have a hard limit on how small you can make the ball. Now why is that?
Paper is a material made of molecules, which are made up of atoms. In other words: paper is made of “matter” and this takes up a certain amount of space. The amount of space gets determined by the electromagnetic forces in the atoms. We’ll leave this at that for now, just remember, these forces are extremely strong.
So these forces try to push back against you (the “gravity”) trying to make the ball smaller. So you’ll eventually create a state where you cant get the ball smaller because you use the same amount of force as the paper ball is pushing back. You created an equilibrium.
Now take this back to earth. Gravity is pushing on the earth to make it smaller (again extremely oversimplified but just go with it) and the material in the earth is pushing back in an equilibrium. Now gravity is way stronger then we can exert on the planet because it is on such a big scale. The earth’s material has no issue pushing back against even multiple metric tons worth of weight. This provides the “support” you are talking about.
Earth doesn’t collapse in on itself because gravity doesn’t increase, it is a constant meaning that as far as we know it will always be the same, so equilibrium has been reached and thats it.
Rocks are hard. The earth is a big rock. Imagine squeezing a rock with some dirt on the outside, nothing happens. If you want to break through, you would use another rock or a hammer, and hit it very hard. We are so small and soft compared to the earth, we are basically just dust sitting on the outside of a rock.
So what is stopping matter from collapsing under its own gravity?
First layer of support is the electric repulsion between the electron clouds of atoms. Electrons are all negatively charged the closer two coulds get the stronger the repulsion. If it equals gravity its in a balance. For a while this is a stabil balance more gravity more compression stronger repulsion balance maintained.
But there is a point where the electric repulsion isn’t enough anymore. Electrons are forced into similar states but that once all possible states available are occupied there is no where to compress anymore. The Pauli exclusion principle is the result that all fermions like electrons can only pair up in antisemitic states. Or in simpler words no two electrons can occupy exactly the same state. This effect keeps an object from collapsing further and is called electron degeneracy pressure. And this effect keeps white dwarfs from collapsing further.
But gravity could be even stronger accelerating the material as it falls inwards creating energy conditions where where the protons and electrons turn into neutrons and they get compressed, neutrons are fermions two so the same thing applies and we call this neutron degeneracy pressure keeping neutron stars stabil.
But when the infilling material is accelerated so much there is too much gravity neutrons are forced to have very different momentums which allows them to bi pushed into a single point whatever that really means. Thats a singularity that we imagine as a point of infinite density. Thats a black hole.
So material structure comes from electric repulsion between the electrons. Then we got degeneracy pressure between fermions and after that we got a singularity.
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