Think for a moment about why, if you slam your hand down on a solid table, it doesn’t pass straight through. You might regard this as trivial: surely it is because both your hand and the table are made of solid stuff. But don’t forget that down at the level of atoms, matter is mostly empty space—diffuse clouds of electrons surrounding a tiny nucleus—and so there should be plenty of room for the atoms that make up your hand to easily pass through the atoms of the table without any physical matter coming into contact. The reason they don’t is because of the electromagnetic force between the
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