One of the most surprising facts in atomic physics is that matter โ including your body, the chair you sit on, and the Earth beneath your feet โ is almost entirely empty. Atoms, the basic units of matter, consist of a very small and dense nucleus surrounded by a "cloud" of very sparse electrons.
To illustrate how empty atoms are: if you were to enlarge the nucleus of a hydrogen atom (a single proton) to the size of a tennis ball, the electron orbiting it would be about 2 kilometers away โ and between the tennis ball and the electron, there is nothing but empty space. Atoms are 99.9999999% empty space by volume.
So why does matter not feel empty? Why don't we fall through the floor if everything is empty? The answer lies in electromagnetic forces. Electrons surrounding the nucleus of an atom create an electric field. When two objects collide, the electrons in the atoms on the surface of both objects repel each other because they are both negatively charged. This "repelling" electromagnetic force is what we feel as the solidity and rigidity of matter.
If we truly removed all the empty space within the atoms of the human body and compressed only the nuclei and electrons, all 7 billion people on Earth would fit into a volume no larger than a grain of sugar. This is not an exaggeration โ it is the real mathematics of atoms.