The inability to pass one atom through another is primarily due to the fundamental forces and properties that govern atoms and their interactions. Atoms consist of a central nucleus made up of protons and neutrons, surrounded by a cloud of electrons.
One of the key forces at play is the electromagnetic force. Electrons carry a negative charge, while protons have a positive charge. Like charges repel each other, so when two atoms come close together, the electron clouds and nuclei repel each other due to the electromagnetic force. This repulsive force prevents the atoms from merging or passing through each other.
Additionally, quantum mechanics, which describes the behavior of particles on a microscopic scale, dictates that electrons occupy specific energy levels and orbitals around the nucleus. These energy levels and orbitals create a well-defined structure for each atom, with specific spatial distributions. When two atoms approach each other, the overlapping electron clouds and the Pauli exclusion principle (which states that no two identical fermions, such as electrons, can occupy the same quantum state simultaneously) further prevent them from passing through each other.
The combination of electromagnetic forces, electron cloud repulsion, and quantum mechanics principles creates a barrier that prevents atoms from passing through each other. This behavior is a fundamental aspect of atomic and molecular interactions in the physical world.