Particles with opposite spins can indeed be found in identical states under certain conditions. This behavior is described by the Pauli exclusion principle, which states that no two identical fermions can occupy the exact same quantum state simultaneously.
Fermions are a class of particles that include electrons, protons, and neutrons. They have a property called spin, which is a fundamental quantum mechanical property related to angular momentum. Spin can have two possible values: up spin (+1/2) or down spin (-1/2).
The Pauli exclusion principle dictates that if two fermions are in the same system, such as an atom or a solid, they cannot occupy the same quantum state simultaneously if they have the same spin. In other words, if one fermion has a spin-up state, the other fermion must have a spin-down state in order to satisfy the exclusion principle.
This principle has important implications, such as the filling of electron orbitals in atoms and the behavior of electrons in conducting materials. It leads to the formation of electron shells and determines the electronic properties of matter.
On the other hand, particles called bosons, such as photons (particles of light) or certain types of atomic nuclei, do not obey the Pauli exclusion principle. Multiple bosons can occupy the same quantum state, even if they have the same spin.
So, in summary, particles with opposite spins can be found in identical states, but only if they are fermions and they have opposite spins as required by the Pauli exclusion principle.