The concept of "spin" in particle physics is different from the classical spinning motion of macroscopic objects. It is an intrinsic property of elementary particles and is not caused by their physical rotation. Spin is a fundamental property of particles, akin to their mass or charge.
Spin is often described mathematically as an angular momentum intrinsic to the particle. It is a quantum mechanical property that does not have a direct analog in classical physics. The spin of a particle is a fundamental aspect of its quantum wave function and is associated with its intrinsic angular momentum.
It's important to note that the term "spin" is somewhat misleading, as particles do not physically rotate like spinning objects. The name was coined based on similarities between the angular momentum equations for spinning objects and those describing particle spin.
The conservation of angular momentum applies to spinning objects, but it does not directly apply to particle spin. The spin of a particle does not require any external force to keep it spinning because it is an inherent property. It does not cost the particle any energy to maintain its spin.
The value of spin for particles is quantized, meaning it takes on specific discrete values based on fundamental constants. Particles are classified as either fermions or bosons based on their spin values. Fermions, such as electrons, have half-integer spin (e.g., 1/2, 3/2), while bosons, like photons, have integer spin (e.g., 0, 1, 2).
The spin of a particle is not directly related to its physical rotation or speed. It is a purely quantum mechanical property and does not have a classical analog. Therefore, it does not have a defined "speed" of rotation.
Our understanding of particle spin comes from decades of experimental observations and theoretical developments in quantum mechanics and quantum field theory. The behavior of particles with spin has been extensively studied, and our understanding of their properties continues to evolve through ongoing research and experimentation.