The deflection of particles or radiation due to interactions with other particles or fields.Scattering is the process by which particles or radiation—such as light, electrons, or neutrons—are deflected from their original path due to interactions with other particles or fields. It is a cornerstone of experimental physics: by analyzing how a beam scatters off a target, scientists infer the target's structure, from the arrangement of atoms in a crystal to the forces inside an atomic nucleus.
The modern understanding began with Ernest Rutherford's gold foil experiment in 1909, which used alpha particle scattering to reveal the atomic nucleus. The theoretical framework was later developed by quantum pioneers like Max Born in the 1920s.
When a projectile (e.g., a photon or electron) encounters a target, it interacts via forces like electromagnetism or the strong nuclear force, changing its direction and sometimes its energy. The pattern of scattered particles—angles and intensities—encodes information about the target's size, shape, and internal dynamics. Quantum mechanics describes this via probability amplitudes, but the practical result is a scattering cross-section that quantifies the likelihood of deflection.
Scattering is used in X-ray crystallography to determine molecular structures, in particle accelerators to probe subatomic particles, and in medical imaging techniques like ultrasound and radar.
The blue color of the sky is a result of Rayleigh scattering, where sunlight is scattered by air molecules—shorter blue wavelengths are scattered more than longer red ones, a phenomenon first explained by Lord Rayleigh in 1871.
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