reflection

Reflection is the change in direction of a wave or particle when it encounters a boundary between media, or the act of thinking back on one’s experiences. It encompasses both physical phenomena and deliberate mental processes.

In optics, reflection occurs when light strikes a boundary and bounces back into the original medium. The law of reflection states that the angle of incidence equals the angle of reflection, measured to the normal. Smooth surfaces produce specular reflection, creating clear images; rough surfaces yield diffuse reflection, scattering light in many directions.

In acoustics, reflection of sound waves can produce echoes and reverberation, influencing room acoustics and audio design. The study of how waves reflect helps in applications ranging from architectural acoustics to sonar and radar.

In mathematics, reflection is a symmetry operation that maps each point to a mirror position across a line or plane, preserving distances. It underpins geometric transformations and group theory, and it generalizes to higher dimensions and various geometric spaces.

In computing, reflection refers to a program’s ability to inspect and modify its own structure and behavior at runtime. This capability enables dynamic type discovery, method invocation, and runtime adaptation in several programming languages.

In psychology and education, reflective practice involves the careful consideration of one’s actions and experiences to improve future performance and understanding, often through journaling, feedback, or structured reflection exercises.