Its all about Physics.

  Solid-state physics : Introduction: Solid-state physics is the study of rigid matter, or solids, using techniques from metallurgy, electromagnetism, crystallography, and quantum mechanics. The study of condensed matter is dominated by this field. In solid-state physics, it is investigated how the atomic-scale characteristics of solid materials translate into their large-scale characteristics. As a result, the theoretical foundation of materials science is solid-state physics. It also has direct uses, such as in semiconductor and transistor technologies.   Atoms that are tightly packed together and interact vigorously give rise to solid materials. The mechanical (such as hardness and elasticity), thermal, electrical, magnetic, and optical properties of solids are produced by these interactions. The atoms may be arranged in a regular, geometric pattern (crystalline solids, which include metals and common water ice) or randomly, depending on the material and the circumstances o...

  Waves: A wave is a dynamic disturbance that propagates and causes a change in equilibrium of one or more parameters in physics, mathematics, and related subjects. Quantities may oscillate regularly around an equilibrium (resting) value at certain frequency if a wave is periodic. A traveling wave is one in which the entire waveform moves in one direction; in contrast, a standing wave is one in which two periodic waves are overlaid and move in the opposing directions. In a standing wave, there are some points where the wave amplitude seems reduced or even zero, and these positions have null vibration amplitudes. A wave equation (standing wave field comprising two opposing waves) or a one-way wave equation (for single wave propagation in a certain direction) is frequently used to describe waves.   In classical physics, two types of waves are most frequently examined. Stress and strain fields oscillate around a mechanical equilibrium in a mechanical wave. A mechanical wave is a ...