A chick hatching from an egg. The chicken or the egg causality dilemma is commonly stated as which came first: the chicken or the egg?. The dilemma stems from the observation that all chickens hatch from eggs and all chicken eggs are laid by chickens.
Unpolarized light can also become polarized when it is scattered in air (also known as Rayleigh scattering). This occurs due to the fact that the EM waves cause the electron in air to vibrate, producing radiation and causing polarization of the light.
Light scattering is a form of scattering in which light in the form of propagating energy is scattered. The scattering is inelastic, meaning it is shifted in energy from the Rayleigh line frequency by an amount that corresponds to the energy of the elastic wave or phonon, and it occurs on the higher and lower energy side of the Rayleigh line, which may be associated with the creation and annihilation of a phonon.