Polarization (waves)
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string "(see image)"; for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids. In some types of transverse waves, the wave displacement is limited to a single direction, so these also do not exhibit polarization; for example, in surface waves in liquids (gravity waves), the wave displacement of the particles is always in a vertical plane.
Polarization (economics)
One way of quantifying the polarization of the economy is to compare the fraction of those with incomes that are close to the middle—for example, a range that goes from 50 percent greater than the median to 50 percent less than the median—has fallen since 1970 from just over 50 percent to just over 42 percent. Similarly, the U.S. and the E.U. have shown almost identical trends in the share of employment rise by the high and low skill jobs, and a loss by the middle skill jobs, between 1993 and 2006. Polarization became an issue during the 2012 United States presidential election when Joe Biden asserted that the previous policies had "eviscerated" and "buried" the middle class. This picked up on Stiglitz' statement: "But in recent years, America’s middle class has become eviscerated..."