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 (politics)
The vast majority of studies on elite polarization focus on legislative and deliberative bodies. For many years, political scientists measured polarization by examining the ratings of party members published by interest groups, but now, most analyze roll-call voting patterns to determine trends in party-line voting and party unity. Many political scientists studying American politics rely on Poole and Rosenthal's DW-NOMINATE scores, which assign a single liberal-conservative score to each congressperson, enabling comparisons of members from different Congresses. There is much more research on polarization in Congress than on polarization in the other branches of government or in state governments. Azzimonti's political polarization index is more comprehensive instead because it is based on media coverage of newspaper articles reporting political disagreement about policy in all branches of government. Recent work by Gentzkow, Shapiro, and Taddy has used the text of the Congressional Record to document differences in speech patterns between Republicans and Democrats as a measure of polarization. They find that polarization has increased dramatically since 1994.