Tuesday, June 4, 2013

Polarization in Light and Politics

The essence of an electromagnetic (EM) wave is defined by two key parameters: its frequency and the strength (amplitude) of its electric field (E).  The strength of the magnetic field (B) is not a 'free variable' - it is given by E/c, where c is the speed of light.  Light is just one variety of EM wave.  It, like all others, is self-sustaining because the oscillating electric field produces an oscillating magnetic field and vice versa.  The relationship between the orientations of these fields and the direction of wave travel is shown below:

Figure 1: EM Wave Field Orientations (courtesy of: astronomy.swin.edu.au)

Here, the wave propagates in the x-direction, the electric field oscillates in the z-direction, and the magnetic field oscillates in the y-direction.  The electric and magnetic field vectors are always perpendicular to one another and exist in a plane that is itself perpendicular to the direction of travel of the light wave.  If the light wave is headed towards you, then you can be sure that the magnetic field vector is pointing 90 degrees counter-clockwise from that of the electric field.

While these relative orientations are always maintained, the particular orientation of the electric and magnetic field vector pair (z and y Fig. 1) is a free variable - it is known as the light wave's polarization.

Just as a given light wave has a particular polarization, so do people.  It is a term often used to describe how a person or a group of people leans in terms of political views.  Conservative tendencies are deemed 'right', while progressive ones are deemed 'left'.

Stars, like the Sun, emit light with random polarizations, with no particular orientation favoured in the 360 degree spectrum.  Politically speaking, it seems that most Western societies are not like this.  In America in particular, the voting public, each voter representing one light wave, is polarized.  Republicans to the far right, and democrats to the far left.  It seems unnatural that a group should be so divided, but this is the way the political system has evolved.  Politicians purposely divide - polarize - voters.

Speaking again of light, there exist optical tools that filter out all but one polarization.  The polaroid, discovered in 1938 by the American entrepreneur E. H. Land, does just this.  Land mixed tiny crystals into a clear plastic solution, cooled it, and then stretched it into thin sheets.  The stretched molecules allow for only one orientation of electric field to pass through.  So a polaroid may be thought of as a filter for light.

Politicians are kind of like lasers - they are stubborn, emitting light with just one polarization.  They then act as Polaroids, stimulating that same viewpoint in as many voters as possible.  While purposeful polarization of EM waves is used in a number of practical applications, the polarization of the voting public serves nobody but the politicians.  

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