Electron Drift and Murder Rates

     I have met with a lot of criticism for my posts on income inequality and muder rates (e.g. here). The primary criticism is that people are far more complex than my posts might suggest and that it is not abstract notions such as 'income inequality' that determine a person's actions but rather their personal history. As a result I am compelled to respond.

     To do so I begin with an (classical) analogy from physics; the notion of drift velocity. Electrons in a conducting wire tend to'wander' about in random directions at approximately 1570 km/s. This random movement is akin to the complex lives of individuals. Impossible to describe and predict, it accounts for most of the movement of the electrons. Likewise, individual events in our lives account for our characters and habits.
     Now, what occurs when we apply an electric field to our copper wire. The electrons dash off! Well........at a speed of the order of roughly one metre per hour (in the wiki example of 1mm diameter copper wire with a current of 3 amps). Clearly this 'drift velocity' is swamped by the random motion of the electron (illustrated well here). In this case the applied field acts as the 'environment' or 'backdrop' for the charges.
       In a similar vein, income inequality forms the backdrop and environment for members of a society. The slow drift of the electrons is comparable to the increase in murder rates. While it is the individual's life and circumstances that determine whether or not they will murder, certain conditions (be they economic or otherwise) tend to make certain experiences, certain viewpoints, certain actions more likely. So to claim that high levels of income inequality affect the homicide rate is not to make a deterministic statement and the remarks "Oh I grew up in such a neighbourhood and yet I'm not a murderer!' miss the point entirely. It is simply the case that certain conditions make certain results more likely. In any case, I strongly recommend reading some papers about income inequality and homicide rates. (A very nice example can be found here).