Temporal Anisotropy . In a short video clip showing two billiard balls bouncing off each other, forward and backward in time are indistinguishable if one ignores friction and inelasticity. In a longer video of a billiards break, the future is the end in which the balls are no longer in a nicely ordered triangle. If causes can be attributed to effects as easily as effects can be attributed to causes, then causal laws do not distinguish past and future, and the future for an event is the direction of increasing disorder in the system. Traces and memories of the past are a localized increase in order at the expense of an increase in system-wide disorder. Due to statistical considerations, some systems can cycle between order and disorder. In such systems the direction locally considered to be future can vary over the timeline of the system.
Option 2: Wal-Mart stores are now being sued for gender-based discrimination in hiring practices, promotions, and pay. Students are shown a chart from a recent newspaper article comparing the salaries of men and women at Wal-Mart in different occupational categories along with the percentage of each job category that is male or female. Students discuss whether they believe this chart is evidence of gender-based discrimination. (If they do not, they are asked what type of evidence they would need to see to be convinced that a company was practicing illegal discrimination against women.) This discussion often leads to many students suggesting that the women at Wal-Mart just weren't working as hard or were not as smart as the male employees. This is used to launch into an exploration of research-based findings about gender differences and careers along with myths about working women.