Examinations of Time

Kevin Mullins, Science Department, Coconino Community College

I teach several geology classes, a Natural Disasters class and a Planetary Science class as well at a small community college with a diverse student population. Although I've long thought that a complete lecture/lab or even a short course on time and its various aspects would be valuable and fun, the opportunity to develop such a class just never seems to present itself. I think that this workshop could go a long way toward making that happen. I've read a few of the ideas from other workshop attendees and each has its own merits depending on the focus of the overall class. This must dictate the approach and methods in how time should best be taught, although I think some tangential examples or sub-topics could pull such a focused lecture or lab together.

My work experience bridges the gaps between terrestrial and planetary exploration and research. In planetary studies time is always a critical factor from a whole host of different aspects, each with its own problems, values and consequences. Thinking of time in a planetary sense has become second nature to me but can also cause problems in that most students arrive in class with a very different sense of time (a fundamentally important concept that needs to be addressed before real understanding and communication in the classroom can be achieved). This is partially a generational condition but other factors are involved as well. Added to this is a personal fascination with relativity and the concept of time-space as inseparable components of the physical world we live in. Sometimes bringing the personal experience to such lectures can be enlightening and a method for getting students to transition from the familiar to the unknown or new. Unfortunately, my education and training in how the brain, and its invisible compadre the mind, work is woefully lacking. However, there are a few of initial exercises I have my students do to segue into time scales and the idea that time is not "fixed" or constant.

The first few exercises I use are pretty simplistic but can yield effective, and sometimes interesting, results, although like everything this changes from class to class. After introducing the topic in a broad sense I ask them to consider the passage of time relative to a particular event or significant occurrence in their lives and then think about how the passage of time in that situation relates to "normal" time. We use immediate and familiar examples of marking time and compare/contrast its passage between individuals. We also consider other historical ways humans mark the passing of time and the students begin recording such obvious celestial time-pieces as the lunar phases, planetary motions (varies from semester to semester) and seasonal cycles. We then examine what those different time-pieces can mean and do both culturally and practically. Eventually, we get into topics like the relationships between mass, velocity and time (investigating how the GPS system works and what role relative-time plays in it is always a great exercise). As we get into relativity, the Big Bang (before, during and after), cosmological distances, etc. we examine how time can become the unit of measuring distance throughout our Universe. What successful interstellar space travel might mean to our concept of time and whether time is truly constant or relative is always a good wrap-up discussion.

Geologically speaking, discussions about time and the history of the Earth can make use of some of the above examples (particularly the more general ones) but I find discussing the change of familiar landscapes (from day-to-day, generation-to-generation, etc.), sedimentation, erosion and evolutional rates to be a good starting place. Nothing beats standing at the base of the Coconino Sandstone or Redwall Limestone along a trail in the Grand Canyon and discussing sedimentation rates to truly bring home the enormity of geologic time and the inexorably slow rate of some geological processes at regional scales. Getting students to understand the difference between time as they live it and time on a planetary scale is always an important part of my pedagogy.