I enjoy leisurely browsing the various time theories while trying to wrap my brain around even the simplest concepts. Most recently, I've read portions of God and Time: Four Views which has contributions from William Lane Craig and others [Paul Helm, Alan G. Padgett, and Nicholas Wolterstorff]. Brian Greene's The Fabric of the Cosmos has a couple of chapters on time ["The Frozen River: Does Time Flow?" and "Chance and the Arrow: Does Time Have a Direction?"]. Mind warping stuff. And several years ago I read at least a portion of About Time by Paul Davies.
This week, I listened to physicist Dr. Julian Barbour on Quirks and Quarks talk about his idea that time is optional in relativistic physics as well as in quantum physics (if I heard him correctly). His book is titled The End of Time.
Philosophies of Time
Here are the major philosophies of time, if I have them straight:
- Presentism - only present things exist
 
- Eternalism - things past, present, and future are equally real
 
- Perdurantism - an object exists continuously through time; existence at each time is just a portion of its whole existence throughout time. Eternalists are typically perdurantists.
 
- Endurantism - an object exists completely at different times; existence at each time is separate from its existence at other times. Presentists are typically endurantists.
 
The Flow of Time
Then there's the idea of time's flow. Why does it flow in only one direction? Paul Davies has a fascinating essay on the subject titled That Mysterious Flow. And, as mentioned earlier, Brian Greene has a couple of chapters on the flow of time in his book, The Fabric of the Cosmos.
 

