Metaphysics lecture notes - Time & time travel

XX. Time & time travel

XX. a. Direction of time

- Appeal to intuition  time having distinguished direction
o Ability of going forward in time
o Inability of going backward in time
o Impossibility of altering past
o Possibility of altering future
o Certainty of knowledge of past & future different
o Memory of past
 Time asymmetrical according to intuition/psychology

XX. b. Accounts of time

1) Dynamic account of time or the growing block view

- Past & present existing
- Future ≠ existing
- Reality added through passage of time (i.e., carpet unrolling)
- Time ≠ fixed set of events
- Time having property of progressing
 Asymmetrical intuitive understanding of time – present = edge of unrolling carpet

2) Eternalism

- Past/present/future all existing equally (i.e., car on road)
- Time symmetrical with ≠ direction
- Economical view of reality
- Possibility of predicting future in every detail with complete knowledge of world
- Clash with intuition of time
- ≠ sense of temporal becoming/free will

3) Presentism

- Only present existing
- Past & future ≠ existing
- Accounting for peculiar significance of present in intuition

- Moving spotlight theory (?)

XX. c. Arguments for an asymmetrical account of time

1) Appeal to the second law of thermodynamics

- Law of entropy – universe evolving from highly ordered state to highly
disordered state  time asymmetrical
- Past differing from future due to future being more disordered than past
- Example: eternal timeframe – possibility of ordered universe evolving to
disorder & evolving further to order  universe working backwards