Phil 105: Science and Philosophy - Fall 2004 Lectures

!You will be sorely disappointed if you think that these are a substitute for attending class!

Topic Four: Time

1. 'Passing Time' in the bock universe

• What is the cause of the asymmetry in the ways we experience space and time?
• What is our 'shape' in the block universe?
• What do the paths of 'causal influences' – e.g., light, sound waves – look like?
• How do they intersect our path?
• Thus our experiences are
  
• a temporal sequence (because of our shape) of
• things arranged in space at approximately the same time (because of the paths of light and sound).
  

• To see the asymmetry, consider paths 'rotated' in space and time: i.e.,
  
• imagine a creature whose worldline is  stretched out in a flat curve in space, and
• suppose causal influence travel a long way in time but not far in space.
• Then how do the paths intersect the worldline?
• Thus the creatures experiences will be
• a spatial sequence (because of its shape) of
• things arranged in time at approximately the same place (because of the paths of light and sound).

• The point is that the asymmetry in experience requires nothing more than the block universe – and the asymmetric way in which things are arranged in it.

2. A paradox of time travel

Stonehenge – imagine the stones (not menhirs) in the foreground contain a time portal for one minute starting at the solstice – image from http://rdmteam.piranho.at/kultstaetten/stonehenge/stonehenge.htm. (For reliable information check out http://www.stonehenge.co.uk/history.htm.)