1. According to Stephen Hawking, there are three "arrows of time."
2. These arrows he calls the thermodynamic, psychological, and cosmological.
3. The thermodynamic arrow points in the direction of entropy.
4. The psychological arrow points in the direction of memory.
5. The cosmological arrow points in the direction of the expansion of the Universe.
6. Hawking states the psychological arrow is dependent on the thermodynamic arrow, that is, the direction we perceive as being forward in time is the direction in which entropy (or disorder) increases.
7. Hawking posits that God could have made the Universe in such a way that order increases (he later discards this proposition, but let's take it to its logical conclusion).
8. If this were true, since the psychological arrow is predicated on the thermodynamic arrow, we would perceive the Universe as operating in the opposite direction as what it is actually operating. (That is, even though the Universe would be contracting, we would perceive it as expanding.)
9. Because we would perceive the Universe as expanding whether or not it was actually expanding, Hawking's cosmological arrow does not, in fact, state anything whatsoever.
This is a response to an argument Stephen Hawking puts forth in the chapter "The Arrow of Time" in his book A Brief History of Time. In it I'm showing that one of his propositions, when taken to its logical conclusion (which he suspiciously neglects to do) undermines his argument vis-a-vis cosmological time (which he subsequently buttresses the remaining part of the chapter on).
It's also a textbook in my IH 2 class, thank yew vewwy much.
Really?!? Eeek! :eek:
Exactly! As I have mulled over the book, I have realized that the only way Hawking doesn't contradict himself is by eliminating the Western idea of God, that He is extrauniversal, acting ex mundi. Hawking, though himself an atheist, takes great pains to maintain that QM allows quite a large place for God, but for Hawking's theory to make any sense, we have to (ironically enough) totally deny this concept of God, because with God in the picture, there is no real reason that the cosmological time arrow is oriented the way it seems, and if there were such a God, it seems most reasonable that it would be His will the universe would proceed from the most disordered to the most ordered possible state; since human memory and perception of time is bound up with entropy, we would be traveling backwards in cosmic time and never be able to know it.