The idea of both way memory is possible: Once one knows the past, and knows ALL about the present, future is very well predictable- that's a great part of science: predicting things that weren't seen or didn't happen yet. However, Carroll is taking the idea one step forward that brings up absurd similar to the "grandfather paradox" in the case of time machine: The knowledge of the future can be used in order of doing things that might change it but it doesn't happen:
- The King's Messenger could be warned not to commit the crime, but no, he is punished now so after being punished, there is no reason not to commit the crime.
- The Queen could use the knowledge of the future to avoid pricking her finger. However, such an idea doesn't cross her mind. Moreover, I think that if Alice would offer such an idea the answer would have been something like "what for ? I have cried already".
In our world the whole ides of predicting the future is to change it: avoid risks, get ready to events etc. Through the looking glass things work differently....
"you can't look ALL round you -- unless you've got eyes at the back of your head"
The fact is that we can't see what's behind us since we don't have eyes at the back. If we turn around (as Alice did) our back is turning with us and stays behind us. The only way we can know about our back is using the real subject of this book: Looking Glass.
Alice's falling from her seat in the boat
I'm puzzled by the description of the small accident: The way it seems Alice should have fallen backward, on her back. And the rushes where at her feet- in front of her. So, how could she fall "down among the heap of rushes" ? Somehow, I don't think that any looking- glass trick can explain this and I'm puzzled what's the explanation.