Tell me.
In Douglas Adams’ Hitchhiker’s Guide to the Galaxy, the characters keep traveling back and forth in time, i.e. keep changing their (x,y,z,t). Or, the author keeps juggling them through and in between space-time co-ordinates. Notice that at no point they forget what has happened to them before? Irrespective of who the character is, or when they met each other or even how many times they have gone through the rollercoaster ride!
This would imply that “Recollection” can be considered as another co-ordinate? Say ‘r’.
Then the book is written in (x,y,z,t,r) co-ordinates and moves in the positive direction of ‘r’.
What say?
In a reader
The NITK Numbskulls Page 
WHAT :O 😛
Welcome back!
This post was initially OHT, even Google Translator didn’t help 😦
what do you mean ‘before’? they travel back and forth in TIME.
@sg
Any specifics ? 😛
@Nitin
Glad you figured it out!
@Wanderlust
Thats what im talking about. Memory wise story moves in positive ‘r’ direction.
When Ford and Arthur come to the earth two million years before it was demolished, they know that it is going to be demolished in two million years, and that they are going to be there, just escape getting blasted into smithereens. But At the start of the book, they dont know that they landed on the Lords cricket grounds through a time warp two months ago. But they knew two months ago when they landed on the grounds that a certain municipality guy is going demolish arthur’s house in a second’s notice.
So, the story has another co-ordinate to define it completely. Recollection, ‘ r’ , which moves in the positive direction!
now i understand it better. this makes more sense than the original post.
Quite possibly, the only reason the book moves in the direction of increasing r is because it would be impossible to tell a coherent story without it- which in turn, is because the reader can only move forward in time. Irrespective of whether Dent and Prefect remember their present exploits when they’ve gone into the past, you certainly do. If r jiggled in an unknowable manner, the book would have been nigh unreadable.
But then again, perhaps it was.
You just gave me a crazy idea for a story. Thank you.
Now I’m curious to read the original post. 🙂
It is possible to give a good answer to this, and I hope someone does, but for now, the following rambling.
The whole point of time travel is the disentanglement of time from causality. “Normally” (without time travel), events at one time cause events at later times — this is the (causal) “arrow of time”. With time travel, this is not necessarily true: “time” is just another “position” like space — (x,y,z,t) coordinates as you said — and people move to “another time” while preserving their causality. That is, things that have happened to them (such as their recollections, their body’s ageing, whether they’re hungry, their clothes, their clocks etc.) are carried with them to wherever(“whenever”) they go, and continue to behave causally. So they have a “personal time”, that continues to always move in a positive direction. (‘r’, as you said.) This is the “arrow of causality”; it’s just the same as before except that now “time” has nothing to do with it. 🙂 They do not forget things that have happened to them (in personal time), and do not remember things that have not “yet” happened (where “yet” is not the absolute “time”). Of course you might go back in time and meet yourself (isn’t there something about Arthur Dent phoning himself? And something in Harry Potter too?), and there are the questions like whether it is possible to kill your own grandfather before your parents were born, etc.
Note BTW, that time travel is not just all fiction — as this Philosophy paper about time travel observes, we already know it to be true (from Relativity) that it’s possible to travel two weeks on a fast spaceship, and return to earth to find 20 years have passed. This is “time travel” by any reasonable definition. (And it has been observed at smaller scales, with atomic clocks on aeroplanes.)
The other kind of time travel, where time and causality are not disengaged, in which when you go back in time you become younger and forget everything (and so does the world because, well it’s an earlier time), is pretty useless, at least as a literary device. I don’t think I’ve seen it anywhere. Also, note that it might even be happening all the time (whatever that means) and we would have no way of knowing it!
If you find time travel fun, Asimov’s The End of Eternity is a novel I liked very much when I read it as a kid, and the greatest time-travel short story ever written is Heinlein’s “All You Zombies”. (Read! And pay attention to the dates. 🙂 )
Shreevatsa’s explanation seems very believable.
@Tuna: Let’s call r as T’. There, everyone’s happy.
As for Hitchiker’s and Harry potter, there were just two character instances created, which was pretty catchy.
But for the real deal, we’ve got to increase this. The permutations become mind boggling, and at all times, basic timetravel paradoxes/rules apply.[killing ur father, stealing some invention from the future etc].
eg. Timecrimes – A spanish movie,there are subtitles. There might be an english version as well. Three instances. The plot structure looks flawless.
http://www.imdb.com/title/tt0480669/
Futurama – Bender’s Big score. They manage to answer many of the previous time related issues with their earlier movies. An really worked out plot.
And since we’re on the aspect of time-travelling, I’ve a preliminary doubt:
If you go back in time from say 2030, to some years before your birth, say 1881, and your time machine got screwed up,
Would you die based on the biological clock/personal time, say some 1940?
Or would the very fact that you lived to some age where you could achieve time travel, make it necessary that you live till 2030 to achieve time travel in the first place?
the best bit of time travel i’ve seen is Blackadder Back And Forth. Fuggetabout logic and all that, it’s plain hilarious.
and I guess Hitchhikers proceeds according to this value R coz that’s the only way we can follow what’s going on. It can actually be ordered according to T… who’s gonna do that? i’ll digg it, i swear.
@Shreevatsa: “All You Zombies” is amazing! I read it a second time, this time following ‘t’ instead or ‘r’ (Well, the narrator’s ‘r’). Makes for a fantastic puzzler if you read it this way- unlike in the original narration, there’s no actual point in the story where everything fits together (no “reveal”), and I was forced to reconstruct all I knew several times to keep from scrunching up my face. More time travel stories should be written this way.
“All You Zombies” is self-reliance and self-sufficiency epitomized 🙂
and several other self- words as well. 🙂
Blackadder Back and Forth was great too. Something in the same vein, and definitely an inspiration, although nowhere as funny (or even watchable) was Time Bandits by Terry Gilliam (who also made Twelve Monkeys, another take on time travel).
To answer Logik’s question: in most time travel fiction, those who go to the past, and don’t return, die in the past. There is no contradiction here: if it is possible for someone to just pop in from the future before time travel is invented, surely it is possible for them to die too. (This is an argument against time travel ever being possible, actually: how come there aren’t “tourists” from the future all around us? Then again, maybe there are…) In fact, some stories have someone from the future taking a trip and causing/helping the invention of time travel itself! (e.g. Back to the Future.)
Any story can be ordered by ‘t’, but that’s usually a mess: often it requires labelling several ‘t’s and using GOTOs and even COMEFROMs. 🙂 (Imagine ordering a story by place instead of by time.) Often, as All You Zombies shows, there isn’t even such a thing as ordering by ‘r’: each instance of each time-traveller has his/her own ‘r’ (as in Hitchhiker’s when they go to Milliways and find that Marvin has got there by just waiting for millions of years). (“One of the major problems encountered in time travel is not that of accidentally becoming your own father or mother. There is no problem involved in becoming your own father or mother that a broad-minded and well-adjusted family can’t cope with. [..] The major problem is quite simply one of grammar…”)
COMEFROM lol.
How did I ever end up with you guys :O
OMG GEEKS 😛
Time travel jokes never get old. It’s clone jokes that age prematurely.