Temporal Physics 101

[Death Mage]

Do you think time travel effects the dimention it's in, that when you go back in time you're effecting your own past? Or do you think when you shift out of time, you shift out of your dimention as well, thus preventing any possable paradoxes from occuring? And if the later is right, when you come BACK, are you back in your dimention, or another alternate?

[Internet Stranger]

Going back in time invariably affects the past by you being there. Even if its by a miniscule amount. So by that logic time travel can only occur by switching universes to explain the changed timeline.

[Chuck]

You don't change the past when you travel back to it. You helped to make it what it was by having been there.

[Death Mage]

I personally tend to like the latter, myself. It leaves less room for causing problems.

Let's look at some examples:

Let's say Bob goes back in time to save Fred. Fred later builds a tiem machine so that Bob can go back and save him. When Bob is going back in time, he isn't going back to his own dimention. That way if something happens slightly different than his Fred remembers, then it's not a real delemia. He wasn't effecting his own past, we was effecting the past of another BOb. And it was a Bob from another dimention that went back to save his Fred.

Now let's say Susan has someone she REALLY hates. Hates enough that she thinks the world will be better if this person, we'll call him Al, never existed. So Susan steals the aforementioned time machine, and goes back in time, kills Al's father. When she returns to her present, Al is still alive and well. What's done is already done and cannot be changed, but the Susan in another dimention will lead a better life (maybe), and thus won't go back in time to kill Al's dad.. in another dimention.

It seems to work a lot better than assuming there's a single dimention in whcih all of this is taking place, and making a royal mess of things.

[zeek]

Funny we should mention this. I was killed last year by the son I haven't had yet when he came back in time to prevent me from giving birth to his supposedly terrible life. So I don't really exist any more.
Time travel's a bitch.

[Ümläüt]

I've always preferred the Chuck version myself. The universe is deterministic, and if you're going to go back in time to forty years ago and kill your mother, you should probably think back to that story your mother told you about the guy who appeared out of thin air and tried to kill her once, the one who looked just like you.

[Will]

or you can take it as the grandfather paradox

ex:
H.G. Wells is writing a book but he is having problems writing the book and can't come up with any ideas on a subject. In the future his grandson doesn't like the book time machine. So the grandson goes back in time to kill him so he can't write the book. H.G. Wells captures his future grandson that was trying to kill him and put him jail. H.G. Wells goes to meet his future Grandson in jail to ask his murderer who he was. The grandson says "I cam from the future. I am your grandson. I also came in a time machine to try and kill you."

So his grandson didn't prevent him writing his story. He is actually the one that caused the story. To happen. Because while he was in jail he gave H.G. Wells the motive to write The Machine.

[This message has been edited by Will (edited 01-10-2004 10:51 AM).]

[extropalopakettle]

Terminator and Terminator II contain a number of those time loops. In Terminator, Schwarzenegger, the Terminator, comes back in time to kill the mother of the future rebel leader, and the rebel leader sends a man back to stop him, who ends up meeting the mother and being the father of her child. So the rebel leader causes himself to come into existence.

In Terminator II, we see that the robot scientist who started the whole race of mechanical oppressors started the technology with a chip that came from the Terminator in the first movie, so the machines also cause their own existence by sending a part of themself back in time.

In both cases a future that never would have happened the way it did, happens because it comes into the past and makes it happen.

Sometimes I think the whole notion of time travel is silly. What does ordinary travel mean? It means change in location over time. At time T1 I'm at position P1, then, after travelling through space, at time T2 I'm at position P2. So what does time travel mean? At time T1 I'm at time ... T1. Then, after travelling through time, at time T2 I'm at time ... ?

[Agamemnon]

Firstly, my apologies, I'm drinking.

Secondly, One has to define first what way time actually works. If One sees time as a continual line then I believe One would dissappear from One's current time, and would go back in time to nothingness. If One sees time as a parallel set of time lines, then One would go back along a time line to something happening and still dissappear from One's current time. If One sees time as a singular line with a continual time exsistance, then One would go back an see something happening, but would also still exsist in One's own time band.

There was a theory on ghost sightings that someone (sorry, can't remember who they were) attributed to parallel time band clashes. His theory was that now and again our current time line drifs out of it's path, then it entwines with a small part another past line, thus us being able to see someone from that time for a brief moment.
He tried to prove this by taking a sighting of a ghost, by numerous folk, at Hampton court palace. Said ghost was spotted walking several feet above the floor in a large room. When old architectual prints were studied on this room, it was found that where said ghost walked was actually a two story hallway, above the room, about the same height as folk estimated. This he tried to enforce for his theory saying that said ghost was actually alive, but only within their time zone, and we were seeing them doing what they were doing because of the time line clash.

I personally like to keep an open mind on time travel, though I edge towards a nothingness theory.

[Death Mage]

Good theory on ghosts, but it cannot explain all ghost sightings.

[Will]

well if you can time travel if you go back in time and disappear from your own time and go back. Well if you decide to return back to your own time you can return at the exact moment you left. So in other words it would seem like you have never left your own time.

or like that movie where the people on a plane went back in time and where stuck there because they were the only ones asleep and things started to eat the place. but that theroy really doesn't work out.

[Coyote]

If you were trying to re-arrange the furniture in your living room and at 1:00 PM you realized you couldn't move the couch by yourself, you could just wait till 2:00 PM, go back in time to meet your 1:00 PM self, and the two of you together could move the couch.

So I guess time-travel really is pretty useful, because otherwise you'd have to resort to some kind of magic spell to move the couch. And everyone knows magic is scientifically impossible.

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"But I don't want to go among mad people," Alice remarked.
"Oh, you can't help that," said the Cat: "We're all mad here. I'm mad. You're mad."
"How do you know I'm mad?" said Alice.
"You must be," said the Cat, "or you wouldn't have come here."

[Will]

But coyote there is a paradox there. If you couldn't move the couch. Then that means nobody had been there to help you so it couldn't happen. But if at originally 1 p.m. there were two people to move the couch then you would have never had to go back in time to move it. If you never had to go back in time to move then at 2 p.m. you wouldn't go pack in time to move it cause it has already been moved but since you don't go back in time it doesn't get moved and never happend.

Or would that cause a never ending time loop?

[Coyote]

Well, you see Will, the 2:00 PM you doesn't just poof away after the two of you move the couch at 1:00 PM. He hangs around till 2:00 PM and makes damn sure you do use the time machine to go back to 1:00 PM. Otherwise, he'd have to move the couch all by yourself, see?

[ubb error fixed by my future self]

[This message has been edited by Coyote (edited 01-10-2004 07:47 PM).]

[zeek]

Like Austin Powers said, it's best not to think about it. It's just a movie. Enjoy it. Real life, I mean.

[Legend of Tenshi]

So, if I for instance, went back in time and convinced myself not to accuse the principal girl in our panto of goosing me she would still think I was insane because I didn't go back to tell myself not to?

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The Minister for thread hijacking wants you!

[Samadhi]

Pastwatch: The Redemption of Christopher Columbus by Orson Scott Card is a very interesting Novel that deals with time.

[Chuck]

I read it too. It disposes of time travel paradoxes by stating that cause and effect don't work as simply as we think. The time travelers erase our timeline and replace it with the one they create. That causes them to not be born but there's no paradox. Erasing their births doesn't mean they can't exist in the past.

[jadesmar]

Coyote: Wouldn't it be more fun to make the "2pm you" use the time machine to go back and help you move the couch?

[Hitchhiker]

Start sending people back every five minutes. Then you'll have a whole team of movers.

[Samadhi]

If you went back in time (or forward) so that there were two of you and you "pleasured" your other self, would that make you gay?

[One Skunk Todd]

Arguably it would just be an extreme form of masturbation.

[Future Samadhi]

Shhhhhh!

You said you wouldn't tell...

[Vinny]

What if you traveled back in time, have a sex-change operation, married yourself, and make a baby. Would that be incest?

[Huey]

[Borodog]

All You Zombies.



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Insert humorous sig here.

[d8P]

[plucked from Stephen Hawking's website]
There is also the paradox of the man who is his own mother. (My apologies to science fiction writer Robert Heinlein.) “Jane” is left at an orphanage as a foundling. When “Jane” is a teenager, she falls in love with a drifter, who abandons her but leaves her pregnant. Then disaster strikes. She almost dies giving birth to a baby girl, who is then mysteriously kidnapped. The doctors find that Jane is bleeding badly, but, oddly enough, has both sex organs. So, to save her life, the doctors convert “Jane” to “Jim.”

“Jim” subsequently becomes a roaring drunk, until he meets a friendly bartender (actually a time traveler in disguise) who wisks “Jim” way back into the past. “Jim” meets a beautiful teenage girl, then accidentally gets her pregnant with a baby girl. Out of guilt, he kidnaps the baby girl and drops her off at the orphanage. Later, “Jim” joins the time travelers corps, leads a distinguished life, and has one last dream: to disguise himself as a bartender to meet a certain drunk named “Jim” in the past. So, who is “Jane’s” mother, father, brother, sister, grandfather, grandmother, and grandchild?

From an essay called "Is Time Travel Possible" by Michio Kaku

[Samadhi]

Borodog beat me to it.

[Pablo]

Is time a vector or scalar quantity?