Quote: Original post by Estok

Quote: yes... but it aint a real paradox then right?

what are you smoking? I just said that there is NO paradox.

In the Doraemon example time is linear. You can't change the past. If you put the story in a timeline, it goes like this:

May 10 Evening
The Doraemon from May 11 stole the coin.
The Doraemon from May 10 is sleeping.

May 11 Morning
The Doraemon that have been sleeping is accused of stealing the coin.

May 11 Evening
The accused Doraemon goes into the time machine.
The accused Doraemon comes back with a gold coin as proof of innocence.

May 12 Morning
Doraemon with the gold coin meets the professor again to prove his innocence, just to realize that he in fact stole the gold coin.


If you compare the gold coin to other gold coins, the gold coin in Doraemon's hand is one day younger, so to speak.

The paradox is that the chain of events is a circle that has no cause at all.
To make this clear to you, here's the same story expressed as cause-and-effect.

May 10: Event A occurs (coin is stolen)

May 11: Event B occurs (d. is being accused)
Event B causes Event C
Event C occurs (d. travels back in time)
May 12: Event D occurs (d. realises he's the thief)

In logical terms it looks like this:
1) B => C => A
2) A => B

Now you have these two formulas. You cannot transform them using logical expressions to find a cause for event A that is not related to events B and C. Trouble is, that events B and C where causes by event A [smile]

This is a paradox. No causalties, no broken logic in the chain of events itself. As Agony pointed out, the paradox is that the circle has no cause. It is just there - *plop* - coin stolen, d. goes back in time and steals it to resolve the paradox.

In conclusion: cause and effect have been swapped by the time travel. The effect (coin stolen) came first and resulted in the cause (d. goes back in time to steal it) to be established.

Do you get it now? In your story cause and effect have been swapped.

Yes i am aware that there is a circle of cause and effect.

But why not? i don't see any paradox.

Quote: Original post by Estok
Yes i am aware that there is a circle of cause and effect.

But why not? i don't see any paradox.

Effect follows cause. Not vice-versa. The paradox is that no effect can create itself, which is the case in the stolen coin story: The effect occured out of itself and created the cause for it.
The paradox is 'Who has stolen the coin in the first place?'. If it wasn't for Doraemon to be accused for doing it and thus travelling back to steal it, what happened?

Geez, a guy goes away for one weekend and that happens to be when one of the most interesting posts in a long time pops up... grrr...

Anyways, Estok, the paradox is because in order for Doraemon to have the motive to go take the coin, he had to have ALREADY taken the coin. One action would seemingly nullify the need for the other, and yet because of the time travel, they are both possible. Are you seeing where the paradox comes in yet?

It is my contention (and I've given this a fair amount of thought over the years) that time travel IS possible, but changing something in history is NOT possible. If you think about it, you only really exist in this time because your conscious and unconscious fits into it. By that I don't mean "I am because I think I am"... but the way you fit in to whole world is based on what you know to be true in history. Dinosaurs went extinct millions of years ago. Christ was born about 2000 years ago. Hitler reigned over germany over 60 years ago. These are the facts, and you are who you are, when you are, and how you are because of them.

If you were to go back in time and change any of that, the future you used to know would not exist for you. You would instead be conscious of that timeline. You now fit in to that universe, with a whole new set of rules, possibilities, and impossibilities. Mankind may never have survived among the presence of enormous dinasaur like predators. Christianity would never have risen to the religion it is today. World War II may not have ever happened, countless lives would have been saved.

But those things happened only one way in the universe we know now, and the fact that you are aware of them makes you belong to it. If you change that, then you can't go back to the future and expect that you'll have some place in that timeline, things could be drastically different. Even if the change isn't very drastic, the universe you want to return to doesn't exist for you. The only way to see the future you are trying to control or alter is to live through that timeline; to witness the events that now have defined that universe.

Ugh, too many thoughts, very difficult to articulate... basically, you can go back in time, you just can't come back to any future but your own. If you change something, and want to witness that future, you must live through the new time.

This sort of fixes any temporal paradoxes you might come up with. It's just something I've sort of pieced together in my own way. Then again I have a lot of strange views on things.

This kind of thing is very akin to PoP:Sands of Time, since you could rewind time a bit, but if you changed something then you couldn't just skip ahead again and have everything right. You've got to do it over again. I'm not sure exactly how this relates to Writing for Games, but it is a great topic.

SUCH an interesting topic. Rating++ for orion!!

As ever, (time travel or not)
*******Cosmic*******

Probably you may say, effect causes cause.
Why shouldn't the cause be earlier in time than the effect.

Have you heard of the guy that made microwaves go through a whole where they shouldn't be able to pass through, but they did and they even traveled through time. The music starts to play before you hit the play button...

Maybe this would be interesting.

And also this one.

The branching universe theory (which is, by the way, accepted by most of the scientific community, and not just pseudo intellectuals) explains this in a pretty clear cut manner. In the example, the time travelling robot does not prevent his own creation, he prevents alternative-universe versions of himself from being built. The world is still destroyed by robots in the timeline he came from - he doesn't save it. When he travels back in time, it spawns a new POSSIBLE future starting at the point in time he travelled to... at the instant he arrives, the two alternative futures are identical, but they begin moving apart as soon as his presence affects anything. (much like star systems and galaxies in the material universe are flying apart over time, never to meet again.)

Oh, btw, it's also kindof an important point that the spawned worlds wouldn't be "parrallel" or "identical" at all - they'd be divergent.

What if the alternate timeline is not spawned by the robot, but it is already there. The robot just switches to it...

Little broblem of dumb programer.

Time machines weight = 10 kg.

Time machines programing.

10 Start
20 Wait 5 minutes
30 Time Travel 5 minutes to past.
40 Goto 10



How meny time machines there would be after
6 minutes from start of first on?

Change to mass of universum?

/Aki

I think that backward time travel could exist, but paradoxes cannot. Using the Grandfather example: You could go back in time attempting to kill your grandfather, but it would be impossible to finish the act. The fact that you exist to travel back is proof of your failure in the past.

Also, in the argument about the atheist saying there is no God: If someone said that, according to the theory a new universe would be created where the person simply didn't say it, not a universe where there is a God.

This argument reminds me of the theory of immortality I heard once: Whenever you die, an alternate dimension is created where you survived. Therefore, there must be some universe where people like Caesar, Jesus, and Hitler are still alive. I don't know if I agree with this theory, I just think it's interesting.