View Full Version : Help me with my "Time Machine"

2012-07-28, 04:46 PM
This is for a setting I am working on. I am using Planescape terminology here, but otherwise it doesn't really follow standard D&D rules for magic and such.

I like messing with time, but never liked all these "go back in time to undo the reason that made you go back in the first place" plots. They don't make sense and fall apart at the first closer look. So that's the First Rule: You can not undo what already happened.
But there's all kinds of other fun stuff you can do with the rate at which time flows, which does actually happen in real world physics all the time, but becomes notable really only at massive scales at huge distances, incredible speeds and massive gravity. And even then the different seems tiny unless you start dealing with black holes and light speed. But it's real.

Some background on the setting, which might not be entirely neccessary, but might help understanding what I'm going for if I explain myself poorly.
In the setting, the normal state of the Cosmos is The Void, which is basically a combination of the Astral Plane and the Far Plane. There's no time and distance, but still there are some temporary bubbles in which there is time, distance, and mass, which is the normal Universes or Material Planes. At first the borders between these Universes and the Void are thin but slowly become solid, and after some billions of years they disintegrate again. That happens for all eternity. Each Universe is actually a pair of a Material Plane and a Spiritworld between which hopping around is relatively easy, but they are still just two "sections" of the same single "bubble".
However in the case of the Metarial Plane the setting is located, there one hole in the border to the void in the form of a demiplane that connects to the Material Plane, the Spiritworld, and the Astral Plane, combining features of all three, which makes it a really weird place. Once somebody shaped it into an island and build a fortress on it, so it's now the Fortress of Time. Figuring out what happens when one goes there is what this thread is about.

I have prepared three graphs.
First is how time and space normaly seems to be.
At the top you have a couple of physical locations in space, A, B, C, D, E, F, and G. They could be anywhere and the distance between them and their relative positions to each other are irrelevant. Could be a few meters away or on different planets, it doesn't matter.
At the side there are some moments in time, 1, 2, 3, 4, 5, 6, and 7. Again, it does not matter how much time passes between them, but in this case it is important that they happen in order. 2 after 1, 3 after 2, and so on.
In reality, there's an infinite number of locations and moments and there are no units on either axis. The lines and the dots at the intersections are only a grid for orientation.

Now in this first graph, this is what people normally see.
Let's say there are people in A, B, C, ... and at a magical signal that travels instantaneously, they all light a candle of the same size at the same time, which are the events A1, B1, C1, ... The candles burn at the same speed and when As candle burns out, so do the other candles at the same moment, which are the events A2, B2, C2, ...
Thats how thing happen in everyday life.

But now in the case of the setting, time does not flow at the same rate everywhere, but sometimes it speeds up or slows down, and it does so at different rates in different locations.
Which we see in this second chart:
Here the horizontal lines become important. Because even when using magic to send telepatic messages or teleport, magic still seems to work just like in the first chart. When you are in location C at the moment 5 and teleport (event C5) to location B, you still arrive at B5. Even with magic, you can not go to B4, despite the time distortion between the locations B and C.
I call these vertical lines Causality Lines. Because if B4.3 had send a magic message to C4.3 and in reply someone would travel from C5 to B4, there would be no need to send the message in the first place. Cause and effect can never be reversed and the causality lines represent which events happen "simultaneously" in respect to causality.
What you could have is sending a message from D4 to C4 and someone at C takes 1 minute to start the teleport from C5 to D5 and the person at D is waiting for 3 minutes. Normally it's just a few seconds or minutes in duration difference that nobody notices, but it can get massive when traveling between the Material Plane and the Spiritworld, so you can visit spirits for an hour and be gone for weeks.
(There is an infinite number of causality lines between to moments so you don't get time paradoxes when thousands of people are teleporting between thousands of locations.)

Now, why does this all matter?
Because as mentioned in the setting spoiler, there's the Fortress of Time that lies outside of the normal flow of time and space.
That grey bar, that's the Fortress of Time. Imagine the causality lines connecting behind of it, it does not break them.
Outside in the normal world, causality lines still rule supreme. But inside the Fortress of Time, things get freaky. The First Rule is still in place. When someone entered the Fortress at causality line 1 and left it at causality line 2, you will not find him there when you enter at causality line 3.

This is what I have so far, but I think you might be able to do a lot of crazy stuff with that Fortress of Time. And here I'd really appreciate your input.
All I really require is that it is not possible to create time paradoxes in the normal world.
I think it might even be possible that you enter the Fortress after someone else and arrive before him.

2012-07-28, 07:25 PM
Have you seen Novikov's Consistency Principle?

It leads to some very !!Fun!! use of time travel. Mind-shatteringly crazy time travel. XD

In your case, your rule about not violating causality is really more a "causes always come before events" rule. In most consistent-only time travel scenarios, all events have causes but causes can come after the event.

Partially irrelevant ideas, feel free to steal if you wish:
In this one is a basic diagram for the ontological loop, where events happen before causes, and a more complicated cousin.

This one uses a more complex notation:
Red lines denote events that require other events (same as first pic)
Black lines mean the two events cannot happen in the same path
Green lines denote the flow of information
Thick blue lines denote the "path" of actual objects

This one was a proposed method to ensure you could "borrow" a piece of metal from the future to repair a 2nd time machine, by exploiting time loop logic.
It operates off the idea that the 2nd law of thermodynamics is actually a "chance" problem and specific arrangements of atoms can "solve" it... at least for a short time.

If your causes and events in the Fortress of Time can swap places, then you have a situation like mine and the spoiler stuff applies.

2012-07-29, 05:35 AM
So the self-consistency principle basically says that every time loop will repeat until it becomes stable? Since it's a time loop, it can repeat billions of times before an arrangement is achieved that remains stable. That's neat.

But I'm not sure how to make that into stories, especially for RPG campaigns. The PCs would obviously experience the shortest possible path that eventually leads to exiting the loop, since that would be the one that "always" happens now that the loop is stable. Though it might include several time jumps. It would mean that they do not change things, but only learn what path the chain of event takes. Good for a novel, but for an adventure it seems like a hyper-railroad. Or you send them through time portals for as long as it takes until everything lines up. Which becomes more complicated and unlikely with every time jump and probably stop being fun for anyone involved relatively soon.

2012-07-29, 05:58 AM
Not exactly. Time loops don't repeat.

The principle states that only consistent time loops occur. That's it.

Travelling into the past and killing some random stranger does not change the timeline. The timeline in which you went back to do this already had you arriving and killing the stranger in the past.

The key point is that you arriving and killing said stranger happens before you leave. Anyone, including the people involved, will see a stranger, then see you appearing to kill him, then if tracking you will find your original time clone go to the time machine and time travel back to when you arrived.

This is also why grandfather paradoxes do not happen. Some other solution will be found. (after all, anything that arrives just has to be the same thing that leaves... which has no requirement to be you)

In this example from a superhero style story I am still writing, Anne's superpower is to time travel.
Joey turned out to have little commitments and he visited Anne's house for dinner to discuss her time travel power. Her mother had paid more attention than usual to the meal and her younger brother Mark was sucking happily on the sweet mints. Anne watched her parents share some wine with Joey, feeling a little too old to be happy with the after meal sweets.

"Ok," Joey said after explanations, "the police will be very grateful for your help. Obviously, since you are still in school, we will keep your involvement a secret. "

Anne nodded, swallowing the sweet quickly, "how will I help though? I could always do what I did with the bank this morning, but its alot of walking. " She didn't mention that she'd be waiting alot as well, afraid that she was complaining too much.

Joey thought for a bit before brightening up. "Let me try something. "

He asked Anne's father, "Mr Lacross, would you play the role of a thief?" After gaining his assent, Joey continued, "now, your father will go to the kitchen and pretend to steal some small item. I will play the role of the police," he laid his phone on the table and addressed Anne, "and you will pretend to be in school. "

He gestured for her to put her phone on the table, "Mr Lacross, will you lend your phone to your daughter for a moment?"

Anne acquired two phones in front of her. Joey turned her father's phone off.

"Right, in a moment, your father will carry out his theft. What will happen is that you will receive a call from me, after the crime has been resolved. You will then turn off your phone and turn on your father's phone, before going back in time to a sufficient time before the crime to call me. I will go investigate, and once the case is settled, call you to complete the loop. "

Anne thought about it for a moment. She didn't pretend to know how that loop would work, it sounded complicated. But if it was just following instructions, then she could do that.

"Why not guide me through it one time?" she asked Joey, who nodded at her father.

Anne's father got up to go to the kitchen. As soon as he disappeared, Joey's phone rang. He placed it on speaker mode for all to hear.

"Dad is getting the cookies," Anne's voice came from the phone before hanging up.

Mark cheered at the thought of the treat. Joey got up and went to the kitchen, "Yup, it's cookies. "

He came back, "ok, now we've investigated the cookie criminal. " That drew some smiles.

Picking up his phone, Joey called Anne's and said, "Hi, this is Joey. We caught a cookie criminal in your kitchen at... 8.37pm. Please do the usual. "

Anne nodded, "What do I do now?"

Joey pointed at the two phones on the table, "You turn off your phone, turn on your father's phone, then go to your room and jump back in time. You then call me with your father's phone and say 'Dad is getting the cookies'. "

2012-07-29, 06:10 AM
But if all time loops are stable and have always been there, where is the story?
It's a whodunit. You learn that there is a time loop... and that's it. It's an interesting realization, but you don't affect anything.

2012-07-29, 06:25 AM
The point is that you create and use time loops to acheive things not normally possible.

An idea for how to work this into a game (use at your own risk, I haven't actually tried this)

A different time travel mechanic actually used in a game is Achron's (http://www.achrongame.com/site/). Time Travel RTS. XD
The time wave mechanic in Achron is very similar to a consistency enforcer.

2012-07-29, 06:46 AM
I also did a time travel adventure and it was VERY complicated to create.

Mine did involve the players entering a dungeon, accidentally traveling to the past for a few moments and saving someone from a fire, while someone else (actually it was themselves) shouting at them not to do it.

Saving this person lead to catastrophic conseuquences, with a person being the father of itself (he built a time machine to save the father that died in the fire, only the father didn't die anymore because the PC saved him), an inevitable replacing a kid with a clone, and many more things.

First thing you should do before starting a time travel campaign, is decide WHICH form of time travel you are using.

There are many, and you must choose one.

I suggest you start here:


2012-07-29, 07:29 AM
Also, more on consistent time travel.