It's about time...

[ffutures]

We're in MAJOR spoiler territory here, so using cuts. This is my explanation of how time really works for FF IX, the first bit of the referees information for the time travel section. Let me know what you think. See previous posts for the itinerary of the Corinthic and some of the other stuff you can do with time travel, then re-interpret it in the light of what follows...

WARNING - REFEREES ONLY If you're going to play a character in this setting DO NOT READ ON - there's information in this section which may spoil your enjoyment and will certainly ruin many of its surprises.

TIME travel is statistically the safest form of travel. Ships fitted with displacers almost always return from the past; the exceptions to date are the attempts to colonise the past mentioned above, and two ships which were investigating the extinction of the dinosaurs and are believed to have shared their (still unknown) fate.

Think about that for a minute. Ships are going into the past. Once there they're isolated, can't get help in an emergency, and have no way of returning if the displacer is destroyed and another can't be built. But they nearly always come back. There's something odd about that, isn't there? The idea that the past can't be changed is just that. An idea. There is no evidence that the past has been changed, even after attempts are made to change it. Therefore, it's assumed, time can't be changed. It's an assumption, and it's wrong. The adventurers come from a world at the extreme edge of a probability curve.

Whenever someone goes back in time, whether they're trying to change history or not, the arrival of the time ship and the events that occur when it's in the past must inevitably cause changes. But the universe doesn't tolerate events with multiple outcomes, so what happens is that each change creates new timelines without destroying the original timeline. Depending on events there can be tens, thousands, or millions of new lines, each of them containing the time travellers. But the time travellers continue to exist in their original timeline too, and when they go home they'll find that nothing has changed. They don't know - they can't know - that their world is the freak. The original timeline (or more likely one that was modified by time travellers who weren't recorded in the history books) is surrounded by near-identical doppelgangers, each with at least one historical change if you know where to look.

The diagram to the right is an extremely simplified view of just a few of the changes produced by the cruise of the Corinthic mentioned in the opening text.

• She travels back from "now" A to 1588, where her tourists spend a day or two exploring London. As a result dozens or millions of time lines form (an example is 1588 to "now" B), in all of which a ship-full of strangers from the future appeared in 1588 and made an enormous stir. If the Corinthic were to return to "Now" at this point one version of the ship would return to "now" A and find it unchanged, but the overwhelming likelihood is that the ship will return to one or another version of "now" B.
• In most time lines she carries on into the past, as promised in the prospectus for the trip, with her next port of call in 1000 AD. Here another group of time lines form, 1000 AD to "now" C, in many of which the Vikings hear about the wonders of North America and go in to colonise it. In some of them time travel is invented at some point and another group of time lines form, ending at "now" D.
• Going on to 75 AD the Corinthic causes another enormous stir, and there will be endless tales of the strangers who arrived in a floating island and warned of the devastation to come. As a result in many worlds there are far fewer casualties in Pompeii and Herculaneum, with an enormous effect on all subsequent history. Call the resultant worlds E through G (with a few million others) since time travel will probably be invented early and often.
• Next stop 500,000 BC, where there are fewer opportunities to mess up history, but any lasting effect will probably be major. For example, one of the tourists might accidentally infect a tribe of Homo Erectus with influenza, leading to an epidemic which wipes out a large percentage of the species. As a result the history of Homo Sapiens is a little different, forming more timelines leading to "now" I, which will be unrecognisably different from "now" A. Or something might help Erectus, eliminating Homo Sapiens altogether.
• Similarly, in 150 million BC most of the things the travellers can do have minor effects... but there might be a few timelines where the dinosaurs were never wiped out, where they were wiped out early and the mammals weren't under extreme pressure to survive, or where the Corinthic came to grief in this period and her passengers and crew colonised 150 Million BC. One of these timelines leads to "now" H.
• On the timelines where the Corinthic survived she probably heads for 500 BC, where there's another chance of divergence.
  • In the original timeline ending at "now" A one spinoff might lead to "now" J.
  • In the timeline where history changed in 500,000 BC (leading to "now" I) the alarmed travellers find a world that is nothing like they remember. Maybe there are no Greeks, maybe there are no humans - perhaps Homo Erectus is still the dominanant species. Their arrival in this line can precipitate yet more time lines, such as line K which will eventually lead to its own "now".
  • In the timeline where history changed in 150 Million BC (leading to "now" H) there are no humans - or if the world was colonised by humans in the deep past they have by now evolved to something totally unrecognisable. Again, the arrival of the the Corinthic creates yet more time lines, one of which is L.

While in the timeline ending in "now" A the Corinthic returns home to find nothing changed, in every other timeline the passengers and crew will find changes, some subtle and others devastating.

---

That's what I've written so far this evening. The next bit will be rules for handling this, how to give the players a bit of a chance to survive, etc. All comments VERY gratefully received.

Comments

[dsample.livejournal.com]

The problem I have with this is that as soon as you do *any* interaction in the past, it is no longer just improbable that you will be able to get back to point A. It is impossible. If you only go back a week or two, you might be able to get back to a point B that is hard to distinguish from your original start, but it will be different. Go much further than a few weeks, and the differences will start to become noticable, even if your time ship just sat in the middle of the ocean, doing nothing. They will have still affected the weather. Anyone going back 100 years will return to a world in which they, and none of their contemporaries, had ever been born. Go back a million years, and they won't be able to get back to a world where homo-sapiens ever evolved. It won't be improbable for them to get home, it will be impossible.

And many of your crime scenarios won't work. If your time travelling cops intervene, and prevent a murder, they will not be able to get back to a future in which the murder happened. The cops may be able to observe the crime, and then return to a future a few days later that they can't distinguish from the one they left, but if they intervene in any way, they won't get back home again.

[dsample.livejournal.com]

An addendum:

In the case where the cops go back a couple of days, prevent a murder, and then try to return home, they will return to a "present" that they never left, because there was no reason for them to. They will now have duplicates in the world.

[ffutures.livejournal.com]

I agree that theory says it's impossible. What I'm saying here, and I'd agree that the explanation needs more work, is that the timelines don't finalise until the ship leaves a particular time, and that as it does so one version of the ship continues in the original time line. It's wildly improbable... but given an infinite number of possibilities it'll always happen. I know that technically speaking it ought to be completely impossible, but to quote Pratchett "It's probably quantum"

Anyone going back 100 years will return to a world in which they, and none of their contemporaries, had ever been born.

Why? If I change the outcome of the Boer war, for example, which didn't involve my family in any way, why should I cease to exist? Let's see... at that point, for example, my grandfather on my mother's side was dodging conscription in Tsarist Russia and about to get the boat to Britain with my grandmother and two kids. My grandparents on my father's side were still in Poland and Russia. Don't see why any of that should be changed by a change in the outcome of a war in Africa.

As for the crime scenarios, given the splitting above most of the time travellers will return to a world in which the crime was prevented and they've just learned that it is possible to change history. Not exactly comforting news, I agree. But there will also be some going back to find no change.

[dsample.livejournal.com]

The world is chaotic. Tiny changes become big changes very quickly. A couple of weeks after your time travelers arrive in the past there will be noticable changes in the weather, all over the world. There simply being there will have that effect, no matter how much or how little they do. Think about the effect that weather has had on world history, or simple human interactions. Would your Russian grandparents have made the boat? Would they have decided to settle in the same town in England? Would your parents have even met?

In order for you to be born, it isn't sufficient for your father to have met your mother, and for them to decide to get married. *One* of his sperm cells had to meet up with *one* of her egg cells. That particular pair of cells getting together is literally a one in a billion type chance occurance. Of the generation born starting 9 months after your time travellers showed up in the past you could expect maybe one person to be born with the same set of genes as was born in the world without the time travellers. Even that wouldn't be very likely.

[ffutures.livejournal.com]

I've never been 100% convinced by this argument. There is still relatively little knowledge of the chaos (or lack of it) of weather patterns. Sure, there might be minor variations caused by something the size of a ship - it's something I'm mentioning in my "how to put time back the way it was" thing - but to suggest that the global weather pattern as a whole will change seems a little extreme.

As for genes, the female gene is one chance in three or four in any given month, because eggs seem to ripen on a sort of conveyor belt system, not randomly, and there are various theories suggesting that the selection of the sperm that actually fertilises it is a lot less random than it might appear. I don't actually agree with a lot of what these theories say, but it does suggest that things might not be quite as clear-cut as your suggesting.

But apart from anything else, total chaos is more or less impossible to run in RPG terms, and that's what I'm writing here, so I have to choose more conservative options where I can.

[raygungothic.livejournal.com]

Surely it makes sense to choose to omit chaos theory from a FF treatment of time travel, regardless of whether you hold it true or not, strong or weak, purely on the grounds that it's an idea that's quite out of era? (where, say, paradox isn't)