How do you handle time travel?

[Hopeless]

My question is to you hard science fiction buffs.

Lets assume time travel is possible but there are definite consequences.

Say a century or so from now a child prodigy comes up with a formulae that predicts a method of working time travel but the child seeing the problems and flaws decides to destroy the only notes mostly by mixing it with trash including some uneaten spaghetti Bolognese but is unaware her trash is sorted through and although badly smudged they successfully recover the formulae but takes god knows how many years before with the aid if an extra terrestrial intelligence develop a means of travelling back in time.

They go back and start tinkering thinking to make things better naturally what they think is better is mostly for their own benefit and this is the important part this doesn't involve parallel realities so whatever changes they make to the past has serious consequences for the time they originated from.

So my question to you is what is your hard science fiction view of this?

Are you a Star Trek Reboot or Doctor Who or perhaps a Bill &Ted's Excellent Adventure style of temporal theorist?

 

[ShawnDriscoll]

I've done some Re-Kill stories. Where the players think there is a series of murders going on. Like Jack the Ripper stuff. But the murderer uses time travel to hide the fact. I let the players come up with their own ideas, rather than use their character's skills, to figure things out. So metagaming sessions. Not much role-play.

 

[Cheesy_Nacho]

Have you ever seen Looper?

Time travel just gets way too complicated!

 

[twodsix]

Most hard science fiction methods of time travel I've seen don't let you travel to a point earlier than the time machine you've set up (they generally involve wormholes and relativity).

Now the problem is, we have just removed causality form the universe (probably, I'm not 100% certain on how this all works). Things can happen because they're caused by events that take place after them. Oh well physics, it was nice knowing you but it looks like we might need to start again.

As soon as we bring time travel into this we are getting into soft science fiction. But in probability you can only travel to the future, so no problems with causality.

If you can travel to the past, we're getting into serious 'we don't have any clue what would happen'. Maybe an alternate universe branches off, maybe the only way to travel through time is to go into a universe in a different time period, these keep us relatively safe.

But in all honesty? If we can achieve FTL travel we can probably assume paradox free time travel is along for the ride. I don't know why, a friend explained the frames of reference reason to me but I only get it as far as relativistic travel. At this point we can throw causality out of the window, things can arrive from nothing, and I'm not 100% certain if reversing entropy comes along with it (it likely depends on the type of time travel).

Although I've had the fun idea of a universe where FTL drives actually send the ship to the other destination at relativistic speeds, and then jump back in time to roughly the time the ship started. The time jump would be fuelled by the relativistic mass so that you couldn't just jump as far as you want, and most crews would still spend the trip in cryonics, but you get this weird time travel FTL drive because we'd already be introducing magic into the setting. I've had another setting idea where the universe is only mostly causal, and is full of high-tech civilisations that have spread throughout time and space. Once a species breeches the last technological barrier (time travel) they discover that our 21st century understanding of physics is wrong enough that they can essentially reverse entropy and teleport wherever and whenever they want. But that's a stupidly soft setting.

 

[ShawnDriscoll]

A jump takes a week.

An alternate jump takes a +/- week.

Then there are the alternate misjumps that take a +/- year.

A serial killer that knows this can murder someone. Make their jump back to a week ago before they murdered the person. So no crime has been committed. And detectives haven't been called to a scene.

Lots of cool ideas for players to role-play in. Travel logs suggest a passenger is living a re-booted life as it were. Even cloud servers he's connected to appear to be clean of personal device recordings of his. Anyway, SOLSEC agents know how to deal with such people.

 

[Dagorlad]

Time travel assumes that someone's memories are unaffected by the change - so they knew the past-that-was and can now see a present-that-is and can tell the difference. My view of time travel is that everyone affected by a change in the past either no longer exists in the future-that-will-be or has no memory of these past-events-that-never-happened and instead remembers a past-that-is-now-the-reality-for-everyone including the-person-that-jumped-back-in-time-and-changed-stuff.

As you can see, it's pretty messed up and far too many hyphens for my liking. So I don't allow time travel.

 

[ShawnDriscoll]

That's what Post-It notes are for.

 

[TrippyHippy]

If you go and watch the recent Arrival movie there is, at it's heart, a philosophical rationale for time travel as expressed through the alien language. There is also a philosophical rationale in Interstellar too, to an extent. These are pretty much hard sci-fi movies.

I think the key to time travel, in hard sci-fi, lies in recognising that our own perceptions of time are limited to our own experiences of it. We are all 'time travellers' in the sense that we live from one moment to another. If we change our experience of the passage of time - which is relative to the mass of bodies and expressed as 'space-time', remember, in modern physics - then we change ourselves as existential beings. Quantum physics too speculates on the notion of whether particles can exist or not at the same time.

In terms of game play, what you really focus on is the paradox element. A good way to start off a campaign is have your starship crash with an exact replica of itself. Then work backwards.

 

[Hopeless]

I was picturing a game set about the first jump drive.
The original post involved a form of time travel taking advantage of the first "unofficial" actual successful jump drive which was the result of a stolen prototype maneuver drive intended for a Satellite probe but not the new American replacement for the space shuttle.
The event caused it to jump into Mars orbit as it was programmed to but the idiots at NASA desperate to prove their successful test of their maneuver drive didn't properly check out the stolen drive which had already been damaged as the result of the Navy Transport ferrying it from Europe to the States crashing off the shore of the Eastern Seaboard.
What actually happened is that the drive was retrieved and kept in a museum for God knows how many years and used as part of that time travel device to open a portal into the distant past.
Their use of it in the future caused the shuttle drive to jump to Mars creating a paradoxical feedback allowing them to successfully jump into that timeframe but the resulting backlash destroyed the Earth about three centuries later.
The child prodigy mentioned above was continuing her research in deep space developing a way to decrease the amount of time it takes between jumps so she was working on breaking the Zimm drive barrier.
Witnesses the destruction of the Earth attempts to prevent it by using the event to jump into the past successfully sealing the breach but trapping her in the past...
Meanwhile an American Space Shuttle is stuck in Mars orbit when it comes face to face with humanities first working jump ship and time traveller...
I still think this would work better if I just had the means to create modern day adventurers on Earth who encounter her fixing her ship instead and have to decide how to persuade her to rescue those astronauts or just go on a Doctor Who style ride through the galaxy!

 

[ShawnDriscoll]

In terms of game play, what you really focus on is the paradox element. A good way to start off a campaign is have your starship crash with an exact replica of itself. Then work backwards.

It happened in Spacewreck: Ghostships and Derelicts of Space (Terran Trade Authority Handbook). That encounter will make for great jump scenes in Traveller.