An addendum to Chapter 3 of GURPS Time Travel, by John G. Wood, with assistance from Dataweaver (chief erratum hunter), Todd Dennis and T. Carter Ross of GURPSnet.
Travelling into the future is easy - everyone's doing it, day after day, one second at a time. In fact, we take it so much for granted that we don't even think of it as time travel.
Of course, things are never as simple as that. What is the "we" that is travelling into the future? In a Time Travel campaign the past is in some sense still there, so it is easiest to think of it as our consciousness rather than our body. And what is a "second" in terms of conscious experience? As we get older the years seem shorter, and five minutes spent waiting for a bus seem much longer than five minutes role-playing. Then there are the sudden jumps we make into the future, every time we go to sleep.
We are all travelling into the future, but very few of us have any control over the speed of our journey.
So, the first problem with travel to the future is getting there fast enough. Rip Van Winkle managed this just by taking a nap, but there are problems with this method (as demonstrated in the film Awakenings, which concerns victims of the real-world "sleepy sickness" encephalitis lethargica). The main problem for long trips is the likelihood that the condition of your body will have deteriorated (or at least vastly changed) during your time asleep. There are a number of ways to get round this:
Your sleeping body can be protected from the ravages of time during the trip. This can be achieved via the Suspended Animation spell (p.M44) or through TL 9+ cryonics (pp.BIO113-115). Age-retarding methods such as the Halt Aging spell (p.M45), the psionic ability Life Extension (p.P15), or TL 10+ anti-agathics (p.UT99) would also work.
A campaign seed using cryonics is presented on p.TT13.
Rather than protecting your body from time, you can make sure it experiences less of it during the trip. The "traditional" way to do this is to accelerate a spaceship to a significant fraction of the speed of light with respect to earth, cruise around for a while, then come home. At TL 15, you can achieve a similar effect much more efficiently with a Stasis Web (pp.UT80-81); the spells Slow Time, Suspend Time, and Time Out (pp.G50-51) will also do the trick.
If Braintaping is available (p.BIO115-123), you can forget about your old body altogether. Have the tape stored for the duration of your jump and then transferred into a clone or other freshly prepared body.
With the new advantage Progression (40 pts) you can send your consciousness to the future while leaving your body in the present. This is very similar to Retrogression (p.TT30/CI43) - only the direction of travel differs. The description in Chapter 5 of GURPS Time Travel applies verbatim.
If you just want to see the future rather than interact with it, you can use Precognition (p.P14), Divination (p.M48 and pp.G59-60), or a technological device such as a variant future-Timescanner (TL 16, p.TT47/UT21).
Finally, you can jump bodily into the future. This has been the traditional science-fantasy method since H.G. Wells' The Time Machine. It can be achieved using the Time Travel (p.TT42), Timeport (p.G46) or Create Gate (p.G49) spells, the Time-Jumper ability (p.TT31/CI46), or via temporal technology - a literal time machine, be it stage, portal or conveyor.
Of course, the PCs don't have to be the ones in charge of the mechanism. Atomic Horror includes a campaign seed based on stealing people to the future (pp.AH5759); there is no effective difference between being bundled through a timegate by a traveller from 2112, and inventing the timegate and walking through to 2112 of your own free will...
Some of the time travel techniques given above are one-way - suspended animation, time dilation and body replacement can get you to the future but they can't bring you back. If these are the only methods available you don't have to worry about paradox, but you are stuck with a "Through the Rabbit-Hole" campaign. To make proper use of GURPS Time Travel you will need one of the other three techniques.
Time-jumping can bring back physical objects from the future whereas mental projection and observation fetch only information. However, this makes no difference to the paradoxes involved - using just observation (the most limited technique) you can generate a Grandfather Paradox. For instance, granddad observes his future grandson describing the lucky circumstances in which his grandparents first met. Granddad follows the description to the letter - and gets hit by a truck because he isn't paying attention crossing the road.
You can also blend different methods and different assumptions. Imagine a precog who forsees the death of her best friend, and starts to work toward changing that future; then the Time Patrol arrives on the scene to deal with this "rogue time traveller who's messing with the time-stream"...
The GM will have to think just as hard about the ramifications of travel to the future as with travel to the past. The problems are the same - only the focus has changed.
Curiously enough, most of the principles presented in the Temporal Physics chapter (pp.TT39-47) have a future analog. All of the sidebars and many of the options for alteration of the past can be applied directly, with actions in the present instead of the past and results in the future rather than the present. If that sounds confusing, see p.CCS33 and remember what Mike Callahan said in The Mick of Time: "you just plain can't frame a meaningful question about time-travel in English. The language itself hasn't got the room; it's based on the assumption that time travel is not possible..."
This is the default option presented in the Time Corps campaign. There is an Absolute Now beyond which time does not exist, except in potentia. Time travel to the future side of the Absolute Now is impossible (except via one-way methods). This option is fully covered in GURPS Time Travel.
Actions in the present can "edit out" any future previously seen. World at Risk is the most playable result here since the changes aren't made while the traveller is uptime, but all are possible. "Traveller at Risk" results in the person who has visited the now-invalid future forgetting that future, and changing so that all evidence of that future ceases to exist; "Return Blocked" can also come into play as the loss of the ability to travel into the future and back again (Mental Projection, Observing, and Time-Jumping only). If they reach the future by other means, they will find the altered version.
This basically means that every time you visit the future it will be different. It is more playable than the past-time version, but can require a lot of creativity from the GM.
The future is alterable, but it's hard to alter it. Small changes will be cancelled out by the noise of history. This works very much like the past-time version, and is a good choice for GMs who fancy plotting a future history but don't want to railroad their players.
This is effectively predestination, and could be frustrating for players. The free will argument from p.TT41 still applies, but with weaker emotional force - it is hard to imagine feeling free when nothing you can do will change a future set in stone.
This option isn't available, since you are already in your own time when making changes and so can't be "bounced back".
In a single-timeline-travel campaign this is identical in effect to Plastic or Chaotic Future Time (depending on the size of effect needed to start a new timeline), though temporal physicists can argue about which is the "true" mechanism. If crosstime travel is also possible, it is way of spawning new parallels!
Similar to the Recency Effect, but covering the immediate future as well as the recent past.
Observing your older self is just as much a problem as visiting your younger self. All the usual options apply.
Again this is similar to the past-time version, but remember to switch Forward and Reverse!
This can work fine when applied to future trips, but a little care is needed. One problem arises when you find out information relating to your personal future (such as whether you have any children, or are alive on a certain date). This ties your hands in the same way as a Destiny (p.CI35), and should be played as such. For these purposes a zero-point Destiny should be allowed if the observed events are neutral or balanced. Optionally, the Death Vision spell (p.M63) has slightly different effects if the Observer Effect applies - the presentiment is always accurate, and counts as an observation!
GMs wanting a future Observer Effect without too many Destiny-ridden PCs should certainly consider some form of Proximity Effect.
Another question to resolve is who qualifies as an observer, particularly if there are multiple time-travelling groups from different ages (as in Callahan's universe). The basic premise that "locals don't count" provides two likely cases if we discard the Absolute Now:
If observers have to come from the future, the effect will operate exactly as described on pp.TT45-47 - but with the proviso that changes can be made to the PCs' present, except where that present has been observed by those further up the timestream. The future Observer Effect as described above doesn't exist.
Anyone can act as an observer for events outside their own time. This means that the future Observer Effect can work hand-in-hand with the past. It also leads to time-travel-aware locals in one era attempting to show travellers evidence for all their most valued features, and keeping them away from those they would rather see changed. Mutual (Non-)Observation Pacts between eras become a distinct possibility. Espionage and anti-espionage (with agents trying not to find the wrong things out) could lead to interesting temporal politics...
All in all, looking to the future can open out a brave new world for the Time Travel campaign - one well worth exploring. Oops, was that the time? Must dash - I've got an appointment with a pair o' docs...
This page originally found at http://www.elvwood.org/GURPS/TimeTravelFuture.html
Last updated: 14 March 2002