Levels Of Time Travel

The previous post suggests perhaps five levels of time travel fiction.

(i) Wells: the Time Traveler visits the future (or it could also have been the past) but does not experience or even consider any temporal paradoxes.

(ii) Various authors, including Wells and Anderson: time travelers experience increasingly complicated circular causality paradoxes. (This started with Wells' "The Chronic Argonauts," which preceded The Time Machine.)

(iii) L Sprague de Camp and Ward Moore: time travelers either deliberately or accidentally change the past.

(iv) Anderson: the Time Patrol exists to prevent (iii)...

(v) ...and also exists to counteract random temporal changes.

In this summary:

Wells appears twice and Anderson three times (counting (v));
Anderson has three novels in (ii);
both (iv) and (v) refer to a single series by Anderson;
other authors contribute to only one of the five levels.

Original Time Travel Ideas

Poul Anderson's Original (Or As Near As Damn It) Time Travel Ideas
(i) Mutant time travelers.
(ii) Time corridors.
(iii) A usually stable but occasionally mutable timeline.
(iv) Random space-time-energy fluctuations.

(i) and (ii) are unusual means of time travel, both incompatible with the Time Patrol series, in which conventional (!) temporal vehicles are used. (Wells' Time Traveler would recognize them as improvements on his contraption.)

(iii) is the premise of the series. A mutable timeline necessitates a temporal police force. (iv), a new idea introduced at the culmination of the series, turns out to be the meaning of the Patrol. Even if no time traveler ever deliberately or accidentally changed the timeline, an organization of time travelers would still be necessary to counteract random changes.

(i) and (ii) are each the premise of a novel exploring elaborate circular causality paradoxes in an immutable timeline. As ever, Poul Anderson is systematically comprehensive.

Here And Now

Both collectively and individually, our past is like a ladder to where we are now. Without a past, there would be no present. While climbing, we need a stable ladder but, having climbed the ladder, we can leave it behind.

The Time Patrol guards the stability of Terrestrial evolution which is the ladder from microbes to Danellians. The Danellians' present is a million years hence. Each human generation is one rung on their ladder. However, each human being lives now with the illusion of moving from birth to death. Like the Danellians, we can transcend our past by attending to the present.

Thus, reading science fiction connects with the practice of meditation.

Wells, Anderson And Niffeneger

Poul Anderson's Time Patrolmen are like HG Wells' Time Traveler in that they sit on their time machines. Audrey Niffeneger's Henry DeTamble is like Anderson's Jack Havig in that he time travels without a time machine. However, Detamble travels involuntarily to psychologically significant times and places - thus, the novel is neither historical nor futuristic but contemporary - and, logically, does not take his clothes with him. Arriving naked at unexpected destinations is a whole new problem for a time traveler.

DeTamble, like the Time Patrollers, space-time jumps instantaneously (from his own perspective) whereas Havig, like the Time Traveler, sees his environment fast forward or rewind. Niffeneger presents an intricate circular causality romantic novel. Thus, like several other writers, she develops one aspect of time travel where Anderson develops every aspect and can be compared favorably to authors as diverse as Wells, Asimov and Niffeneger.

Foundation And Guardians Of Time

(i) Isaac Asimov's Foundation Trilogy is nine stories collected in three volumes whereas Poul Anderson's Guardians Of Time is four stories collected in one volume. Both series were later extended.

(ii) Foundation replays the Fall of the Roman Empire as the Fall of the Galactic Empire whereas Guardians... puts time travelers into real Roman and other historical periods.

(iii) When an unpredictable mutant diverts history from Seldon's Plan for a Second Empire, the hidden Second Foundation restores the Plan whereas, when Neldorian time criminals divert history form the Patrol-protected path towards the Danellians, surviving Patrollers restore the preferred history.

(iv) Guardians... is better written with strong characterization, detailed historical knowledge, well realized past periods and clever presentation of time travel paradoxes.

18,244 BC II

During the first part of that short period in 18,244 BC, the secret Time Patrol group is trying to prevent timeline alpha, whereas during the concluding part of that same period, they are trying to prevent timeline beta, which replaces alpha. If, when the second task has been completed, Everard returns to that short period and then travels futureward, will he remain in the Time Patrol timeline or instead return to one of the two divergent timelines?

I think that the answer is that an Everard who knows of a divergent timeline but has not yet prevented it will enter the divergent timeline whereas an Everard who has prevented it will not enter it even if he travels futerward from the exact same moment as his younger self who did enter the divergent timeline.

Suppose that one of the time machines that had entered timeline alpha was not a timecycle but a large, enclosed "time-liner" carrying a crew of several hundred. Suppose further that Everard, having prevented timeline alpha, travels back and enters the time-liner before its departure. Will he then enter the divergent timeline that he has prevented? (Anyone wanting to escape from the Time Patrol could enter such a timeline and live the rest of his life within it.)

In an earlier divergent timeline, Everard had said:

"'...the Patrol and the Danellians are wiped out. (Don't ask me why they weren't "always" wiped out; why this is the first time we came back from the far past to find a changed future. I don't understand the mutable-time paradoxes. We just did, that's all.')"
-Poul Anderson, Time Patrol (New York, 2006), p. 187.

The real reason is, of course, that the author has decided to write a Time Patrol story in which the past is changed but Everard cannot say that - although he comes so close to saying it that this passage might count as "metafiction," i.e., as a work of fiction that somehow acknowledges its own fictional status.

Guardians Of Time is comparable to, although much better than, Isaac Asimov's Foundation Trilogy in which history also diverges from its preferred course when one of Hari Seldon's psychohistorical predictions goes wrong.

18,244 BC

For a short while in 18,244 BC, Time Patrol members who happened to have been holidaying at their lodge in the Pleistocene Pyrenees operate in secret from the rest of the Patrol. If they travel futureward from that short period, then they enter timeline alpha even though it is their job to prevent that timeline from coming into existence. If they succeed, then futureward chronokinesis will again take them and any other time travelers into the preferred timeline guarded by the Patrol and, in that case, no other time traveler need even be told that this crisis has occurred. The object is to ensure, as far as possible, that history continues to flow as it would have done if there had been no temporal disruption.

Unattached Agent Manson Everard is a leading member of this secret group but the secret must be kept even from the younger Everard who visits the lodge in earlier and later periods of its existence. To seek the help of the younger Everard would be to change the course of Everard's life and indeed to duplicate him since the secret group would then include an Everard whose earlier life has just been interrupted by the need to deal with the crisis and an older Everard who has no memory of such an interruption to his earlier career.

In the absence of a Danellian or of any higher ranking human agents, the small group in the lodge is, temporarily, the leadership of the Patrol. This is extremely paradoxical but Poul Anderson makes it plausible.

Historical Causality Violations

Both the original Time Patrol collection, Guardians Of Time, and the later Time Patrol novel, The Shield Of Time, culminate with the crisis of a changed history that must be rectified by the Patrol. These changes are not both "causality violations" because that paradox involves an event preventing its cause whereas, in the second case, earlier events have changed randomly.

In The Shield..., Anderson takes the opportunity to present a far more detailed discussion of this issue but also acknowledges the limits of the discussion. To summarize a dialogue in The Shield... (New York, 1991), p. 304 -

A Chinese cosmonaut: You spoke of persons who entered the alternate future... Apparently, only a relative few entered it... Why not many?

Everard: Those were just the ones who happened to cross the crucial moment, bound uptime, in that larger section of time during which there were related events, like the Patrol's salvage work. We've got a longer section now, with a lot more traffic in it, so our problem is correspondingly bigger. I hope you understand what I'm saying. I don't.

Komozino: It requires a metalanguage and metalogic accessible to few intellects...We haven't time to quibble about theory. The span in which we can use this base without seriously perturbing things is limited. So is the number of personnel, therefore the total lifespan at our disposal.

When Everard flounders, Komozino rescues him first by invoking "metalogic," then by calling to action. If the Patrollers had needed more time "to quibble about theory," then they could have traveled into the further past to do it before returning to address the crisis.

In the Time Patrol scenario, whenever a time traveler leaves his present to visit the past, then returns to the present, it may be to an altered present but why does he sometimes find the present altered and sometimes not? Everyone traveling futureward from far enough back in the past travels through the moment at which the change occurs.

Maybe there is an element of randomness. We are told that randomness is a factor in the mutable timeline. Because Wanda Tamberly departed from 18,244 BC to return to the twentieth century just before Everard was informed of the temporal change, he assumed that she would enter the alpha timeline but I think it is possible that, like many other futureward time travelers, she would enter the Patrol-guarded timeline and therefore, if she stayed in it, would be "deleted" with it.

Another possible explanation is complicated causal relationships involving time travelers. Thus, to invent the simplest possible example:

after a journey to the past, Everard returns to his familiar twentieth century;

then, the timecycle that he had used is stolen by a time criminal;

 

that time criminal uses the stolen timecycle to change history in the Middle Ages;

therefore, when Everard on his next pastward trip using a different timecycle travels further into the past and returns to the present, it is to an altered present.

Time Travel Reviewed

We have had a lot about time travel recently. Let's recapitulate. My article, "The Logic of Time Travel: Part I" (see here), discusses the concept. "The Logic of Time Travel: Part II" (see here), applies this discussion to particular works. These articles became the basis of the Logic of Time Travel blog.

On the current Poul Anderson Appreciation blog, I have, at various times, discussed:

Anderson's thirteen-installment Time Patrol series;
his three independent time travel novels;
seven short stories about different kinds of temporal displacement.

Merely futureward "time travel" is not real time travel but can be used to present the culture shock that is one theme of time travel fiction. Anderson's time travel canon is more comprehensive than any other fantasy or sf writer's.

By scrolling through this blog from the beginning, it would be possible to compile a systematic list of the treatment of both causality paradoxes and of many historical periods in these twenty three works. I might do this eventually, just as I have started to gather together Anderson's "Cosmic Environments." Meanwhile, anyone else is welcome to systematize the posts on time travel!

The Time Machine And The Time Patrol IV

HG Wells' Time Traveler sits on his Time Machine and Poul Anderson's Time Patrolmen sit on their time cycles whereas other fictional temporal vehicles enclose their passengers.

Wells colorfully describes 802,701 AD, the Further Vision and the experience of time traveling whereas Anderson, equally colorfully, describes many historical and prehistorical periods, including 31,275,389 BC and the transition from the Miocene to the Pliocene epoch.

Both authors describe time travel technology and analyze historical processes:

how the conquest of nature and the creation of a paradisal environment cause the Victorian bourgeoisie and proletariat to devolve into Eloi and Morlocks;

how a change to the course of events in ancient Tyre or Persia would have transformed history.

These two works share several comparable features not found in any other accounts of time travel.