Anything that happens, happens.

Anything that, in happening, causes something else to happen, causes something else to happen.

Anything that, in happening, causes itself to happen again, happens again.

It doesn't necessarily do it in chronological order, though.

Douglas Adams in the preface of his Sci Fi novel Mostly Harmless (1992)

In Science Fiction works involving time travel, causal loops are a common trope: Some event indirectly causes or enables itself.

Some examples even occur in the story presented in the popular online Esperanto course of lernu.net "La teorio Nakamura":

  • Said namesake Theory

    is passed by Heleno (visiting from 2182) to Filipo Nakamura in 1982, who will later (somewhen in the early 21st century) publish it in an unimportant scientific journal, where it's mostly forgotten because it cannot be well understood yet. From there, the theory is rediscovered at some time after Filipo's death and

    ... once the advancement of the rest of the field of physics has caught up enough that the theory and its once too-novel-to-comprehend concepts can be readily understood, all physics students have to learn it. This includes Heleno,

    thus enabling her to pass the theory on to young Filipo when she travels back to 1982.

  • Filipo's older self, visiting from 1982 from (probably again) 2012, instructs young 1982 Filipo to go to the 67th Universala Kongreso in Antwerp, Belgium and to meet


    at the train station there and to invite her to a coffee. Older Filipo can tell younger Filipo that she'll accept the invitation and also what she'll wear (how young Filipo can recognize her despite never having seen her, yet), because he himself can remember

    that very meeting he had with his then-future wife when he was 30 years younger.

So I came to wonder: How is the concept / term causal loop properly expressed in Esperanto?

The "causal" part seems straight forward: kaŭza

definition from PIV
Rilata al kaŭzo, konsistiganta kaŭzon: kaŭza interrilato; la kuracado devas turni atenton al la kaŭza momento; kaŭza verbo (➞ faktitivo).

But what kind of loop is a causal loop?

  • buklo (PIV, ReVo; not just locks of hair, but also loopy bands etc. and loops in graphs, so this might fit)
  • lopo (PIV, ReVo; a looping when flying, so probably not?)
  • maŝo (PIV, ReVo; can be a whole mesh or a single loop, so maybe?)
  • banto (PIV, ReVo; a bow or knot, so probably not)
  • fermita vojo (ReVo; technically the most fitting, but kinda lame, isn't it?)

(Let's ignore that some fictional timelines, such as in the movie plot of Predestination or the Jeremy Bearimy of The Good Place aren't simple rings but loop back in complex manners forming a knot, which would probably be nodo or in more involved cases plektaĵo in Esperanto.)

  • While there doesn't seem to be an Esperanto Wikipedia article about the subject, the Wikidata entry (currently) names it paradokso de tempobuklo and alternatively buklo de kaŭzeco, probably mirroring the French terms boucle de causalité and boucle causale.
    – das-g
    Commented Aug 18, 2021 at 6:58

4 Answers 4

  • causal loop = kaŭza ciklo / kaŭzociklo
  • causal chain = kaŭza ĉeno / kaŭzoĉeno

Cyclic already is cikla.


From the field computer science you also have the term iteracio for a loop for repeating actions. However I do not think that the term iteration is suitable here, as the idea of iterating is to stepwise refine something.

I would approach this question from another angle. As far as I understand, here we have a happening that kicks off a series of happenings which finally kick off the first happening. In essence a cause causing itself can be described as memkaŭzo. Furthermore since all causes in that chain are such memkaŭzoj, would the chain not be memkaŭza serio, serio de memkaŭzoj or if you prefer the word ciklo, a cycle, memkaŭza ciklo, ciklo de memkaŭzoj?

  • iteracio could be used for each time of performing (i.e., traveling along) the causal loop, though would probably make more sense in a time loop where every iteration can and usually will be (be it blatantly or every so slightly) different. (A causal loop in contrast is never-changing and, from its own perspective, eternal. As all its "iterations" are indistinguishable from each other. One could say that there really is only one iteration, which kinda goes against the idea of what an "iteration" (and probably an iteracio) is.)
    – das-g
    Commented Aug 17, 2021 at 23:13
  • 1
    @das-g, thank you for your feedback. I see iteration as a process of stepwise refinement, which we are not talking about. On a second thought you are right, ciklo is ok. I have rewritten my answer. Commented Aug 18, 2021 at 6:41

feedback loop - retrokupla ciklo; https://eo.wiktionary.org/wiki/Aldono:Vortaro_angla-Esperanto_f


Dependas de la situacio. Dum parolata priskribo de filmo oni tre verŝajne povus uzi tempa buklo. Kvankam nerigora, tiu koncepto estas facile komprenebla kaj iel ampleksas ĉiujn ceterajn aferojn: interrilatojn, kaŭzojn, ktp.

En tia kunteksto, destina buklo ankaŭ bonus, kaj ĝi altirus la atenton ĉefe al la travivaĵoj de la partoprenantoj. Destini povas signifi: Antaŭdecidi, kion iu spertos aŭ faros.

Iom pli science oni povus paroli pri spacotempa buklo.

Sub tiuj bukloj troviĝas la koncepto retrokaŭzo. (retro signifas movon aŭ agon faratan kontraŭe al la normala direkto ) [ĉi okaze, de la direkto de la tempo]. Retrokaŭzo povus utili por difino de "causal loop".

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.