The Ontological Paradox

I'm no temporal mechanics expert, but here's a post about time travel.

The ontological or 'predestination' paradox is the idea that, in the case of time travel to the past, effect precedes cause. Future Temporal Ranger A travels to the past, inciting event B, which then forces Past Ranger A to create chronovehicle C to return to the past.

In my limited understanding, this series of events can be described as a "closed time loop," or a "closed timelike curve."

This could result in something such as the events of Star Trek IV, where Scotty gave the design for transparent aluminum to an engineer in the past. The effects of this were ambiguous, and he suggested to Bones that he may have invented it in the first place. If the engineer had, and Scotty were just giving him the design that he supposedly patented, this is an example of a temporal causality loop.

But where did the design come from in the first place? The engineer obviously didn't do the footwork to create the design, even though the idea will be attributed to him.

My idea concerns what I like to think of as "imaginary time" or "hypothetical time," wherein the events in a causality loop were created by a linear temporal ray ending in a time displacement event. The time displacement results in a causality loop, eliminating the hypothetical time that's no longer part of the causal events, since an effect preceded a cause.

An example: Doc Brown (played by Rainn Wilson) invents a time machine through years of hard work. The machine is capable of temporal displacement with X number of passengers, and when he's finished with it, the machine automatically transports itself to the past to give Past Doc Brown the plans to design it (via email), then returns to its present. Instead of decades, Past Doc Brown uses the plans to complete the machine in days, which is programmed to execute its automatic transport-and-email script as soon as it's turned on. The effective reality we now have is that Doc Brown receives two identical emails for one loop, and the next loop and every loop after that, only one from the machine going back days instead of decades.

The decades of hard work are deleted from reality ('reality' used in this case to represent present-future-history), becoming imaginary or hypothetical time (use hypothetical if imaginary could refer to the square root of negative or inverse time). The causal loop is now the only reality, and the years of hard work aren't even a memory, because they never existed - only the design of the time machine now exists. (The time machine itself couldn't continue to go back infinitely, because eventually it will either run out of power or destroy itself, though it may be able to repeat the process many times. The point is, an artifact cannot survive in a time loop, only information can. An artifact CAN, however, survive in a time coil, a reality which loops back on itself in a decaying spiral, but has a distinct past and future.)

It's in this way that the universe and reality itself CAN allow time travel, with the caveat that there can be no caveats: you can't say "only time travel without paradoxes" because the ontological paradox ISN'T a paradox, we just don't understand effect before cause. There are no time travel paradoxes because all of 'reality' includes all time travel events in all of past present and future. The present is such because it accounts for all of future and past time travel.

Can you go back in time and kill your own father while he was a child? While this is a topic for another time, I believe that you can. Doing so simply creates an alternate reality; think of your reality as being coded with a serial number, say #1486. When you kill your father, it - the reality with your father's baby corpse - becomes #1486-a. If you remain in that reality, you can see yourself never be born. Should you travel back to the time from which you came, you'd may be surprised to find that your father was never killed as a child, if your time machine travels back to its own non-a reality in addition to traveling to the future of that event. If, however, your travel to the future involves relativistic speed and time dilation, not wormholes, you'd remain in the alternate reality; you'd still be in reality #1486-a, while you and your time machine are still #1486. You don't fade away as the probability of your birth begins to dwindle to zero, you simply have your own entire reality without timelike curve. The effect of you exists without any cause except the time machine itself.

They say that faster-than-light travel is impossible because it leads to time travel, which can cause paradoxes. Einstein himself, however, couldn't rule out the idea of time travel. In fact, by his calculations, time travel is theoretically possible. As you can see, time travel won't upset reality, it just makes it a bit more well-trod.

So, to paraphrase Enrico Fermi, if time travel is possible, where's the temporal tourism industry? If temporal father murder results in people existing only because of a time machine, where are all the time travelers and their gear?

I see several possibilities:

First, we might actually have time travelers, but they just get locked up as crazy people or murdered as heretics and their time machines are volatile or self-returning (since artifacts can't survive time loops) or just so tiny they're overlooked. They could also just all be really careful.

Second, our reality might be a source reality, where all the time travelers come from, and they go to other realities, making those realities 'alternates.' Perhaps every reality could be a source reality where time travelers come from, but is created as an alternate reality from exactly one temporal displacement. As you can imagine, this implies many realities, but each one may only ever have one fatherless babykiller, or perhaps even only one temporal tourist group. Like, every time displacement - without an associated ontological paradox - creates its own alternate reality.

Third, it might be that we destroy ourselves prior to the invention of time travel. This is the most grim.

Whatever the case may be, the universe is okay with time travel because it heals itself.

Partial Glossary:

Ontological paradox - any set of events that causes themselves to occur.

Predestination paradox - an accident or series of events (intentional or otherwise) resulting in a temporal displacement (time travel event), which causes itself.

Closed time loop - a part of reality that with a distinct past and future that will loop infinitely, from the perspective of a piece of information. (Not an artifact. An artifact in an infinite loop has a history of those iterations and will degrade over time. It cannot loop infinitely). Compare with....

Closed timelike curve - a reality that repeats itself exactly, with a temporal displacement at each end, forming a bridge between past and future.

Imaginary or Hypothetical Time - the footwork (or alternate reality) required to provide a specific time loop the information it requires to fuel itself.

Alternate reality - a branch of history with a trunk common to yours, but adjacent to yours and rapidly distancing itself from yours as time goes on.

Time Coil - a reality that loops back on itself for a limited number of iterations due to the fact that its being caused by an artifact going back to its past, and existing, not traveling, to the time when it goes back to its past. Eventually, the artifact breaks, and time no longer loops.