What is the most mind boggling example of a time travel paradox?

Even though it violates a cardinal rule of physics known as causality, Einstein’s theories of relativity do not rule out time travel. Here are some paradoxes that have kept scientists and fans of time travel movies up at night over the years. They happen because the laws of cause and effect don’t apply when people travel through time. The following time-travel paradoxes can be put into two groups: In the Predestination Paradox and the Bootstrap Paradox, cause and effect repeat but are consistent with history. When you can change the past, consistency paradoxes like the Grandfather Paradox, the Hitler Paradox, and Polchinski’s Paradox cause timeline inconsistencies.

The Problem of Predestination

A predestination paradox happens when a time traveler’s actions change the past and end up making the event he is trying to stop happening. A “temporal causality loop” in which Event 1 in the past affects Event 2 in the Future (time travel to the past) causes Event 1 to happen. It ensures that the time traveler doesn’t change the past and that if they try to stop something from happening in the past, they will only make it worse instead of stopping it. According to this paradox, everything is set to happen similarly, and what has happened must continue.

You have made a predestination paradox by trying to change the past. One way to deal with this kind of paradox is to assume that the version of events you’ve seen is already built into a self-consistent version of reality and that if you try to change the past, you’ll play your part in making an event happen instead of changing it.

How a film is made

In the 2002 movie The Time Machine, Dr. Alexander Hartdegen builds a time machine to go back in time and stop a thief from killing his fiancee. \]The Über-Morlock tells Hartdegen the following after he sends him hundreds of years into the Future to see if a solution to the temporary problem has been found:

Emma’s death caused you to build your time machine. How could you go back in time with your machine and protect her if she had lived? You can’t get away from your tragedy like I can’t get away from yours.

12 Monkeys (1995), TimeCrimes (2007), The Time Traveler’s Wife (2009), and Predestination are all movies with predestination paradoxes (2014). Phoebe Fortune and the Predestination Paradox, written by M.S. Crook, is an example of a predestination paradox.

The Bootstrap Paradox.

A Bootstrap paradox happens when a person, thing, or piece of information is sent back in time, and it creates an endless loop where the thing, person, or information exists despite never being made. It is also called an ontological paradox because ontology is a branch of philosophy that studies the nature of being or existence.

Information:

George Lucas could theoretically hand himself the scripts for the Star Wars films from the past because there is no definitive starting point. He would then direct the movies and become famous, leading to a bootstrap paradox about information.

Person:

Let’s say a 20-year-old man who can travel through time meets a woman, has an affair with her, and then comes back home three months later without knowing that she is pregnant. It is a good example of a person-centered bootstrap paradox. Her child grows up to be a time traveler who goes back 21 years to meet a woman, and so on. In his 1959 masterpiece “All You Zombies,” American science fiction writer Robert Heinlein wrote a strange short story about a sexual paradox.

These ontological paradoxes mean that the Future, present, and past are not well-defined. Origin, a term that once meant the past but no longer does, is difficult for scientists to pin down. Information about the item’s production process and location is also crucial. None Kip Thorne was the first theoretical physicist to realize that wormholes that can be passed through and go back in time are theoretically possible, but only under certain conditions. Einstein’s field equations allow time to go around in closed loops.

Movies:

Some movies with bootstrap paradoxes are Somewhere in Time (1980), Bill and Ted’s Excellent Adventure (1989), Terminator movies, and Time Lapse (2014). The Netflix show Dark is based on the book “A Journey Through Time,” another well-known bootstrap paradox (2017–19).

The Trick on Grandfather

The Grandfather Paradox is about how traveling back in time can lead to “self-inconsistent solutions” to the past. Say you killed your grandfather because he started a dynasty that killed everyone. You think if you get rid of him before he meets your grandmother, everything will be fine. Theoretical physicists think the following will happen:

The schedule is safe to use.

Back in the present, you walk up to him and point a gun at his head. The bullets in the chamber have dents on their firing caps. While moving the gun, pull the trigger.  Then you try to kill him in another way, but all it does is leave scars, which the victim later blames on the world’s worst mugger. Until a police officer chases you away, you can do many things as long as they don’t kill you.

Various universes are possible.

Back in the present, you walk up to him and point a gun at his head. BOOM! When you pull the trigger. The show is now over. Coming back to the “present,” even though you were never there. Your family, friends, home, things, bank account, and history have all been erased. Scientists think you may have made or entered a parallel universe right now.

Dr. Quantum in the Grandfather Paradox by Fred Alan Wolf, The Grandfather Paradox by Steven Burgauer, and Future Times Three (1944) by René Barjavel, the first novel to deal with a grandfather paradox, are all examples of books that talk about the grandfather paradox.

Movies/Shows:

The Twilight Zone episode Cradle of Darkness presents this idea best, and it shows how hard it is to try to change the past. Another example from the Dr. Who series is Let’s Kill Hitler.