Time Travel ParadoxA paradox is a contradiction of a person's argument or statement. To my understanding, a paradox made by time travelling could lead to the death of the time traveller's ancestors...

Time Travel Paradox

A paradox is a contradiction of a person's argument or statement. To my understanding, a paradox made by time travelling could lead to the death of the time traveller's ancestors and, therefore, cease to exist. However, if the ancestor of the time traveller died and the time traveller did not exist, the ancestor would not die and this will result with his death again. The main idea is that this paradox is when you do something and prevent yourself from doing that. Can someone give me their opinion about this?

Expert Answers
literaturenerd eNotes educator| Certified Educator

Al I can think about is Back To The Future. Doc repeatedly reminds Marty about the consequences of coming into contact with his parents and changing the future. While this is fictional, I cannot help but think that there could be some truth to it (if one could time travel, then they could alter how things would/could play out later).

Regardless, I see no way where true time travel could be made possible. Therefore, all we have to go off of are the assumptions made by the movies and interpretations regarding the problems which could be associated with time travel.

mwestwood eNotes educator| Certified Educator

Ray Bradbury's "A Sound of Thunder" has as its theme this very paradox of time travel, as you call it. In this story, a man travels back to prehistoric times in order to kill a tyrannosaurus-rex that did die in the past.  However, in order to not disrupt anything else and reap different effects for the future, he must remain on a virtual path created for this purpose. Accidentally, he steps off and a dead butterfly returns to the present on the sole of his shoe. When the man rearrives in the present several circumstances are different as a result of his accident.

shake99 eNotes educator| Certified Educator

When the universe was planned and created, time was created along with it to give it a coherent structure. Time enables human beings to live in an unfolding universe in which they can develop and grow and change. This design would probably include safeguards that would make it impossible manipulate time and thus create the problems and paradoxes that you described.

I realize that some would not share my interpretation of this, but I believe the universe was designed by someone much more intelligent than any quantum physicist.

wannam eNotes educator| Certified Educator

This paradox is generally accepted. I don't really understand all of the physics and arguments behind it. Sometimes the argument is shortened to just include the first part. This means that we could theoretically travel back in time but if we change the past we change the future we came from. Of course, most theorist would argue that by going back at all we change the past so there's no real way around the paradox. Science fiction tends to ignore large parts of this paradox. It is a complicated theory. 

rrteacher eNotes educator| Certified Educator

It all seems pretty implausible to me, but some pretty big names in physics, especially quantum physics, have tried to wrap their brains around it. My understanding is that this paradox is usally cited as a reason why time travel is actually impossible, but that some have argued for loopholes in quantum mechanics (which I absolutely do not understand) that would make it mathematically possible to travel back in time without altering or destroying one's self.

Jessica Pope eNotes educator| Certified Educator

Stephen Hawking says that one of the laws of the universe is that cause must preceed effect. If you got into a time machine and killed your ancestor, the cause of your ancestors death (your killing him) would have come after his actual death. Hawking postulates that there's some kind of build-in mechanism within the universe to preven this from happening. 

Kristen Lentz eNotes educator| Certified Educator

I agree that time travel can make you go crazy if you think about it too long.  My biggest problem is the effect of the changes and the immunity of the to the traveler to those effects.  I can't imagine that traveling through hundreds or thousands of years of time could have no effects on the traveler itself, regardless of the effects to the timeline.

litteacher8 eNotes educator| Certified Educator
Time travel messes with my head. It makes me crazy to even think about it. However, I personally think that if a person dies he dies. What difference does it make what dimension he's in? If you die you die! Death is permanent. Dead in the past means dead in the future.
pohnpei397 eNotes educator| Certified Educator

My opinion is that this is all just fantasy.  We can't travel in time so these sorts of issues of causation and paradox do not exist in the real world.  They make for extremely interestingly science fiction stories, but they are not going to happen in real life.

quantatanu | Student

# 14 thanks & yeah... this is a reason.

astrosonuthird | Student

# 13 Nice one!!!


So, this can be the reason of parellel universe. ANTI-MATTER UNIVERSE


quantatanu | Student

travel to future is always possible and you  can do it well. Regarding travel to past question of causality comes into play. One nice solution is, suppose you are starting your journey from now and you went back and killed your grandfather in his childhood, at that point the time will be divided into two branches, one will follow the usual path where he will be alive and will make good family and you will be born, but in the other one he is dead so the world will proceed without you. So there will be two parallel worlds, in one you will be there with your family and in the other one your family won't exist.


see the Speilberg movie, "Back To The Future" nice one.

astrosonuthird | Student

In reply #1.


I believe that we can travel time. To travel time we need to go faster than light.
If we go at this speed everything in our surrounding will look as if they are acting very slow. And by this way we can travel time.



Its the most complicated branch in science. '' Time travel ''


Albert einstein said that nothing can travel faster than light.



wrong!!!!  that's absulutely wrong.

And an important note - everybody in this world is using only 1 / 100 of their brains. 10 / 100 is been used by me.


Its true.


Because i can think tooooo deeeeeeeeep!!!!!!!!




mikbjorn | Student

Relativity by itself allows for travel into the future by traveling at near light speeds. I believe there is the mathematics in quantum mechanics to travel into the past, but I am quite fuzzy on that stuff. I think the real question that lies at the heart of the time travel paradox is what is the structure of time. If we accept time as a simple linear progession then there is definitely a paradox. However, if you allow for a more complicated view of time, by traveling back and changing something, you may in fact be changing to a different time line. So everything you have done still exists on your original timeline, and everything you have changed is on a new one. Meaning there is an uncountably infinite number of different timeline, or universes out there, each with there own set of events. If this is the case, changing the time line may in fact be as simple as crossing to a new universe, instead of traveling back in time. It is all weird stuff.