A paradox is a seemingly true statement or group of statements that lead to a contradiction or a situation which seems to defy logic or intuition. For the short-lived UK sci-fi series, use the tag paradox-tv, and for the 2010 film staring Kevin Sorbo and Christopher Judge, use the tag ...

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86 views

Did any universe address the problem of double DNA [closed]

When you mess up time travelling and become your own ancestor, there is a big problem: At some point in time, a child will be born with exactly the same DNA as you. Did any franchise address ...
3
votes
1answer
69 views

What will happen when David-A returns after 8 years?

At the end of Flight of the Navigator, David time travels, creating an alternate timeline where he didn't go to Phalon{sic} for 8 years. Lets call the David who disappeared for 8 years, David-A, and ...
4
votes
0answers
95 views

Where is Everybody? [duplicate]

Someone wrote a short story about the Fermi paradox—well, probably more than one person—but I have a specific story in mind. I can only recall the broad outline. A group of human explorers find a ...
3
votes
1answer
113 views

In Back to the Future Part II, how does Doc avoid creating a paradox?

In Back to the Future: Part II, Doc Brown discovers that the McFly family is destroyed in the future, and it can all be traced back to Marty, Jr. agreeing to some proposition by Griff and his gang. ...
3
votes
2answers
173 views

Did Edith Keeler really have to *die*?

In the Star Trek TOS episode 28, "The City on the Edge of Forever", we find that McCoy's drug-fueled tear through the past caused serious and far-reaching effects on the space-time continuum; to wit, ...
9
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2answers
307 views

Who came up with the name Melody Pond?

On season 9 episode 4 (Before the Flood) of Doctor Who, The Doctor talks about the bootstrap paradox: So there's this man. He has a time machine. Up and down history he goes, zip zip zip zip zip, ...
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votes
2answers
212 views

What kind of paradox is this? [duplicate]

I was wondering something regarding the Back To The Future movie: Marty McFly is on stage and he's playing Johnny B. Goode. Marvin Berry phones his cousin Chuck Berry (the person who wrote the song). ...
4
votes
2answers
455 views

In the Back to the Future trilogy, does Doc ever piece together the letter about the terrorists?

In the Back to the Future trilogy, Marty writes a letter to Doc to warn him about his impending demise. We learn at the end of the first film that: Nevertheless, at the end of the second film and ...
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votes
2answers
347 views

Is there a way to bypass the paradox system with a Time Turner in Harry Potter?

Is it possible to not create a paradox by using a Time Turner to stop someone (e.g Voldemort) from the past? For example, a theory could be that somebody would go back in time by 3 hours, poison ...
5
votes
2answers
442 views

Where did 2015 Biff hide the Delorean in 1955 when giving himself the Almanac in BTTF 2?

With the 30th anniversary of the Back to the Future trilogy this year, and several networks showing it, I watched all three for the umpteenth time (and enjoyed every second of them), but wondered ...
1
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1answer
193 views

Red Dwarf: time and space travel paradoxes in “Tikka to Ride”?

The Red Dwarf episode Tikka to Ride has confused me more than any previous episode: How was it possible for the crew to use the Time Drive to travel back to 1960's Earth, when in the previous ...
4
votes
1answer
216 views

Man goes back in time to observe WW2 and gets stranded in an alternate future

Anyone know the name of this science fiction short story. Man goes back in time to observe Second World War, falls in love, tries to return to future but ends up in a alternate future with no power ...
1
vote
1answer
560 views

Predestination (movie) - predestination or bootstrap paradox? [duplicate]

In the movie Predestination: Is Jane's birth because of a predestination paradox or bootstrap paradox? which one is it?
6
votes
1answer
954 views

Predestination and Bootstrap Paradox?

Can someone please help me understand the difference between Predestination and Bootstrap Paradox by pointing me in the direction of movies that deals with each of them? For instance, Predestination ...
1
vote
1answer
283 views

Somewhere in Time - Who is this character?

In the time-travel romance movie "Somewhere in Time", a young playwright from 1972 uses an old pocket-watch to mystically travel back to 1912 and meet an actress he has fallen in love with from old ...
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votes
1answer
302 views

Doctor Who time paradox Captain Jack [closed]

Jack is the face of Boe and has lived for millions (or billions) of years; The Doctor has called him a fixed point in time and space. In the short of 'time crash' the paradox of meeting himself and ...
8
votes
0answers
666 views

Looking for a short story about time travel; characters attempting to fix a boat

I'm looking for a short story that I read once about time travel. One thing that I remember from the story was that the characters were attempting to fix a boat using a time travel device that took ...
1
vote
0answers
98 views

Why can't the Doctor visit a particular point in his timeline to return to Gallifrey (at least temporarily)? [duplicate]

We already know the Doctor never follows the rules of space-time, so why is Gallifrey inaccessible? Shouldn't he be able to, you know, travel to a point in his past when Gallifrey still existed in ...
6
votes
4answers
776 views

Does Terminator 3 undermine the 'No Fate' concept?

"The future's not set. There's no fate but what we make for ourselves… !" John Connor, quoting John Connor, quoting Kyle Reese, quoting John Connor - Terminator 2: Judgment Day One of the ...
4
votes
1answer
734 views

I am trying to find the title to a Time Travel SF short story

I am trying to find the title of a short story published around 2009, in which a boy travels back in time and has to murder his own grandfather in order to erase his own identity and become a member ...
14
votes
3answers
1k views

Identifying a short story about time travel and paradoxes

I remember having read a short story in which the main character, thanks to a series of happenings also involving time travel, grew up, changed sex, made sex with himself and had a son... who of ...
14
votes
1answer
696 views

Short story: temporal paradox caused by experiment ends world

This might be one of Fredric Brown's short-short stories, but I've tried and could not find a reasonably quick way to look up summaries of all his stories. A group of scientists in a lab decide to ...
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votes
5answers
2k views

Why did future John Connor bother to send the T-101 Terminator back?

In the movie Terminator 2: Judgement Day, future John Connor sends the Terminator back in time to save himself from being killed. But from the perspective of past John Connor (the kid), he sees a ...
8
votes
2answers
1k views

How do Future Bill & Ted know Rufus' name?

In Bill and Ted's Excellent Adventure, we never see Rufus introduce himself to Bill and Ted. Instead, Future Bill says to Present Bill and Present Ted: "Listen to this dude, Rufus. He knows what he's ...
9
votes
4answers
2k views

How intelligent is Skynet? [closed]

If Skynet sees humanity as a threat to it's existence, why did it send a robot back to kill Sarah Connor in the first film, and then John Connor in the second and third film? Why not just send a robot ...
2
votes
1answer
942 views

Does Doc Notice His Past/Future Self?

In Back To The Future Part 2, when Doc Brown is riding a bike and ends up coming upon himself (in the past) working on his "weather experiment" to get the old Marty back to 1985, is there any proof ...
8
votes
3answers
3k views

How do Amy and Rory know who River is in The Wedding of River Song?

So in the Doctor Who episode The Wedding of River Song, the entire episode is an alternate version of the season opener, which means the Amy and Rory in the alternate universe haven't been through the ...
3
votes
3answers
289 views

How did this [spoiler] interaction occur in Dr Who “Journey to the Centre” episode?

In the episode Journey to the Centre of the TARDIS This character Goes through the rift to warn How can this even possible without destroying the fabric of space time? Or creating a paradox, or ...
16
votes
8answers
7k views

How did Clara dedicate Emmett's tombstone in Back to the Future 3?

In Back to the Future 3, Doc Brown is only able to save Clara Clayton because of Marty's presence (as they had to scout that area for the plan). Though if Marty had not traveled back in time, Doc ...
1
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2answers
5k views

Doctor Who: Clara Oswin Oswald Paradox

How does Clara Oswin Oswald die twice? We know that in all of time a person can die only once, and we see Clara die in 2 episodes of Season 7 (Assylum of the Daleks and The Snowmen)? My question is ...
13
votes
10answers
6k views

How could Walter send Peter the letter in the last episode?

THIS QUESTION CONTAINS SPOILERS FOR THOSE WHO HAVE NOT VIEWED THE LAST EPISODE In the last episode of Fringe, Peter finds a tape addressed to him, which was encased in amber. In this tape Walter ...
10
votes
1answer
2k views

Why did time travelers in Timecop turn into gelatinous blobs of goo-energy if they came into contact with their former selves?

We're told throughout the movie that "the same matter cannot occupy the same space". Yet, even after a few months it's very unlikely that there are many of the same atoms in your body that were there ...
12
votes
2answers
2k views

On the nature of paradoxes in the Whoniverse?

Loosely: How do Paradoxes work in Doctor Who? We see in previous episodes, To allow a paradox to occur. We also have the the weeping angels, that feed off of time loops. They are however ...
7
votes
2answers
647 views

Does the Doctor have a black list of times and places?

In one of the latest episodes of Doctor Who (The Angels Take Manhattan) Is this the only such place, or does the Doctor keep a list of places that he can't go?
25
votes
4answers
4k views

What would happen if you portalled the TARDIS inside itself?

The TARDIS is one of the few fictional objects that could contain themselves. Firstly, because "it's bigger on the inside" but secondly because the TARDIS has some means of sustaining paradoxes (which ...
3
votes
0answers
354 views

Does “Isaac Asimov's Robots in Time” series violate the grandfather paradox?

As anyone who is familiar with the Isaac Asimov's Robots in Time series by William F. Wu is already aware, the Mojave Center Governor does not realize that sending his component parts backwards ...
5
votes
3answers
2k views

Primer: Will Thomas Granger still be sent back in Time?

In the movie Primer: At first, just as in any timeline, what Abe/Aaron experience is always determined by the past. However, as the boxes are developed and the characters start looping back, it would ...
7
votes
5answers
1k views

How did Senator Travers not just survive as a Time Paradox Duplicate

In Decision 3012 (stop reading if you do not want spoilers): Senator Travers uses the time paradox code from Bender's Big Score to go back in time to stop Nixon, and then he disappears when he won ...
3
votes
2answers
5k views

What will happen if Pinocchio says: My nose will grow [closed]

If his nose is not growing, he is telling a lie and his nose will grow but then he is telling the truth and it can't happen. If his nose is growing, he is telling the truth, so it can't happen. If ...
2
votes
1answer
226 views

How did Garth manage to avoid the Grandfather Paradox?

In Cyborg 2087, Garth travels back in time and ends up preventing his own existence, a prime example of the Grandfather Paradox in action. If that's the case, how was he able to even go back in time ...
23
votes
6answers
6k views

How did the T-1000 avoid the bootstrap paradox?

I have watched Terminator 2 several times now, but there is one major problem with it that has been bothering me. The Terminator* was sent back in time to (unsuccessfully) assassinate Sarah Connor, ...
49
votes
7answers
7k views

Why was Marty present in his jump to 2015 in Back to the Future 2?

I was doing some thinking about the paradoxes that arise during Back to the Future 2 when Marty, Doc and Jennifer travel to 2015 to see their future selves and help Marty's kid. It was shown that ...
17
votes
5answers
1k views

Could SG1 have used the Time Jumper to steal as many ZPMs as they wanted?

In the events of Moebius, SG1 travels back in time to steal a ZPM from Ra in ancient Egypt. It went something like this: SG1 resolves to steal the ZPM. They travel 3000 years back in time. They ...
2
votes
1answer
413 views

Would guys from the Red Dwarf respawn if their future bodies kill themselves?

Would the Red Dwarf guys respawn in case (1) is the group that is to the present (2) is the group that is traveling in the past to visit (1) (1) is in year 8 000 000 for example (2) is in year 8 ...
6
votes
5answers
2k views

Trouble of time travel in Harry Potter?

What would happen when Harry and Hermione would meet other Harry and Hermione while using time travel clock? For example scene of execution of hippogriff in Prisoner of Azkaban.
18
votes
15answers
15k views

How do the timelines from Misfits align?

In episode 6 of the second season, we saw the fulfillment of a number of predictions made earlier in the series. There are a number of spoilers involved in this question. Specifically: However... ...
11
votes
1answer
554 views

Shouldn't there be a puddle jumper in Egypt at the end of Moebius in Stargate SG-1?

I've just rewatched Moebius, and made a realisation at the end of the episode regarding the puddle-jumper they use (the one discovered in It's Good to be King: But, I don't remember the ...