74
votes
Does Doc Brown sabotage himself in Back to the Future 2?
Maybe I am missing a point to your question, but the wrench is a wrench, it either is good for the nut/bolt you use, or it is not. Ie. if the future Doc gave the past Doc the five-eighths wrench the ...
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29
votes
Accepted
Wouldn't the paradox machine be useful for the Doctor?
There are several reasons The Doctor would decide against building a Paradox Machine:
He doesn't know how
The original Paradox Machine was created by The Master. There's no reason to suspect The ...
- 20.2k
29
votes
Does Doc Brown sabotage himself in Back to the Future 2?
Of the options you presented, I'd go with...
A) The whole interaction is indeed harmless and will have no effect.
In regard to your second option...
B) He gave himself the right wrench, but that was ...
- 108k
27
votes
Accepted
Earliest instance of the grandfather paradox
1929: "Paradox", a novelette by Charles Cloukey, mentioned on p. 286 of Paul J. Nahin's book Time Machines: Time Travel in Physics, Metaphysics, and Science Fiction, Second Edition; ...
- 159k
22
votes
If Marty had faded out, would that have destroyed the universe?
I think the case of Old Biff applies here.
In BttF Part II Biff from 2015 goes back to 1955 and changes the timeline. He then goes back to the future (roll credits), where he walks off. Offscreen, ...
- 11.8k
16
votes
Did Edith Keeler really have to die?
In the following remember that the entire Federation had disappeared, these people were in a very serious quandary, Captain Kirk even instructed them to wait and each try to correct the time stream in ...
- 9,672
15
votes
If Marty had faded out, would that have destroyed the universe?
It is impossible to give an in-universe answer
All talks of time paradoxes are Doc's scientific speculations, which may or may not be true. Nobody had such experiences before, and time travel theory ...
- 12.9k
14
votes
Who came up with the name Melody Pond?
There is no easy answer
Welcome to the wonderful world of paradoxes.
The naive answer is that Amy and Rory chose the name, on behalf of their childhood friend Mels:
Doctor: Mels, short for...
Mels: ...
- 163k
13
votes
Why was Marty present in his jump to 2015 in Back to the Future 2?
This was answered in the official BTTF FAQ which was done by the script writers, Bob Gale and Robert Zemeckis:
1.13: When Doc takes Marty and Jennifer out of 1985 and brings them to the future, how ...
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13
votes
At the end of the first Back to the Future movie, how come Marty can witness the original events happening then wake up to visit an alternate family?
From what we see of Marty's post-timeline change family (the one that exists because of Timeline 1's Marty changing how his parents meet), it looks none of the changes prevented Marty and Doc Brown ...
- 81.8k
12
votes
In the Back to the Future trilogy, does Doc ever piece together the letter about the terrorists?
When Marty re-visits the Doc in 1955, he doesn't spend much time there before going to 1885. All versions of 'the Doc' have approximately 30 years to piece together the letter that he had ripped up ...
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11
votes
Did Edith Keeler really have to die?
SPOCK: I was recording images at the time McCoy left. A rather barbaric period in your American history. I believe I can approximate just when to jump. Perhaps within a month of the correct time. A ...
- 111
10
votes
Jennifer from BTTF left behind
There is a single changing timeline
I tried to illustrate why I think there must be a single changing timeline.
To sum it up, if alternate timelines persist in the BTTF universe, I can't think of ...
- 2,439
10
votes
Accepted
Jennifer from BTTF left behind
The single changing timeline seems to be the one the writers imagined, and they also imagined that when time traveler A is in one era and time traveler B in earlier era changes history, the world will ...
- 56.4k
10
votes
At the end of the first Back to the Future movie, how come Marty can witness the original events happening then wake up to visit an alternate family?
AncientSwordRage gave a great out-of-universe answer. Here is an in-universe one.
Because Marty had already told him the flux capacitor worked, and left a note telling him what to do (in a round-...
- 1,186
10
votes
Does Doc Brown sabotage himself in Back to the Future 2?
There was no "snap"
If you rewatch the original movie, you'll see that in both cases (up on the clock tower and down at the street post) the cable uplugged. Nothing was broken, it just came ...
- 1,104
9
votes
SF short story about equation that can answer any question and agents sent back in time to destroy it
This is "Things Undone" by John Barnes. It can be read online here.
equation (or series of questions? something like that) written in the 1700s or 1800s
Six hundred years ago, in the One ...
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9
votes
Wouldn't the paradox machine be useful for the Doctor?
he could save anyone and do anything he wanted to do
The Doctor himself has had this exact thought once before: during the Tenth Doctor episode "The Waters of Mars".
The deaths of the Bowie Base One ...
- 15k
8
votes
Did Edith Keeler really have to die?
I think there are three reasons why Edith Keeler had to die. One is the purely practical "real world" script writer's reason. It was suggested that Kirk, et al take Edith back through the Guardian of ...
- 151
8
votes
Earliest instance of the grandfather paradox
René Barjavel novel Le Voyageur imprudent (Future Times Three) written in 1944. Is not as old as beichst example but I think it captures the spirit of Granfather Paradox better.
Pierre Saint-Menoux, ...
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8
votes
Accepted
What type of paradox kills Weeping Angels?
Angels can also be starved to death - they literally waste away, their forms decaying, looking like erosion. The time frame needed to do so in unknown.
The way they feed is somewhat unclear - in ...
- 13k
8
votes
Trying to find a time travel short story
Sounds like "The Chronology Protection Case" by Paul Levinson.
Summary from Amazon:
When NYPD forensic detective Phil D'Amato takes a call from a lady physicist about her missing husband, ...
- 9,235
7
votes
Accepted
Did any universe address the problem of double DNA
This is not, in fact, a problem. Your DNA is made up of bits of the DNA of your ancestors, but you might coincidentally share bits of DNA with other people outside of your family. Yes, there might be ...
- 1,692
6
votes
Why couldn't the Doctor save Adric?
He tried, but the TARDIS was damaged
From a plot summary:
The Doctor tries to pilot the TARDIS back to the bridge to rescue Adric, but the controls have been damaged during the fight.
Adric ...
- 20.2k
6
votes
Accepted
Earliest example of an AI being defeated by a paradox
I believe the earliest such story was "Liar!" by Isaac Asimov, circa 1941. In the story a mind-reading robot had been created and its unique ability produced unforeseen and unfortunate ...
- 53.5k
6
votes
In Back to the Future Part II, how does Doc avoid creating a paradox?
In the Back-to-the-Future-Verse, time travelers seem to be largely insulated from the results of their own actions. Marty, for example still has detailed memories about his family and their lives ...
- 677k
6
votes
Accepted
What kind of paradox is this?
What you are describing is called a Bootstrap Paradox. They talked about it in the Doctor Who episode Before the Flood. This is a casual loop, which means: (quote from the wikipedia page, emphasis ...
- 3,555
6
votes
In the Back to the Future trilogy, does Doc ever piece together the letter about the terrorists?
The answer posted by Mazura is spot on. He had to have put the letter back together, or his story would stop in 1985. He also had 30 years of normal linear living to do it in, it's not like he had ...
- 35.9k
6
votes
Accepted
Is there a way to bypass the paradox system with a Time Turner in Harry Potter?
This is basically the "Bill-and-Ted theory" of time travel you're asking about. Is it possible to go back in time and set things up in the past that you will require in the present or future?
Let's ...
- 3,371
5
votes
Looking for a short story about time travel; characters attempting to fix a boat
In the absence of other answers, I think your story, as described, has two features suggestive (albeit only approximately) of Frederik Pohl's "The Tunnel under the World" (copyright 1954, published in ...
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