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Questions tagged [time-travel]

For questions relating to travel in time. Such travel often involves FTL travel; consider also using the [tag:faster-than-light] tag.

2
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2answers
559 views

How would I NOT get rich by going back in time and telling myself about Google? [closed]

Suppose someone gets a time machine, somehow, and decides to make some extra cash the usual way. S/he goes back in time to 1997 and tells his/her Past Self about Google. Under the following ...
8
votes
5answers
563 views

As a time traveler, how would I see quantum randomness change history?

Suppose I have a time-traveling DeLorean (of all things), and I've used it to travel back to 1955. But then I ran out of juice. Fortunately, I just happen to know that a certain clock tower will be ...
-1
votes
1answer
140 views

About time travelling, multiply yourself

About time travelling, if I go back one year, find my past self, wait until a little before I first went back in time (11 months and 29 days) and both of us go back, we keep repeating this until we ...
5
votes
7answers
678 views

How far in the past could unprepared humans survive?

A small late medieval county, consisting of a very small town, a small castle, and a couple of surrounding small villages suddenly and inexplicably gets transported into the past. It's not a spherical ...
43
votes
21answers
12k views

How much could a time traveler earn from selling 2016 tech having traveled back to 2000?

Joe, the average Worldbuilder accidentally slips through time sixteen years back. From September 11, 2016 to September 11, 2000. He gave saving the World Trade Center a thought, but then he decided to ...
6
votes
4answers
582 views

How to prove you're not from the future?

Imagine this situation: One warm night of 1890, you go home from a pub. You pass a creepy house. In the half-open door, you see the outline of a machine. You go in, and open the lights. You see a big ...
2
votes
5answers
441 views

Travel (how far?) into the future using a black hole and light-speed space craft?

A person is traveling in a space craft that was designed and built by sufficiently advanced aliens. This space craft left from Earth and is capable of traveling infinitely close to the speed of light. ...
20
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17answers
8k views

Avoiding preventing your own birth in a time travel paradox?

Assume a world with no multiverse theory, just a single unbroken timeline. If you were to go back in time to the town your parents lived in on day of your conception, the air displacement due to your ...
27
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14answers
5k views

Can a single time travelling person prevent the World Trade Center attacks? [closed]

You are a fellow Worldbuilder and while travelling by train, you fall asleep. Next time you wake up you realize you woke up at Grand Central train station. You quickly realize that you traveled not ...
2
votes
4answers
365 views

If I travelled to 1979 how easy would it be to become the Worlds richest person? [closed]

Lets say I was teleported back in time as an healthy average intelligence but street smart 21 year old reconstituted in NYC naked in Central Park at 23.59 hours on December 31st 1979. How easy would ...
13
votes
7answers
2k views

How could a time-traveler change a medieval society if he can prepare and bring something from our time?

I have been daydreaming about this scenario a lot. There are many similar questions here about time travellers being thrown to the middle ages, but they usually can't prepare and can't bring anything ...
1
vote
4answers
207 views

How to keep a machine running for thousands of years

How would I future-proof a complex machine or set of machines so that they will still be running 2000-3000 years from now? Is this possible with our current level of engineering and we just don't do ...
38
votes
13answers
7k views

Keeping supplies for 1000 years

My main protagonist is going to fast-forward himself in time by 1000 years. He will simply reappear in the same place (marked by a small beacon), the process being instant for him (no hibernation etc)....
37
votes
11answers
6k views

Where could a person from the 14th century appear such that they would not notice modern technology for a week?

In this case, a person from a world similar to ours, at a time and technology roughly equivalent to our 14th century, but with magic. Through some odd spell, this person was teleported far away from ...
3
votes
4answers
917 views

How to jerry-rig a power cable for laptop when time traveling back in time

Say I have a 2016 era laptop, and I travel back in time something like 20-70 years, but forgot to bring my power cable. How can I jerry-rig a power plug? Sure, including adapter / surge protection is ...
5
votes
8answers
189 views

Best way to bring information back in time

When traveling back in time, if you want to bring as much information as possible with you, there are 2 competing things you need to balance. On the "future" / giving end, you want to gather ...
7
votes
6answers
353 views

Concealing your accidental backwards time travel, finding other backwards travelers

Say you are 30 years old, and something happens and you wake up and find that you've been transported backwards in time to when you were a teenager [you were inadvertently sent back, you do not have ...
1
vote
5answers
381 views

How do 21st century time travelers tour prehistory safely?

Suppose in this modern era we have the technology and means to time travel a couple millions of years into the past with a return trip less baggage of course! The science community owns the tech and ...
0
votes
2answers
160 views

If Time travel exists [closed]

Time travel hasn't been invented yet. Which sucks:< Who wouldn't want to change their past mistakes. What if it has been invented in the future and people do travel back. However, every time they ...
7
votes
2answers
455 views

Is our memory capable of repeating exactly a full day of memorized actions?

Major William die in a combat versus aliens. Now he have the capacity to wake up on the same point of time every time he dies. (Movie: Edge of tomorrow) He uses this power to win the war, but he has ...
4
votes
3answers
246 views

Sending some people into the far future

And I mean faaaaar future. Like, twenty thousand years minimum. 13 million years at maximum. Let's say the Earth is doomed and to avoid the impending extinction of the human race, we throw most of ...
2
votes
2answers
1k views

Time travel: theories about how it could really work with all these incoherences [closed]

Time travel is in many movies, books and video games. But there are differences on how it works and its consequences. A thing I always think is: OK, they go back to the past to change the future, but ...
0
votes
1answer
135 views

Making an internally consistent, logical set of rules for time travel (based off of this video)

https://youtube.com/watch?v=XayNKY944lY Something similar to this. Okay, so the basic plot structure I want is that there are two parallel timelines, both of them potential futures for our world. ...
7
votes
2answers
293 views

What psychological problems can result from experiencing death on several occasions?

I am a clockmaker: I work with time and can control it on a small scale. One of my powers allow me to return some minutes back in time after having experienced my death, but I remember everything ...
142
votes
39answers
46k views

If time travel is possible in the future, no matter how distant, why haven't they come back to tell us?

In a world where time travel is possible, but has not been invented yet, would travelers from the future come back to prove it exists? Surely, they would bring that technology back in time to let the ...
29
votes
10answers
10k views

How far back in time would Maths be understandable to a modern mathematician?

Shamelessly inspired by this question (sorry), but I got this question after Michael gave a answer - my mathematician would essentially have to relearn maths, as mathematics in Ancient Greece is ...
9
votes
4answers
1k views

How would a mathematician compare to a scholar in Ancient Greece?

Somewhat based on this question, let's say a normal person from our world for some reason goes back into time - to the Hellenic Greece around 490 BC and somehow manages to become a philosopher. My ...
48
votes
10answers
14k views

How could we time travel backwards without killing everyone with germs from the future?

Consider a world in which time travel has been made viable possibility. Initially, many are ecstatic at the new technology and the knowledge it will unlock. However, biologists and other scientists ...
108
votes
8answers
29k views

How far back in time would English be understandable to a modern speaker?

As we all know, language in England has changed massively over the centuries. How far back would someone be able to travel in time and still have a basic understanding of what most people are saying?...
17
votes
24answers
3k views

Time travel, assassination, and stunting technological growth [closed]

You are an evil person, and you have a Paradox Free 9000 Time Travel Ray Gun(tm). Sadly it came with only one shot left. You can pick one person in the last 2000 years to shoot and kill at any point ...
1
vote
7answers
432 views

Safely inventing in the past?

Some questions focus on what the most important discovery will be (in the past), while others wonder if we can survive in certain time-periods. However, my question is - is it even possible to be able ...
64
votes
19answers
15k views

What modern technology would be most revolutionary to ancient Greeks?

In Mark Twain's "A Connecticut Yankee in King Arthur's Court" a nineteenth century character finds himself in medieval England and shortly manages to build all the "modern" inventions: from steam ...
1
vote
3answers
389 views

How could people on our world recognize time travelers if they are trying to hide their identity? [closed]

Regarding time travel to our timeline, many have assumed that time travelers would reveal themselves as such, most notably Stephen Hawking's party for time travelers that he announced after the fact. ...
50
votes
9answers
6k views

Are there any ways to allow some form of FTL travel without allowing time travel?

Faster than light travel is a really cool thing to have in sci-fi settings. It allows humans, in relatable time scales, to travel the galaxy and see a variety of worlds. It allows for conflicts ...
7
votes
11answers
1k views

What should a modern human-turned-king do to accelerate medieval society and science to modern standards?

Bob is a thirty year old atheist man from our modern times. One day, he is irreversibly thrown back into medieval France around 1300 C.E. His education consists of a Bachelor's degree in mathematics, ...
1
vote
4answers
211 views

Will I ever make it from Paris to New York in 10 hours when I'm in a time loop? [closed]

I'm in a time-loop. I wake up in Paris, under the Eiffel Tower, at 13:00, July 2, 2016. And then I have 10 hours to do whatever I want. But after 10 hours, at 23:00, it turns to be 13:00 again and I ...
7
votes
3answers
1k views

When transported suddenly to ancient Persia - how to quickly show that I am from the future?

(This question is quite similar to How do you prove you're from the future?) I am an average person in the year 2016, living in, say, the USA. However I suddenly get transported back in time to ...
20
votes
17answers
3k views

Lost in the multiverse: how to find home?

You have an individual who can travel backwards and forwards in time. They normally maintain an observer status but occasionally a butterfly is stepped on. Because, home is where the heart is, how ...
8
votes
11answers
2k views

Could a Time Traveller prevent the Civil War in the United States?

A sequel to Could a Time Traveller Prevent the Black Plague? Todd the time traveler's a cool dude and has decided to use his powers for good, more specifically he wants to stop the American Civil War ...
10
votes
9answers
1k views

Most scientifically accurate way for time travel

I'm looking to use time travel as a big element in my world. I want there to be a somewhat reasonable explanation for it though, so it doesn't turn into some magical wooble-booglly tech stuff. (...
0
votes
2answers
163 views

“Tachyonic precurors” as an early warning system

Hypothetical tachyons (not the kind suggesting field instability in superstring theory) are thought of as superluminal particles that are always traveling faster than light, in this case suggesting ...
23
votes
13answers
11k views

Could a time traveler prevent the Black Plague?

Meet Todd the time traveler. He's a good boy and has decided to use his powers for good, more specifically he wants to stop the black plague from happening. His powers work in a similar fashion to the ...
3
votes
2answers
278 views

Tri-Helix trajectory for a 4D magic system allowing time-travelling

I am designing a magic system that allows for some degree of both time travelling and teleporting. Although it is a magic system, I want it to be as scientific as possible because it will be used in a ...
0
votes
2answers
353 views

Forward time travel via strong gravitational forces

A scientist has recently invented a gravity machine. This machine pulls all mass within a certain radius (say 50 feet?) towards it at an adjustable rate. The machine can... create as strong a ...
10
votes
4answers
609 views

How could “groundhogging” work, and what explanation would require the least handwaving?

Provoked by a comment by Steve Mangiameli. In my short story series, Penniless Joe is a down on his luck archaeologist/(al?)chemist that is struggling to get employment. One day he goes to a pawn ...
18
votes
10answers
5k views

Would a very successful groundhogger day trader be in trouble?

The story so far: Pennyless joe gets a "groundhog potion" that supposedly allows to repeat one day once. He drinks it and proceeds to win the state lottery by memorizing the numbers. He then discovers ...
12
votes
4answers
594 views

A charred human arm appears from thin air; what can we learn from it?

Setting: Modern day Earth, no special technology advancements. Situation: On day, in a relatively populated American city (the specific city is unimportant...the purpose of this point is that it's ...
2
votes
2answers
140 views

Business Assets of Time Travel [closed]

So, if at one point in the future humanity discovered a new type of wormhole allowing them to travel to whatever time era they wanted, past or future, what could a large scale corporation feasibly ...
3
votes
2answers
144 views

Traversable Wormholes and or an Alternative Naturally Caused Time Portal?

I am writing a series about time travel to various different time eras across history while remaining scientifically accurate and I have a question about the method that the main characters use to do ...
11
votes
10answers
2k views

Live die repeat, and win: how do we fight an army that can reset time?

Commander WE NEED YOUR HELP Aliens invaded three days ago and they have been slaughtering us, but now we might have information to fight them. Many soldiers have died to bring you this information ...