Questions tagged [time-travel]

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

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1answer
81 views

How can a time traveller save Jews on refugee ships like MS St. Louis who were refused entry? [closed]

Pretend you travelled back time and are on MS St. Louis, after sailing to Cuba, North America, and UK. MS St Louis still got 620 Jewish passengers, and Captain Schröder is intending to disembark ...
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3answers
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Can we time travel to the past physically? [closed]

What is the most scientifically realistic way to accomplish time travel?
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9answers
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What era would find today's technology overwhemling? [closed]

(note I believe this is not a duplicate of Would relatively primitive people really confuse technology with magic? - that person's question is if there were precedent for primitive people finding ...
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1answer
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What is the past tense of 'to be' on a 747? Will we need new language constructs to accommodate time-travel usage?

The 747 of the title is not the well-known plane. It in fact refers to a Tardis-like craft that can jump through time and space. It was/is/will be named after the well-known Boeing airliner. The jokey ...
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9answers
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How might an astronomer discover they have been transported 50 years in the future? [duplicate]

Specifically, I'm considering a situation where: The entire planet, as well as all other bodies in the solar system are sent forward in time fifty years, so it's not possible to notice purely from ...
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8answers
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How to prove character is a time traveller in the 16th century? [closed]

A character (person from the 21st century) is going to be sent back to Europe in the late 16th century. The plan is to upon arrival, immediately attempt to contact someone who is both reasonably ...
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1answer
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A Good Gift for a Medieval Worker? [closed]

I'm a time traveller, and on my last trip back to the 1300s I befriended several of the locals. One is a fairly wealthy farmer, and the other is the village blacksmith. Now, since they helped me when ...
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5answers
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How would Police (and the government) respond to a time traveler? [closed]

Say a house is suddenly thrust backward in time (In this specific case, the house ends up in 1985, but the question can be answered more broadly than that) along with everything inside it, and the ...
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18answers
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How to Limit the Power of Resetting Time

The protagonist has the ability to reset themselves back to a place in time a limited amount of times. With that said, what other limitations can I place on the protagonist, so they are not ...
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5answers
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Back in time to year 0: how do I produce acetone?

I'm stuck back in time, in the year zero, and lost in India; I need acetone, but how do I produce it? Also, I must avoid contact with people for safety reasons, so I'm living alone.
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11answers
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WW2 Era Soviet Rifle Squad, Time Travels to 1066 England, attempts to take over [closed]

(This part is pretty hand-wavy, and only exists to provide context for a fun thought-experiment/fictional story. Feel free to skip to next paragraph) In 1943, the Soviet Union has developed what they ...
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3answers
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I’m a billionaire that will time travel to the year 1100 CE with a shipping crate. How can I take over the world? [closed]

I have recently bought a time machine. It’s capable of sending me as well as a shipping crate full of items back to 1100 CE. I have one year to prepare and learn any skills that will help me I ...
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Is three-dimensional time consistent and paradox-free for time/dimension travelers?

This question was edited based on answers already submitted. I am designing a universe with both time travel and alternate realities, but I don't want the whole thing resting on hand-waving and ...
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Benefits of time-traveling back to the late Cretaceous period? Economic/financial, resource extraction etc

Let's say a tech company has figured out a way to travel back in time, but for reasons involving the programming of their machine, they can only go back about a 100 million years into the past, to the ...
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0answers
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How could you legally obtain all the documents you need in modern English society? [duplicate]

My hero, who is pronouncing his name as Gee-yohm, is blinked into existence in Mary's home in England in 2018. His dress and appearance (T-tunic and leggings) are well-worn medieval European. He doesn'...
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0answers
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How could a character verify they aren't crazy after accidental time travel [closed]

A 40-year-old character from today (April 2020) with a good memory is unexpectedly transported back in time 30 years. One instant he is at work, the next he is back in grade school in his 10-year-old ...
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2answers
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How to start a life in a different time without attracting unwanted attention?

If Adam (from the current year) goes back in time and brings Eve from the 1920's to the current year, what can Eve do to obtain normal things in life like any other citizen in the community (i.e ...
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What educational resources could help someone who knows they will time travel to the future?

In H. P. Lovecraft's The Case of Charles Dexter Ward (1927), a character is resurrected approximately 150 years after his death and (being an accomplished and intelligent wizard), decides that before ...
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1answer
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Time reversal by the means of lightspeed

In Star Trek, going faster then light will take you back in time (Possibly in real life too!). But I've noticed one inconsistency. Ships, even when going faster then light, have a finite speed. By ...
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8answers
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How could a pre-gunpowder army challenge the enemy's air superiority?

Imagine I'm a time traveller or someone, who has been transported to an alternative reality. Against all odds I established myself as a respected inventor, teacher and noble in one of the local ...
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3answers
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Epidemic friendly time traveller

My time traveller from the distant future is about to get stranded back in time, but realises that by travelling back a short time, maybe 100000 years, he is going to leave a trail of destruction by ...
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1answer
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Time travelling virus anno 1900

One of the most well known, but commonly ignored issues of time travel is this: Due to the fact that viruses and bacteria constantly evolve, diseases that we are today resistant to have never before ...
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16answers
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How can a modern medic help medieval patients

My modern doctor has been time-slipped to a medieval city, without any equipment. She has the patronage of a powerful, rich noble, so being accused of witchcraft is not a problem. She will be ...
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7answers
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Currency exchange across time [duplicate]

Congratulations! The year is 2030 and after a few months of waiting on a list you've been chosen to become one of a select few individuals who will be allowed to time travel to your chosen year of ...
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20answers
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Why can't time machines go back any further than year 1900 A.D.? [duplicate]

Set in the distant future humanity has successfully developed working time machines which can allow user to go back in time, but no further back than the year 1900 A.D. Nowadays companies are making ...
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8answers
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In a world with time travel, would it be possible to be your own mother's mother?

Given that you can travel back in time and have a baby there, or alternatively, send your baby back in time, would it be possible that this baby one day becomes your own mother (gives birth to you)? ...
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Can a world where everyone has a time machine be consistent?

In a universe everyone has a time machine and can travel both in the past and in the future. At some point, no one knows when, an eternal war to control the time started. The concept of history has ...
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1answer
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Kirov-class battlecruiser time travel to WWII [closed]

A russian scientist wanted to develop a new superweapon : Time travel, will be like if one Kirov class cruiser modernization return in 1942, what they will do, how their technology will affect history ...
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3answers
262 views

Convince 11th century people that I am from the future [closed]

I am a time traveller. I want to change the result of the Battle of Hastings. To achieve this, I need to learn king Harold Godwinson's (and his baronets') trust. To do this, I decide to reveal that I ...
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4answers
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What would be valuable in a world with time travel? [closed]

In a world that exists in the close future (think 24th century) TARDIS-style time travel is fairly common; most governments and businesses have access to it. The ability to jump anywhere, anywhen ...
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5answers
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How to optimise the use of 10 nuclear fuel pellets in medieval period?

Suppose 10 standard nuclear fuel pellets have been sent back in time to the 14th century A. D. scattered across 10 adjacent towns via a disposable time machine. Would people in the medieval period be ...
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7answers
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How to make money in the renaissance?

2019 sucks. I'm going back to the Renaissance -- specifically, Florence Italy in the year 1503. I've never been that great a planner, but I should think ahead at least a little. How do I earn a ...
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3answers
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How would a time-traveler maximize their profits with minimal impact on history? [closed]

A time traveler has a time machine that will take him back to any point in the past once, and they may choose to return to the present or stay. They have $100 in your possession, nothing more, and can ...
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17answers
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How much tech advancement could be made out of modern processor appearing in 1980s?

I rewatched terminator 2 and got intrigued by a particular quote: [microchip] scary stuff, radically advanced. I mean it was smashed, it didn't work, but it gave us ideas, took us in new directions. ...
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Time Traveler's Paradox Prevention Guidelines

I'm running a mysterious, shadowy, acronym-lettered agency which deploys agents all across the world (and beyond) to deal with supernatural and paranormal events. What they encounter is often ...
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26answers
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My time machine can go back farther than yours — why?

I was once in a roleplaying campaign where time machines had this odd quality. None of us knew why; we abstracted that as stuff the characters knew. But is there any (pseudo)scientific justification ...
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1answer
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What if Modern Furniture was Brought to the Renaissance? [closed]

A protagonist equipped with unstable time traveling powers is shopping at their local furniture store when they realize their powers will knock them back to the Renaissance period. They only have a ...
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18answers
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What information could a Time Traveller give to Nazi Germany to make them win WWII?

So, let’s say a certain type of person steals a Time Machine and travels to Berlin August 1st, 1939. He shows his time machine to Adolf Hitler, and tries to give him advice necessary to win WW2 before ...
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6answers
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The scientific description of time-asymmetric retro-causality?

Doing research into my time braking world I was referred to Split Second by Douglas E. Richards. It turns out he conceived of the exact same machine that I did, however he handled the paradoxes ...
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1answer
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How does 1963 science work with 2013 materials?

This question reminded me of a Nanowrimo attempt of mine a few years ago. Main Character is bicycling in modern day (2013 at the time), and creates a time-portal, finds herself in 1963 near Xavier's ...
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3answers
314 views

Your computer made you rich by perfectly predicting 50/50 and 1:3 decisions, but only 50µs in the future. What did you control? [closed]

You have a Time Displacement Teleportation Device (or two). Your computer is making split-second decisions, & it knows an outcome or event 50µs from now and can correct decisions. You now control ...
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4answers
278 views

The entire city of New York City appears in America in 100AD. What happens? [closed]

One day every light in New York goes out and everything goes dark. 5 minutes later the lights come back on. New York is now located at its usual place but 1900 years into the past. (just so people don'...
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31answers
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If 120 experts in 12 different fields were sent back 10,000 years, could they recreate the 21st century in 100 years?

Ten experts (CEOs, professors) of each of the fields of math, physics, chemistry, economics, engineering, electrical engineering, CS, sociology, psychology, art, politics and education (120 total) are ...
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16answers
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I'm on the Titanic, what should I do to survive? [closed]

I time traveled to the date of April 14th, 1912 with my time machine. It’s evening, 6:00 PM to be exact and my location is the deck of the ship Titanic. We all know what is going to happen not too ...
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9answers
380 views

Time traveller's first occupation

What would be the best thing that time traveler can do if he is dropped in the distant past? If a modern person is dropped in the year 1 AD (assume it's Roman Empire), without any supplies, but with ...
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1answer
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I killed baby Jesus - now what's the biggest religion is in modern age? [closed]

I'm a time traveler terrorist, I want back and murdered baby Jesus in his crib on the day of his birth, to his family it would seem like he just stopped breathing at the middle of the night (no one ...
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17answers
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Modern warfare theory in a medieval setting

Let's assume a medieval lord named Gary I of Flowers lives in a "Europe-ish" continent with no gun powder or magic. Somehow, he's aware about modern warfare theory. Maybe he found out a time-traveler ...
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17answers
11k views

If I travelled back in time to invest in X company to make a fortune, roughly what is the probability that it would fail? [closed]

Say I found a time machine and decided to go back 20 years in time replacing my past self while retaining my current memory then sell my house (which is my largest asset at that time) and invest in 1 ...
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10answers
5k views

Designing a time thief proof safe

I'm a time traveler. Yes I know it's amazing for you to grasp but once Jebsus invented time travel in the mid 54th century we all became time travelers (he open sourced it). Now recently I came ...
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6answers
372 views

How to figure out that you traveled 570 million years into the future while in space on a small shuttle craft?

I want a character to get sucked into what she thinks is an FTL-wormhole-gate. While it turns out that the gate is indeed a traversable wormhole, it does not allow for FTL travel. The gate transports ...

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