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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.

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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 ...
272
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42answers
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How do you prove you're from the future?

Let's say a time traveler from the year 2100 comes back to the year 2015. He has a very important message: [horrible thing] is about to happen soon, and he wants to warn us so we can avoid/prevent it....
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11answers
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Could medieval people produce automatic firearms if they had access to the schematics?

Assume you traveled back in time to the middle ages, and you brought with you the schematics of a fully automatic firearm. Could a group of experienced smiths and jewelers reproduce it? What would the ...
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29answers
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How can I explain that a time travelling apparatus moves itself through time but appears in the same location?

For the purposes of this question, let's ignore the causality issues of time travel itself. Suppose our hero, or an accomplice of our hero, has invented a time travelling apparatus. It works like ...
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21answers
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A small group recreating modern technology

Suppose a group of people get transported back in time (say 2500 years). Then, in a manner reminiscent of A Connecticut Yankee in King Arthur's Court, they try to re-design modern technology. Assume ...
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3answers
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Determining your universe's Time Travel Paradigm

How might the occupants of any given universe identify which (if any) of the many proposed Time Travel Paradigms govern their potential use of time travel? By "Time Travel Paradigms" I refer to the ...
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1answer
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How long can language drift before it becomes indecipherable, and how to minimize drift?

A general question here, relevant to many world-building scenarios. Language drifts, to the point that I likely could never understand old English, but I'm not sure how much. I want to know how long ...
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8answers
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Stopping time, by speeding it up inside a bubble

Imagine I have a device that can stop time for the person who holds it (similar to Bernard's Watch). This device works in a very specific way - it creates a bubble around the user (just large enough ...
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19answers
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Time travel coordinates

My problem is as follows: mr Average Joe has designed a device for time travel in his garage/basement at the moment he has sent the device forward in time (for testing purposes) a couple of times (...
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10answers
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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 ...
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4answers
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When could a microscope first be made?

Imagine you have someone sent back in time without warning. He is smart and has a good generalist grasp of science and technology, but is not a master of any particular field. He wants to use a ...
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6answers
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How to make the most wealth out of a single “Groundhogday Potion”?

Pennyless Joe, the broke archeologist, finds an old pawn shop selling something curious. A ceramic vial labeled "Groundhog Day Potion". It's a bargain for $1.99. (He buys it, because he is not quite ...
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26answers
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Would relatively primitive people really confuse technology with magic?

It's common for people to say that if a time traveler or an alien displayed advanced technology to ancient or medieval people, that they'd assume it was magic, and either worship him as a god or burn ...
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14answers
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What would be the impact of a modern programmer and laptop being dropped into World War II, possibly breaking Enigma?

I've always found the idea of intelligent every-man sent back in time using his knowledge of the future tech to realistically impact the past. The first time something like this came to my mind was ...
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22answers
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How would you bring wealth back to the past?

Edit: A few people have argued that this question is off-topic, and as I write this it looks like it will be closed soon. However, I have written a new (and hopefully better) version of the question ...
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5answers
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How do I manage disease risk while time traveling?

Time travel works...just invented, by you. The tests prove it! Now for the human tests. It works by poking the residual timey-wimey weebley-woobley stuff just enough for you to move yourself and ...
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12answers
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Unscrupulous Time-Traveler: How to convince modern people you are a god

You are an dishonest time-traveler from the year 3100. You would like to travel back to our present day, and with your advanced technology, convince us that you are a god. You have unlimited energy, ...
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7answers
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How far can a time traveller go into the past before his electrical equipment becomes unchargeable?

My time traveller has a maybe 20-minutes-into-the-future smartphone and laptop. They can store large amounts of data, on the Petabytes level or higher. The time traveller can effectively store the ...
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5answers
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What happens at the interface between two universes with opposite thermodynamic arrows of time?

I saw this old closed question on Physics.SE and thought it would be perfect for here. The original author is long gone, so I thought I'll just have to post it myself. We can consider factors of plot ...
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12answers
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Travel back in time and rise to power

In my story, the protagonist gets sucked almost a millennia into the past (unintentionally) and lands in medieval Europe. How does he take advantage of the situation and rise to power without getting ...
140
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39answers
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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 ...
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13answers
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If I went back in time, how could I handle being among the Black Death and survive?

In the near future time I invent time travel. But when perfecting it, something goes wrong and I'm transported back to the time and place of the Black Death. I wasn't prepared for this, and try as I ...
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12answers
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How would people in 17th century Salem react to modern day clothing

So I and two others are working on a time machine, and I accidentally press a wrong button and whoosh, all my friends and I are in 17th century Salem, Massachusetts. Nobody sees us appearing out of ...
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19answers
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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 ...
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16answers
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Suitable jobs in Ancient Rome for time travelers

The people of Handwave-land have created time travel technology and are training people to send back to Ancient Rome and become part of the community without disturbing the future too much (to observe ...
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18answers
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Can time travel make us rich through trading, and is this a problem?

At different points in history, commodities have been at different levels of supply, and therefore have been at different prices. One good might be valuable in the present while another is nearly ...
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13answers
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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 ...
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5answers
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How to test a time machine?

Eureka! I have a time machine in my garage and it works. I put an apple in it, close the door, set the timer, open the door to an empty machine, wait five minutes and the apple reappears. (Still ...
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6answers
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Could a modern times time traveler produce an antibiotic in medieval times?

Joe Everybody, a modern day man with average knowledge (high school and Wikipedia) in biology, medicine and chemistry, wakes up in an medieval city. He sees a lot of sick people and remembers about ...
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7answers
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The Tricky Trouble with Two Time Travelers

tl;dr: What adjustments to a "rewind" power allow multiple equally powerful characters? Background There are many different models of time travel. Personally I find it easiest to tell stories using ...
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3answers
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Will a modern time traveler survive diseases of the past?

Joe Schmo is your average college graduate who is suddenly transported back to medieval times, without time to prepare. From there the stories, and questions on this site, are all about how he can use ...
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7answers
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Logically consistent time travel

What internally consistent time travel rules would make for an interesting world to model and explore in a game or a book? I exclude the "no free will" setup (where everyone is pre-destined to behave ...
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10answers
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How would a time traveller conquer the ancient world?

I have found myself approximately 2000 years in the past, I didn't bring anything with me. But since I am here, I want to conquer the world with my knowledge from the future. Or as much as is possible ...
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2answers
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How far in the future would a modern human need to go before they were functionally a different species than people of the time?

A staple of fantasy involving time travel is the hero (or heroine) zipping off into the future and then meeting a future lover with whom they go on to have wacky time-based adventures before ...
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3answers
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Using “time travel” to prove past events (e.g moon landings) occurred?

The light (images) from every event in the past are travelling through space at the speed of light as we speak. So.....I am going to build a powerful enough telescope and a spaceship capable of ...
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3answers
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time travel paradox [closed]

If you were to go back in time, how would you account for the extra mater in the Universe? Would not every atom in your body, the oxygen in your lungs and all that you brought with you, already exist ...
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0answers
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Would germs brought back in time by a time traveler threaten to kill the population of the past? [duplicate]

This question is in direct response to the early comments on my last question: Time traveler has identified a unknown epidemic is likely spread by mosquitos. How much can he help combat it? The ...
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33answers
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What cheap modern items can I use to bribe medieval people? [closed]

Inspired by this question about a time traveller. So, I've travelled to the medieval age. Think 12th / 13th century Europe. Unlike the time traveller in the other question, I did bring batteries for ...
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8answers
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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?...
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31answers
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My time machine needs to know when it is

I've built a time machine and it works in unmanned testing... sorta. I tell it to go into the past, it disappears, and then comes back to the present. The problem is that it isn't terribly accurate. I ...
43
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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 ...
36
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9answers
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Time-traveling Combat

Introduction This question is based on the time travel mechanic discussed in my previous question The Tricky Trouble with Two Time Travelers. I'll lay out the rules that I've decided on so far: ...
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14answers
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How to find out a year I'm in?

Let's assume I can travel in a space-time on Earth. Every time I jump I get to almost the same place, but in different past time relative to the first jump: it solves the problem of planet rotation, ...
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13answers
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I travel back in time: how could I know when I landed?

Today a weird guy with a pointy hat offered me and my friends to play a game: We will all travel back in time, to a random date somewhen from the antiquity to modern times. We will have a limited ...
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17answers
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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 ...
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27answers
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How could a time traveler have prevented climate change

Let's say a Moon colonist in the future has discovered an alien time machine. A small remnant of humanity still exists on colony worlds in the solar system, but due to runaway climate change, they are ...
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Temporal Ethics for bidirectional time-travel with branching time-lines

Before humanity develops actual bidirectional time-travel – assuming it’s possible at all – there will be years, probably decades or even centuries before that during which physics theories prove the ...
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6answers
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How Could A Time Traveller Communicate With Neanderthals?

Context: Your spaceship encountered a Grade III Anomaly (now you really wish you'd have read the darn safety manual to figure out what that would be -- too late now). Structural integrity of the ...
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10answers
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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 ...
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15answers
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What advice could a time traveller give for use of an atomic bomb to end WW2 while minimizing loss of life or later nuclear brinkmanship [closed]

Say someone was sent back in time to roughly the time that they were considering using the nukes on Japan to end WW2. The time traveller wishes to minimize loss of life for both sides, but more so for ...