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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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3
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4answers
100 views

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
150 views

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 ...
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3answers
187 views

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
4k views

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
95 views

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
4k views

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
1k views

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 ...
5
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1answer
221 views

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 ...
4
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3answers
288 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
254 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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30answers
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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
350 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
292 views

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 ...
61
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17answers
11k views

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 ...
31
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17answers
10k 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
355 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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3answers
271 views

If we brought ancient germs to the present

If germs from the past was brought to the present/future on a person (or by some other means of transportation) and we have immunity to its descendants, like the modern germs for example, would we be ...
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6answers
358 views

How can a time-resetter prove the range of their ability?

Consider the magic power of being able to 'reset time' in the style of Groundhog Day or The Edge of Tomorrow, ie revert one's environment and physical state to that of an earlier time while retaining ...
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8answers
375 views

What could “time manipulation”'s weaknesses be? [closed]

I've been writing a short anime-like story, in which a villain has time-controlling powers. His abilities enable him to: Freeze someone physically, even though they're able to think and perceive ...
2
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3answers
194 views

Would you carry the exact same DNA if you were concieved at a different time?

In this world, time travel is possible, but the only thing that can be sent back in time are thoughts. From the perspective of your past self, you suddenly one moment realize that you have "memories ...
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4answers
318 views

How can something be “one second out of sync”?

In many sci-fi shows, an object is placed a few seconds "out of sync" with the rest of the universe. This hides the object from sight, scanners, etc. How would such a device work in real life? Here's ...
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1answer
159 views

What are some modern policies that can be applied to or improve 17th-century European society? [closed]

Supposedly, a relatively smart + educated young woman from modern society is transmigrated into a body of a woman living in a country that is similar to 17th-century Europe. Monarchy and nobility ...
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5answers
347 views

How could one become rich when suddenly be transferred back in time by 100 years? [closed]

I assume he is unprepared for such an event and therefore does not have specific detailed knowlede of the stockmarket, ground prices or similar assets. Also without initial capital buying some ...
1
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1answer
145 views

What would religious debates look like in a religion designed by a time-traveler to help mankind? [closed]

A time traveler, Roy, is marooned in the ancient era. Time and place are negotiable: ancient Greece, Roman Judea, ancient China, etc. There's no hope of getting back, but he's an intelligent fellow ...
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2answers
167 views

The North Star in the ancient world sky

Question: Would a modern-day teen, trained in using the north star for directions when camping/hiking, notice a difference in how the "north star" (Polaris) works when transported suddenly to 1350 BCE?...
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5answers
222 views

Advance human society by time-transporting a book. Which to choose? [closed]

Humanity has done it - the first time-machine was built! However, the machine's capabilities are very limited as it is very costly and fragile, which means we only have one shot. Building another one ...
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22answers
5k views

How could an engineer advance human civilization by time traveling to the past? [closed]

Earth in the near future (in 2081) is invaded by aliens who are just "a bit" more technologically advanced than humans. The war is not a one sided extermination of humans, but humans are about to lose ...
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11answers
7k views

Which modern firearm should a time traveler bring to be easily reproducible for a historic civilization?

Eureka! Our hero just discovered the secret of time travel, but what to do with it? "I know!", he says. "I will travel back in time as far as I can and hand them a modern firearm. They will learn how ...
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8answers
6k views

What does it actually mean to have two time dimensions?

The trivial answer is that it just means "you have two dimensions with inverted sign in your spacetime metric". But the perceptual result of that kind of choice doesn't actually look qualitatively ...
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2answers
331 views

Intragalactic velocity past the central black hole

In my story people are traveling from somewhere beyond the opposite side of the galaxy to Earth. The distance traveled is approximately 66 million light-years. I would like the travelers to ...
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6answers
4k views

Bootstrap paradox with a time machine in iron

I wonder if a time machine can be the cause of a bootstrap paradox? Background: Let's say one day I found in my room a portable time machine. I use this machine to travel to the future, where I ...
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1answer
187 views

Which languages would be most useful for time travelers to learn? [closed]

Title pretty much says it all. Which languages would be most useful to a time traveler?
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1answer
251 views

What would happen if we sent a modern computer into the past? [closed]

According to Moore's law, the number of transistors in an integrated circuit doubles about every two years. Therefore, a modern household computer has the computational capabilities of a supercomputer ...
11
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5answers
2k views

If you had a giant cutting disc 60 miles diameter and rotated it 1000 rps, would the edge be traveling faster than light? [closed]

As if there was a giant angle-grinder in space that slowly increased its speed. The question assumes that material exists to make this super-disk that doesn't rip apart. What happens as the edges ...
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6answers
4k views

At what point in European history could a government build a printing press given a basic description?

Say a time traveler ends up back in time and has earned the good graces of one of the nations' kings by sharing some of his future knowledge. Knowing that the printing press was an important ...
3
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1answer
238 views

The World is ending, but we have a time-machine [closed]

Let's say an event is occuring that within a short timeframe makes at least the entire solarsystem uninhabitable. However, in a global effort, scientists and engineers have developed a backwards time ...
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4answers
3k views

Would a US marine teleported in the Cretaceous be able to survive a T-rex attack [closed]

A US marine fighting in the Middle East inadvertently falls in a hole that happens to be a time portal and is teleported in the Cretaceous era, 70 million years in the past. Our Marine is equipped ...
3
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3answers
246 views

Solar cells in the Renaissance

An engineer goes back in time to attempt to rewrite history: since global warming has wiped out all but a few living species at his home timeline, he wants to prevent it without preventing an ...
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0answers
115 views

Can you mine bitcoins or other data a time loop? [closed]

You have your own time loop. For one day only: at midnight, if you choose, you can transport your mind back 24 hours and relive the day, but with all the memories you have gained. Nobody else will be ...
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3answers
227 views

Passing a message back in time

I have built a machine that I have connected to an ordinary desktop computer, which is in turn connected to the internet. When turned on, the machine isolates a pair of quantum-entangled particles; ...
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1answer
111 views

Speed of light, Motionlessness, and Time Travel [closed]

i want to ask something I quote from some web and got this : 'According to Einstein’s Special Relativity Theory, time is affected by speed. It’s already been proven in the lab that subatomic ...
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3answers
388 views

Non-causality-violating FTL travel. / Can omnipotence beat causality?

While building my sifi world I dug into ftl-travel and encountered these mean bullies, causality and relativity. They told me I can't have faster than light travel, because effect can't precede cause ...
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13answers
5k views

What historical events would have to change in order to make 19th century “steampunk” technology possible?

I know this is similar to this question but I'm not interested in suppressing 20th century tech to create 21st century steampunk, but in creating late 19th century steampunk with fantastic, Jules ...
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12answers
16k views

What steps are necessary to read a Modern SSD in Medieval Europe?

So the main team of characters is traveling back in time from "modern day" to medieval Europe, arriving around the 1300s. Assumptions: They Know they are going, they have space and time to prepare, ...
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3answers
165 views

Preventing the Big Bang

I travel back in time to the Big Bang in my time machine. I am equipped with all the present day equipment I need. I locate the infinitesimal 'point' where the Universe would come into existence and ...