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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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14answers
22k views

Is there a single historic event which could be changed to cause the USA to use SI units?

I am time traveller with aim to make world better. Last time I went to the past, all I heard was: "Kill Hitler!" So I went to the past and I must tell you, April 1945 was pretty loud in Berlin! ...
-1
votes
1answer
44 views

Moving someone along their timeline [closed]

If one would use something like the Time Stone from the MCU to move someone along their own timeline, would they have all of the memories that they would have made if they had lived out their lives ...
8
votes
4answers
774 views

Victorian astronomer detecting artificial satellites

To make it short, time-space shenanigans transported everything in a 60 kilometers circumference around an old space-based particle collider to the year 1855. The particle collider was in ...
1
vote
1answer
192 views

If you could travel back in time by transfering your state of mind/memories to your former self, would you transfer your tiredness to him? [closed]

Let's suppose you can travel back in time by passing your state of mind/memories to your former self. You go back to your former self who has slept some hours ago, a day passes without sleeping and ...
1
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2answers
80 views

Plausible way to time travel 10,000 years into a future where there is zero technology [closed]

Ideally the subject(s) would be stashed deep in a cave, and the process would be timed to wake him(them) up after 10,000 years have passed. Because of the low-tech nature of the future and the absence ...
3
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5answers
1k views

Logical explanations for the corpse of a time traveler

Tim managed to create a time machine in secret. Foolishly, he used it on himself, like all good (movie) scientists do and traveled back in time. He thought he configured the machine to five minutes, ...
0
votes
0answers
112 views

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 ...
8
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4answers
3k views

Time traveler has identified a unknown epidemic is likely spread by mosquitos. How much can he help combat it?

In the world I'm envisioning, an individual has been accidently sent to a sort of alternate history version of the world, one that is at roughly feudal level of tech/culture, but with the nations ...
2
votes
0answers
246 views

How can I make this religion believing in “creating time traveling gods through science” believable?

I want to popularize the following or a similar belief. In many thousand years people will travel back in time to give us an afterlife, if we make it possible, by going the steps, that will lead to ...
2
votes
2answers
102 views

If one traveled along a Closed Time-like Curve to arrive in a parallel universe/world-line, would the previous universe cease to exist?

This question makes several assumptions: 1) The "Many Worlds" Interpretation will have been proven through future observation 2) CTC's exist within the rotating event horizon of a Kerr black hole 3)...
29
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11answers
3k views

How to identify or authorize members of a time travel organisation?

Many organizations today have identity cards, and use passwords and multi-factor authentication to authenticate and authorize people. If there's trouble, things can be done: Identity cards can be ...
29
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5answers
4k views

How could the Mafia retain its power in New York into the new century?

A mutant who sees multiple futures has predicted that the world will be invaded by aliens. Every future ends disastrously for the human race with us being wiped out. The only one in which we survive ...
13
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10answers
706 views

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 ...
-1
votes
2answers
97 views

Maximum span of Time Travel without being detected [closed]

Our protagonist is a completely normal 25-year old who just went on a walk through the city. What he doesn't know: The morally dubious scientists of Evil, Inc. have decided that he is the perfect ...
3
votes
7answers
312 views

Strategy to capture a TRex alive?

For context : A squad hunters has been assigned to capture a Tyrannosaurus Rex for the grand opening of a new amazing zoo. They will be sent to a location in Montana 66 million years ago using a time ...
2
votes
1answer
112 views

Prevent getting destroyed in the middle of time travel

In H.G. Wells' The Time Machine, the time traveler uses an open-air time machine that does not immediately teleport through time, but rather speeds up time for the person inside the time machine. So, ...
1
vote
3answers
128 views

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 ...
4
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15answers
2k views

Why would time travel affect the body in any major way, especially damaging? [closed]

Obviously, I'm talking about sci-fi time-travel and not just being as time moves by, slowly but surely. Is there a reason one would actually bleed from any orifice? For any pain to occur? Dizziness? ...
3
votes
6answers
186 views

I am writing some short stories and can't wrap my head around a time travel paradox

I put an object in a time-travel device (say something that looks like a microwave ). I am now going to transport the object in time, but leave it in the same position relative to the Earth. If it was ...
0
votes
4answers
133 views

Make money by bringing an invention back in time

I found a time travel machine. It can travel back in time very precisely. I don't have any specific skills, except for my very good knowledge with programming languages and programming patterns. I ...
32
votes
10answers
4k views

Which jobs could western geniuses, who lived between 1643-1900, have in the modern age related to their talents?

I'm trying to write a comedy where as a plot device I have: Some of the greatest western minds of human history, who lived between 1643 and 1900, are transported into the modern age. I still haven't ...
-2
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3answers
58 views

How can I modern time traveler determine solstice and equinox?

A XX century researcher time traveled back into the prehistory. He is not in danger of death or anything, but he has only energy to attempt one jump. He must jump back during the sunrise either in a ...
-1
votes
2answers
160 views

What happens when you create a time paradox? [closed]

Let's say that we have a time machine. We take a trip to the past to.. Let's say, kill Hitler. We go back, kill Hitler while his was still a child and return to the present day. But now in this ...
5
votes
7answers
521 views

Uses for “Pocket Universe” backwards Time Travel? [closed]

As it turns out, Time Travel is possible! It's just not as useful as we thought it would be, that's all. You can only go back in time, and not really. Whenever anyone goes back in time, a pocket ...
60
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12answers
12k views

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 ...
29
votes
13answers
3k views

With future knowledge, can I prevent the Columbian Exchange epidemics?

I have traveled back to the 15th century with the goal of facilitating the discovery of the Americas by the rest of the world without causing epidemics to wipe out 90% of the American population. How ...
2
votes
3answers
155 views

Theoretical: If you were to psychologically examine people that have time-traveled, what would you look for?

Let us say there is an adult male, adult female, a boy, and a girl. They experience time-travel. As a psychologist, what would you examine before and after the travel to ensure that psychologically, ...
1
vote
2answers
156 views

Extrapolating from the GPS network for time travel

One of the aspects of most sci fi time travel representations that I find most challenging for my suspension of disbelief is this idea of people travelling through time and not travelling through ...
-4
votes
3answers
92 views

“Moving” through time doesn't actually involve motion [closed]

In regards to the concept of time travel, physical travel isn't possible or necessary. "Going" to other points in time, one would actually remain in the same place, not actually travel through space. ...
13
votes
15answers
5k views

How might a Professor of Mathematics Change History?

A professor of mathematics is sent back in time to a post-Neolithic farming village. They accept him as their wise man, and he spends 30 years teaching them all he knows about mathematics until he ...
50
votes
46answers
18k views

Plausible reason why my time machine can only go back a certain amount of time?

So, I have built a Time-Traveling machine. It’s a prototype, and I’ve noticed a few kinks in the machine. If the control pad gets jammed in home mode, the universe will repeat the same day for all ...
1
vote
9answers
316 views

If time travel exists and there's only a timeline, how can a event assured to happen be avoided without breaking physical laws? [closed]

Let's begin with the premise of that type of time travel, the one in which no matter what you try, the past cannot be changed, if you tried to kill your grandfather you wouldn't be able to as much as ...
8
votes
6answers
750 views

Survival strategy for a time traveller in the Roman empire [closed]

I would like to know what would be the best strategy to survive and prosper in the roman empire for a time traveller? Let's say that the time traveller is a 30-year-old Italian from the XXI century ...
3
votes
6answers
416 views

How does a time travel paradox actually begins?

A while ago I was conceiving a story about a guy that actually creates a method for viable time travelling but gets stuck in a paradox after using the machine. The background story for this is that ...
1
vote
2answers
188 views

King Arthur in Connecticut [closed]

In the middle of a joust, King Arthur receives a severe blow to the head and is somehow transported in time and space to Connecticut in 1889. After some initial confusion and his capture by the local ...
41
votes
15answers
12k views

How does a time traveler prove he or she is from the near past?

Assume a college student from 2018 accidentally traveled to 2023. He is accidentally taken by an alien spaceship that travels close to the speed of light away from earth and then travels back. He is ...
87
votes
31answers
16k views

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 ...
0
votes
1answer
87 views

Help with “2012 meets Groundhog's Day” Scenario [closed]

This is a looping-day time-travel plot akin to Groundhog's Day. There is a sudden global cataclysmic disaster taking place. This doomsday disaster is almost impossible to survive. Those who died ...
38
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28answers
10k views

Why buy tech from the future?

The Demonstration You're a rich, successful CEO/capitalist working in the electronics business. Your R&D division is exceptional and routinely fabs state of the art processors at bleeding edge ...
3
votes
4answers
136 views

Effect of time travel on the collectible market

Another spin on the recent question How would you bring wealth back to the past?, this one will attempt to look at the effect on collectibles. Almost by definitions, things are collectible because ...
21
votes
8answers
967 views

How could an inter-temporal banking system work?

(This question is meant to be an improvement and/or replacement for How would you bring wealth back to the past?, which some users have argued is off-topic for this group.) Imagine a future world in ...
50
votes
22answers
13k views

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 ...
-2
votes
1answer
137 views

What to do for money while stuck back in the 17th century? [closed]

So, a group of three people were experimenting with a time machine, and were transported back to 17th century Salem. The male is wearing a red hoodie and some jeans, the female is wearing leggings and ...
-1
votes
2answers
118 views

How to make someone who can time travel fail at preventing the death of one of his friends? [closed]

In my world, there is a character who can space-time travel (he creates an alternate reality each time he travels). He doesn't have a good control over his power but he can still think where and when ...
-2
votes
4answers
257 views

Does this kind of time travel exist? [closed]

WARNING: If this question is off-topic or in any way a bad question for this site, please don't downvote it, but migrate it to where it belongs. I cannot find an adequate place for this question, but ...
4
votes
1answer
244 views

Time travel to the mid-1980's - how do you sneak into society and make a ton of money as fast as possible? [closed]

The scenario: You are from the distant future, and are trapped in a parallel universe in the mid-1980's. You cannot expose your true identity and your only resource is a hidden laboratory where you ...
3
votes
5answers
319 views

The Paradox Men - Cosmology

In Charles L Harness's 'The Paradox Men', a spaceship crashes on earth several years before it launches, having circumnavigated the universe faster than the speed of light. It is a good read, but I ...
2
votes
2answers
157 views

How would age change when crossing into an alternate universe? [closed]

For a project I'm working on, a pair of "immortal" characters end up crossing from their dimension (a fantasy world) into what could be described as the "real" world, and I'm considering aging them ...
5
votes
2answers
149 views

Is there any way to build a world with science-compliable time travel without disproving the Theory of Relativity?

I want to make a world similar to ours, with one additional feature: Time travel. There is no difference to me if its loop-based or infinite universe based. But there is a catch: The theory of ...
5
votes
3answers
162 views

Time travel parental DNA shenanigans

If you and your significant other traveled back in time 50 years, had a child (who gets citizenship of the fictional country in question due to being born there) and left the child with a trusted ...