Writing about time travel - please help

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Hi

I'm currently writing a YA novel where the protagonist needs to leave earth to save his mother.

Meanwhile, the protagonist's mother is back on earth.

I would prefer if he could be back "instantly".

Superluminal traveling is possible in this story.

If the protagonists travels at superluminal speeds, would he travel "back in time"?

Somehow, I need to make it possible for him to be away from earth for a couple of months, without time actually passing as much back on earth. So when he returns, only a couple of hours have passed.

Can anyone help me with this?
 

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  • #2
Vanadium 50
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Can anyone help me with this?
Sure. "Time runs differently there".
 
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Sure. "Time runs differently there".

So, time travel is possible at superluminal speeds?

And by "there" you mean when traveling faster than the speed of light in space?
 
  • #4
Drakkith
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Superluminal travel already violates the known laws of physics, so there is absolutely no way we can give you a yes or no answer. We can't even give you a reasonable guess. The laws of physics state that superluminal speed can be used for time travel, but it creates paradoxes, like receiving a signal from a distant ship, traveling to the ship, and reaching the ship before the signal was ever sent. The fact that it creates paradoxes is a strong indication that it is impossible to travel backwards in time in the real world.

The best thing you can do is to come up with a few different ideas about how your character can get back to Earth with only a small amount of time passing and develop the one that has the most potential for your particular story. It may be that superluminal travel in your book's universe does indeed cause time travel. Or it could be that you character goes to a region where time passes far more quickly for them, letting them live out months of their life while only a few days pass back on Earth. Or it could be absolutely anything else you can come up with. Time travel machines, magic (or its sci-fi equivalent), gods, whatever.
 
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Superluminal travel already violates the known laws of physics, so there is absolutely no way we can give you a yes or no answer. We can't even give you a reasonable guess. The laws of physics state that superluminal speed can be used for time travel, but it creates paradoxes, like receiving a signal from a distant ship, traveling to the ship, and reaching the ship before the signal was ever sent. The fact that it creates paradoxes is a strong indication that it is impossible to travel backwards in time in the real world.

The best thing you can do is to come up with a few different ideas about how your character can get back to Earth with only a small amount of time passing and develop the one that has the most potential for your particular story. It may be that superluminal travel in your book's universe does indeed cause time travel. Or it could be that you character goes to a region where time passes far more quickly for them, letting them live out months of their life while only a few days pass back on Earth. Or it could be absolutely anything else you can come up with. Time travel machines, magic (or its sci-fi equivalent), gods, whatever.

Hi Drakkith, this was exactly the thoughtful answer I was looking for. Thank you very much for taking the time to speak to me!

You understand the laws of physics (=time travel is impossible) and the laws of artistic license (=time travel is possible in my book's universe).

I was thinking about (and it might sound very stupid as I'm not a mathematician, so please bear with me) the following. Traveling at superluminal speeds equals traveling back in time. But gravitational time dilation (when they are in a massive object heavier than earth), would "slow time down". So, the crew members could basically "manipulate" time, so that the protagonist would just have been gone for a few hours. Does this make sense? If the spaceship travels faster than the speed of light (backwards in time), then enters the gravity well of a heavy planet (where time slows down relative to the time passing for his mother on earth), could I use these two explanations to why time has passed a couple of hours back on earth?

I hope this question makes sense. If not, then I'm sorry.
 
  • #6
Drakkith
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No, that wouldn't work. You need time to pass more slowly on Earth, not where your main character is at. Since you can't really manipulate the rate of time passing on Earth (well you can if you want to, but that's a whole other bag of issues), they need to be in a region where time passes more quickly than it does on Earth. The problem is that there is no natural source of such a difference in the passage of time. Compared to an intergalactic void, Earth has lost perhaps a few days over the last 13 billion years. And since voids are where the least amount of mass is, and thus the least amount of gravitational time dilation, you have to come up with an alternate source. It could be artificial or it could be a phenomenon unknown to current science.
 
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No, that wouldn't work. You need time to pass more slowly on Earth, not where your main character is at. Since you can't really manipulate the rate of time passing on Earth (well you can if you want to, but that's a whole other bag of issues), they need to be in a region where time passes more quickly than it does on Earth. The problem is that there is no natural source of such a difference in the passage of time. Compared to an intergalactic void, Earth has lost perhaps a few days over the last 13 billion years. And since voids are where the least amount of mass is, and thus the least amount of gravitational time dilation, you have to come up with an alternate source. It could be artificial or it could be a phenomenon unknown to current science.
Hi again! And thank you!

Yes, well, in this story the crew will basically travel through the entire universe (that's why they will need to travel at superluminal speeds or using wormholes). I think this is important to mention as they will be in intergalactic voids but also close to black holes and other very massive objects. I was thinking about the movie Interstellar when I thought about time dilation. The first planet the crew visit in the movie is said to be so close to a black hole that one hour on the planet equals seven years on earth, due to the gravity of the black hole affecting the gravity of the planet they are visiting. Using this same logic, and having superluminal travel possible for the crew in my book's universe (=travel backwards in time), would it not then be at least reasonable to say that you could manipulate time given these two factors?

So, if they travel backwards in time (say 300 years). Then they stop at the very same planet they use in Interstellar for X amount time (say they stay there for 3 weeks and that equals 300 years on earth)... and so manipulate time?
 
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Drakkith
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Ah, I see what you meant now. Sure, that's possible.
 
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Another possibility to get round the time-travel limitations is to adopt (or else filch parts of) the 'multiverse' interpretation - although I appreciate this could wreck your plot/storyline and create horrendous complications. Just a thought, though.

https://en.wikipedia.org/wiki/Many-worlds_interpretation
 
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Another possibility to get round the time-travel limitations is to adopt (or else filch parts of) the 'multiverse' interpretation - although I appreciate this could wreck your plot/storyline and create horrendous complications. Just a thought, though.

https://en.wikipedia.org/wiki/Many-worlds_interpretation
The multiverse is present in my story, so it might work. Could you explain how I could use the multiverse interpretation? Because I don't know much about it.
 
  • #11
As a fellow science fiction writer, I might (notice thst I said "might") be able to add something constructive.

In Carl Sagan's 'Cosmos' series, he explores cosmolgy in one of the later episodes, and the possible consequences of an expanding Universe.

He said that in some models (almost 40 years ago, so maybe his ideas at the time are no longer current), causes will preceed effect if the Universe expands to it's maximum, and begins to contract.
"First you see the ripples . . . and then you throw the stone," is a direct quote.

Perhaps you can work things out in your story where the protagonist enters a contracting Universe (perhaps in something akin to a black hole) and leaves before he entered?

I hope this helps you. Let me know how things work out.
 
  • #12
Zap
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To move forward in time, you should be near a black hole. To move backward in time, you should be near a white hole.
 
  • #13
Bilal Rajab Abbasi
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Use the concept of Black Holes...
You can make him enter a black hole and time will pass very very slow there relative to earth...
Make distance of Days longer in that planet...
Time will pass slowly, then..
 
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  • #14
Time travel is possible at least theoretically. You can use the idea in your novel making it consistent with relativity. I am also writing about time dilation which you need to understand.
 
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  • #15
Bilal Rajab Abbasi
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You might want to see some of the lectures of Stephen Hawking.
 
  • #16
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Obviously, it would easier to have the mother leave on a relativistic voyage so her time is slowed down.

Otherwise, two possibilities present themselves:
1. The protagonist "voyages" into a place where time runs super fast - like a virtual trip inside a computer (Tron).

2. Come up with a wacky theory about FTL travel:
As you approach the speed of light, the traveler's time slows. If it were possible to travel faster than light, perhaps the same curve applies on the other side, but time effectively flows backwards from C to twice C. At twice C the traveler will go back in time at the same rate as time flows forward on earth. So depending on how much faster than light the protagonist goes, they will go back in time at variable rates.

Clearly, no science supports that idea, but relativity doesn't really say you can't exist faster than light, just that you can't get there by accelerating through it. Perhaps that realm is accessible and has a symmetrical relationship to ours.
 
  • #17
DaveC426913
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I have some meta advice.

Whatever flogistonic reason you come up with to get him to travel around for a whole novel, only to get back just in time to save his mom, don't make it a small issue in the story. It must be at the core.

Being able to do whatever you want and still get back in time to save the say is - to any discerning reader - essentially the Magical Holy Grail of Fiction. It must be "InconthEEvable!".

It's akin to being able to raise the dead. You do not introduce that kind of element into a story. If you can simply raise any of your comrades from the dead, then there is no reason to worry about them dying.

Likewise, if you tell the readers that the protagonist has the ability to make it back in time, you've torpedoed any risk. And your readers will be see it as the tacked-on necessary plot device it is.

[ Spoiler ]
Imagine sucking all the frenetic tension out of Around the World in 80 days by having Phileas Fogg announce as they're lifting off "Oh, it's all right. We actually have an extra day because of crossing the International Date Line."



That being said, it is possible to have such an element in your story - but it must be at the core of the story, not some We-Can-Go-Home-Any-Time-Drive.

Better yet, lay the groundwork for your flogiston, and how it works normally, without pointing out that an unanticipated side-effect is that one can get back just in time to save the day. That is your climax - the protag realizing the implication just in time.

You'll have your readers saying "Of course! That's brilliant!"
 
  • #18
DaveC426913
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Another piece of meta advice - this one from Larry Niven:

"If you must tell a lie*, tell it early in the story. The bigger the lie, the earlier it must be."

*eg. this sci-fi world has magic / psychic powers / FTL drive / time travel.
 

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