General Question

inunsure's avatar

Can someone help clarify what is believed to be how time travel would work and why that is believed?

Asked by inunsure (423 points ) April 29th, 2012

Imagine I travel 50 years into the future to 2062 a future that didn’t have me to influence it for 50 year, I think we would all agree that future would be different than a future were I didn’t decide to go into the time machine and maybe had a wife and kids.

This is because the future is set by rules and systems and if I was God and could pluck someone out of existence the future would be different as the system loses me and how I would effect everything within the system.

But we dont seem to think this way when thinking of traveling back in time. The past when traveling on the time line like we would to get to the future I dont see why it’s just not the rules but in reverse.

So if we turned back time 50 years ago it would be at some state from now when the rules happen in reverse, but if some 60 year old man went in a time machine plucked himself out of the universe lets say the rules wouldn’t give the same result.

Just like traveling forward in time it matters if you are there as the rules give different results, why is this not how people see going back in time?

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23 Answers

Jeruba's avatar

It’s fiction. You can make any rules you want.

Imadethisupwithnoforethought's avatar

I am under the impression that time works backwards and the future is set, while observations in the present cause the past to shape into conformity.

So there are a few ways to think about this.

flutherother's avatar

It doesn’t matter if time travellers affect the future because it hasn’t happened yet. In fact we all do it. Through our actions today we change tomorrow. But we can’t change the past because it has already happened. If we could time travel into the past we might inadvertently prevent our great grandmother from being born, which is a paradoxical situation because then you would never have existed. The arrow of time moves from past into the future.

inunsure's avatar

@Jeruba
How are the rules of physics fiction?

SpatzieLover's avatar

Quantum physics and time travel
There are many theories on the possibilities of this @inunsure. If you do a google search you could read up on it all day. There are some good YouTube videos to explain some of the theories, too.

There is a Through the Wormhole you could watch to see some of the theories, too.

inunsure's avatar

Is seems how other people view time travel lead to ontological paradoxes, plus you can have two yous in the universe meaning there is more mass in the universe meaning there is more energy and you cant create energy. When the way I think doesnt have any of that :/

Jeruba's avatar

@inunsure, are you suggesting that “rules of physics” = “rules of time travel”?

inunsure's avatar

@Jeruba
Um yes theories like the Theory of relativity are theories on physics about time.

funkdaddy's avatar

Physics doesn’t deal with the sort of things you’re talking about, a good place to start on some educated theories would be looking into the grandfather paradox.

It explores possible outcomes if you went back in time and killed your grandfather, would you still be born and then be able to go back in time? And if not, who killed your grandfather?

There’s no single provable answer at this time (pun intended).

Also related, watch Primer.

Roby's avatar

Time travel is a farfetched idea of some scientist who has too much time on their hands. It will never be invented even if the world stands for another million years.

funkdaddy's avatar

Some guy named Albert went through some reasonable steps and came to the conclusion that it was at least possible moving forward.

Take a look, it might actually change your mind.

Lightlyseared's avatar

The real time travel paradox is how Biff managed to take the delorean back to 1955 change the past and then travel forward along the original time line to leave the car where he found it instead of travelling along the divergent time line that Marty and the doc end up in.

wildpotato's avatar

I wish I could find my copy of Pastwatch to quote for you. Check out page 215 & a few pages following – unfortunately, the meat of the discussion is on p 216, which is not included in the preview. Card does a good job of describing a difference between time and causality, which helps me think about things like the grandfather paradox a little more clearly.

righty's avatar

There is nothing that can make time travel possible. Not even Dr Emmett Brown or his flux capacitor.

wundayatta's avatar

As far as I know, physicists don’t believe time travel could work, except perhaps at a quantum level. It wouldn’t work at the level that allows humans to travel through time. So most of the discussion of time travel is fantasy. The little that might be real is dumbed down so much for normal people that the reality of it is lost.

Dr_Lawrence's avatar

As I understand Einstein’s theory of General Relativity, if we are able to travel near or especially much above the speed of light, that would allow us to travel through time.

We once believed that humans could never travel faster than the speed of sound. We know that this happens routinely now. Who know if future technology will allow us to travel at warp speed?

LostInParadise's avatar

We can in fact travel forward in time, as explained by the twin paradox of relativity theory. What we can’t do is travel backwards in time.

inunsure's avatar

@LostInParadise
I know this seems a pointless thread when I say this but this is not if time travel is possible.

Kurt Godel came up with an idea for going back in time is the universe span but it doesn’t but hypothetically we could travel back in time if the universe did spin. So I know its seems pointless to talk about how time travel would be if it isn’t even possible but thats what Im asking.

LostInParadise's avatar

The grandfather paradox, as already mentioned shows that problems that you get into if you allow time travel. In general, going back in time will necessarily change things, which will lead to a change in the present. That gives us two present states, which is absurd. I have seen a use of the multi-universe interpretation of quantum mechanics that gets around this. This view of quantum mechanics allows for multiple realities, so there can innumerable copies of the present moment.

Skaggfacemutt's avatar

Time travel is scientifically impossible, because time doesn’t exist except as a means to measure… time! There isn’t a baby you still existing somewhere in a different time warp. If that were true, there would be another you for every second that you’ve been alive, maybe every nano-second, and also another you for every nano-second that you will exist. The concept is what science fiction is made of. But I can guarantee you that, regardless of all the amazing scientific breakthroughs we have had, no one will ever invent time travel. The most we could hope for is perhaps capturing a reflection of something that happened millions of years ago. You know, kind of along the concept of how fast light travels and how, when we look at the planets, we are actually seeing what that planet looked like a million years ago. If we could transport ourselves there, however, it would be as it is in real time.

funkdaddy's avatar

It seems that a larger percentage of people believe there is an omnipotent being in the sky, another in the ground, and they spend their days fighting over your everlasting essence, than believe that any form of bending time is possible.

this isn’t directed at anyone in particular, just an observation

Skaggfacemutt's avatar

There is no past, there is no future, there is only the present. The past doesn’t hang around like smoke lingering in the air. The future doesn’t exist because it hasn’t happened yet.

flutherother's avatar

@Skaggfacemutt Maybe, but how can anything exist in an instant of time that has no connection to the past and to the future?

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