Time travel impossible?

[Kron]

Errr... sure?

The point behind constructing the restrictive rulesets for the time machines was to act as a simple counter-example to the so-called "logical disproofs" of time travel.

They're just thought experiments, designed to point out that time travel may certainly be possible without running into various issues (like conservation law violations).

[Lancefighter]

Sounds to me that people are just trying to rationallze why time travel does exist, given that it would have appeared that it doesn't.

[Kron]

Might as well use that line of reasoning to argue that flight was impossible in the 18th century. ^^

... Still, I can see where you're coming from. I may sound like someone who simply desperately wants time travel to exist and knows just enough math to squint her eyes and pretend that something that is highly improbable is possible.

It's not like that, I promise. I'm a physicist. In my studies, I've simply found causality to be a somewhat unnecessary axiom for describing our world around us, and we arguably already have causality-breaking experiments.

I can see low-level time travel (on the order of pushing electrons up and down a few picoseconds) being implemented in the next 50 years.

[eRe4s3r]

... Wormholes have absolutely nothing to do with quantum mechanics. They are General Relativistic constructs.

Are you confusing wormholes with quantum tunneling?

Objection: Unproven constructs and unobserved constructs Physics be damned, but even if math predicts wormholes we have yet to see any or see the predicted effects on their surroundings anywhere. Which to me means, they don't exist and whatever calculation was used to predict them is based on wrong assumptions OR we simply don't look in the right places (so could be, who knows ,p).

I am indeed - sorry, to me only Quantum Tunneling sounds like an realistic/possible concept so i was getting ahead of my thought ,P

... No? That's not how a traversable wormhole metric works. You may be confusing with another metric, as "wormholes" are basically a family of similar equations.

Now now, my Physics education is years ago and i am not debating on a scientific level on the specific Math that is the equation for wormholes. To me its a simple thought - a wormhole sounds like a paradox and is (probably) why we will never *find* natural wormholes.

I really have no idea as to what you're talking about. Time exists within a wormhole's throat... and at its mouths... and basically everywhere within its structure.

It's how wormholes can be used for time travel; you manipulate its temporal nature to shift the mouths up and down time relative to each other.

Furthermore, you say there's no proof that we can build a physically traversable wormhole... and yet there's no proof that we can't. I'll place the burden of evidence on you here, since history has shown us that if something isn't impossible, it's possible... maybe even doable.

Mhh, rather I said "no wormholes have been observed". I do not contest that they are build-able in 5000 years +. I merely contest the calculations that claim they EXIST right now, like in our reality and dimension and universe without us doing anything and i also strongly would object any claim that we could create wormholes with our current physics models, be it Quantum Mechanics or Standard Model.

I was actually confused as to whether you were a guy or a girl until I asked on the IRC channel! I was reading your earlier posts in C2's voice!

Well you could just click on my Gallery ( http://ere4s3r.deviantart.com/ ) where my Gender and Nationality (and too many other things..) are publicly Displayed - the curse of a Freelancer ;P

I have no idea as to what you're talking about here. Can you elaborate on this?

• Why does the law of conservation imply knowledge of the location of all matter and energy in the universe?
• Why do you reject the reality of the dimensionality of time? Minkowski Space is basically the foundation of relativity.
  
• You keep attributing really weird characteristics to time travel. "KNOWING where everything was at that specific point in subjective time"? Why? It's not like you need to know this to travel through space.
• "Quantum Theory"?! ... I do not think it means what you think it means.

The Machine you use has to know the location of you and all your particles, how else would you traverse time without ending up in a gooey state? Or are you saying you see time travel more like a shift in dimensions as opposed to a "physical" travel? And even if true, lack of time travelers NOW means no time travelers in our entire races future. So that tells me something - not necessarily that time travel is impossible mind you

I reject time travel for basically 2 reasons. If time at any point in (sorry) time did not exist, then traveling backwards is a paradox. If you by accident travel too far back you might end up before time existed - and the universe would end, in which case i'd send you a strongly worded (hehe) complaint letter for ending the universe

Quantum Mechanics <3 -> Slip of words,

One could argue that this merely means that our current models of physics are wrong

Physics is not intuitive. Look at relativity or QM.

I find QM intuitive actually, at least a lot more than time travel or math (heh), but our current physics do not explain why
1) Energy has a MASS
2) What Gravity is (I don't mean what it does, i mean WHY it does what it does)
3) The Universe is the way it is now (Expansion from single point of origin?)
4) What Dark Matter is or where it comes from
5) What Dark Energy is or where it comes from
6) Why our Universe is expanding and faster

Which leads me to believe that our current physical understand is not complete ergo, flawed ;/ Then again, in the future it might be less flawed.

Lastly, i am not Physics geek (In fact, theres 2 things i hate, WATER (don't ask) and MATH (don't ask) ;p), i am Artist, so from an Artistic Standpoint i see time as a subjective state of existence thats relative to each individual. And yes, i do realize how absurd it is that a 3D Artist hates Math.  

Never the less, read my replies with that in mind Artist bored while doing artsy staff, this is also why my replies are less than in-depth.. no time to read up on all things just for 1 post

Though your link to the Minkowski Space was Interesting, as a 3D Artist i regard Time as snapshot of a state not as stream (or even streams). So the "now" (whenever you read this) exists exactly once for the global universe.

The traveling back to MY subjective now is impossible as you would alter it with your presence alone. And something in me absolutely disproves of Time theories that "push" changes ahead of the stream. because if THAT were true then why isn't the END(or rather "before) of time pushing ahead of the stream as well?

So you see, you first gotta say what you think time even is.

Edit: Hit submit too fast ;p See, working on a Model and Writing about Time travel really confusing.

[Lancefighter]

*shrug* in the 17 century, they had to completely rethink thinking. I think Newton had something to do with that..

Also, i was hoping by now youd realize i have no intentions of actually arguing either way tbh.

Oh, and people have been able to do flight since around the late 1700s, with the Montgolfier brothers. the wright brothers only figured out the angle of attack/airfoil bit for heavier than air flight.

[wyvern83]

http://www.mjyoung.net/time/index.htm

This is a cool site that reviews time travel in movies.

He has some good theoretical concepts for how time travel would work logically if it were possible. (If you scroll down you can find some graphs and articles illustrating his ideas.)

Just figured some of you might find it interesting since you posted in this thread. Hope you enjoy it.

[Kron]

Okay, I have a slightly better understanding of where eRe4s3r is coming from. And rather than make a page long point by point rebuttal to the sheer volume of bad physics within his last post*, I'll simply respond to this:

Which leads me to believe that our current physical understand is not complete ergo, flawed ;/ Then again, in the future it might be less flawed.

Lastly, i am not Physics geek (In fact, theres 2 things i hate, WATER (don't ask) and MATH (don't ask) ;p), i am Artist, so from an Artistic Standpoint i see time as a subjective state of existence thats relative to each individual. And yes, i do realize how absurd it is that a 3D Artist hates Math.  

Never the less, read my replies with that in mind Artist bored while doing artsy staff, this is also why my replies are less than in-depth.. no time to read up on all things just for 1 post

I have a big problem with this. I'll break down why:

• You are an artist, and admit you don't have a very strong understanding of physics.
• ... yet you still run around talking about how you know that our current understanding of physics is flawed,
  
• ... and you're using your nature as an artist as a get out of jail free card.

This is horribly intellectually dishonest!

I know next to nothing about art. If I were to run around talking about how 3-point perspective is bunk, and then say "Hey, I'm a physicist! Cut me some slack... (it's still bunk)" whenever any artist tried to point out I was wrong, I'd get a smack upside my head.

Now, I want to make this clear: I am not implying that "only physicists are allowed to talk physics". That's an extremely elitist thing to say.

What I am trying to say is that you should approach subjects you are not familiar with with a certain degree of caution and self-doubt, and be willing to change your mind. I generally defer to my economist friend on matters of global macroeconomics, and defer to my molecular biologist friends on matters of genetics.

* If you still want me to point out where you are wrong, I will. I'm not trying to shirk the responsibility of supporting my points, I just don't want to TL:DR you.

[RCIX]

Well, i'm not a physicist either, but i do do a lot of thinking and research on the subject, so i'll try and provide those rebuttals.

... Wormholes have absolutely nothing to do with quantum mechanics. They are General Relativistic constructs.

Are you confusing wormholes with quantum tunneling?

Objection: Unproven constructs and unobserved constructs Physics be damned, but even if math predicts wormholes we have yet to see any or see the predicted effects on their surroundings anywhere. Which to me means, they don't exist and whatever calculation was used to predict them is based on wrong assumptions OR we simply don't look in the right places (so could be, who knows ,p).

Durr, when we're talking  about theoretical physics (as we have to when examining time travel as a possibility), we kinda have to use unproven stuff. Referring to "we haven't seen them or their effects" is nonsense in this case. What matters is if the models are accurate, and if they are then time travel can exist...

Now now, my Physics education is years ago and i am not debating on a scientific level on the specific Math that is the equation for wormholes. To me its a simple thought - a wormhole sounds like a paradox and is (probably) why we will never *find* natural wormholes.

A good example of wormholes is this:
Take a sheet of paper, bend it in half so that the two halves are hovering over each other. Poke a hole through both sides of the paper, and fabricate a tunnel connecting both points. That's a wormhole, only in 2D. It would obviously be quite tough to imagine a 3D version (since our brains are not geared to think in 4D very well), but it makes perfect sense if you think about it.

I really have no idea as to what you're talking about. Time exists within a wormhole's throat... and at its mouths... and basically everywhere within its structure.

It's how wormholes can be used for time travel; you manipulate its temporal nature to shift the mouths up and down time relative to each other.

Simply, you take one end of the wormhole, and send it off at a sizable fraction of the speed of light. This causes one end of the wormhole to "slow down in time". Which means that traveling through the un-slowed down side of the wormhole will push you back in time (and vice versa for going through the other side). If that's what you mean, then yeah. The issue i have with this though is A: since wormholes are part of spacetime, how can they be subject to temporal effects, and B: how can they be moved?

I find QM intuitive actually, at least a lot more than time travel or math (heh), but our current physics do not explain why
1) Energy has a MASS

Because you can convert it to matter?

[Kron]

I'm not sure what he meant by the "Energy has a MASS and that is not explained by our current physics" thing.

Last time I checked, it was one of the most incredible examples of physics preceding reality. The energy / mass equivalence principle wasn't experimentally discovered, it appeared as a by-product of Einstein's Special Theory of Relativity.

To reiterate: The physics theory came first and capitalizing on it lead to the atomic bomb. I'd consider this a win for "current physics".

http://www.mjyoung.net/time/index.htm

This is a cool site that reviews time travel in movies.

He has some good theoretical concepts for how time travel would work logically if it were possible. (If you scroll down you can find some graphs and articles illustrating his ideas.)

Just figured some of you might find it interesting since you posted in this thread. Hope you enjoy it.

Thanks a lot wyvern! Took a look at the site... and unfortunately didn't like it very much?

The author rejects Eternist models of the universe (causal loops, etc.) on fairly flimsy "logical" grounds despite it basically being general scientific consensus at this point.

Update: For the love of Bayes, the author even rejects Occam's Razor when he got into a debate with someone. O_O

[RCIX]

The author rejects Eternist models of the universe (causal loops, etc.) on fairly flimsy "logical" grounds despite it basically being general scientific consensus at this point.

By "eternist models of the universe", do you mean models that suggest that a universe (if not ours) has been around forever? If so, i don't see how the Novikov self-consistency principle applies.

[Kron]

I mean models where time travel doesn't change anything. "You already changed the past"

[Ktoff]

I find QM intuitive actually, at least a lot more than time travel or math (heh), but our current physics do not explain why
1) Energy has a MASS
2) What Gravity is (I don't mean what it does, i mean WHY it does what it does)
3) The Universe is the way it is now (Expansion from single point of origin?)
4) What Dark Matter is or where it comes from
5) What Dark Energy is or where it comes from
6) Why our Universe is expanding and faster

Well, as a physics geek (physicist), let me reply to this:
First with a question: Could you please name one phenomenon where physics explain WHY it exists?

A physicist will of course always ask why, but ultimately an answer is never given. What you get from there is a description that gets more and more refined the deeper you delve.

Take Newton. He found gravity. But did he at any stage say why bodies attract each other? He described what rules govern this interaction (and he was not completely on target, but good enough for his time ).

Through description and discovery of underlying principles you can get a better understanding of the processes of nature. But you will always end up with another underlying principle.

Also 2) Gravity does what it does because of the curvature of space-time caused by large masses of bodies.    But why do said bodies have mass and why does the mass curve space-time....

Cheers,
KToff

[wyvern83]

Thanks a lot wyvern! Took a look at the site... and unfortunately didn't like it very much?

The author rejects Eternist models of the universe (causal loops, etc.) on fairly flimsy "logical" grounds despite it basically being general scientific consensus at this point.

Update: For the love of Bayes, the author even rejects Occam's Razor when he got into a debate with someone. O_O

No problem, I am in no way offended. I thought the time change graphs might have been helpful since they are easy to read, (I liked them the best). My main attraction to the sight was that he examined stories with time travel in them for consistency, which I thought was interesting. 

I dislike the idea of time travel in general as its potentially very messy in terms of cause and effect. I agree that rejecting Occam's Razor is ridiculous however I don't follow you on the author rejecting causal loops and the like.

If you scroll down and look at his graphs he diagrams what a loop would look like. It was my understanding that he more or less said that it'd be a catastrophe if the time line didn't eventually find a way forward.

Could you point out what you are basing your impressions on? (Its been a while since I visited his site.)

[Echo35]

Obviously time travelers have been around since 1928 - http://www.youtube.com/watch?v=TiIrpEMbQ2M

[RCIX]

I mean models where time travel doesn't change anything. "You already changed the past"

Oh. Well, yeah, that's sort of a "why didn't i think of that before!?!?!?!" type thing once you hear about it