NationStates Jolt Archive

I don't know how many people on here have enough physics to seriously discuss this, but do you think time travel is possible under generally accepted modern theory? Why or why not? If yes, how might it be accomplished? What could the effects be, and what are the implications?

I ask because I seem to have gotten into a nascent debate over in the UN forum about whether global causality violation, aka time travel into the past, is possible, and whether quantum entanglement, closed timelike curves, and effective superluminal travel are "pseudoscience."

So, thoughts?

I don't know how many people on here have enough physics to seriously discuss this, but do you think time travel is possible under generally accepted modern theory? Why or why not? If yes, how might it be accomplished? What could the effects be, and what are the implications?

I ask because I seem to have gotten into a nascent debate over in the UN forum about whether global causality violation, aka time travel into the past, is possible, and whether quantum entanglement, closed timelike curves, and effective superluminal travel are "pseudoscience."

So, thoughts?
It's not possible right now. Sorry, come back in two million years.

NO FRIKIN' WAY!!!!!!

I'm not a theoretiacal physicist, so I like to use simple terms and reasons why it is impossible on an absolute level.

You are supposed to go back in time if you walk backwards enough, aren't you? Then why haven't I traveled into the future?

It's not possible right now. Sorry, come back in two million years.

I didn't say right now; I said possible. As in allowed under the laws of physics. Theoretically physically possible.

NO FRIKIN' WAY!!!!!!

I'm not a theoretiacal physicist, so I like to use simple terms and reasons why it is impossible on an absolute level.

You are supposed to go back in time if you walk backwards enough, aren't you? Then why haven't I traveled into the future?

You know, the first phrase of the first sentence was kind of meant as a hint that I was looking for serious posts....

I'm damn serious.

If time travel could exist then it would always have existed.

I'm damn serious.

I'm sorry to hear that; I was giving your intelligence the benefit of the doubt...

If time travel could exist then it would always have existed.

Why? Explain your reasoning.

This 'time' dimension is just theory and isn't what I'd call accepted.
Based around our current knowledge, no.
Here's what I'd love to know, how does anyone propose we go back in the past.

...global causality violation...

We have no irrefutable evidence that causality exists.

I don't know if it's possible, but I've been moved to put on an episode of Doctor Who in honour of this thread. 'Nightmare of Eden', with Tom Baker. Not that this episode or its' title or its' star have any bearing on the thread - I just thought I'd mention it.

This 'time' dimension is just theory and isn't what I'd call accepted.
Based around our current knowledge, no.
Here's what I'd love to know, how does anyone propose we go back in the past.

The field equations for general relativity allow for a set of solutions called closed timelike curves. There are basically trajectories followed either effectively faster than light, or in an extreme gravity well like that of a black hole. If followed, they theoretically allow for travel into the absolute past.

Why? Explain your reasoning.

Presumably because someone from after it had been invented would have travelled back in time to a point prior to its invention and shared the technology with the past.

Possible. I mean what's to say that we are not one of the alternate universes that time travel would have to ultimately create?

(FYI: I beleive that life is on a set coarse that cannot be changed...)

Presumably because someone from after it had been invented would have travelled back in time to a point prior to its invention and shared the technology with the past.

That's actually a really interesting point.
It makes sense.

I guess if you believe that somehow past events still exist somewhere, going back in time is "possible." However, I don't believe it. The nature of the universe is to move forward, and time is just our measurement of the passage of events. I understand that as you approach the speed of light, you somehow go forward in time, but you're still going forward, never backward.

Presumably because someone from after it had been invented would have travelled back in time to a point prior to its invention and shared the technology with the past.
Unless that action would in some way alter the events of the future that had led to the traveler's journey to the past.

Unless that action would in some way alter the events of the future that had led to the traveler's journey to the past.

But if the events of the future were altered, then who would travel back in time and alter the future in the first place?

Presumably because someone from after it had been invented would have travelled back in time to a point prior to its invention and shared the technology with the past.

Not necessarily. How could people in the distant past understand or use such technology? And even besides that, why would the downstreamers who invented the tech give it to the past? Give the future some credit for being something less simplistic than the population of a bad scifi novel. The likelihood that they would care about their antecedents at all, that they would be stupid enough to give history-destabilizing technology to ancients, or that they would even pursue the use of causal tech if it was possible isn't huge. Not to mention, how do we know that they haven't tried, and destroyed themselves and any obvious markers of their interference by meddling with history? Someday we may look at the structure of spacetime, reality, and history and see the acausal detritus of a deep-future species trying to be gods.

That's actually a really interesting point.
It makes sense.

Of coarse if they did so than they would quite possibly put them selves out of existance therefore the people would not have the technology because the person who brought it to them would never have existed...

(My brain hurts)

I want to invent a time machine so I can blow off this shitty era and go to the goddamn 60's and chill for once and for all. Damn '00s. Dammit....

you can move backwards and forwards in space, so why shouldn't you be able to move backwards and forwards in time? or spacetime for that matter.

it'll be something to do with travelling close to the speed of light, and time travel, just like length and mass, will become relative at these fast speeds. but 'backwards' in whatever dimension time is in

the reason we havent heard about it until now would be, i think, because after lots of people going back and forth and screwing around with world history, time travel, when they finally figure out how to do it, will become heavily regulated by a committee of sorts. only allowed back for historical studies, phd's, and NEVER allowed to mess with the timeline. and if they did mess something up, all u would have to do is go back a few minute before the catastrophe, and avoid it happening.

i don't know about going backwards or forwards but im pretty sure that if you travel really fast ( like light speed) you can slow downtime...or something

the reason we havent heard about it until now would be, i think, because after lots of people going back and forth and screwing around with world history, time travel, when they finally figure out how to do it, will become heavily regulated by a committee of sorts. only allowed back for historical studies, phd's, and NEVER allowed to mess with the timeline. and if they did mess something up, all u would have to do is go back a few minute before the catastrophe, and avoid it happening.

The future's 0th Commandment: Thou shalt not fuck with history.

i don't know about going backwards or forwards but im pretty sure that if you travel really fast ( like light speed) you can slow downtime...or something

And the extension of that here is that if you traveled effectively faster than light, you could do some very interesting things with time....

I can't imagine blackholes having anything to do with travelling backwards in time. They basically freeze time, correct? Wouldn't that be used for travelling FOWARD in time?
Like if you could lobby in a blackhole for a few decades then blast out?

What if time is not a continuim?
What if it like pendulm, just going back and forth, constantly reversing itself?

(I got this idea from an episode of Red Dwarf...)

What if time is not a continuim?
What if it like pendulm, just going back and fort, constantly reversing itself?

And we wouldn't notice that because..

A simple path through or close to an event horizon would basically send you to the future, yes. Traveling into the past using one would be following a trajectory through, near, or within an event horizon such that you were effectively accomplishing a closed timelike curve that would deposit you in the absolute past. This is unlikely, though; it's rather hard to get back out again once you've passed the event horizon. Effective superluminal (FTL) travel along such trajectories is more likely.

And we wouldn't notice that because..
Because as time reversed itself so would our memory, we do the same exact actions as before, only in reverse order...

Whats to say the we haven't already been through several time 'relapses'?

What if time is not a continuim?
What if it like pendulm, just going back and forth, constantly reversing itself?

(I got this idea from an episode of Red Dwarf...)

That may be; but it wouldn't be on a scale meaningful to us. It may be that the Big Bang is paired by a Big Crunch, and that they endlessly cycle within a noncausal (timeless) preferred external frame of reference where we and everything else exist in a perpetual Schrodinger-esque binary superposition of existence v. nonexistence.

According to your theory, there is a 'stop' period in which time can not progress any further, pendulms only swing so high, correct?
According to that, nothing is ever gone.
Stars will be destroyed but re-created later.
Everything will happen again but we will be unknown to it.

One problem,
how are we going to de-evolutionize?
How do we go from that final point in technology back to caveman era?

And the extension of that here is that if you traveled effectively faster than light, you could do some very interesting things with time....

nope. you can't go faster than the speed of light. its to do with the mass, length and time equations. if u travel AT the speed of light, you end up dividing by zero and therefore, you have no lenght, time or mass : you don't exist.

if you go faster, you end up with imaginary numbers, and presumably you exist only in argand diagrams...

NO FRIKIN' WAY!!!!!!

I'm not a theoretiacal physicist, so I like to use simple terms and reasons why it is impossible on an absolute level.

You are supposed to go back in time if you walk backwards enough, aren't you? Then why haven't I traveled into the future?

You have and are, at the rate of 1 second per second :-)

The future's 0th Commandment: Thou shalt not fuck with history.

in 'jumpman' [admittedly a kids book], rule #1 was DONT TOUCH ANYTHING
rule #2 was DONT EVEN THINK ABOUT IT
lol

According to your theory, there is a 'stop' period in which time can not progress any further, pendulms only swing so high, correct?
According to that, nothing is ever gone.
Stars will be destroyed but re-created later.
Everything will happen again but we will be unknown to it.

One problem,
how are we going to de-evolutionize?
How do we go from that final point in technology back to caveman era?

With the changing od the wrold throught global warming and such the needs of creatures would change as well there for possibly causing an eventual turn around in evolution...

if you guys really want to talk about it besides a more metaphysical sence with philsophy and everything playing a part

the only SAFE way to time travel by avoiding all those nasty time travel paradoxi is to use a system made possiable with the M-Theory
if you use the 2 3branes (quantum parealle universes) with a seprate 3spaces could possiably have a replicate universe at a different quantum time, providing a possiablity to time travel with no ill effects on our 3 space (with the exception of gravity)
its all a little complicated and completly theorical as far as scientific expermentation has gone . . . but its lots of fun to read about :)
hawking, penrose, heisenberg, whitten ... all great guys, take a read

Or how do we know that time travel itself has not yet been accomplished?
You say you cannot go back in time because it would interfere with causality, but how do we know that everything that happened didnt happen because the person came from the future. Just because they are here now doesnt mean they couldnt come from the future, or in the past, etc.

I hope you all get what Im saying...

And Drexel, which episode was it?
Tikka to Ride?

Okay,

A. Current theories involving time travel say that you cannot go back in time before the time machine was made, so no, it would not already exist.

B. You can actually go through mathematically and prove (with billiard balls) that if something goes back in time it cannot cause a paradox, this is called the Novikov Self-Consistency Priciple.

C. Time is most likely, at least in my opinon, a block, truly static only our consciousness moves along it. Now this does conflict with free will, but what they hey, I'll doublethink.

Einstein's theory of relativity states that when an object is traveling at a certain speed, objects around it seem to slow down, it also states that at the the speed of light, moveing objects around it seem to slow down so dramaticly, that they almost seem to move in reverse, therefore stateing, Time travel is possable in reverse.

our whole concept of time makes it sound like it is possible. our concept of time is nothing but distance, but that is just our view of time. its how we keep track of it.

*goes into low mumble and tells the real secret of how to go back and forward through time, too bad none of you can understand what i am saying*

.....and that is how i won this medal from emperor nero of the roman empire

Because as time reversed itself so would our memory, we do the same exact actions as before, only in reverse order...

Whats to say the we haven't already been through several time 'relapses'?

That's chilling to me. Could have sworn that I've seen some clocks hop back a second before ticking forwards again.:eek:

Deja vu! Something has changed in the Matrix!

But seriously, don't things that travel faster than light also go back in time? The right "tail" of the probability curve of an electron's velocity extends faster than the speed of light. So I guess energetic electrons sometimes do back in time.

Getting a whole person to do that though...

I don't know how many people on here have enough physics to seriously discuss this, but do you think time travel is possible under generally accepted modern theory? Why or why not? If yes, how might it be accomplished? What could the effects be, and what are the implications?

I ask because I seem to have gotten into a nascent debate over in the UN forum about whether global causality violation, aka time travel into the past, is possible, and whether quantum entanglement, closed timelike curves, and effective superluminal travel are "pseudoscience."

So, thoughts?

It is impossible to change the past unless it's already happened and the current world is the result.
For example, that guy who went back in time to save Lincon's life.
Didn't work, did it?

On the other hand, that guy who went back and convinced Booth to kill Lincoln; he succeeded.

Under the currently accepted theories of timetravel.
Yes, its possible. Under several theories

One of which is using a virtural world (ie something like 'The matrix' to recreate something so accuratly, that you could fool the mind into thinking it was there)

Another is a matter-antimatter combination, which COULD open a wormhole which would distort time and space... but it may also start off another BigBang

Theoretically, there are 'strings' which govern passage of time, if you can connect the end of one, to its start, you can loop time to travel back to an earlier point (The Strings theory, I think its called)

Not so much travel...as controlling...but if you move fast enough away from something.. you can observe it in slow motion

But like someone said before.. you CANNOT travel faster than the speed of light. It isnt physically possible. Scientists have accelerated atoms to ALMOST the speed of light, and the atoms have become distorted (they lose length but gain height) One thing you have to remember when talking about light.. it is both a particle AND energy.

Having studied quantum physics, it really opens your mind to theoretical science, such as timetravel.

And for the guy who said "if it was possible, it'd have happened before" or something on an earlier page... 'teleporting' things IS possible...but it hasnt happened before because we didnt know how to control it before. It's not a natural phenomenon, like timetravel (I assume)

I guess if you believe that somehow past events still exist somewhere, going back in time is "possible." However, I don't believe it. The nature of the universe is to move forward, and time is just our measurement of the passage of events. I understand that as you approach the speed of light, you somehow go forward in time, but you're still going forward, never backward.

[didn't read the rest of this thread yet, so sorry if this has already been said]

you don't go forward in time, so much as time slows down around you.

all you have to do to get this effect, and have it noticable, is use very accurate nukeular clocks [though mechanical ones would probilby work as well.. just can't get quite so accurate, so you'd need a larger difference] and stick one on a plane flying around the world one way, and another going the other way.

becasue the earth it's self is moveing, our time passes at a rate based on that. those planes are then moveing relitive to that, so their absolute speed is different, thus the passage of time within them is different.

one clock will lose some secconds, or parts there of, and the other will gain some.

now, neither plane went backwards in time, but the rate at which they progressed forward in time did change.

in theory [and this apprantly isn't generaly possible] if you could accelerte something with mass beyond the speed of light, it would go back in time.. i don't know if it works or not, no one's done it, that i know of.

i came accross something else that said [and i don't know the accuracy of this] that if you tryed to accelerate matter past the speed of light, it gained mass rather than speed. .. i have no idea ... heh.


i don't know the numbers, and i don't know who said stuff, but i do generaly understand how these things work, so long as we avoid the almost inevitable quantum theory.

and to whoever said they should have gone forward in time due to walking? guess what, you have. the current now no longer the now that was then. problem solved, have a nice day.

If time travel were possible (at least reverse time travel) we would know because Rome would have been taken over with a nuke or two, and Hitler would have been tea-bagged to death. However, most time travel theorums state that you cannot got back to before when the contraption was created.

in 'jumpman' [admittedly a kids book], rule #1 was DONT TOUCH ANYTHING
rule #2 was DONT EVEN THINK ABOUT IT
lol

rule #3 was "SEE RULE ONE!"

This is an interesting one. If for the sake of argument we could go back in time (say 10 years) and we met ourselves. Would it be possible for us to kill ourselves (if we did than our past selves wouldn't be able to live 10 years and then go back in time to kill himself again :rolleyes: )

And if we could what would happen. I kinda think this applies to all time travel. Anything we do in the past is likely to effect the whole world in some way, which is very likely to effect the circumstances we would have had right before time travaling therefore by going back in time we're likely to prevent ourselves from going back in time therefore not ever doing it. Even if time travel is possible to do it seems impossible (aka buttifly effect).