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United States24740 Posts
Haha these discussions are always enjoyable to read. The same things always end up happening.
I have to agree with those saying that time travel as we see it in fiction is mostly beyond anything we have reason to suspect we are capable of....
Relating time travel to actual science is nice, but people seem to get too confident in their conclusions. It's important to identify how speculative everything you say is, even if you took it from a professor of physics.
Also, I see people always throw around 'quantum mechanics' and then say stuff which has almost nothing to do with quantum at all. To those of you who actually have a reasonable understanding of general relativity, if any, then you are the only ones who have a hope of forming a reasonable opinion on this topic... and even then this is all pure speculation.
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if i ignore the mechanics of supposed time travel, and look only at the variants not breaking causality at the first look i can imagine no possibility not violating some physics. one possibility would be a closed loop in spacetime. a lightbeam i.e. traveling in circles in spacetime through our wormhole timemachine. this would not e able to take information form the future to the past hat was not already there else it wouldnt be a loop.. so a human in a timeloop would need to be "reset" which is bc ofc.also the light should not interact with anything, bcos any interaction with the quantum field(pardon my french) would be random by nature thus wouldnt allow for a loop.
the possibility also not violation causality is creating another universe. but where does it get its mass? also our universe would lose the mass of the timetraveller, which on the first look violates energy conservation.Maybe there is a simple solution for this massproblem i dont see, dunno.
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those r both separate theories and ones we could never test... also it depends on ur terminology, some people don't consider reality jumping to be time traveling...
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On May 23 2009 01:55 micronesia wrote:
Haha these discussions are always enjoyable to read. The same things always end up happening.
I have to agree with those saying that time travel as we see it in fiction is mostly beyond anything we have reason to suspect we are capable of....
Relating time travel to actual science is nice, but people seem to get too confident in their conclusions. It's important to identify how speculative everything you say is, even if you took it from a professor of physics.
Also, I see people always throw around 'quantum mechanics' and then say stuff which has almost nothing to do with quantum at all. To those of you who actually have a reasonable understanding of general relativity, if any, then you are the only ones who have a hope of forming a reasonable opinion on this topic... and even then this is all pure speculation.
the thread is rather about the causal implications than about the actual mechanics.
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On May 23 2009 01:50 Aegraen wrote:Show nested quote +On May 23 2009 01:38 aqui wrote:On May 22 2009 23:50 Aegraen wrote:On May 22 2009 23:49 Caller wrote:
From what littler about quantum physics that I understand, it is technically possible to time travel if one were able to travel faster than the speed of light. Because of relativity, as traveling close to the speed of light causes time in realspace to rapidly "slow down," some theorists believe that surpassing the speed of light would allow one to travel backwards in time compared to realspace. Of course, it would also depend how fast compared to the speed of light one is traveling.
Of course, traveling faster than the speed of light is impossible. It is not impossible (theoretically anyways). The universe expanded, and is expanding faster than the SoL. its impossible, what makes you say "theoretically anyways"? your example is flawed. spacetime does expand not any mass or something. its pretty simple, you cant accelerate any reel mass on the speed of light. since we have mass, gg. you also cant move detectable information faster than light. Scharnhorst Effect for one. Coupled with the Casimir Effect, and Alcubierre drive, the theories are there. When we finally figure out dark matter, and dark energy, I'm sure there will be ways. This is how the universe is expanding FTL. Dark energy/matter will be the secret mark my words. (That and manipulation of time space)
ill answer that when im back later. oi
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On May 23 2009 02:03 aqui wrote:
if i ignore the mechanics of supposed time travel, and look only at the variants not breaking causality at the first look i can imagine no possibility not violating some physics. one possibility would be a closed loop in spacetime. a lightbeam i.e. traveling in circles in spacetime through our wormhole timemachine. this would not e able to take information form the future to the past hat was not already there else it wouldnt be a loop.. so a human in a timeloop would need to be "reset" which is bc ofc.also the light should not interact with anything, bcos any interaction with the quantum field(pardon my french) would be random by nature thus wouldnt allow for a loop.
the possibility also not violation causality is creating another universe. but where does it get its mass? also our universe would lose the mass of the timetraveller, which on the first look violates energy conservation.Maybe there is a simple solution for this massproblem i dont see, dunno.
The only plausible solution to the dilemma of 'how do humans travel across great distances and not die' is that of either 1. Wormholes 2. Time Dilation, the latter having significantly more problems to tend to than the former (namely any matter that stands in the way will pulverize the vessel and secondly, that of great quantities of energy needed).
The latter also having the problem that, when you get back, you will essentially have lived for hundreds of thousands - millions of years 'into the future' so to say.
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On May 23 2009 01:50 Aegraen wrote:Show nested quote +On May 23 2009 01:38 aqui wrote:On May 22 2009 23:50 Aegraen wrote:On May 22 2009 23:49 Caller wrote:
From what littler about quantum physics that I understand, it is technically possible to time travel if one were able to travel faster than the speed of light. Because of relativity, as traveling close to the speed of light causes time in realspace to rapidly "slow down," some theorists believe that surpassing the speed of light would allow one to travel backwards in time compared to realspace. Of course, it would also depend how fast compared to the speed of light one is traveling.
Of course, traveling faster than the speed of light is impossible. It is not impossible (theoretically anyways). The universe expanded, and is expanding faster than the SoL. its impossible, what makes you say "theoretically anyways"? your example is flawed. spacetime does expand not any mass or something. its pretty simple, you cant accelerate any reel mass on the speed of light. since we have mass, gg. you also cant move detectable information faster than light. Scharnhorst Effect for one. Coupled with the Casimir Effect, and Alcubierre drive, the theories are there. When we finally figure out dark matter, and dark energy, I'm sure there will be ways. This is how the universe is expanding FTL. Dark energy/matter will be the secret mark my words. (That and manipulation of time space)
the low energetic modes which cant be excited between your plates are also very unlikely to be excited in vaccum, also the timescale for the excitations we are talking about are bordering the plancktime/causality. also taking into account that your confinement has to be very small ( this way you could also argue with the uncertainty principles that some photons might be faster than light) the effect is neglectable on reasonable times/spaces and most certainly cant be used on a macroscopis scale.
Alcubierre drive or Warp Drive. I dont know how this is supposed to work but this is no more an example for an object moving through space with a velocity faster than light than the expansion of the universe is. locally the dude in your "warp bubble" isnt moving at all. ergo no time dilation in the sense that you travel backwards in time.
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As I see it there are only two positions one can take on time travel:
Reasonable person:
- There is no way I could possibly know given my limited knowledge. Too many variables are still unkown.
Forum troll:
- I think this would happen: "blablabla"
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On May 22 2009 23:50 EsX_Raptor wrote:
haha that got me thinking.
so i guess 90% of the stars we see when we look up may be already dead? o,o
Most star live for extra-ordinary amounts of time hundreds of millions or years, there probably still there but are now red giants, brown dwarfs, etc... most of the stars we can see in constellations are within our galaxy so theres no chance there "burned out" as we speak.
Its when Hubble or other telescopes starts looking Deeper into the cosmo that things may be different there now.
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if you travel back in time 10 minutes, wouldn't you run into yourself, who then will go back in time 10 minutes from now
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On May 23 2009 05:55 VIB wrote:
As I see it there are only two positions one can take on time travel:
Reasonable person:
- There is no way I could possibly know given my limited knowledge. Too many variables are still unkown.
Forum troll:
- I think this would happen: "blablabla"
Your branding someone with an imagination as a troll? Surely at the moment we haven't the foggiest of what could happen, but taking someone down a notch for expressing an idea is a hindrance at best.
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On May 23 2009 09:31 SkY wrote:Show nested quote +On May 23 2009 05:55 VIB wrote:
As I see it there are only two positions one can take on time travel:
Reasonable person:
- There is no way I could possibly know given my limited knowledge. Too many variables are still unkown.
Forum troll:
- I think this would happen: "blablabla" Your branding someone with an imagination as a troll? Surely at the moment we haven't the foggiest of what could happen, but taking someone down a notch for expressing an idea is a hindrance at best. I think that what you're missing is the existence of something we call a "bad idea". Beating your head against the wall, is, by definition, an "idea". But it doesn't mean you're any less of an idiot for having such fertile imagination 
Being humble enough to admit you do not have enough knowledge to extrapolate any further. Is often, the best (aka reasonable) idea you could possibly have.
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United States17042 Posts
There are two common ways of viewing time travel (that have been played with in common science fiction anyway). One way is the "loop" theory of time, where everything is on one track. This is expressed in douglas adam's famous book (most notably anyway, there are several other places, like in harry potter).
The other way of viewing time travel is the "parallel universe theory" which says that when you travel back in time, you'll go to a different future, where different things happened. This is expressed in michael criton's book timeline, as well as in + Show Spoiler +
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EPT
