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  1. #1
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    Info Are Wormholes Tunnels for Time Travel?

    As any self-respecting science fiction fan knows, wormholes—theoretical shortcuts through space and time—make for excellent time travel portals.

    The latest movie to transport people into the past is this summer's A Sound of Thunder, based on the classic 1952 Ray Bradbury novella. In it, a group of hunters build a time machine, which looks like a wormhole of sorts, to travel back to the dinosaur era. There, things go awry when one hunter kills a butterfly, which completely changes the course of history.


    The movie was widely panned by critics and seems to have quickly slipped out of theaters. But the questions it raises—the mystery of time and the possibilities of traveling through it—remain among the thorniest in physics, keeping a growing number of scientists occupied.

    It's not like scientists are looking for a way to actually travel through time. But some believe that theorizing about how it could be done—maybe by using a wormhole in space—will help them understand and perhaps even revise the laws of physics.

    "Traversable wormholes are extremely useful as gedanken experiments"—the term describes experiments that can be reasoned theoretically but are impractical to carry out—"to probe the limitations of general relativity," said Francisco Lobo, an astrophysicist at the University of Lisbon in Portugal.

    Quantum Leap

    Albert Einstein's relativity theory set the speed of light as the universal speed limit and showed that distance and time are not absolute but instead are affected by one's motion.

    A clock in motion will always appear to run slowly compared with one at rest, because time is relative to the speed at which a body is moving. That fact would, in theory, allow for time travel—at least if you have a very fast spaceship.

    Consider this: If an astronaut travels into space for six months at a substantial fraction of light speed and takes another six months to return to Earth, he would land in the future.

    While a year will have elapsed on the astronaut's clock, tens of thousands of years may have gone by on Earth, depending on how close to light speed the astronaut traveled.

    "The bottom line is that time travel is allowed by the laws of physics," said Brian Greene, a Columbia University physics professor and the author of The Fabric of the Cosmos: Space, Time, and the Texture of Reality.

    But the laws of space and time as Einstein laid them out may be revised by the quirky rules of quantum theory. Quantum theory describes the microscopic randomness that fills the universe.

    At the subatomic scale, where the universe is jumpy and discontinuous, physicists don't know how gravity behaves. They theorize that space and time could collapse.

    "We may discover some new laws of physics that could change the rules," said Richard Gott, an astrophysicist at Princeton University.


    Jumping Through

    Relativity theory does not allow for travel into the past. But such travel could possibly be achieved using Einstein-Rosen bridges, better known as wormholes.

    The theoretical shortcuts through space and time connect two distant points in space, like a worm tunnel through an apple.

    Kip Thorne, a gravitational theorist at the California Institute of Technology in Pasadena, showed in 1988 that these tunnels could be kept open by an exotic form of matter known as Casimir energy.

    This energy, which has been measured in a laboratory, is a sort of quantum vacuum. Weighing less than zero, Casimir energy would have an anti-gravitational effect, keeping the wormhole's walls apart.

    "It has been conjectured that general relativity prohibits the existence of negative energy densities, [but] quantum mechanics demonstrates that the vacuum may not always have a zero energy density," Lobo said.

    Gott, the Princeton scientist, envisions the wormhole effect as being like that of a mirrored garden ball. When looking through the wormhole, however, one would not see a reflection of that same garden, but instead a garden on, say, Alpha Centauri, the star closest to our solar system.

    "You can jump through the wormhole and pop out on Alpha Centauri, and you've just gone through a very narrow tunnel that connects these two very distant places," Gott said. "The shortcut of the wormhole allows you to beat a light beam to Alpha Centauri."

    If one opening of the wormhole was moved around using the gravitational effect of a spaceship traveling at a speed close to light, a clock at the opening would run slow compared to one on the other end of the wormhole. This could turn the wormhole into a portal between two different times, past and future.

    "I should point out that these wormholes are not something you put in your kitchen. Each mouth weighs 100 million solar masses," Gott said, referring to a unit of measurement equal to the mass the sun. "This is a galactic-scale engineering project at best."

    Phantom Energy

    But the material needed to construct and support wormholes has been given a boost from the recent discovery that the universe is undergoing an accelerated expansion, says Lobo, the University of Lisbon scientist.

    A possible driver of this cosmic expansion, he says, is "phantom energy," a hypothetical matter that may comprise as much as 70 percent of the universe.

    Phantom energy may be pushing space apart and is so anti-gravitational that it will eventually rip everything apart, ending everything. However, before then, it could be used to prop open wormholes, Lobo theorizes.

    "In a rather speculative scenario, one could imagine an absurdly advanced civilization mining the cosmic fluid for phantom energy necessary to construct and sustain a traversable wormhole," he said.

    http://news.nationalgeographic.com/n...imetravel.html

  2. #2
    DF VIP Member AJ_007's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Just read all the way through this as Space / Time travel really interests me ever since a was a kid.

    But now I have one mutha of a head ache

    So does anyone ever wonder what is at the end of space?

    Do you hit a wall?

    Does it end? or is it expanding that quickly it is impossible to reach the end before it has moved again?

    It surely can't expand for ever! how long till it pops and we start all over again?

    Where is the Games Master when you need him

    AJ..
    "The cream has floated to the top" - Midnight_Toker on his work fantasy football team's recent form 08.11.06

  3. #3
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    Default Re: Are Wormholes Tunnels for Time Travel?

    This might shed some light (so to speak)

    http://science.howstuffworks.com/time-travel4.htm

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    DF VIP Member dan288's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    good read, doesnt physics state that everything has to end? if space is expanding, what is it expanding into?? more space? hmmm


    What nerds we are

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    DF VIP Member RaggoVibes's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Quote Originally Posted by dan288
    good read, doesnt physics state that everything has to end? if space is expanding, what is it expanding into?? more space? hmmm

    It's making it's own space as it expands. As far as we know it's expanding into something that doesn't exist :nowords: nothingless... not even time.

    Not only that bit it's a oddly shaped so IF you were to get to the edge you'd appear back at the other end, a bit like snake 2 with not walls

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    DF VIP Member whatnow's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Quote Originally Posted by RaggoVibes
    if you were to get to the edge you'd appear back at the other end, a bit like snake 2 with not walls
    where's that emoitocn for a spanner'd head.... - yeah that'll do.

    thinking of what's on the 'edge' of the galaxies is perplexingly head-fucking material
    I'm new to this :huh:

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    DF VIP Member Epiphany's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Consider this: If an astronaut travels into space for six months at a substantial fraction of light speed and takes another six months to return to Earth, he would land in the future.

    While a year will have elapsed on the astronaut's clock, tens of thousands of years may have gone by on Earth, depending on how close to light speed the astronaut traveled.
    I dont get that. Surely if he travels for 6 months away from earth at a fraction of lightspeed, he'd take just as long to get back at the same speed so only a year would have passed.
    The faster he goes, the farther away he travels, so the longer it'll take to get back. Surely the time that it takes him to travel away and back will be the same as the amount of time that passes on Earth

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    DF VIP Member marcode's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Damn, i remember reading a sound of thunder at school and really enjoying it... shame the movie gets a shockingly bad 3.9 on imdb..

  9. #9
    DF VIP Member whatnow's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    If you travelled at any speed regardless of the speed of light your still taking an amount of time to do something, regardless of what you do and where you go. When you get to wherever you're going on earth it's still going to be on time. So if you travelled to the edge of the milkyway and it took 4 months it's still going to be 4 months on earth. Time is a measurement not a variable factor. If you then travelled back and it took another 4 months you're going to have missed 8 months of earth time...you wont ever travel in time. regardless of how fasdt you went, it'll just take less time.

    I dont belive time travel is possible. I don't even see how under any theory it is possible as time isn't something which can stop, start or reverse...if that did ever happen it wouldn't be time it would be everything that exists ever and cycling back on itself or developing/undeveloping quiickly then it does now.

    it seesm there's too much theory behind how everythng works to be able to control that with a machine/wormhole or anything else for that matter. The universe would have to be compleatly altered to change the flow and although that could be possible it seems highly unlikely to me....but i'm basing all this on laymens minimal knowledge like anything else i say, lol

    ///ohh i dribbled


    marcode - dont do it! I gotit last night and got rid of it last night. I wanna read the book as this film was PANTS!!!
    I'm new to this :huh:

  10. #10
    DF VIP Member RaggoVibes's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Quote Originally Posted by Epiphany
    I dont get that. Surely if he travels for 6 months away from earth at a fraction of lightspeed, he'd take just as long to get back at the same speed so only a year would have passed.
    The faster he goes, the farther away he travels, so the longer it'll take to get back. Surely the time that it takes him to travel away and back will be the same as the amount of time that passes on Earth
    Sounds logical but strangely enought it's not the case. Here's a reply I made to a similar post a few months back:

    Quote Originally Posted by RaggoVibes
    Theoretically if you could travel at 99% of the speed of light and you went on a two year mission to the nearest star and back. You would have aged 2 years, while everyone else on earth would have aged 8 years. Think about that for a minute

    That's the law of relativity for you. Time is relative to the speed you are travelling and the strength of gravity. Time is interwoven into space and objects bend space, and therefore time.

    That Russian guy, who has spent the most amount of time in space, is about a millisecond or so yonger (compared to everyone else) than he would have been if he stayed on Earth, lol.

    Also it's unlikely we'll ever be able to travel at that kind of speed, because the faster you go, the greater your mass and it just gets harder and harder to accelerate. We either need to make an inertia dampening device (that would mess with law of physics) or skip the whole space/time guff and go via another dimension (this is the preferred route).
    We could make Worm hole, however a decent sized one (to sqeeze a spaceship through) would require more than all the energy in the universe to create (that's what they say).

    At some point i reckon all our current laws of physics will be thrown on their head, already we can't explain alot of the stuff going on at the quantum level (and where's that unifying theory?).

  11. #11
    DF VIP Member marcode's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Quote Originally Posted by shangrula
    marcode - dont do it! I gotit last night and got rid of it last night. I wanna read the book as this film was PANTS!!!
    Its actually a short story... only something like a few pages if i remeber correctly

  12. #12
    DF Probation $wish's Avatar
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    Default Re: Are Wormholes Tunnels for Time Travel?

    Quote Originally Posted by shangrula
    I dont belive time travel is possible. I don't even see how under any theory it is possible as time isn't something which can stop, start or reverse...if that did ever happen it wouldn't be time it would be everything that exists ever and cycling back on itself or developing/undeveloping quiickly then it does now.

    time is man made. time travel is not possible as far as i can see, and as much as id like to beleive it is, its not. whats happened has already happened, and what will happen hasnt happened yet, so how can you go to either?

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