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Space Science

Time Dimension To Become Space-like 587

Posted by Zonk
from the you're-not-thinking-fourth-dimensionally dept.
KentuckyFC writes "The Universe is about to flip from having three dimensions of space and one of time to having four dimensions of space. That's the conclusion of a group of Spanish astrophysicists who have calculated that observers inside such a Universe would see it expanding and accelerating away from them just before the flip (abstract, full paper pdf on the physics arXiv). 'We show that regular changes of signature on brane-worlds in AdS bulks may account for some types of the recently fashionable sudden singularities. Therefore, the fact that the Universe seems to approach a future sudden singularity at an accelerated rate of expansion might simply be an indication that our braneworld is about to change from Lorentzian to Euclidean signature. Both the brane and the bulk remain fully regular everywhere.'" Update: 10/09 16:06 GMT by Z : A few readers have written in to point out that the article is not peer-reviewed; your mileage may vary.
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Time Dimension To Become Space-like

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  • by andyh3930 (605873) * on Tuesday October 09, 2007 @11:04AM (#20912657)
    So that's whats going to happen when the Mayan calender rolls over in 2012.
    • by dark404 (714846) on Tuesday October 09, 2007 @11:08AM (#20912753)
      There will be a patch to update the calendar software to granite instead of sand stone, this will push the calendar into 4096.
    • Re: (Score:2, Funny)

      by xanadu113 (657977)
      No, that's just the Mayan Y2.012K bug...
  • by fyngyrz (762201) * on Tuesday October 09, 2007 @11:04AM (#20912667) Homepage Journal

    Oh, I'm living in a tesseract,
    a four dimensional box.
    It's bigger on the inside,
    what why my four-space rocks!
    When you get on the inside,
    the outside becomes the in,
    Dimensionally speaking,
    it's all about the spin.

  • E=MC^2 (Score:4, Funny)

    by jshriverWVU (810740) on Tuesday October 09, 2007 @11:04AM (#20912673)
    If only Einstein was around to see it :)
  • My advice (Score:4, Funny)

    by Weaselmancer (533834) on Tuesday October 09, 2007 @11:05AM (#20912685)

    Avoid poetry, coastal cities, and the Catskill mountains. Seriously. [wikipedia.org]

  • by Anonymous Coward on Tuesday October 09, 2007 @11:06AM (#20912707)
    Nobody Expects the Spanish Astrophysicists! In fact, our two main weapons are theory and telescopes, theory and telescopes, and an insane amount of genius, wait that's three, our three main weapons are...
  • by downix (84795) on Tuesday October 09, 2007 @11:06AM (#20912711) Homepage
    If time becomes space-like, what would that mean for us? Would we be able to transverse time as easily as space? Would time itself become irrelevent as we could look "forwards"? Will the cubs win the world series? These important questions have to be answered!
    • Another important question is, "When is this expected to happen?"
      In our lifetime?
      In the lifetime of our species?
      In the lifetime of our sun?
      Before the expected "heat death" of the universe?
    • Re: (Score:3, Insightful)

      by caramelcarrot (778148)
      Physics as we experience it will go to shit, since much of the base derivations are a consequence of a non-spacelike time.
      • Actually, in a lot of quantum stuff, time is space like already.

        Namely - if you see an action in forward and reverse, both make sense. As opposed to macroscopic, where if you show a picture of a man falling from a roof in reverse, most people can tell you its in reverse.
        • by Goaway (82658)
          That's not what "spacelike" means. Quantum mechanics takes place in Lorenzian space, with one timelike and three spacelike dimensions.
    • If time becomes space-like, what would that mean for us? The "flux capacitor" prop they built for Back to the Future will start to work. Would we be able to transverse time as easily as space? Yes. Would time itself become irrelevent as we could look "forwards"? Yes. Will the cubs win the world series? No. These important questions have to be answered!

      Done.
    • by brunes69 (86786)
      I am pretty sure you'd be dead and would not have to worry about it
    • by Anonymous Coward on Tuesday October 09, 2007 @12:38PM (#20914219)
      ..maybe if I wait a few feet it'll feel better
  • Now we are all going to have to get jobs working for Inetech fixing the Y4D problem with computers........
  • Will DHS raise the Astrophysical Phenomenon Terror (APPT) alert level to Orange? ...But seriously I wonder if we as 3 dimensional beings would even notice such a change? Isn't "time" only subtlety different from a physical dimension?
    • Indeed they will. So great a threat does a dimensional flip pose that they'll be putting out a compendium of interactive simulations to illustrate such a treat to us "3 dimensional beings." Look for the DHS APPT Orange Box on October 10th!

      Be wise. Be safe. Be aware.
    • Re: (Score:3, Insightful)

      by pclminion (145572)

      Isn't "time" only subtlety different from a physical dimension?

      This phrasing suggests that time is not a physical thing. Given that the variable "t" occurs in practically all dynamic equations of physics, I'd have to disagree with the assertion that time isn't physical.

  • Plagarism! (Score:4, Funny)

    by Jeremiah Cornelius (137) * on Tuesday October 09, 2007 @11:08AM (#20912765) Homepage Journal
    I first read this theory in Oolong Caloophid's seminal work: "Where God Went Wrong."

    More of this is elaborated in his development of these themes: "Some More of God's Greatest Mistakes," and "Who Is This God Person Anyway?".
  • So what does this mean for us, exactly? Would we still perceive things as we do now (only with some relativistic stuff changing), or does everything suddenly go nuts? FTL travel, maybe?

    And mostly-OT but seemed related: I remember a couple of SF short stories about something like this... one was "Mimsy were the Bogroves" or something like that, where two kids discover 4-dimensional toys from the future, then read "Jabberwocky" and figure out how to move in time.

    The other one was about a kid who befriends a
    • by Qzukk (229616) on Tuesday October 09, 2007 @11:24AM (#20913053) Journal
      The other one was about a kid who befriends a neighbor working in 4-D stuff. The kid (because he's young and has an open mind or something) learns to move about in that dimension as well, and communicate with creatures living in other dimensions. Don't remember the title of that one, thoguh.

      I believe that's The Boy Who Reversed Himself [amazon.com]. I remember having read that when I was in highschool.
    • by Goaway (82658)
      Without time, it's pretty hard to experience anything.

      Of course, it's kind of hard to tell how that would actually work out, as we still don't really understand time.
    • by Cyberax (705495)
      The second one is called 'Tangents' by Greg Bear.

      But if our space-time will flip to 4D, then it will be a sad future for the Earth. For one thing, there's no stable planetary orbits in 4D...
  • by Arthur B. (806360) on Tuesday October 09, 2007 @11:10AM (#20912813)
    Jeebus will return ! Clean your browsing history and cache.
  • The title of the article is: "Is the accelerated expansion evidence of a forthcoming change of signature?". It indicates that a change of signature is certainly a possible explanation, but that doesn't mean that there aren't other explanations.

    That being said, what is the best way to handle the signature change? Should I stand in a doorway or head for the storm cellar?
  • Can anyone explain, by way of analogy, what having four time-like dimensions and no time-like dimensions would entail? Would everything just . . . stop? Would our current motion through time carry forward through Newton's Laws, so that we don't even notice the switch? I did RTFA, and it's light on details. I attempted to RTF paper, and immediately zoned out. So, anyone understand this well enough to attempt to clarify?
    • Can anyone explain, by way of analogy, what having four time-like dimensions and no time-like dimensions would entail? Would everything just . . . stop? Would our current motion through time carry forward through Newton's Laws, so that we don't even notice the switch? I did RTFA, and it's light on details. I attempted to RTF paper, and immediately zoned out. So, anyone understand this well enough to attempt to clarify?

      Clearly, this means you will end up sleeping with your grandma and becoming your own grandfather.
      It is... inevitable.

    • by Belacgod (1103921)
      For that matter, a spacelike Time is at least 2 degrees of wierdness beyond what we have now. Right now we're in a 1-dimensional, 1-way Time. Time travel would involve turning Time into a 1-dimensional, 2-way time. The Many Worlds theory is an endless branching-off of different 1-dimensional Times. 2-dimensional, 2-way Time would be, I guess, the ability to switch to any of the Many Worlds in order, and to go backwards and forwards along those timelines. 3-dimensional, 2-way Time, I guess, wouldn't be a
    • What happened to TFA will happen to all of the rest of the universe.
      It isn't slashdotted, it is just frozen in time.
    • Re:Explanation? (Score:5, Interesting)

      by xPsi (851544) * on Tuesday October 09, 2007 @11:34AM (#20913215)
      Lets say I told you we had two spatial dimensions. You would imagine a plane with perpendicular x-y axes everyone knows and loves. If I asked you to draw the set of points that were equidistant from the origin, you would probably assume the geometry was Euclidian and would probably instinctively draw a circle (a good guess!). It is commonplace to hear "time is the fourth dimension." As first pass to visualize this, you might try to draw a two dimensional space-time plot: an x axis and a perpendicular time axis in a plane. If I then asked you to draw all the points equidistant from the origin, you would probably again draw a circle in this x-t plane. It seems to make sense, but is only true of time is a "space-like" dimension like "y" in the x-y plane. This is way Newton thought of things and it seems to be what the authors of the paper are advocating. But, unbeknownst to some people who cite "time as the fourth dimension," according to the theory of relativity, the set of equidistant points from the origin on a x-t graph would actually be hyperbole, not circles. This is because in relativity space-time is a Minkowski geometry, not Euclidian. All the weird stuff in special relativity like time dilation and length contraction come about because of this weird geometry. In fancier language, time has an opposite sign than space in the metric. The metric determines how distances are calculated in a given geometry. If time has the same sign as space in the metric, then space-time becomes Euclidian and one would say that time was a space-like. The article is probably extra confusing to non-physics people because most probably didn't know time wasn't space-like to begin with.
  • From An Unearthly Child [whopix.net]:

    SUSAN: It's impossible unless you use D and E!

    IAN: (OOV) D and E? Whatever for? Do the problem that's set, Susan.

    SUSAN: I can't, Mr. Chesterton! You can't simply work on three of the dimensions!

    IAN: (OOV) Three of them? Oh. Time being the fourth, I suppose. Then what do you need E for? What do you make the fifth dimension?

    SUSAN: (After a pause) Space...

  • where the theories and calculations of the brightest brains in the room become indistinguishable from the random brainfarts of two stoners sitting on a smelly couch in a dorm room at 4:20 AM
  • great (Score:2, Funny)

    by nomadic (141991)
    I really hope I'm not in the DMV when time ends.
  • Peer review (Score:5, Funny)

    by MillionthMonkey (240664) on Tuesday October 09, 2007 @11:19AM (#20912955)
    The peers are going to review this a few centimeters from now; give them time.
  • How many goddamned times do we have to have this discussion on here?

    Math is a language. It is a means whereby describe things to the best of our comprehension in a manner that best conveys our impressions to others.

    Just because a bunch of numbers add up does not mean it is proof of anything. Otherwise, Creationists are right and the world began in 4004 BC.

  • Human physiology is fairly dependent on the laws of physics remaining the same. For example; Our cells consist of fluid, constrained by a cell membrane that prevents it escaping in any of the three spacial dimensions. The introduction of a fourth spacial dimension means instant, messy death.
  • "... about to ..." (Score:5, Insightful)

    by dpilot (134227) on Tuesday October 09, 2007 @11:19AM (#20912963) Homepage Journal
    So dpilot was talking with God, and God said, "To Me, a minute is like a million years, and a million years are like a minute." So dpilot said, "In a that vein, is a penny like a billion dollars, and a dollars like a penny?" God replied, "You've got it." Which led dpilot to ask of God, "Can you spare a penny?" "Sure," said God, "in just a minute..."

    When you say "about to" in sports, something generally happens pretty fast.
    When you say "about to" in geology, something generally happens pretty slow.
    Generally speaking, saying "about to" in cosmology is to geology as geology is to sports.

    But not always. At some points in time, the volcano under Yellowstone does go off. Likewise, supernovas happen, and perhaps brane changes too. But to say "about to" or "soon" is just meaningless to human scales of time.
  • That strangely fits with the book I've just finished yesterday ;)

    hopefully The Chaos will save us [wikipedia.org]!

  • YOU can profit from the coming singularity! Singularity Investor [singularityinvestor.com] has the answer!

    Sure, it sounds bad, but with every big change comes winners and losers and you can be one of the winners if you act now!

    Oh, wait, that's how to profit from that other singularity...
  • Does this mean that the universe is going to suddenly go All of an Instant [amazon.com] on us? Because that'd be pretty sweet.
  • Define "about to"? (Score:5, Insightful)

    by WibbleOnMars (1129233) on Tuesday October 09, 2007 @11:21AM (#20913009)
    I'd like to know how they define "about to flip".

    Are we talking about something they see as imminent -- could happen at any moment?
    Or are we talking about geological time scales -- it'll happen in a few hundred thousand years, give or take?
    Or do they mean cosmological scales -- where 'about to happen' means somewhere in the next ten or twenty million years?

    Or is the whole question of when a silly thing to ask, given that they're talking about the end of time as sequential/chronological?
  • This explains [xkcd.com] the rudiments of string theory.

  • Old, old old news (Score:2, Informative)

    by bradgoodman (964302)
    This is nothing new at all.

    Relativity talks of space and time as a single 4-dimensional 'spacetime'.

    M-Theory, Superstrings, p-Branes, and a billion other theories all say there are 10 (or 11) dimensions, including things like two-dimensional "time" and "imaginary-time" dimensions, smaller "curled-up" spacial dimensions, etc.

  • we are going to transcend into another dimension with the flip... wait ! thats nothing new is it ! "when the mooooon is in the seveenth houuseeee, and jupiteeerr aliiggnss wiiith maaarss"

    maybe mamas and papas got it right.
  • ...they want their band [wikipedia.org] back.
  • Don't put anything you want smart people to see in a directory named /ads/
  • by Ilan Volow (539597) on Tuesday October 09, 2007 @11:33AM (#20913195) Homepage
    Get that last game in before your game stops working with your newly created 144-sided dice.
  • by jnaujok (804613) on Tuesday October 09, 2007 @11:33AM (#20913211) Homepage Journal
    All this talk about time becoming a spatial dimension and realities collapsing is making my brane hurt.

    Yeah, I said it.
  • Mileage? (Score:5, Funny)

    by TheRaven64 (641858) on Tuesday October 09, 2007 @11:45AM (#20913375) Journal

    Update: 10/09 16:06 GMT by Z : A few readers have written in to point out that the article is not peer-reviewed; your mileage may vary.
    So may your yearage, presumably.
  • Hope not. (Score:5, Interesting)

    by mattr (78516) <mattr&telebody,com> on Tuesday October 09, 2007 @11:46AM (#20913397) Homepage Journal
    I knew 3 answers to the Fermi Paradox. Either intelligence quickly builds into quiet-looking shells like in Charlie Stross' Accelerando, or by virtue of being conscious we humans have somehow carved out a light cone or domain excluding other intelligences, some wierd cocoon: it is impossible physically to communicate because other domains have other physics. There's a neat scifi story about that too. The third is a land mine in physics, waiting for young civilizations to liberate enough power to fry them. Heinlein did that one, it's a nasty one. Now a fourth: the universe really is out to get us. Not just out to get aggressive monkeys that want to learn high-energy physics, but even to the point of making a state flip ever so often. I think this last one (today's news) is pretty unlikely to happen any time soon but nevertheless it is a future killer, something harder to understand than the burning out of the stars in the far future. None of these are very nice ideas but I hope some physicists will step up to answering what the latest theory says about when it might happen and whether it could operate on a patchwork basis, killing other civilizations while our planet was still cooling.
  • by davidoff404 (764733) on Tuesday October 09, 2007 @11:48AM (#20913425)
    Unfortunately, while the ArXiv is where important results are first published by working physicists, it's also a place where an increasing amount of junk papers are posted. For those who are interested, this is an example of just such a junk paper as it amounts to nothing more than a fancy way to produce a (parameterized) Wick rotation in a braneworld model.

    Of course, let's not even mention the fact that they're proposing that braneworlds and AdS are reasonable approaches to physics...
  • My crude guess (Score:4, Interesting)

    by khallow (566160) on Tuesday October 09, 2007 @11:56AM (#20913555)

    It appears to me that this is a purely mathematical result. They are basically saying that an anti-de sitter bulk, the interior of anti de Sitter (AdS) space which is a constant negatively curved (or constant positive cosmological constant) with one time-like dimension (Lorentzian space) can be glued to a euclidean space smoothly along the boundary of the two spaces. Classically, this is of little relevance since time-based trajectories would stop at the boundary (either take infinite time to arrive or the system would "rip" itself apart at the boundary). Instead there could be (though not addressed in the paper) observable quantum effects from having something past the boundary even if it is purely spatial. Space-time states might extend over the boudary into this other space. So you might end up with the strange situation where parts of the universe are interacting beyond the end of time.

    This paper doesn't tell you whether that occurs or not. But it does indicate that it is possible for quantum systems to have both Lorentzian and Euclidean space components seamlessly connected.
  • Consequences (Score:4, Insightful)

    by xPsi (851544) * on Tuesday October 09, 2007 @12:43PM (#20914331)
    Ok, as others have pointed out, this "paper" is not peer reviewed. I want to make it clear that I don't personally feel slashdot is the place to debate random physics papers on the arXiv. But, being slashdot, I will ignore my own pleas for sanity. What would be the physical consequences of time suddenly becoming space-like? First, on most mesoscopic scales in our everyday life, time already appears like a spatial dimension. Newton certainly thought so and our (incorrect) intuition tells us this is the case. The degree to which special and general relativity play a role in your everyday life is a measure of how "time-like" time feels. Probably not much. Nevertheless, if time suddenly physically became space-like, physicists all over the world would know it right away. All the weird stuff in relativity like time dilation and space contraction and so on, comes from time having an opposite metric sign as space. These effects all go away if time is space-like. For example, in a typical advanced undergraduate physics lab, you might measure the lifetime of a muon that is sitting in the lab as opposed to one that is crashing down from the sky. The one coming from above (at a large fraction the speed of light) lives longer in the frame of the ground because of time dilation. Easily verified in an afternoon. But I guess no more (at least after next Thursday or whenever this is supposed to happen). Similarly, all the special relativity equations required to perform basic momentum, energy, and lifetime calculations at colliders like Fermilab, CERN, and Brookhaven would suddenly stop working. That would be a big deal and it wouldn't be a subtle thing. IMHO, it makes for great science fiction, but I'm not sure where these guys are going with it.

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