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Sci-Fi Science Technology

Space-Time Cloak Could Hide Actual Events 129

Posted by samzenpus from the out-of-sight-out-of-time dept.
An anonymous reader writes "My first thought was, a hypothetical space-time invisibility cloak? That must be what hypothetical crime-fighting Einstein wears when he wades into the fray! Sadly, the researchers who thought up this trick to 'hide events' say that the metamaterials we have on hand will only allow for a nanoscale demonstration at best."
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Space-Time Cloak Could Hide Actual Events More

Space-Time Cloak Could Hide Actual Events

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  • RE: post (Score:3, Insightful)

    by alphatel ( 1450715 ) * on Thursday November 18, 2010 @05:39AM (#34266370)
    I will post my reply using my spacetime browser but you won't see it until several nanoseconds later!

  • Minkowski you bastard (Score:5, Insightful)

    by Adambomb ( 118938 ) * on Thursday November 18, 2010 @05:48AM (#34266400) Journal

    mwahaha! if i'm never a part of events intersecting the light cone i dont exist!

    oh shiii-

  • Ffs (Score:1, Interesting)

    by Anonymous Coward

    Fuckin jounalists, I'm sure every scientist tells them metamaterials are not going to lead to invisibility powers, but they put it into every fuckin story until it's overplayed bullshit central.

    • Re: (Score:3, Insightful)

      by JustOK ( 667959 )

      Maybe we just can't see the ones that get it right.

      • Re:Ffs (Score:4, Interesting)

        by delinear ( 991444 ) on Thursday November 18, 2010 @06:59AM (#34266598)
        Even though it's a joke it's probably not far from the truth. A dry scientific explanation is never going to make front-page on the millions of blogs, while "INVISIBILITY CLOAK NOW MONTHS AWAY!" is a shoe-in (unfortunately). Of course, you also then get a subset of scientists overstating their case to garner exactly this response, which doesn't help matters at all.

        • Re: (Score:3, Interesting)

          by DJRumpy ( 1345787 )

          The first question I had is how they are going to speed light up beyond the speed of light? I know it's theoretically possible for that to happen around gravity wells from black holes as they drag actual space-time around the event horizon, but how would they do this with a piece of fabric regardless of the machinery embedded in it?

        • Re: (Score:2)

          by Gilmoure ( 18428 )

          I thought they already created an invisibility cloak but misplaced it?

      • Re: (Score:1)

        by azalin ( 67640 )

        WYCSIWYCG What you can't see is what you can't get

  • Am I missing something or is it just more journalistic hyperbole? Hiding an event just means it can't be seen. I think we knew this much already.

    • Re: (Score:3, Informative)

      by Jojoba86 ( 1496883 )
      Clicking through to the CNN article tells us:

      "A safe cracker would be able, for a brief time, to enter a scene, open the safe, remove its contents, close the door and exit the scene, whilst the record of a surveillance camera apparently showed that the safe door was closed all the time,"

      So it's a way of hiding something in time, without anyone really knowing anything is being hidden.

  • How not to be seen . . . (Score:3, Interesting)

    by PolygamousRanchKid ( 1290638 ) on Thursday November 18, 2010 @06:20AM (#34266488)

    The seminal work on this was produced in the UK in the late 60's or early 70's, and shown on the PBS network in the USA, who frequently interrupted the program to beg for money: http://en.wikipedia.org/wiki/How_Not_to_Be_Seen [wikipedia.org]

  • Better article (Score:5, Informative)

    by ath1901 ( 1570281 ) on Thursday November 18, 2010 @06:27AM (#34266516)

    I found another article about the article which makes more sense: http://physicsworld.com/cws/article/news/44320 [physicsworld.com]

    There is a chicken and car analogy that should appeal to the crowd here:

    An analogy, says McCall, is a chicken crossing a busy road. Once the chicken steps onto the road cars must stop to let it pass, but as soon as it leaves the other side the cars would accelerate to catch up with the traffic ahead. To an observer farther down the road, the stream of passing cars would display no evidence of having slowed down.

    So, there is no magical disappearing of time or events or 4D cloaking of spacetime. That's just bullshit from some journalist who doesn't understand what spacetime or 4D means... Not more than a recorded tv program is cloaking space time.

    • Re:Better article (Score:5, Informative)

      by ath1901 ( 1570281 ) on Thursday November 18, 2010 @06:58AM (#34266594)

      Ok, so here's my personal rant:
      Why are all the non-linear optics experiments ALWAYS misinterpreted as having something to do with spacetime or relativity?

      A optical black hole [wikipedia.org] is NOT a black hole. It's a piece of glass. Radiation from such an optical black hole is NOT Hawking radiation [slashdot.org]. It just happens to have the same explanation.

      Just because light in a vacuum "happens" to travel at the fastest possible speed ("the speed of light" = c) doesn't mean that when light is slowed down, the maximum speed is somehow slowed down. Spacetime is completely unaffected by the bending/stretching/slowing down of light. You CAN travel faster than the speed of light in a piece of glass but you CAN NOT travel faster than the theoretical speed limit known as "the speed of light" / c.

      Light isn't special. It is just another particle (photons). It doesn't affect spacetime in any way except by the gravitational force which happens to be tiny since it is so light (pun not intended).

      • Re: (Score:2, Interesting)

        by rtb61 ( 674572 )

        However it is logically demonstrable that time does not exist. For time to exist, the present is the infestimally small sliver between the past and the future, so infinitesimally small as to logically be zero, the past of course no longer exists and the future is yet to exist, hence for time to exist the universe can not.

        • Re:Better article (Score:4, Interesting)

          by XxtraLarGe ( 551297 ) on Thursday November 18, 2010 @07:58AM (#34266844) Journal

          However it is logically demonstrable that time does not exist. For time to exist, the present is the infestimally small sliver between the past and the future, so infinitesimally small as to logically be zero, the past of course no longer exists and the future is yet to exist, hence for time to exist the universe can not.

          Sounds oddly similar to Zeno's Dichotomy Paradox. Thanks to calculus [wolfram.com], the issue has been solved.

          • Re: (Score:2, Funny)

            by Anonymous Coward

            Sup dawg, I heard you like to talk about time as a continuous function,
            so I put a plank length in your spacetime, so you can quantize your time measurements

        • Re: (Score:3, Funny)

          by MadKeithV ( 102058 )
          Time is an illusion.
          Lunchtime doubly so.

        • Re: (Score:3, Interesting)

          by uglyduckling ( 103926 )
          Yup, and in fact the integer 1 is the infinitesimally small sliver between the infinity 0..1 and 1..2, so logically 1 does not exist. Therefore, logically, nothing exists.

        • Re: (Score:2, Funny)

          by Anonymous Coward

          500 BCE called, they want their arguments [wikipedia.org] back. ;)

        • Re: (Score:3, Interesting)

          by mcgrew ( 92797 ) *

          Time does indeed exist. It is the measure of entropy.

          • Re: (Score:2)

            by wurp ( 51446 )

            When I was about 17 I had that same thought in what felt like a great epiphany at the time. My slant on it was that we necessarily remember in the direction of entropy... the notion of "why does time pass in one direction" is begging the question. Entropy will necessarily drift in one direction or another, and by definition we will experience time in the direction of increasing entropy.

            Now, the question of why entropy was very low at one time is still worth asking, but asking why time passes or why only i

        • Re: (Score:2)

          by geekoid ( 135745 )

          That's only logical to the ignorant; just like the stupid idea that if you only wak half way over and over again you can never get to your goal.

          There is a smallest piece of time and there is a smallest distance anything can move.

          What next? that dumb ass question about the chicken and the egg?

          Science has shot those, and most other, "philosophical" questions down.

        • If all the space, matter, and energy that was in the past is now in the present, and all the space, matter, and energy that will be in the future is now in the present would not that leave the past and the future completely void of everything? If there is nothing in the past or the future how can we say with any confidence that the past or the future actually exist? For that matter of space and time are inseparable and space was created at the big bang (just like every thing else) then space is locked int

      • Re: (Score:3, Insightful)

        by AstrumPreliator ( 708436 )

        Light isn't special. It is just another particle (photons). It doesn't affect spacetime in any way except by the gravitational force which happens to be tiny since it is so light (pun not intended).

        A photon (most likely) does not have mass. Although, interestingly enough, it does have momentum. It is affected by gravity, such as passing by a star, because spacetime is curved and the photon is merely following a geodesic (generalized notion of a straight line through curved space)..

        • Just curious, if photons did have even the most minuscule amount of mass could that mass possibly account for all the missing dark matter? I mean empty space is completely awash with photons. I know the logic that an object with mass can not travel at the speed of light. But photons have energy and e=mc^2 .

          • Re: (Score:3, Insightful)

            by JustinOpinion ( 1246824 )
            Yes, in principle if photons had mass that could lead to something like dark matter.

            However, in practice we know this isn't the case. First of all, if photons had mass (and quantum mechanics as we understand is roughly correct), this would modify a whole slew of predictions in all kinds of bizarre ways (down to fundamental things like the number of particles we observe and the stability of matter). Basically, the only way to match all our experimental data is with a massless photon.

            Even beyond that, h

          • Re: (Score:3, Interesting)

            by AstrumPreliator ( 708436 )
            If photons did have mass then they wouldn't be traveling the speed of light. The speed of light would still be a constant, but light wouldn't actually travel at that speed. As far as an alternative to dark matter, I'm not really qualified to answer that. According to wikipedia the upper bound for the mass of a photon is 1 x 10^(-18) eV/c^2 which is miniscule. For reference an electron has a mass of about .5 MeV/c^2. Considering dark matter is supposed to take up 80% of all matter in the viewable universe, I

          • Re: (Score:3, Interesting)

            by locofungus ( 179280 )

            No - photons cannot account for the "missing mass". It's called "dark matter" because we know that it (whatever it is) does not interact with the electromagnetic force.

            Indirectly, we can experimentally confirm that photons have a rest mass of zero from the fact that unless EM is exactly inverse square then there would be an electric field inside a hollow conductor. (proving this is relatively straight forward for a perfect sphere - I understand that it can be proved for a general closed conductor but that's

        • Actually, a photon has zero rest mass. It has energy and to an observer it is a massive object since it bends spacetime just like any other massive object.

          You could probably make up some kind of thought experiment about photons with energy mc^2 in a black box being indistinguishable from apples of mass m in a black box...

      • Re: (Score:1)

        by zpki ( 1942988 )

        Ok, so here's my personal rant: Why are all the non-linear optics experiments ALWAYS misinterpreted as having something to do with spacetime or relativity?

        You have this one backwards. The theory is based on fully covariant (relativistic) EM; the fibre implementation (ie the nonlinear optics) is a suggested experiment that mimics many of the basic features of the spacetime (event) cloak concept.

      • Re: (Score:2)

        by geekoid ( 135745 )

        "the maximum speed is somehow slowed down."

        Yes it is. The maximum speed of light within the environment is whatever light is moving at. There is no "Maximum speed of light" only "the Speed of light" which is the maximum any information can move.

        "You CAN travel faster than the speed of light in a piece of glass"
        Not within that material you can't. Sure, an object in a different environment may get 'around' the piece of glass faster, but thats a different thing. An observer inside the glass wouldn't never see

        • Nope, you've got that wrong. Take two really thick pieces of glass. Shoot light through one and a neutrino throught the other... Guess which one comes out the other side first?

          There is nothing special about light which prevents other objects from travelling faster than light in a medium.

        • Traveling faster than light is what produces Cherenkov radiation.

    • Re:Better article (Score:4, Insightful)

      by locofungus ( 179280 ) on Thursday November 18, 2010 @07:26AM (#34266696)

      So, there is no magical disappearing of time or events or 4D cloaking of spacetime.

      It's slightly more subtle than that. IIUC, it's impossible to detect something happening in the cloaked region of space. So in the chicken crossing the road scenario, to an outside observer, it looks like the cars travel at a constant speed and the chicken "magically" teleports from one side of the road to the other.

      The idea that something is in one state or another without being able to detect intermediate states is not new to physics. If you attempt to "watch" the transition between two eigenstates you will always measure one state or the other. We can have a mathematical model of how the wave function evolves, we can do experiments that demonstrate that the wavefunction must have been in a state that our mathematical model describes as a superposition of eigenfunctions, but we can never measure that superposition.

      In QM terms, I suppose the chicken would be described as "tunneling across the road"

      (note that I have no reason to suppose there is any relationship between 4d cloaking and QM tunneling - it's merely an analogy that came to mind)

      Tim.

    • So you're saying that the chicken crossed the road to keep from disrupting the space-time continuum and ending the universe as we know it?

      • Re: (Score:3, Funny)

        by ultranova ( 717540 )

        So you're saying that the chicken crossed the road to keep from disrupting the space-time continuum and ending the universe as we know it?

        Well... Nobody's ever seen a chicken cross the road to prevent the apocalypse. I think that's evidence enough.

    • Re: (Score:1)

      by zpki ( 1942988 )
      I suggest reading the original paper. The theoretical machinery used is 4D and fully (spacetime) relativistic. If you can't cope with the physics literature, the press releases are more complete than the mangled stuff in the press (but the New Scientist isn't bad at all: http://www.newscientist.com/article/dn19727-how-to-cloak-a-crime-in-a-beam-of-light.html [newscientist.com]) Press release (Imperial) : http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_16-11-2010-9-5-43 [imperial.ac.uk] Press Release (IoP):
    • This sounds way better out of context.

      I can see how an analogy might be compared to a chicken crossing a busy road, but is it really appropriate to say that analogies don't interrupt the flow of language to an observer?
  • The first thing I thought upon reading the headline, War of Omission. http://www.fantasticfiction.co.uk/o/kevin-odonnell-jr/war-of-omission.htm [fantasticfiction.co.uk]

  • And may I be the first to say (Score:3, Insightful)

    by boogersniffer500 ( 1525409 ) on Thursday November 18, 2010 @06:43AM (#34266560)
    I'll believe it when I don't see it!
  • I understand why both researchers and journalists sometimes foster this kind of hype, and I'm sure this is an interesting quantum-scale optical effect. However, can we have a new rule that until they can make a Klingon Bird-of-prey invisible to the naked eye, they're not allowed to call it a cloaking device? Everybody remember where we parked!
  • You know the one where Kirk steals an invisibility cloak in order to hang out undetected in the women's shower room?

    • Re:Wasn't this an episode of Star Trek? (Score:5, Funny)

      by uglyduckling ( 103926 ) on Thursday November 18, 2010 @08:09AM (#34266910) Homepage
      Ahhh! So you spotted that massive plot hole in the Harry Potter films too ;).

      • Re: (Score:3, Insightful)

        by jellomizer ( 103300 )

        Why do you think after the second book they no longer care which house wins. Griffendorf keeps on getting a bunch of points taken away do to slipping accidents in the girls dorms.

      • Re: (Score:1, Troll)

        by quatin ( 1589389 )

        I would like to make the request that we stop with the Harry Potter references. Can we not go through one legitimate discussion of this topic without mentioning that buffoon?

        I don't insert "Hackers" movie quotes into articles about network security. You shouldn't trivialize actual science with little boys playing fairies. (Yes, it really is that annoying.)

    • Re: (Score:2)

      by geekoid ( 135745 )

      Kirk would only need an invisibility cloak to get into the womens restroom. Far to confident with the ladies for that. Picard on the other hand would... and possibly Janeway

  • Unfortunately it worked so well that it hid the entire inventing event, so no one noticed.

  • That could be a new 2012 presidential platform... "I have never inhaled marijuana outside a space-time invisibility cloak."

  • Hmmm... This sounds familiar [wikipedia.org]...

  • Some interesting info on Space Time [youtube.com]

    Sorry, it's been in my head since reading the article title, had to get it out there.
  • If this becomes reality we will never hear about it ! (the first thing it would be used for is to hide the invention itself)

  • Implementation is hard. But everyone who has a "great" idea always seems to think the implementation will be easy. Go to it, scientists! We don't need to prove anything!

  • An anonymous reader writes

    Anonymous.... OR INVISIBLE??!?!?

  • Look, an SEP field! (Score:1, Funny)

    by Anonymous Coward

    Look, an SEP field!

  • **FIRST POST!!!

    Yes! I knew it would happen eventually, thank goodness for my time cloak!!!

    ** Posting position may be affected by relative velocity, gravitational forces, temporal coordinate system and speed of light relative to observer and OP. Your mileage may vary!

  • you have a theoretical time lock.

  • If an event were truly hidden from space time, wouldn't their observations of the effects of it also be hidden?

    Sorry... maybe I've just seen too many time travel movies.

  • Correct me if I'm wrong, but this sort of invisibility cloak would not be perfect as described.

    As light is initially slowed down to make "room" for the invisible event to take place, there is going to be a red-shift in the light because the waves must start arriving more slowly. While this change can be made subtle, that means that an "attacker" needs to either spend a long time slowing down the light, or the "attacker" would only create a small gap in time in which to work.

    Still very cool though!

  • ...Stays inside a spacetime invisibility cloak .

  • Finally... the Chrono-legionnaire has arrived!

  • So, if I were within the space-time cloak, although I would exist, I would no longer exist in time, and for me time itself would not exist? That is, although I'd still be mass, I would no longer be an event in space-time; I would be a non-event mass with a quantum probability of zero?

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