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Study: Our 3D Universe Could Have Originated From a 4D Black Hole 337

Posted by Soulskill
from the useless-physics-trivia dept.
New submitter TaleSlinger sends this quote from Nature: "Afshordi's team realized that if the bulk universe contained its own four-dimensional (4D) stars, some of them could collapse, forming 4D black holes in the same way that massive stars in our Universe do: they explode as supernovae, violently ejecting their outer layers, while their inner layers collapse into a black hole. In our Universe, a black hole is bounded by a spherical surface called an event horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional object (a surface) to create a boundary inside a black hole, in the bulk universe the event horizon of a 4D black hole would be a 3D object — a shape called a hypersphere. When Afshordi's team modeled the death of a 4D star, they found that the ejected material would form a 3D brane surrounding that 3D event horizon, and slowly expand. The authors postulate that the 3D universe we live in might be just such a brane — and that we detect the brane's growth as cosmic expansion. 'Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang — but that is just a mirage,' says Afshordi."
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Study: Our 3D Universe Could Have Originated From a 4D Black Hole

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  • Sorry (Score:5, Funny)

    by krovisser (1056294) * on Saturday September 14, 2013 @08:09PM (#44852633)
    Turtles all the way down.
    • Re:Sorry (Score:5, Insightful)

      by FredGauss (3087275) on Saturday September 14, 2013 @10:33PM (#44853307)

      Turtles all the way down.

      Funny, but also Insightful? Turtles all the way down, or turtles all the way up? If we inhabit the 3D manifold that resides in a black hole within a 4D bulk universe, and observe 3D black holes (with a 2D event horizon), does this imply 1D black holes inside of the black holes that we observe (with 0D black holes inside...). Is the 4D bulk universe a black hole in a 5D hyper-bulk universe within a 6D ... Is there a physicist in the house that can shed more light on this than the article/paper?

      • by Velex (120469)
        Yeah, that gets weird real quick. Personally I prefer the holographic universe theory. Then everything can stay with three spatial dimensions and it can still be turtles all the way down... or in....
  • NO! (Score:3, Funny)

    by TechyImmigrant (175943) on Saturday September 14, 2013 @08:15PM (#44852663) Journal

    His noodliness wishes to inform you that string theory is closer to the truth but the full truth is that the universe is made of strings of spaghetti.

  • ... but what do I know?
    I personally like the turtles explanation better than spaghetti but I'm just along for the ride.

  • Get out the bong (Score:2, Insightful)

    by wes33 (698200)

    seriously, it's time

  • by pspahn (1175617) on Saturday September 14, 2013 @08:27PM (#44852711)

    So whatever a 4D star is, when it explodes there is a 3D layer that represents the event horizon. We live in this layer. One side of the layer is a 4D black hole, and the other side of the layer is some other kind of nothingness. Yeah?

    Is there someone here I can offer monetary compensation to for them to comprehend this summary for me?

    • by rasmusbr (2186518) on Saturday September 14, 2013 @08:38PM (#44852755)

      If I understood it correctly they mean that on the other side is a universe with 4 spatial dimensions.

      Think of it this way: in a universe with 3 spatial dimensions a black hole has a 2-d surface (shaped roughly like the surface of a sphere) as its event horizon. On the inside of the surface is the black hole. On the outside is the rest of the universe. Generalizing this to a hypothetical universe with 4 spatial dimension, a black hole in such a universe would have a 3-d "surface" surrounding it with the black hole inside of the surface and the rest of the universe outside of it.

      By the way, there is already an idea floating around about how the edge of the visible universe seems be a bit like the event horizon of a black hole. Once something has passed the edge of the visible universe it is effectively lost to us, a bit like when something passes the event horizon of a black hole.

      • by Rockoon (1252108) on Saturday September 14, 2013 @08:59PM (#44852849)
        What will really cook your noodle is if you calculate the mass of a black hole whos event horizon the size of the visible universe, its within an order of magnitude of the suspected mass of the visible universe (including dark matter.)

        A common misconception is that black holes require singularities. Simple thought experiments show it differently.. for example, imagine living in a universe with a mass about that of a black hole that would have an event horizon that is just a little bit smaller than the universe. Now imagine that universe contracting. You can see that as it contracts it will eventually become small enough to form an event horizon without a singularity.
      • by mysidia (191772) on Saturday September 14, 2013 @09:34PM (#44853015)

        By the way, there is already an idea floating around about how the edge of the visible universe seems be a bit like the event horizon of a black hole. Once something has passed the edge of the visible universe it is effectively lost to us

        Because we can only see things that have sent light back towards us, AND that return light has already reached us. If something is further away from earth, than the distance that light could have possibly travelled back from the object towards earth from the time that the object was at that distance, then by induction: we cannot see the object yet.

        Because near the rim of the universe.... the universe is expanding faster than the speed of light; so it's far enough, that light would take longer to travel back to where earth is, than the duration the universe has existed.

        Furthemore: since the universe can continue to expand at a rate faster than the speed of light --- the light travelling back towards earth, can never overtake the rate of the universe's expansion, and find its way back to us.

        It is kind of like an infinite treadmkill ---- very similar to the concept of a gravitational well that is so deep not even light can escape.

        We have an outer rim of our universe expanding so quickly, that not even the very timespace; the spatial dimensions or the passage of time can escape it.

        • by Kjella (173770)

          Because near the rim of the universe.... the universe is expanding faster than the speed of light; so it's far enough, that light would take longer to travel back to where earth is, than the duration the universe has existed. Furthemore: since the universe can continue to expand at a rate faster than the speed of light --- the light travelling back towards earth, can never overtake the rate of the universe's expansion, and find its way back to us.

          I don't really see why you have to bring FTL into it. If the universe is 13.8 billion years old and we're in the middle of it (close enough approximation) we'll only see events up to 6.9 billion years away. Sure, in another 6.9 billion years we'll be able to observe the entire current universe but by then it'll have expanded another 6.9 billion light years. It has a head start on us and our "observable universe" will never catch up to the real universe, because our ability to observe expands at the same rat

        • by the_B0fh (208483)

          did you just claim faster than light?

          • by mysidia (191772) on Sunday September 15, 2013 @01:20AM (#44854013)

            Yes. universal expansion [wikipedia.org] occurs at a speed faster than the speed of light.

            The expansion of the universe causes distant galaxies to recede from us faster than the speed of light, if comoving distance and cosmological time are used to calculate the speeds of these galaxies. However, in general relativity, velocity is a local notion, so velocity calculated using comoving coordinates does not have any simple relation to velocity calculated locally[16] (see comoving distance for a discussion of different notions of 'velocity' in cosmology). Rules that apply to relative velocities in special relativity, such as the rule that relative velocities cannot increase past the speed of light, do not apply to relative velocities in comoving coordinates, which are often described in terms of the "expansion of space" between galaxies. [....]
            There are many galaxies visible in telescopes with red shift numbers of 1.4 or higher. All of these are currently traveling away from us at speeds greater than the speed of light. Because the Hubble parameter is decreasing with time, there can actually be cases where a galaxy that is receding from us faster than light does manage to emit a signal which reaches us eventually.[18][19] However, because the expansion of the universe is accelerating, it is projected that most galaxies will eventually cross a type of cosmological event horizon where any light they emit past that point will never be able to reach us at any time in the infinite future,[20] because the light never reaches a point where its "peculiar velocity" towards us exceeds the expansion velocity away from us

      • So if a 2d star were to explode, there will be 1d surface? So you're telling me that flatland [wikipedia.org] could exist?
      • by 0111 1110 (518466)

        a black hole in such a universe would have a 3-d "surface"

        I'm trying to decide whether this makes any more sense than a square circle. 3D surface is a contradiction in terms. A surface is 2 dimensional by definition.

        Once something has passed the edge of the visible universe it is effectively lost to us

        Only until we build a bigger telescope.

        a bit like when something passes the event horizon of a black hole.

        It's not really the same because anything that collides with a black hole will cease to exist. There is no way for anyone with any sort of conceivable detector to observe what no longer exists. Even if the collapsed star's gravity did not stop the photons from exiting it would effectively vanish out of existence.

        • by JesseMcDonald (536341) on Sunday September 15, 2013 @01:08AM (#44853965) Homepage

          a black hole in such a universe would have a 3-d "surface"

          I'm trying to decide whether this makes any more sense than a square circle. 3D surface is a contradiction in terms. A surface is 2 dimensional by definition.

          The term "surface" normally refers to a two-dimensional shape in 3D space, but it can be generalized to any number of dimensions (a hypersurface). One example would be a hypersphere (x**2 + y**2 + z**2 + w**2 = 1), which has three orthogonal directions of movement along the hypersurface and encloses a four-dimensional space. Movement tangent to the hypersphere it would seem like movement in normal 3D Euclidean space, except that if you travel far enough in any direction you'll eventually end up back where you started.

          Once something has passed the edge of the visible universe it is effectively lost to us

          Only until we build a bigger telescope.

          It's not a matter of how large or sensitive the telescope is; if something is far enough away, the expansion of the space between the object and ourselves causes the distance between us to increase faster than the speed of light, meaning light from the object can never reach us. Once something reaches that distance it's cut off from us for good (or at least as long as the universe continues to expand).

          It's not really the same because anything that collides with a black hole will cease to exist. ... Even if the collapsed star's gravity did not stop the photons from exiting it would effectively vanish out of existence.

          These are one and the same thing. Black holes are not particularly special; the event horizon isn't some solid barrier things crash into. It's merely the point of no return, beyond which escape velocity exceeds the speed of light. Objects which enter a black hole "cease to exist" in exactly the same sense as objects which pass beyond the visible universe: any effect involving the object would need to propagate faster than the speed of light to reach us.

        • Re: (Score:3, Interesting)

          It's not really the same because anything that collides with a black hole will cease to exist. There is no way for anyone with any sort of conceivable detector to observe what no longer exists. Even if the collapsed star's gravity did not stop the photons from exiting it would effectively vanish out of existence.

          This is not true. Hawkings proved this already; Look up Hawking radiation. Black holes will eventually evaporate if it cannot attract enough matter to sustain its size. Highly charged particles are emitted at the poles of a black hole, and it's also been proven that not only does matter in the accretion disc accelerate to the speed of light before crossing the horizon, but that the black hole itself is also rotating at the speed of light creating relativistic frame dragging.

          All of this would not be occurrin

          • Several errors. (Score:5, Informative)

            by rjh (40933) <rjh@sixdemonbag.org> on Sunday September 15, 2013 @11:51AM (#44856269)

            In no particular order:

            1. Hawking proved... No, he did not. Hawking has a mathematical description that's consistent with quantum mechanics and general relativity, but that doesn't mean the universe actually works this way. There have been a large number of highly promising theoretical constructs that have never been observed in reality and are believed to not exist. Hawking radiation may be one of them. Most physicists believe Hawking radiation exists and is a real phenomena, but it has never been observed in reality. (We have, however, observed analogues to Hawking radiation from acoustic 'black holes'.)

            2. Highly charged particles are emitted at the poles of a black hole... No, they are not. Those jets are made of matter that was about to cross the event horizon until they suddenly and violently thought better of it. The area around an accreting black hole is perhaps the most violent spot imaginable in the universe; it should be no surprise whatsoever that once something has gone around the accretion disc a few million times it would have enough kinetic energy to go like hell off in another direction as soon as it collides with another particle. One of the billiard-balls rockets across the event horizon and the other uses its kinetic energy to escape from the accretion disc. (This is handwaving a lot of astrophysics, but is basically accurate.)

            3. the black hole itself is also rotating at the speed of light... No, it is not. Black holes have to obey the cosmic speed limit just like everything else. Also, not all black holes possess angular momentum. General relativity gives perfectly satisfactory predictions for stationary black holes.

            4. The information, that is the quantum state, of mass and energy that is eaten by a blackhole is later ejected as what could be termed high energy 'noise'; x-rays and gamma rays. Not in the slightest. Hawking radiation is about the longest-wavelength (which means lowest-energy) stuff in the universe. The reason for this is really simple: although it started off as unbelievably energetic, it had to expend virtually all of its energy escaping from where it was created a nanometer beyond the event horizon.

            No offense, but you need to sit down with a good book on general relativity. (I like Sean Carroll's Spacetime and Geometry. YMMV.)

        • by wonkey_monkey (2592601) on Sunday September 15, 2013 @07:22AM (#44855087) Homepage

          A surface is 2 dimensional by definition.

          No, it isn't. It's two-dimensional only by everyday common experience.

          Once something has passed the edge of the visible universe it is effectively lost to us

          Only until we build a bigger telescope.

          No, we'll never see it. The light from there will never reach us.

          It's not really the same because anything that collides with a black hole will cease to exist.

          No, it won't.

          YANAP

    • by Anonymous Coward

      The article is about string theory (I think more properly called "M-Theory" these days but not sure). It is the outcome of a lot of very crazy math and complicated equations that are hard to visualize.

      But, what this theory sorely lacks is evidence. By which I mean any evidence at all. It is popular in the physics world because it can resolve the discrepancies between quantum mechanics (for which there is quite a lot of solid, verifiable evidence) and general relativity (for which there is also quite a lo

    • I don't think it said that we live in the event horizon. We're the nebula, right? And since it is a 4D nebula, we're only a tiny slice of it.

      I love/hate these developments b/c I don't understand them but they're interesting, and why really? Why are they sometimes interesting even though I don't understand them?

      Puff puff pass.

      Maybe that's it.

      • by hazah (807503)
        No, the surface speculated is the event horizon. There's only so much one can say about a black hole... mass, and spin.
        • This is the part I don't understand about the model. In order for our universe to be the 3D surface of a 4D black hole, everything in our universe would have to somehow be constrained to move along the event horizon. Otherwise the event horizon would be just one of many possible 3D subspaces to consider within the larger 4D universe.

          What is it that forces matter and energy in our universe to stay on the event horizon, rather than either escaping or falling into the black hole? I don't recall hearing about a

    • by LWATCDR (28044) on Saturday September 14, 2013 @10:57PM (#44853407) Homepage Journal

      I think they are just making this crap up to mess with us at this point.

  • If I understand correctly, the universe we see is the inside of a black hole, and the big bang is the time that black hole created its singularity.

    Now I can imagine that in each black hole we see there is another universe. Or is it always the same universe that is found inside all different black holes? And I still have trouble to imagine what happens to someone taking a dive into a black hole. Is it possible to enter the universe inside a black hole?

    • by mysidia (191772) on Saturday September 14, 2013 @09:50PM (#44853103)

      Is it possible to enter the universe inside a black hole?

      Arguably... to enter the universe inside a blackhole; you have only to enter the event horizon, and merge with it.

      Once you merge with the event horizon; you can never leave the black hole or ever be visible to an outside observer again. Also; you will get squashed into 2 dimensions, and your particles will be scrambled ---- so although the matter that comprises you merges with the universe inside the blackhole: your physical body does not survive.

      Physicists cannot say what happens to your immortal soul --- whether it escapes the pull; or whether it too becomes entrapped in the event horizon of that featureless pocket universe for the rest of eternity.

  • by 93 Escort Wagon (326346) on Saturday September 14, 2013 @08:50PM (#44852799)

    It's a news story on their website talking about a preprint paper posted on Arxiv.

  • by istartedi (132515) on Saturday September 14, 2013 @08:52PM (#44852807) Journal

    What's their point? There's not a singular thing I can see there.

  • by Anonymous Coward on Saturday September 14, 2013 @08:59PM (#44852843)

    "I just had an awesome idea. [xkcd.com] Suppose the entire observable universe exists as a 3d brane on the edge of a 4 dimensional black hole."

    "Okay. What would that imply?"

    "I dunno."

  • by codeusirae (3036835) on Saturday September 14, 2013 @09:10PM (#44852899)
    ".. we happen to live in the causal future of the classical big bang singularity .. we outline a novel mechanism through which any thermal atmosphere for the brane, with comoving temperature of 20% of the 5D Planck mass can induce scale-invariant primordial curvature perturbations on the brane, circumventing the need for a separate process (such as cosmic inflation) to explain current cosmological observations ..."
  • I've been saying just this for years.

  • In our Universe, a black hole is bounded by a spherical surface called an event horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional object (a surface) to create a boundary

    How is a sphere two dimensional? Surely they meant circular?

  • What is the difference between Branes and String Theory? String Theory seems to have about 10 dimensions or so. Do theories with Branes have only 4 dimensions (3 spacial, 1 time)? I thought they were related. I realize this is all mathematical speculation but I wonder.
  • Not sure that the idea of an event horizon as being a 2D object in 3D space is valid. The Event Horizon is not a surface, it's the description of a place in space where information can not pass, because you can't pass information beyond the speed of light. There is no physical surface there. It's not like you could put your hand against this and pull back a stump.

    The next question is are the 'D's between the 4D space as a source, and the resulting 3D space related or concurrent? I.e. does our 3D space x,y,z

    • by AK Marc (707885)
      Because you can't pass the event horizon, then you can fit a universe between it and just outside it. An infinite 3D universe fits in a (roughly) 2D space. Between realspace and event horizon.

      Or something like that.
  • Dimension of us never got around.....

  • That means that... our whole solar system... could be, like, one tiny atom in the fingernail of some other giant being! This is too much! http://www.metacafe.com/watch/an-n_RQb4tJmhY2n/animal_house_1978_smoking_pot_with_professor_part_2/ [metacafe.com]
  • No, actually, I dont see at all. Someone call in an autistic savant to deal with this.

  • by slashmydots (2189826) on Saturday September 14, 2013 @10:08PM (#44853187)
    There's actually some math that proves this theory.
    Baseless claim/theory with zero evidence + inability for anyone anywhere to disprove it = book deal + huge $$$ grant + discovery channel special

    You know, like the theory that the entire universe is a gigantic is a simulation similar to the matrix. There was a very elaborate, college-funded experiment to test that actually (as seen on slashdot)
  • The main problem I have with this the 4D universe could (and would) still interact with our 3D hypersphere. Consider a black hole in our 3D universe. It has an event horizon, the 2D surface of which is analogous to the 3D hypersphere. Mass from our 3D universe does cross through that surface and has a profound effect on the structure and behavior of whatever mass is "living" in that boundary. Thus we would expect to see objects instantly materialize as they cross into our 3D hypersphere, and interact wi

  • by sjwt (161428)

    'Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang — but that is just a mirage,'

    I am sure a black hole forming would count as a big bang..

  • God is the 4D dude who bought the Make Your Own Universe Kit and set it running in his mom's basement.

    If you tick him off by not kissing up to him etc., he'll delete you from his "ant farm". So, sing those hymns, guys! "You are the grandest and mightiest, oh wondrous Father of all we know!"

    He can see you yanking off also, and will blind you if caught; he hates the yanking while he's having sandwiches, ruins his appetite.

  • I'll stick with the turtles story, thanks anyway.

  • In the 4D universe is a book called Cubeland and the readers struggle to understand how creatures might exist in a hypothetical space limited to just width,height and depth. Ie. How their digestive tract is just a tube through them.

  • One could extrapolate that the 4D universe is just a black hole in a 5D universe then. Maybe go up to as many dimensions as String theory expects.

  • by Tony Isaac (1301187) on Sunday September 15, 2013 @12:51AM (#44853893) Homepage

    This is an illustration of where mathematical models can run amok.

    Every kind of model has its limits. Bohr, for example, envisioned atoms as a nucleus of positively charged protons and neutral neutrons, with orbiting electrons. The model works well because it's something people can grasp. But the model has its limits, and there are many aspects of quantum behavior that cannot be explained by the Bohr model. The model is still useful because it does lead to many accurate scientific predictions.

    A newer mathematical model, quantum mechanics, seeks to be even more accurate in its predictions than Bohr's model. It succeeded in many ways, and like the Bohr model, has led to many interesting discoveries. But it too has its limits.

    In pure mathematics, exceeding three dimensions is effortless. Calculations involving four or more dimensions can easily be solved. But just because the mathematical model can do it, doesn't mean that the physical reality it attempts to model, can also do it. A model is designed to represent reality, but it is not itself reality. I suspect that all such mathematical models of the universe, which point to other dimensions, will eventually be shown to be purely mathematical.

    • by jamesh (87723) on Sunday September 15, 2013 @01:06AM (#44853953)

      This is an illustration of where mathematical models can run amok.

      My favourite is:
      There are 4 people in a room, then 7 people leave. How many people have to enter the room for it to be empty again?

      • by oldhack (1037484) on Sunday September 15, 2013 @04:39AM (#44854687)
        I don't know, but maybe they should have used condom.
  • by triclipse (702209) <slashdot.combslaw@cc> on Sunday September 15, 2013 @08:03AM (#44855205) Homepage
    ... hurts my brane.

Wernher von Braun settled for a V-2 when he coulda had a V-8.

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