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

Posted by Soulskill on 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."

11 of 337 comments (clear)

  1. Sorry by krovisser · · Score: 5, Funny

    Turtles all the way down.

    1. Re:Sorry by FredGauss · · Score: 5, Insightful

      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?

  2. Uhhh... what did he just say to us? by pspahn · · Score: 5, Funny

    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?

    --
    Someone flopped a steamer in the gene pool.
    1. Re:Uhhh... what did he just say to us? by rasmusbr · · Score: 5, Interesting

      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.

    2. Re:Uhhh... what did he just say to us? by Rockoon · · Score: 5, Interesting

      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.

      --
      "His name was James Damore."
    3. Re:Uhhh... what did he just say to us? by pspahn · · Score: 5, Funny

      All the way up to 20D, at which point the DM's mother informs him it's time for dinner (corndogs and mac'n'cheese yet again).

      --
      Someone flopped a steamer in the gene pool.
    4. Re:Uhhh... what did he just say to us? by mysidia · · Score: 5, Interesting

      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.

    5. Re:Uhhh... what did he just say to us? by ChromaticDragon · · Score: 5, Informative

      Umm... No.

      http://en.wikipedia.org/wiki/Observable_universe

      http://en.wikipedia.org/wiki/Future_of_an_expanding_universe

      http://en.wikipedia.org/wiki/Big_Rip

      We have no idea how large the universe is. But the current estimates of the radius of the observable universe is about 45 billion light years. That's how "far" we can see. And this is indeed due to the expansion of the universe essentially moving distances apart faster than light can travel. Furthermore, it's not just that we won't "catch up"... It seems rather likely that it's gonna get worse over time - to the point we won't be able to see much at all (relatively speaking).

  3. Re:Get out the bong by binarylarry · · Score: 5, Informative

    That would be Cypress Hill, not ICP.

    --
    Mod me down, my New Earth Global Warmingist friends!
  4. Re:Get out the bong by gl4ss · · Score: 5, Insightful

    ICP could be playing CH, it's his head, his rules.

    but if the clown posse is playing cypress hill songs in his head he might not need another hit for a while...

    --
    world was created 5 seconds before this post as it is.
  5. Several errors. by rjh · · Score: 5, Informative

    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.)