Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Origin of our universe 4D black hole

  1. Oct 20, 2014 #1
    The brains at the Perimeter Institute recently published a paper describing how our 3 dimensional universe could possibly exist as the event horizon of a 4 dimensional black hole in a 4 dimensional universe as the event horizons of black holes have one less dimension than the black hole itself and the universe it occupies.

    I was wondering what others think of this model and if this also suggests that our 3 dimensional black holes have themselves got a 2 dimensional universe within their event horizons.

    Here is a link to an article on the paper: http://phys.org/news/2014-08-black-hole-birth-universe.html
     
  2. jcsd
  3. Oct 20, 2014 #2

    jedishrfu

    Staff: Mentor

    Pretty interesting notion.
     
  4. Oct 20, 2014 #3

    phinds

    User Avatar
    Gold Member
    2016 Award

    Sounds like mathematical nonsense to me, but that's just the engineer in me talking, not anything based on scientific knowledge.
     
  5. Oct 20, 2014 #4

    Drakkith

    User Avatar

    Staff: Mentor

    I'm much more inclined to believe that GR is not accurate at black hole scales and there isn't really a singularity at all.
     
  6. Oct 20, 2014 #5

    Doug Huffman

    User Avatar
    Gold Member

    Out of the White Hole: A Holographic Origin for the Big Bang http://arxiv.org/abs/1309.1487 is the only paper at ArXiv in the senior author's list and with the same junior authors as in the Phys.org.asm article. Citation by Scientific American does their credibility no good.
     
  7. Oct 20, 2014 #6
    I believe they say there is a way to prove it (or disprove it)!
     
  8. Oct 20, 2014 #7

    phinds

    User Avatar
    Gold Member
    2016 Award

    Actually, that's a pretty widespread belief these days, isn't it? I certainly share it and if I do then dammit, everybody should !
     
  9. Oct 20, 2014 #8

    phinds

    User Avatar
    Gold Member
    2016 Award

    Nothing is ever proved in physics, only in math. Things can easily be DISproved in physics.

    If someone develops some solid evidence in favor, I'll reconsider my disbelief.
     
  10. Oct 20, 2014 #9
    Things can be proved? like proving light has wave like properties with the double slit experiment...
     
  11. Oct 20, 2014 #10

    Drakkith

    User Avatar

    Staff: Mentor

    I'm not quite sure what you're getting at here.
     
  12. Oct 20, 2014 #11

    phinds

    User Avatar
    Gold Member
    2016 Award

    This is NOT a proof. It is an empirical observation.
     
  13. Oct 20, 2014 #12

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    To a logician, that proves nothing.

    Think of it this way. Newton published his Philosophiæ Naturalis Principia Mathematica in 1687. Scientists tested this theory, engineers used this theory, and for the next 300 years and never found a chink. There obviously were some chinks. My computer, your GPS unit, and a host of other technical wonders of the 20th an 21st century wouldn't exist if Newtonian mechanics was universally true.

    One challenge confronted by quantum theory and relativity theory was to somehow explain how even though Newtonian mechanics is fundamentally flawed, it still appears to work very, very well in a limited domain. Physicists of the future will be confronted with the same problem when something better than quantum theory and relativity theory comes along. They'll have to explain that even though our quantum and relativity theories are fundamentally flawed, they still do appear to work extremely well in their limited domains.
     
  14. Oct 21, 2014 #13
    not sure I agree, if I see an apple fall off a tree, there MUST be a force acting on the apple, therefore i can say that my observation proves there is a force acting on the apple
     
  15. Oct 21, 2014 #14

    Drakkith

    User Avatar

    Staff: Mentor

    A "force" is a concept invented to explain why objects are accelerated. There is no proof that forces exist. It is simply the best explanation we have and allows us to predict how an object will act in a given situation.
     
  16. Oct 21, 2014 #15
    The proof is the fact the apple falls? It would only fall if the concept of a 'force' was real, thus it is real
     
  17. Oct 21, 2014 #16

    Drakkith

    User Avatar

    Staff: Mentor

    I would say that you observe that the apple falls. In an attempt to explain why and how, you can use the concept of a "force" acting on the apple to predict how fast it falls, when it will hit the ground, at what velocity, etc. There is no "proof" anywhere here.
     
  18. Oct 21, 2014 #17
    lets agree to disagree, this is well off the topic of this thread.
     
  19. Oct 21, 2014 #18
    While I have never studied general relatiovity, I'm wary of black holes as models of a universe since they differ in details:

    "Note that the maximally extended Schwarzschild metric describes an idealized black hole/white hole that exists eternally from the perspective of external observers; a more realistic black hole that forms at some particular time from a collapsing star would require a different metric. When the infalling stellar matter is added to a diagram of a black hole's history, it removes the part of the diagram corresponding to the white hole interior region.[6] But because the equations of general relativity are time-reversible (they exhibit T-symmetry), general relativity must also allow the time-reverse of this type of "realistic" black hole that forms from collapsing matter. The time-reversed case would be a white hole that has existed since the beginning of the universe, and which emits matter until it finally "explodes" and disappears.[7] Despite the fact that such objects are permitted theoretically, they are not taken as seriously as black holes by physicists, since there would be no processes that would naturally lead to their formation, they could only exist if they were built into the initial conditions of the Big Bang.[7] Additionally, it is predicted that such a white hole would be highly "unstable" in the sense that if any small amount of matter fell towards the horizon from the outside, this would prevent the white hole's explosion as seen by distant observers, with the matter emitted from the singularity never able to escape the white hole's gravitational radius.[8]"

    [ http://en.wikipedia.org/wiki/White_hole ; my bold]

    The larger claim of our universe being a variant of a black hole seems generically be an extraordinary claim without any (extra)ordinary evidence. The smaller claim that BHs contain universes can safely be rejected I think.
     
  20. Oct 21, 2014 #19
    hmm I wish I could look at the maths for all this and get to grips with it, i think i would understand it a lot better if i did so. There is only so much you can understand from reading words, a lot more can be understood from the maths.
     
  21. Oct 21, 2014 #20
    Off topic:
    I think this confuses the notion of reality (robust observations) with the notion of theories (robust predictors).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook