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posted by Fnord666 on Wednesday February 27 2019, @09:12AM   Printer-friendly
from the picture-this dept.

Submitted via IRC for Bytram

How Our Universe Could Emerge as a Hologram

The fabric of space and time is widely believed by physicists to be emergent, stitched out of quantum threads according to an unknown pattern. And for 22 years, they've had a toy model of how emergent space-time can work: a theoretical "universe in a bottle," as its discoverer, Juan Maldacena, has described it.

The space-time filling the region inside the bottle—a continuum that bends and undulates, producing the force called gravity—exactly maps to a network of quantum particles living on the bottle's rigid, gravity-free surface. The interior "universe" projects from the lower-dimensional boundary system like a hologram. Maldacena's discovery of this hologram has given physicists a working example of a quantum theory of gravity.

But that doesn't necessarily mean the toy universe shows how space-time and gravity emerge in our universe. The bottle's interior is a dynamic, Escheresque place called anti–de Sitter (AdS) space that is negatively curved like a saddle. Different directions on the saddle curve in opposite ways, with one direction curving up and the other curving down. The curves tend toward vertical as you move away from the center, ultimately giving AdS space its outer boundary—a surface where quantum particles can interact to create the holographic universe inside. However, in reality, we inhabit a positively curved "de Sitter (dS) space," which resembles the surface of a sphere that's expanding without bounds.

Ever since 1997, when Maldacena discovered the AdS/CFT correspondence — a duality between AdS space and a "conformal field theory" describing quantum interactions on that space's boundary—physicists have sought an analogous description of space-time regions like ours that aren't bottled up. The only "boundary" of our universe is the infinite future. But the conceptual difficulty of projecting a hologram from quantum particles living in the infinite future has long stymied efforts to describe real space-time holographically.

[...] Patrick Hayden, a theoretical physicist and computer scientist at Stanford who studies the AdS/CFT correspondence and its relationship to quantum error correction, said he and other experts are mulling over Dong, Silverstein and Torroba's dS/dS model. He said it's too soon to tell whether insights about how space-time is woven and how quantum gravity works in AdS space will carry over to a de Sitter model. "But there's a path—something to be done," Hayden said. "You can formulate concrete mathematical questions. I think a lot is going to happen in the next few years."


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  • (Score: 4, Informative) by PiMuNu on Wednesday February 27 2019, @05:39PM (3 children)

    by PiMuNu (3823) on Wednesday February 27 2019, @05:39PM (#807707)

    > The fabric of space and time is widely believed by physicists to be emergent, stitched out of quantum threads according to an unknown pattern

    I don't think this is true beyond a tiny niche of theoretical physicists. Most physicists don't have expertise to declare one way or another. Possibly even these theorists have no evidence (making them mathematicians rather than physicists).

    FWIW I have studied, in ancient past, quantum field theory and cosmology at a reasonably high level and I still don't have a clue what TFS is talking about.

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  • (Score: 0) by Anonymous Coward on Wednesday February 27 2019, @06:04PM (1 child)

    by Anonymous Coward on Wednesday February 27 2019, @06:04PM (#807718)

    I don't see the point of this post which don't make sense to 99.999% of physicists.

    We could have had a quality aristachu submission instead.

    • (Score: 0) by Anonymous Coward on Wednesday February 27 2019, @10:48PM

      by Anonymous Coward on Wednesday February 27 2019, @10:48PM (#807837)

      The point is to blur the line between scientific and relgious activities:

      The John Templeton Foundation (Templeton Foundation) is a philanthropic organization that reflects the ideas of its founder, John Templeton, who became wealthy after a career as a contrarian investor and wanted to support progress in religious and spiritual knowledge, especially at the intersection of religion and science.

      https://en.wikipedia.org/wiki/John_Templeton_Foundation [wikipedia.org]

  • (Score: 2) by legont on Thursday February 28 2019, @12:05AM

    by legont (4179) on Thursday February 28 2019, @12:05AM (#807887)

    The sad truth is that when physicists do math they typically cut corners so their math is not mathematically correct; not up to pure math standards anyway. Nevertheless, lots of good math were triggered by math amateurs from physics world.

    --
    "Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.