4 ms·

There is one important thing everybody seems to be missing here. This applies to the theoretical AdS universe, NOT to our universe as far as we know.

• 3cats-in-a-coat 3y ago
  But our universe adheres to AdS constraints. As far as we know. When you reach the information density limit in AdS, in our universe you get a black hole.
  • undersuit 3y ago
    A theory used to establish the scene in https://en.wikipedia.org/wiki/Vacuum_Diagrams https://en.wikipedia.org/wiki/Vacuum_Diagrams
    • snarkconjecture 3y ago
      The AdS/CFT correspondence was published slightly after that collection. Are you saying Baxter scooped Maldacena?
      • queuebert 3y ago
        While that correspondence proof is relatively new, AdS as a theory is quite old.
        • snarkconjecture 3y ago
          The great-grandparent comment was talking about an "information density limit" and black holes in our universe, so I assumed the referenced sci-fi collection had something to do with holography. I don't know of any particular emphasis on AdS in that context before 1997. Elaborate? Obviously you can stick GR in AdS, but AFAIK nothing about that would've seemed interesting with regards to holography before Maldacena, let alone plausibly providing inspiration to a fiction author. To be less roundabout than my previous comment: I think Baxter may have been inspired by the holographic principle in general, but I doubt AdS crossed his mind at all when he was writing these stories in the 80s and early 90s. (EDIT: or maybe Baxter was thinking about AdS but not about holography. I haven't read his work.)
          • undersuit 3y ago
            Vacuum Diagrams is a collection of short stories Stephen Baxter has written well before 1997, but the published collection in 1997 included new intertwining narrative stories about an AI named EVE to bind them together. EVE is an AI in a black hole? On the edge of one? Stephen Baxter is known for sch-fi so hard it'll cut you. He may have just accidentally come up with similar concepts during the same year.
  • codethief 3y ago
    > But our universe adheres to AdS constraints. As far as we know. No, as far as we know, it doesn't since the cosmological constant is slightly positive, so the universe would best be described by de Sitter spacetime, not anti-de Sitter. https://en.m.wikipedia.org/wiki/Anti-de_Sitter_space https://en.m.wikipedia.org/wiki/Anti-de_Sitter_space
  • empath-nirvana 3y ago
    Our universe is definitely not an ADS. Think of the spaces in ADS/CFT as mathematical spaces, not physical spaces. It lets you take a model constructed in one space, translate it into another space, perform some calculations there that might be simpler and then translate them back.
• nabla9 3y ago
  Our universe can can be thought as effective de Sitter brane in an Anti-de Sitter space. Conformal 4-dimensional field theory is mapped to AdS_5×S^5
  • dustingetz 3y ago
    ChatGPT expansion: de Sitter Space: A model of the universe with a positive cosmological constant, leading to a universe that expands exponentially. It's a solution to Einstein's equations of General Relativity representing a universe dominated by dark energy. Anti-de Sitter (AdS) Space: A spacetime with a constant negative curvature. It's the opposite of de Sitter space and is a solution to Einstein's equations with a negative cosmological constant. AdS spaces are commonly used in theoretical physics, especially in string theory. Brane: Short for "membrane", in string theory and related theories, a brane is a physical object that generalizes the notion of a point particle to higher dimensions. A universe can be conceptualized as a 4-dimensional brane existing in a higher-dimensional space. Conformal Field Theory (CFT): A quantum field theory that is invariant under conformal transformations, which are transformations that locally preserve angles but not necessarily distances. CFTs are important in studying phenomena like phase transitions and in string theory. AdS/CFT Correspondence: A conjecture in theoretical physics that proposes a relationship (duality) between a type of quantum field theory (Conformal Field Theory) and a theory of gravity defined in an Anti-de Sitter space. This duality suggests that calculations done in one theory can be translated and used in the other. AdS_5: This denotes a 5-dimensional Anti-de Sitter space, often used in the context of the AdS/CFT correspondence. S^5: Refers to a 5-dimensional sphere, a higher-dimensional generalization of a usual sphere. In the context of the AdS/CFT correspondence, the theory of gravity is considered in a space that is the product of AdS_5 and S^5. The universe as an "effective de Sitter brane" in an "Anti-de Sitter (AdS) space": This suggests that our observable universe, which approximates a de Sitter space due to its accelerated expansion, can be represented as a brane (a boundary or membrane) within a higher-dimensional Anti-de Sitter space. AdS spaces are characterized by a constant negative curvature, contrasting with the positive curvature of de Sitter spaces. "Conformal 4-dimensional field theory is mapped to AdS_5×S^5": This is an instance of the AdS/CFT correspondence. It states that a 4-dimensional Conformal Field Theory (CFT), which is a quantum field theory invariant under conformal transformations, can be equivalently described by a 5-dimensional gravity theory in an Anti-de Sitter space (AdS_5) times a 5-dimensional sphere (S^5). This duality allows for the study of gravity in AdS spaces using CFTs and vice versa, providing insights into quantum gravity and string theory.