Not signed in

Want to take part in these discussions? Sign in if you have an account, or apply for one below

• Username
• Password
• Remember me

• Sign in using OpenID
• Remember me

• Forgot your password?
• Apply for membership

2-category 2-category-theory abelian-categories adjoint algebra algebraic algebraic-geometry algebraic-topology analysis analytic-geometry arithmetic arithmetic-geometry book bundles calculus categorical categories category category-theory chern-weil-theory cohesion cohesive-homotopy-type-theory cohomology colimits combinatorics complex complex-geometry computable-mathematics computer-science constructive cosmology deformation-theory descent diagrams differential differential-cohomology differential-equations differential-geometry digraphs duality elliptic-cohomology enriched fibration foundation foundations functional-analysis functor gauge-theory gebra geometric-quantization geometry graph graphs gravity grothendieck group group-theory harmonic-analysis higher higher-algebra higher-category-theory higher-differential-geometry higher-geometry higher-lie-theory higher-topos-theory homological homological-algebra homotopy homotopy-theory homotopy-type-theory index-theory integration integration-theory internal-categories k-theory lie-theory limits linear linear-algebra locale localization logic mathematics measure measure-theory modal modal-logic model model-category-theory monad monads monoidal monoidal-category-theory morphism motives motivic-cohomology nlab noncommutative noncommutative-geometry number-theory of operads operator operator-algebra order-theory pages pasting philosophy physics pro-object probability probability-theory quantization quantum quantum-field quantum-field-theory quantum-mechanics quantum-physics quantum-theory question representation representation-theory riemannian-geometry scheme schemes set set-theory sheaf simplicial space spin-geometry stable-homotopy-theory stack string string-theory superalgebra supergeometry svg symplectic-geometry synthetic-differential-geometry terminology theory topology topos topos-theory tqft type type-theory universal variational-calculus

1. • CommentRowNumber1.
   • CommentAuthorUrs
   • CommentTimeOct 30th 2019
   • PermaLink
   Author: Urs
   Format: MarkdownItexextracted the best quotes from Tom Banks' rant (yesterday's [arXiv:1910.12817](https://arxiv.org/abs/1910.12817)) on lack of rigour and non-perturbative perspective in contemporary string phenomenology. Will add some of these also to other relevant entries: *** > these considerations lead to conclusions at odds with the seemingly similar arguments of $[$ the [[swampland conjectures]] $]$. $[\cdots]$ Perturbative moduli space completely distorts the true nature of the class of consistent models. > It’s important to realize that the entire procedure just outlined for finding (meta) stable AdS minima of a non-perturbative effective potential is purely hypothetical and has no basis in well founded string theory calculations. $[\cdots].$ > The hypothesis of the String Landscape is entirely based on low energy effective field theoryideas about finding "vacua" by minimizing an effective potential. Everything that’s been said above indicates that this idea has no validity in genuine models of quantum gravity. $[\cdots]$ > The most serious issue, in my opinion, is the contention that one can make the AdS radius much larger thanthe size of the compact manifold. All well established examples of large radius AdS/CFT havea compact manifold of dimension 2 or greater whose radius is comparable to that of the AdSspace. In Appendix A we’ll present an argument based on the properties of AdS black holes,that this is in fact necessary. > The next step in the construction of "realistic" models involves "adding an anti-brane to break supersymmetry and make the c.c. positive". This is supposed to be a small modification of the model, calculable in low energy effective field theory, and that seems manifestly incorrect. $[\cdots]$. > even if one believes that the construction of meta-stable dS models is reliable, there is no clear argumentabout what the proper observables of the model are nor that different dS constructions arepart of the same model. Neither is there an interpretation of these correlators as transitionamplitudes in a quantum mechanical model. $[\cdots]$ > The conclusion that effective field theorists should draw from this is that unlike super-symmetric string models in flat or AdS space-time, many of which have at least perturbative definitions as mathematical models obeying the axioms of quantum mechanics, all literature on the String Landscape is speculation based on the unfounded notion that all string models with a given amount of SUSY are part of one single model and that it makes sense to define an effective action that encompasses all string models. Every single non-perturbative construc-tion of string models contradicts this claim $[\cdots]$ <a href="https://ncatlab.org/nlab/revision/diff/Tom+Banks/3">diff</a>, <a href="https://ncatlab.org/nlab/revision/Tom+Banks/3">v3</a>, <a href="https://ncatlab.org/nlab/show/Tom+Banks">current</a>

   extracted the best quotes from Tom Banks’ rant (yesterday’s arXiv:1910.12817) on lack of rigour and non-perturbative perspective in contemporary string phenomenology.

   Will add some of these also to other relevant entries:

   ---

   these considerations lead to conclusions at odds with the seemingly similar arguments of $[$ the swampland conjectures $]$. $[\cdots]$ Perturbative moduli space completely distorts the true nature of the class of consistent models.

   It’s important to realize that the entire procedure just outlined for finding (meta) stable AdS minima of a non-perturbative effective potential is purely hypothetical and has no basis in well founded string theory calculations. $[\cdots].$

   The hypothesis of the String Landscape is entirely based on low energy effective field theoryideas about finding “vacua” by minimizing an effective potential. Everything that’s been said above indicates that this idea has no validity in genuine models of quantum gravity. $[\cdots]$

   The most serious issue, in my opinion, is the contention that one can make the AdS radius much larger thanthe size of the compact manifold. All well established examples of large radius AdS/CFT havea compact manifold of dimension 2 or greater whose radius is comparable to that of the AdSspace. In Appendix A we’ll present an argument based on the properties of AdS black holes,that this is in fact necessary.

   The next step in the construction of “realistic” models involves “adding an anti-brane to break supersymmetry and make the c.c. positive”. This is supposed to be a small modification of the model, calculable in low energy effective field theory, and that seems manifestly incorrect. $[\cdots]$.

   even if one believes that the construction of meta-stable dS models is reliable, there is no clear argumentabout what the proper observables of the model are nor that different dS constructions arepart of the same model. Neither is there an interpretation of these correlators as transitionamplitudes in a quantum mechanical model. $[\cdots]$

   The conclusion that effective field theorists should draw from this is that unlike super-symmetric string models in flat or AdS space-time, many of which have at least perturbative definitions as mathematical models obeying the axioms of quantum mechanics, all literature on the String Landscape is speculation based on the unfounded notion that all string models with a given amount of SUSY are part of one single model and that it makes sense to define an effective action that encompasses all string models. Every single non-perturbative construc-tion of string models contradicts this claim $[\cdots]$

   diff, v3, current

2. • CommentRowNumber2.
   • CommentAuthorUrs
   • CommentTimeJun 13th 2023
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded pointer to today's: * [[Tom Banks]], *Hilbert Bundles and Holographic Space-time Models* &lbrack;[arXiv:2306.07038](https://arxiv.org/abs/2306.07038)&rbrack; <a href="https://ncatlab.org/nlab/revision/diff/Tom+Banks/10">diff</a>, <a href="https://ncatlab.org/nlab/revision/Tom+Banks/10">v10</a>, <a href="https://ncatlab.org/nlab/show/Tom+Banks">current</a>

   added pointer to today’s:

   • Tom Banks, Hilbert Bundles and Holographic Space-time Models [arXiv:2306.07038]

   diff, v10, current