# nLab Tom Banks

Selected writings

## Selected writings

Discussion of longitudinal M5-branes in the BFSS matrix model:

On the firewall problem via the BFSS matrix model:

• Tom Banks, Modern quantum field theory, A concise introduction (pdf)

On the landscape of string theory vacua (or not):

Specifically on the swampland conjectures/landscape of string theory vacua in view of non-perturbative effects in string theory (i.e. in M-theory):

• Tom Banks, The Top $10^{500}$ Reasons Not to Believe in the Landscape (arXiv:1208.5715)

• Tom Banks, On the Limits of Effective Quantum Field Theory: Eternal Inflation, Landscapes, and Other Mythical Beasts (arxiv:1910.12817)

from pages 14-22:

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 theory ideas 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 than the 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 argument about what the proper observables of the model are nor that different dS constructions are part of the same model. Neither is there an interpretation of these correlators as transition amplitudes 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 construction of string models contradicts this claim $[\cdots]$

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Last revised on March 18, 2020 at 04:47:48. See the history of this page for a list of all contributions to it.