Interface to future holographic cosmology work

On a chosen spatially flat inflationary branch, let $t\in I$ be proper time of length dimension, $x^i$ dimensionless comoving coordinates, and $a:I\to (0,\mathrm{\infty })$ a smooth scale factor of length dimension with $\dot{a}>0$ and $d^{2}a\mathrm{/}d{t}^2>0$. In units $\mathrm{\hslash }=c_{\mathrm{l}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}}=1$, the line element is $d{s}^2=-d{t}^2+a(t{)}^2{\delta }_{ij}d{x}^{i}d{x}^j$ and the expansion rate is $H(t):=\dot{a}\mathrm{/}a$. Let $k_L,k_S>0$ be long- and short-wavelength comoving wave numbers; the squeezed limit is $k_L\mathrm{/}{k}_S\to 0$. AdS denotes an anti-de Sitter spacetime, a maximally symmetric Lorentzian spacetime of constant negative curvature, and CFT denotes a quantum field theory invariant under conformal transformations. AdS/CFT is the proposed correspondence between a gravitational theory on a $D$-dimensional AdS bulk and a $(D-1)$-dimensional boundary CFT. A wavefunction-of-the-universe proposal assigns an amplitude to specified boundary geometry and field data under a stated semiclassical boundary prescription. A cosmological-collider proposal seeks characteristic primordial correlation-function signatures of fields with mass comparable to the Hubble scale $H$; the mass-sensitive terms are sought in the squeezed limit just defined. A holographic measure would be a proposed weighting of cosmological states or histories derived from a boundary description; no such measure is adopted here. These proposals are contextual interfaces to the future Holography and Quantum Black Holes category, whose later definitions and proof statuses are not prerequisites for the local EFT, flux-statistics, observational or conjecture-formulation items in R5.

The retrieved review's §7.9 treats these as proposals and research directions. Arkani-Hamed and Maldacena, §1, analyze a particular inflationary mechanism in which fields of mass comparable to $H$ may contribute oscillatory or power-law terms to primordial correlators in the squeezed limit; this remark imports no such model or prediction. No holographic dictionary, cosmological probability measure, or local prediction is supplied here.

M. Cicoli, J. P. Conlon, A. Maharana, S. Parameswaran, F. Quevedo and I. Zavala, String Cosmology: from the Early Universe to Today, arXiv:2303.04819v2

Kay Lehnert, Hitchhiker’s Guide to the Swampland, arXiv:2509.02632v1

N. Arkani-Hamed and J. Maldacena, Cosmological Collider Physics, arXiv:1503.08043v1