• Corpus ID: 215769038

# Baby Universes, Holography, and the Swampland

@article{McNamara2020BabyUH,
title={Baby Universes, Holography, and the Swampland},
author={Jacob McNamara and Cumrun Vafa},
journal={arXiv: High Energy Physics - Theory},
year={2020}
}
• Published 14 April 2020
• Physics
• arXiv: High Energy Physics - Theory
On the basis of a number of Swampland conditions, we argue that the Hilbert space of baby universe states must be one-dimensional in a consistent theory of quantum gravity. This scenario may be interpreted as a type of "Gauss's law for entropy" in quantum gravity, and provides a clean synthesis of the tension between Euclidean wormholes and a standard interpretation of the holographic dictionary, with no need for an ensemble. Our perspective relies crucially on the recently-proposed potential…
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## References

SHOWING 1-10 OF 36 REFERENCES
Liouville theory and matrix models: a Wheeler DeWitt perspective
• Physics
• 2020
We analyse the connections between the Wheeler DeWitt approach for two dimensional quantum gravity and holography, focusing mainly in the case of Liouville theory coupled to $c=1$ matter. Our
Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information
• Physics
Journal of High Energy Physics
• 2020
In the 1980's, work by Coleman and by Giddings and Strominger linked the physics of spacetime wormholes to `baby universes' and an ensemble of theories. We revisit such ideas, using features
The String Landscape, the Swampland, and the Missing Corner
• Physics
• 2017
We give a brief overview of the string landscape and techniques used to construct string compactifications. We then explain how this motivates the notion of the swampland and review a number of
Euclidean Wormholes, Baby Universes, and Their Impact on Particle Physics and Cosmology
• Physics
Front. Astron. Space Sci.
• 2018
The euclidean path integral remains, in spite of its familiar problems, an important approach to quantum gravity. One of its most striking and obscure features is the appearance of gravitational
The factorization problem in Jackiw-Teitelboim gravity
• Physics
Journal of High Energy Physics
• 2020
In this note we study the 1 + 1 dimensional Jackiw-Teitelboim gravity in Lorentzian signature, explicitly constructing the gauge-invariant classical phase space and the quantum Hilbert space and
The world as a hologram
According to ’t Hooft the combination of quantum mechanics and gravity requires the three‐dimensional world to be an image of data that can be stored on a two‐dimensional projection much like a
Kodaira-Spencer theory of gravity and exact results for quantum string amplitudes
• Mathematics
• 1994
We develop techniques to compute higher loop string amplitudes for twistedN=2 theories withĉ=3 (i.e. the critical case). An important ingredient is the discovery of an anomaly at every genus in
Bulk locality and quantum error correction in AdS/CFT
• Physics
• 2014
A bstractWe point out a connection between the emergence of bulk locality in AdS/CFT and the theory of quantum error correction. Bulk notions such as Bogoliubov transformations, location in the
Cobordism Classes and the Swampland
• Mathematics
• 2019
We argue that any proposed quantum theory of gravity with non-trivial cobordism classes in the space of configurations belongs to the Swampland. The argument is based on the assumption that there are