Tunneling to Holographic Traversable Wormholes

We study nonperturbative effects of quantum gravity in a system consisting of a coupled pair of holographic CFTs. The AdS$_4$/CFT$_3$ system has three possible ground states: two copies of empty AdS, a pair of extremal AdS black holes, and an eternal AdS traversable wormhole. We give a recipe for calculating transition rates via gravitational instantons and test it by calculating the emission rate of radiation shells from a black hole. We calculate the nucleation rate of a traversable wormhole between a pair of AdS-RN black holes in the canonical and microcanonical ensembles. Our results give predictions of nonpertubative quantum gravity that can be tested in a holographic simulation.Comment: 65 pages, 2 figure

The Stranger Things of Symmetric Product Orbifold CFTs

Symmetric product orbifold theories are valuable due to their universal features at large $N$. Here we will demonstrate that they have features that are not as pervasive: we provide evidence of strange behaviour under deformations within their moduli space. To this end, we consider the symmetric product orbifold of tensor products of $\mathcal{N}=2$ super-Virasoro minimal models, and classify them according to two criteria. The first criterion is the existence of a single-trace twisted exactly marginal operator that triggers the deformation. The second criterion is a sparseness condition on the growth of light states in the elliptic genera. In this context we encounter a strange variety: theories that obey the first criterion but the second criterion falls into a Hagedorn-like growth. We explain why this may be counter-intuitive and discuss how it might be accounted for in conformal perturbation theory. We also find a new infinite class of theories that obey both criteria, which are necessary conditions for each moduli space to contain a supergravity point.Comment: 34 pages, 3 figure

Conformal field theories dual to quantum gravity with strongly coupled matter

A holographic conformal field theory is dual to semi-classical general relativity in Anti-de Sitter space coupled to matter fields. If the CFT factorizes in the large-$N$ limit, then all couplings in its dual are suppressed by the Planck scale, making the matter fields weakly interacting. We propose a mechanism to produce CFTs whose dual matter fields couple weakly to gravity, but interact strongly with each other. We achieve this by turning on exactly marginal multi-trace deformations, and quantify the effect using conformal perturbation theory.Comment: 5 pages, v3: minor changes, version as published in Phys. Rev.

How to Make Traversable Wormholes: Eternal AdS4_4 Wormholes from Coupled CFT's

We construct an eternal traversable wormhole connecting two asymptotically $\text{AdS}_4$ regions. The wormhole is dual to the ground state of a system of two identical holographic CFT's coupled via a single low-dimension operator. The coupling between the two CFT's leads to negative null energy in the bulk, which supports a static traversable wormhole. As the ground state of a simple Hamiltonian, it may be possible to make these wormholes in the lab or on a quantum computer.Comment: 33 pages, 6 figure

Detailed observations of the rippled surface of Antarctic blue ice areas

This paper presents detailed observations of the regularly rippled surface on an Antarctic blue-ice area near Svea, at five sites. The wavelength of the ripples was found to be 20-24 cm, while the wave height (crest-trough) was 1-2 cm. The ripple crests are generally oriented perpendicular to the direction of the strongest winds. Repeated measurements show that wave heights increase throughout the summer, with most ablation occurring in the wave troughs. This implies that traditional methods of measuring ablation (such as stakes when a rod on the ice surface is used to define a mean surface height) tend to underestimate total ablation because they sample only crests. One site exhibited significant migration of the surface ripples of about 2 cm month-1 in the downwind direction, whereas three other sites showed no significant wave movement. The formation and the specific characteristics of the surface ripples are most likely caused by self-amplifying interaction mechanisms between the free ice surface and the overlying turbulent atmosphere, which necessarily involve spatial variations in sublimation. A simple model was used to quantify the interaction between the surface ripples, the airflow aloft and the sublimation rate. The model is able to predict wavelengths and migration rates that are in reasonable agreement with the observations

Deforming Symmetric Product Orbifolds: A tale of moduli and higher spin currents

We analyze how deforming symmetric product orbifolds of two-dimensional $\mathcal{N}=2$ conformal field theories by an exactly marginal operator lifts higher spin currents present at the orbifold point. We find on the one hand that these currents are universally lifted regardless of the underlying CFT. On the other hand the details of the lifting are surprisingly non-universal, with dependence on the central charge of the underlying CFT and the specific marginal operator in use. In the context of the AdS/CFT correspondence, our results illustrate the mechanism by which the stringy spectrum turns into a supergravity spectrum when moving through the moduli space. They also provide further evidence that symmetric product orbifolds of $\mathcal{N}=2$ minimal models are holographic.Comment: 47 pages, v2: minor change

Impacts of Arctic precipitation changes on the downwelling limb of the Atlantic Meridional Overturning Circulation

According to the latest IPCC report, under the RCP 8.5 scenario precipitation in the Arctic region may increase by as much as 50%. The projected 21stcentury decline of the Atlantic Meridional Overturning Circulation (AMOC) is attributed in part to this increase in precipitation and the associated river run-off. Here we analyze a set of 44-year long coupled climate model simulations in which only the precipitation between 70N and 90N is varied, to assess the impacts of the projected Arctic precipitation increase on deep ocean convection and the downward transport of dense waters that constitutes the downwelling limb of the AMOC. With a 50% increase in Arctic precipitation, mixed layer depths in the Nordic Seas and Labrador Seas reduce substantially, albeit with a longer response time in the latter. A 400% precipitation increase completely inhibits deep mixing. At the same time, the simulations display a 10%-50% reduction of the overturning strength, showing that a shutdown of convection does not automatically result in a shutdown of the AMOC. Theoretical studies have pointed out that, while dense water formation in the marginal seas is important for the density structure of the deep ocean, the downward volume transport associated with the AMOC is governed by oceanic conditions along the continental boundary of the North Atlantic Ocean (Iceland Basin, Irminger and Labrador Seas). In addition, the overflows along the Greenland-Scotland Ridge contribute to the AMOC. In the simulation for the present-day climate, the contributions of these two processes are of similar magnitude. The overflow transports are unaffected by a 50% increase in Arctic precipitation. In contrast, the sinking along the boundary of the North Atlantic Ocean reduces by roughly 60%. When the Arctic precipitation is increased by 400%, a clear decline in the overflows is simulated as well. In this study, we analyze the physical processes responsible for these changes in the downwelling transport