85 research outputs found
Energy and Information Near Black Hole Horizons
The central challenge in trying to resolve the firewall paradox is to
identify excitations in the near-horizon zone of a black hole that can carry
information without injuring a freely falling observer. By analyzing the
problem from the point of view of a freely falling observer, I arrive at a
simple proposal for the degrees of freedom that carry information out of the
black hole. An infalling observer experiences the information-carrying modes as
ingoing, negative energy excitations of the quantum fields. In these states,
freely falling observers who fall in from infinity do not encounter a firewall,
but freely falling observers who begin their free fall from a location close to
the horizon are "frozen" by a flux of negative energy. When the black hole is
"mined," the number of information-carrying modes increases, increasing the
negative energy flux in the infalling frame without violating the equivalence
principle. Finally, I point out a loophole in recent arguments that an
infalling observer must detect a violation of unitarity, effective field
theory, or free infall.Comment: 25 pages, 3 figures. v2: minor clarifications, references added;
published versio
Asymptotic states of the bounce geometry
We consider the question of asymptotic observables in cosmology. We assume
that string theory contains a landscape of vacua, and that metastable de Sitter
regions can decay to zero cosmological constant by bubble nucleation. The
asymptotic properties of the corresponding bounce solution should be
incorporated in a nonperturbative quantum theory of cosmology. A recent
proposal for such a framework defines an S-matrix between the past and future
boundaries of the bounce. We analyze in detail the properties of asymptotic
states in this proposal, finding that generic small perturbations of the
initial state cause a global crunch. We conclude that late-time amplitudes
should be computed directly. This would require a string theory analogue of the
no-boundary proposal.Comment: 20 pages, 7 figures. v2: reference adde
Probabilities in the landscape: The decay of nearly flat space
We discuss aspects of the problem of assigning probabilities in eternal
inflation. In particular, we investigate a recent suggestion that the lowest
energy de Sitter vacuum in the landscape is effectively stable. The associated
proposal for probabilities would relegate lower energy vacua to unlikely
excursions of a high entropy system. We note that it would also imply that the
string theory landscape is experimentally ruled out. However, we extensively
analyze the structure of the space of Coleman-De Luccia solutions, and we
present analytic arguments, as well as numerical evidence, that the decay rate
varies continuously as the false vacuum energy goes through zero. Hence,
low-energy de Sitter vacua do not become anomalously stable; negative and zero
cosmological constant regions cannot be neglected.Comment: 18 pages, 13 figures, Mathematica notebooks available from the
authors. v2,v3: typos and omissions fixe
Precursors, Gauge Invariance, and Quantum Error Correction in AdS/CFT
A puzzling aspect of the AdS/CFT correspondence is that a single bulk
operator can be mapped to multiple different boundary operators, or precursors.
By improving upon a recent model of Mintun, Polchinski, and Rosenhaus, we
demonstrate explicitly how this ambiguity arises in a simple model of the field
theory. In particular, we show how gauge invariance in the boundary theory
manifests as a freedom in the smearing function used in the bulk-boundary
mapping, and explicitly show how this freedom can be used to localize the
precursor in different spatial regions. We also show how the ambiguity can be
understood in terms of quantum error correction, by appealing to the
entanglement present in the CFT. The concordance of these two approaches
suggests that gauge invariance and entanglement in the boundary field theory
are intimately connected to the reconstruction of local operators in the dual
spacetime.Comment: 25 pages, 6 figure
Fast and Slow Coherent Cascades in Anti-de Sitter Spacetime
We study the phase and amplitude dynamics of small perturbations in 3+1
dimensional Anti-de Sitter spacetime using the truncated resonant
approximation, also known as the Two Time Framework (TTF). We analyse the phase
spectrum for different classes of initial data and find that higher frequency
modes turn on with coherently aligned phases. Combining numerical and
analytical results, we conjecture that there is a class of initial conditions
that collapse in infinite slow time and to which the well-studied case of the
two-mode, equal energy initial data belongs. We additionally study
perturbations that collapse in finite time, and find that the energy spectrum
approaches a power law, with the energy per mode scaling approximately as the
inverse first power of the frequency.Comment: 19 pages, multiple figures. v2: version published in CQ
A geometric solution to the coincidence problem, and the size of the landscape as the origin of hierarchy
Without assuming necessary conditions for observers such as galaxies or
entropy production, we show that the causal patch measure predicts the
coincidence of vacuum energy and present matter density. Their common scale,
and thus the enormous size of the visible universe, has its origin in the
number of metastable vacua in the landscape.Comment: 5 pages, 2 figures. v2: minor editin
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