29,415 research outputs found
Certified randomness in quantum physics
The concept of randomness plays an important role in many disciplines. On one
hand, the question of whether random processes exist is fundamental for our
understanding of nature. On the other hand, randomness is a resource for
cryptography, algorithms and simulations. Standard methods for generating
randomness rely on assumptions on the devices that are difficult to meet in
practice. However, quantum technologies allow for new methods for generating
certified randomness. These methods are known as device-independent because do
not rely on any modeling of the devices. Here we review the efforts and
challenges to design device-independent randomness generators.Comment: 18 pages, 3 figure
eMoto - Affectively Involving both Body and Mind
It is known that emotions are experienced by both body and mind. Oftentimes, emotions are evoked by sub-symbolic stimuli, such as colors, shapes, gestures, or music. We have built eMoto, a mobile service for sending affective mes-sages to others, with the explicit aim of addressing such sensing. Through combining affective gestures for input with affective expressions that make use of colors, shapes and animations for the background of messages, the interac-tion pulls the user into an embodied ‘affective loop’. We present a user study of eMoto where 12 out of 18 subjects got both physically and emotionally involved in the interac-tion. The study also shows that the designed ‘openness’ and ambiguity of the expressions, was appreciated and under-stood by our subjects
Informational Substitutes
We propose definitions of substitutes and complements for pieces of
information ("signals") in the context of a decision or optimization problem,
with game-theoretic and algorithmic applications. In a game-theoretic context,
substitutes capture diminishing marginal value of information to a rational
decision maker. We use the definitions to address the question of how and when
information is aggregated in prediction markets. Substitutes characterize
"best-possible" equilibria with immediate information aggregation, while
complements characterize "worst-possible", delayed aggregation. Game-theoretic
applications also include settings such as crowdsourcing contests and Q\&A
forums. In an algorithmic context, where substitutes capture diminishing
marginal improvement of information to an optimization problem, substitutes
imply efficient approximation algorithms for a very general class of (adaptive)
information acquisition problems.
In tandem with these broad applications, we examine the structure and design
of informational substitutes and complements. They have equivalent, intuitive
definitions from disparate perspectives: submodularity, geometry, and
information theory. We also consider the design of scoring rules or
optimization problems so as to encourage substitutability or complementarity,
with positive and negative results. Taken as a whole, the results give some
evidence that, in parallel with substitutable items, informational substitutes
play a natural conceptual and formal role in game theory and algorithms.Comment: Full version of FOCS 2016 paper. Single-column, 61 pages (48 main
text, 13 references and appendix
Operational reliability assessment of the GEOS A spacecraft
Decision theory application to GEOS A spacecraft operational reliability assessmen
Narrative Quilts and Quilted Narratives: The Art of Faith Ringgold and Alice Walker
There have been two main streams of influence on Chicano artists aside from the obvious one that is the result of their artistic training, education and development in the United States. The primary influence came from Mexico, first during the colonial period in the form of New Spanish art and architecture, and then in modem times provided by the Mexican muralists through their work and their use of pre-Columbian art. The New Spanish materials formed the nucleus for the second stream of influence composed of the various manifestations of religious folk art found primarily in the Southwest
How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem
We analyze cosmology assuming unitary quantum mechanics, using a tripartite
partition into system, observer and environment degrees of freedom. This
generalizes the second law of thermodynamics to "The system's entropy can't
decrease unless it interacts with the observer, and it can't increase unless it
interacts with the environment." The former follows from the quantum Bayes
Theorem we derive. We show that because of the long-range entanglement created
by cosmological inflation, the cosmic entropy decreases exponentially rather
than linearly with the number of bits of information observed, so that a given
observer can reduce entropy by much more than the amount of information her
brain can store. Indeed, we argue that as long as inflation has occurred in a
non-negligible fraction of the volume, almost all sentient observers will find
themselves in a post-inflationary low-entropy Hubble volume, and we humans have
no reason to be surprised that we do so as well, which solves the so-called
inflationary entropy problem. An arguably worse problem for unitary cosmology
involves gamma-ray-burst constraints on the "Big Snap", a fourth cosmic
doomsday scenario alongside the "Big Crunch", "Big Chill" and "Big Rip", where
an increasingly granular nature of expanding space modifies our life-supporting
laws of physics.
Our tripartite framework also clarifies when it is valid to make the popular
quantum gravity approximation that the Einstein tensor equals the quantum
expectation value of the stress-energy tensor, and how problems with recent
attempts to explain dark energy as gravitational backreaction from
super-horizon scale fluctuations can be understood as a failure of this
approximation.Comment: Updated to match accepted PRD version, including Quantum Bayes
Theorem derivation and rigorous proof that decoherence increases von Neumann
entropy. 20 pages, 5 fig
- …