Randomness and Irreversiblity in Quantum Mechanics: A Worked Example for a Statistical Theory

The randomness of some irreversible quantum phenomena is a central question because irreversible phenomena break quantum coherence and thus yield an irreversible loss of information. The case of quantum jumps observed in the fluorescence of a single two-level atom illuminated by a quasi-resonant laser beam is a worked example where statistical interpretations of quantum mechanics still meet some difficulties because the basic equations are fully deterministic and unitary. In such a problem with two different time scales, the atom makes coherent optical Rabi oscillations between the two states, interrupted by random emissions (quasi-instantaneous) of photons where coherence is lost. To describe this system, we already proposed a novel approach, which is completed here. It amounts to putting a probability on the density matrix of the atom and deducing a general “kinetic Kolmogorov-like” equation for the evolution of the probability. In the simple case considered here, the probability only depends on a single variable θ describing the state of the atom, and p(θ,t) yields the statistical properties of the atom under the joint effects of coherent pumping and random emission of photons. We emphasize that p(θ,t) allows the description of all possible histories of the atom, as in Everett’s many-worlds interpretation of quantum mechanics. This yields solvable equations in the two-level atom case.

Branch-counting in the Everett interpretation of quantum mechanics

A defence is offered of a version of the branch-counting rule in the Everett interpretation (otherwise known as many worlds interpretation) of quantum mechanics that both depends on the state and is continuous in the norm topology on Hilbert space. The well-known branch-counting rule, for realistic models of measurements, in which branches are defined by decoherence theory, fails this test. The new rule hinges on the use of decoherence theory in defining branching structure, and specifically decoherent histories theory. On this basis ratios of branch numbers are defined, free of any convention. They agree with the Born rule and deliver a notion of objective probability similar to naive frequentism, save that the frequencies of outcomes are not confined to a single world at different times, but spread over worlds at a single time. Nor is it ad hoc : it is recognizably akin to the combinatorial approach to thermodynamic probability, as introduced by Boltzmann in 1879. It is identical to the procedure followed by Planck, Bose, Einstein and Dirac in defining the equilibrium distribution of the Bose–Einstein gas. It also connects in a simple way with the decision-theory approach to quantum probability.

Communicating an Empire and Its Many Worlds: Spanish American Mail, Logistics, and Postal Agents, 1492–1620

This article examines the principles underlying Spanish American mail during the government of the first Hapsburgs. I propose that this mail system, in which official and unofficial postal services coexisted, allowed for an intense communicational experience; rather than restricting correspondence, mail circulated at unprecedented levels. To understand this system's rationale I focus on the figure of the correos mayores, who were responsible for the distribution of official information (or information of interest to the crown) within certain Spanish American cities. Using sources in American and European archives, I question the premise that Spanish American communication was chaotic during this period. I also argue that the exceptional circulation of mail within Spanish America and overseas during the sixteenth century is essential for understanding European expansion and the early modern world.

THE PASSAGE TO OTHER WORLDS: FROM MORAL EDIFICATION TO COLLAPSE OF ALL VALUES

Is space relevant in a debate over the ethical dimension of a literary work? If we understand it as Foucault[1], Lefebvre[2], Soja[3] or Marc Auger[4] do, it is. In Andre Norton’s The Crossroads of Time[5], many worlds coexist as versions of an original earth, ruined by wars whose memories set agents under cover travelling across in order to defend what had remained of humanity besieged by monsters against a universal murderer, Kmoat Vo Pranj. The characters’ psychic powers depend on their interference with the environment – an idea probably originating with quantum experiments whose results depend on the interference of the measuring equipment with the system. An agent talks about alternative histories in an ecological version which relates individuals’ growth or success to favourable conditions in the world out there, to their or society’s benefit

Unsupervised Outlier Detection: A Meta-Learning Algorithm Based on Feature Selection

Outlier detection refers to the problem of the identification and, where appropriate, the elimination of anomalous observations from data. Such anomalous observations can emerge due to a variety of reasons, including human or mechanical errors, fraudulent behaviour as well as environmental or systematic changes, occurring either naturally or purposefully. The accurate and timely detection of deviant observations allows for the early identification of potentially extensive problems, such as fraud or system failures, before they escalate. Several unsupervised outlier detection methods have been developed; however, there is no single best algorithm or family of algorithms, as typically each relies on a measure of `outlierness’ such as density or distance, ignoring other measures. To add to that, in an unsupervised setting, the absence of ground-truth labels makes finding a single best algorithm an impossible feat even for a single given dataset. In this study, a new meta-learning algorithm for unsupervised outlier detection is introduced in order to mitigate this problem. The proposed algorithm, in a fully unsupervised manner, attempts not only to combine the best of many worlds from the existing techniques through ensemble voting but also mitigate any undesired shortcomings by employing an unsupervised feature selection strategy in order to identify the most informative algorithms for a given dataset. The proposed methodology was evaluated extensively through experimentation, where it was benchmarked and compared against a wide range of commonly-used techniques for outlier detection. Results obtained using a variety of widely accepted datasets demonstrated its usefulness and its state-of-the-art results as it topped the Friedman ranking test for both the area under receiver operating characteristic (ROC) curve and precision metrics when averaged over five independent trials.

Globalization, deglobalization and knowledge production

Although globalization processes have brought the world closer through the exchange of knowledge, ideas and practices, advances in knowledge dissemination have not been mirrored by expansion in sites and modes of knowledge production. This article probes this disjuncture and asks how deglobalization might chart different pathways by delving into the intellectual history of the making of International Relations (IR). Focusing its gaze on the structuring principles of knowledge creation and modes of knowing rather than specific issues and problematiques of IR, it analyses the historical impact of western Enlightenment thinking through centuries-long imperialism, which continues to limit the agency of many states in the re-making of their life-worlds. The article describes deglobalization as a longue durée historical response that offers different possibilities for countering or challenging the discursive hegemony of the ‘West’. It discusses a ‘nationalist’ response by China—a rising power and a more dispersed, global academic endeavour seeking to decolonize IR's modes of knowledge production to better account for the diverse ground realities of its many worlds.