21,585 research outputs found
The Problem of Confirmation in the Everett Interpretation
I argue that the Oxford school Everett interpretation is internally
incoherent, because we cannot claim that in an Everettian universe the kinds of
reasoning we have used to arrive at our beliefs about quantum mechanics would
lead us to form true beliefs. I show that in an Everettian context, the
experimental evidence that we have available could not provide empirical
confirmation for quantum mechanics, and moreover that we would not even be able
to establish reference to the theoretical entities of quantum mechanics. I then
consider a range of existing Everettian approaches to the probability problem
and show that they do not succeed in overcoming this incoherence
Pseudo Label Selection is a Decision Problem
Pseudo-Labeling is a simple and effective approach to semi-supervised
learning. It requires criteria that guide the selection of pseudo-labeled data.
The latter have been shown to crucially affect pseudo-labeling's generalization
performance. Several such criteria exist and were proven to work reasonably
well in practice. However, their performance often depends on the initial model
fit on labeled data. Early overfitting can be propagated to the final model by
choosing instances with overconfident but wrong predictions, often called
confirmation bias. In two recent works, we demonstrate that pseudo-label
selection (PLS) can be naturally embedded into decision theory. This paves the
way for BPLS, a Bayesian framework for PLS that mitigates the issue of
confirmation bias. At its heart is a novel selection criterion: an analytical
approximation of the posterior predictive of pseudo-samples and labeled data.
We derive this selection criterion by proving Bayes-optimality of this "pseudo
posterior predictive". We empirically assess BPLS for generalized linear,
non-parametric generalized additive models and Bayesian neural networks on
simulated and real-world data. When faced with data prone to overfitting and
thus a high chance of confirmation bias, BPLS outperforms traditional PLS
methods. The decision-theoretic embedding further allows us to render PLS more
robust towards the involved modeling assumptions. To achieve this goal, we
introduce a multi-objective utility function. We demonstrate that the latter
can be constructed to account for different sources of uncertainty and explore
three examples: model selection, accumulation of errors and covariate shift.Comment: Accepted for presentation at the 46th German Conference on Artificial
Intelligenc
Are black holes about information?
Information theory is increasingly invoked by physicists concerned with
fundamental physics, including black hole physics. But to what extent is the
application of information theory in those contexts legitimate? Using the case
of black hole thermodynamics and Bekenstein's celebrated argument for the
entropy of black holes, I will argue that information-theoretic notions are
problematic in the present case. Bekenstein's original argument, as suggestive
as it may appear, thus fails. This example is particularly pertinent to the
theme of the present collection because the Bekenstein-Hawking formula for
black hole entropy is widely accepted as 'empirical data' in notoriously
empirically deprived quantum gravity, even though the laws of black hole
thermodynamics have so far evaded empirical confirmation.Comment: 20 pages; forthcoming in Richard Dawid, Radin Dardashti, and Karim
Th\'ebault (eds.), Epistemology of Fundamental Physics, Cambridge University
Press; minor changes and additions of reference
The Logic of Experimental Tests, Particularly of Everettian Quantum Theory
Claims that the standard methodology of scientific testing is inapplicable to
Everettian quantum theory, and hence that the theory is untestable, are due to
misconceptions about probability and about the logic of experimental testing.
Refuting those claims by correcting those misconceptions leads to various
simplifications, notably the elimination of everything probabilistic from
fundamental physics (stochastic processes) and from the methodology of testing
('Bayesian' credences)
Anisotropic finite-size scaling analysis of a three-dimensional driven-diffusive system
We study the standard three-dimensional driven diffusive system on a simple
cubic lattice where particle jumps along a given lattice direction are biased
by an infinitely strong field, while those along other directions follow the
usual Kawasaki dynamics. Our goal is to determine which of the several existing
theories for critical behavior is valid. We analyze finite-size scaling
properties using a range of system shapes and sizes far exceeding previous
studies. Four different analytic predictions are tested against the numerical
data. Binder and Wang's prediction does not fit the data well. Among the two
slightly different versions of Leung, the one including the effects of a
dangerous irrelevant variable appears to be better. Recently proposed isotropic
finite-size scaling is inconsistent with our data from cubic systems, where
systematic deviations are found, especially in scaling at the critical
temperature.Comment: 12 pages, 14 PS figures, RevTeX; extensively revise
Mirror Symmetry and Other Miracles in Superstring Theory
The dominance of string theory in the research landscape of quantum gravity
physics (despite any direct experimental evidence) can, I think, be justified
in a variety of ways. Here I focus on an argument from mathematical fertility,
broadly similar to Hilary Putnam's 'no miracles argument' that, I argue, many
string theorists in fact espouse. String theory leads to many surprising,
useful, and well-confirmed mathematical 'predictions' - here I focus on mirror
symmetry. These predictions are made on the basis of general physical
principles entering into string theory. The success of the mathematical
predictions are then seen as evidence for framework that generated them. I
attempt to defend this argument, but there are nonetheless some serious
objections to be faced. These objections can only be evaded at a high
(philosophical) price.Comment: For submission to a Foundations of Physics special issue on "Forty
Years Of String Theory: Reflecting On the Foundations" (edited by G. `t
Hooft, E. Verlinde, D. Dieks and S. de Haro)
Consciousness as Integrated Information: A Provisional Philosophical Critique
Giulio Tononi (2008) has offered his integrated information theory of consciousness (IITC) as a ‘provisional manifesto’. I critically examine how the approach fares. I point out some (relatively) internal concerns with the theory and then more broadly philosophical ones; finally I assess the prospects for IITC as a fundamental theory of consciousness. I argue that the IITC’s scientific promise does carry over to a significant extent to broader philosophical theorizing about qualia and consciousness, though not as directly as Tononi suggests, since the account is much more focused on the qualitative character of experience rather than on consciousness itself. I propose understanding it as ‘integrated information theory of qualia’(IITQ), rather than of consciousness
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