Physics Research Works
http://hdl.handle.net/1903/1597
2015-08-23T08:29:18ZCollective phenomena in granular and atmospheric electrification
http://hdl.handle.net/1903/16867
Collective phenomena in granular and atmospheric electrification
Nordsiek, Freja; Lathrop, Daniel
This repository contains data from the Granular Electrification Experiment in the University of Maryland Nonlinear Dynamics Lab. The experiment consists of a cylindrical cell with aluminum plates on the top and bottom. The cell is filled with granular particles and shaken vertically for several cycles. The vertical position of the cell and the electric potential between the top and bottom endplates of the cell are acquired. The data in this repository is from experiments in which the cylindrical cell is filled with only one type of particle. One exception uses two types of particles, pointed out below. A particle type is comprised of its material, form (spheres or powder), and size range. The acceleration timeseries of the shaking is approximately a square wave with amplitude a, meaning that the vertical position is approximately a sequence of parabolas of alternating concavity. The stroke-length of the oscillation is 10.0 cm. The shaking strength is quantified as a/g where g is the free fall acceleration due to gravity on Earth. The amount of particles is quantified by the dimensionless parameter lambda = 2 N_p d^2 / (3 D^2) where N_p is the number of particles, d is the particle diameter (or effective diameter), and D is the diameter of the cell.
See README.txt
2015-07-29T00:00:00ZSupplementary Material: “Because math”: Epistemological stance or defusing social tension in QM?
http://hdl.handle.net/1903/16748
Supplementary Material: “Because math”: Epistemological stance or defusing social tension in QM?
Sohr, Erin Ronayne; Dreyfus, Benjamin W.; Gupta, Ayush; Elby, Andrew
This document provides supporting materials for a paper submitted for review to the Physics Education Research Conference proceedings in 2015 titled, “‘Because math’: Epistemological stance or defusing social tension in QM?” It includes 3 sections: (1) Introduction, (2) Transcript data, and (3) the Particle in a Box tutorial worksheet relevant to the data.
2015-01-01T00:00:00ZProblems with the Newton–Schrödinger equations
http://hdl.handle.net/1903/16000
Problems with the Newton–Schrödinger equations
Anastopoulos, C; Hu, B.L.
We examine the origin of the Newton–Schrödinger equations (NSEs) that play an important role in alternative quantum theories (AQT), macroscopic quantum mechanics and gravity-induced decoherence. We show that NSEs for individual particles do not follow from general relativity (GR) plus quantum field theory (QFT). Contrary to what is commonly assumed, the NSEs are not the weak-field (WF), non-relativistic (NR) limit of the semi-classical Einstein equation (SCE) (this nomenclature is preferred over the ‘Moller–Rosenfeld equation’) based on GR+QFT. The wave-function in the NSEs makes sense only as that for a mean field describing a system of N particles as N → ∞, not that of a single or finite many particles. From GR+QFT the gravitational self-interaction leads to mass
renormalization, not to a non-linear term in the evolution equations of some AQTs. The WF-NR limit of the gravitational interaction in GR+QFT involves no dynamics. To see the contrast, we give a derivation of the equation (i) governing the many-body wave function from GR+QFT and (ii) for the nonrelativistic limit of quantum electrodynamics. They have the same structure, being linear, and very different from NSEs. Adding to this our earlier consideration that for gravitational decoherence the master equations based on GR +QFT lead to decoherence in the energy basis and not in the position basis, despite some AQTs desiring it for the ‘collapse of the wave function’, we conclude that the origins and consequences of NSEs are very different, and should be clearly demarcated from those of the SCE equation, the only legitimate representative of semiclassical gravity, based on GR+QFT.
Funding for Open Access provided by the UMD Libraries Open Access Publishing Fund.
2014-08-01T00:00:00ZGlobal Inequality in Energy Consumption from 1980 to 2010
http://hdl.handle.net/1903/15855
Global Inequality in Energy Consumption from 1980 to 2010
Lawrence, Scott; Liu, Qin; Yakovenko, Victor M.
We study the global probability distribution of energy consumption per capita
around the world using data from the U.S. Energy Information Administration (EIA) for
1980–2010. We find that the Lorenz curves have moved up during this time period, and the
Gini coefficient, G, has decreased from 0.66 in 1980 to 0.55 in 2010, indicating a decrease
in inequality. The global probability distribution of energy consumption per capita in 2010 is
close to the exponential distribution with G = 0.5. We attribute this result to the globalization
of the world economy, which mixes the world and brings it closer to the state of maximal
entropy. We argue that global energy production is a limited resource that is partitioned
among the world population. The most probable partition is the one that maximizes entropy,
thus resulting in the exponential distribution function. A consequence of the latter is the law
of 1/3: the top 1/3 of the world population consumes 2/3 of produced energy. We also find
similar results for the global probability distribution of CO2 emissions per capita.
Funding for Open Access provided by the UMD Libraries Open Access Publishing Fund.
2013-12-16T00:00:00Z