14,915 research outputs found
Little Boxes: The Simplest Demonstration of the Failure of Einstein's Attempt to Show the Incompleteness of Quantum Theory
The failure of Einstein's co-authored "EPR" attempt to show the
incompleteness of quantum theory is demonstrated directly for spatial degrees
of freedom using only elementary notions. A GHZ construction is realized in the
position properties of three particles whose quantum waves are distributed over
three two-chambered boxes. The same system is modeled more realistically using
three spatially separated, singly ionized hydrogen molecules.Comment: To appear in American Journal of Physic
Induction without Probabilities
A simple indeterministic system is displayed and it is urged that we cannot responsibly infer inductively over it if we presume that the probability calculus is the appropriate logic of induction. The example illustrates the general thesis of a material theory of induction, that the logic appropriate to a particular domain is determined by the facts that prevail there
How Hume and Mach Helped Einstein Find Special Relativity
In recounting his discovery of special relativity, Einstein recalled a debt to the philosophical writings of Hume and Mach. I review the path Einstein took to special relativity and urge that, at a critical juncture, he was aided decisively not by any specific doctrine of space and time, but by a general account of concepts that Einstein found in Hume and Mach’s writings. That account required that concepts, used to represent the physical, must be properly grounded in experience. In so far as they extended beyond that grounding, they were fictional and to be abjured (Mach) or at best tolerated (Hume). Einstein drew a different moral. These fictional concepts revealed an arbitrariness in our physical theorizing and may still be introduced through freely chosen definitions, as long as these definitions do not commit us to false presumptions. After years of failed efforts to conform electrodynamics to the principle of relativity and with his frustration mounting, Einstein applied this account to the concept of simultaneity. The resulting definition of simultaneity provided the reconceptualization that solved the problem in electrodynamics and led directly to the special theory of relativity
The periods of the intermediate polar RX J0153.3+7446
We present the first optical photometry of the counterpart to the candidate
intermediate polar RX J0153.3+7446. This reveals an optical pulse period of
2333s +/- 5s. Reanalysis of the previously published ROSAT X-ray data reveals
that the true X-ray pulse period is probably 1974s +/- 30s, rather than the
1414 s previously reported. Given that the previously noted orbital period of
the system is 3.94 h, we are able to identify the X-ray pulse period with the
white dwarf spin period and the optical pulse period with the rotation period
of the white dwarf in the binary reference frame, as commonly seen in other
intermediate polars. We thus confirm that RX J0153.3+7446 is indeed a typical
intermediate polar.Comment: 4 pages, submitted to A&A Letter
Fecal incontinence: the quality of reported randomized, controlled trials in the last ten years.
This study was designed to analyze the characteristics and the quality of reporting of randomized, controlled trials published during the last ten years on fecal incontinence
Software control for large scale on-board checkout: A concept
Two level system checkout in which first level satisfies continuous monitoring requirements and second level provides fault isolation to satisfy maintenance requirements, provides self-checking capability for monitoring system and enables recovery from unexpected error or failure interruptions. System must perform operational duties of navigation, control, and experimentation
Heat addition to a subsonic boundary layer: A preliminary analytical study
A preliminary analytical study of the effects of heat addition to the subsonic boundary layer flow over a typical airfoil shape is presented. This phenomenon becomes of interest in the space shuttle mission since heat absorbed by the wing structure during re-entry will be rejected to the boundary layer during the subsequent low speed maneuvering and landing phase. A survey of existing literature and analytical solutions for both laminar and turbulent flow indicate that a heated surface generally destabilizes the boundary layer. Specifically, the boundary layer thickness is increased, the skin friction at the surface is decreased and the point of flow separation is moved forward. In addition, limited analytical results predict that the angle of attack at which a heated airfoil will stall is significantly less than the stall angle of an unheated wing. These effects could adversely affect the lift and drag, and thus the maneuvering capabilities of booster and orbiter shuttle vehicles
Principles of Discrete Time Mechanics: IV. The Dirac Equation, Particles and Oscillons
We apply the principles of discrete time mechanics discussed in earlier
papers to the first and second quantised Dirac equation. We use the Schwinger
action principle to find the anticommutation relations of the Dirac field and
of the particle creation operators in the theory. We find new solutions to the
discrete time Dirac equation, referred to as oscillons on account of their
extraordinary behaviour. Their principal characteristic is that they oscillate
with a period twice that of the fundamental time interval T of our theory.
Although these solutions can be associated with definite charge, linear
momentum and spin, such objects should not be observable as particles in the
continuous time limit. We find that for non-zero T they correspond to states
with negative squared norm in Hilbert space. However they are an integral part
of the discrete time Dirac field and should play a role in particle
interactions analogous to the role of longitudinal photons in conventional
quantum electrodynamics.Comment: 27 pages LateX; published versio
Testing and analyses of electrochemical cells using frequency response
The feasibility of electrochemical impedance spectroscopy as a method for analyzing battery state of health and state of charge was investigated. Porous silver, zinc, nickel, and cadmium electrodes as well as silver/zinc cells were studied. State of charge could be correlated with impedance data for all but the nickel electrodes. State of health was correlated with impedance data for two silver/zinc cells, one apparently good and the other dead. The experimental data were fit to equivalent circuit models
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