9,705 research outputs found

    Interests without History: Some Difficulties for a Negative Aristotelianism

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    This paper focuses on 3 features of Freyenhagen's Aristotelian version of Adorno. (a) It challenges the strict negativism Freyenhagen finds in Adorno. If we have morally relevant interests in ourselves, it is implicit that we have a standard by which to understand what is both good and bad for us (our interests). Because strict negativism operates without reference to what is good, it seems to be detached from real interests too. Torture, it is argued, is, among other things, a violation of those interests. (b) Freyenhagen identifies the “impulse” in Adorno as an untutored yet moral reaction to morally demanding situations. The plausibility of this primitivism and its compatibility with Adorno's general worries about immediacy are considered. (c) The disruptive character of Adorno's version of the categorical imperative, its willingness to complicate action through wholesale reflection on the norms of what we are committing ourselves to, is set in contrast with Freyenhagen's Aristotelian claim that certain notions, such as “humanity,” cannot be intelligibly questioned

    "Get Up, Stand Up!": a spirituality of resistance and action

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    This article was originally published in The Prophet -- a journal created by and for the students at the Boston University School of Theology (BUSTH) to amplify the voices of STH students by promoting and sharing a range of perspectives on matters of concern including, but not limited to, spiritual practices, faith communities and society, the nature of theology, and current affairs. It serves as a platform for STH students to share their academic work, theological reflections, and life experiences with one another and the wider community."Most people have encountered the power and intensity behind the inflection of the imperatives words "Get Up, Stand Up!"... " [EXCERPT

    Electric charge is a magnetic dipole when placed in a background magnetic field

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    It is demonstrated, owing to the nonlinearity of QED, that a static charge placed in a strong magnetic field\ BB\ is a magnetic dipole (besides remaining an electric monopole, as well). Its magnetic moment grows linearly with BB as long as the latter remains smaller than the characteristic value of 1.2\cdot 10^{13}\unit{G} but tends to a constant as BB exceeds that value. The force acting on a densely charged object by the dipole magnetic field of a neutron star is estimated

    Magnetic response to applied electrostatic field in external magnetic field

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    We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to a simple example of a spherically-symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space, the pattern of lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics

    Particle creation from the vacuum by an exponentially decreasing electric field

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    We analyze the creation of fermions and bosons from the vacuum by the exponentially decreasing in time electric field in detail. In our calculations we use QED and follow in main the consideration of particle creation effect in a homogeneous electric field. To this end we find complete sets of exact solutions of the dd-dimensional Dirac equation in the exponentially decreasing electric field and use them to calculate all the characteristics of the effect, in particular, the total number of created particles and the probability of a vacuum to remain a vacuum. It should be noted that the latter quantities were derived in the case under consideration for the first time. All possible asymptotic regimes are discussed in detail. In addition, switching on and switching off effects are studied.Comment: We add some references and minor comments. Version accepted for publication in Physica Scripta as a Invited Commen

    Magnetic response from constant backgrounds to Coulomb sources

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    Magnetically uncharged, magnetic linear response of the vacuum filled with arbitrarily combined constant electric and magnetic fields to an imposed static electric charge is found within general nonlinear electrodynamics. When the electric charge is point-like and external fields are parallel, the response found may be interpreted as a field of two point-like magnetic charges of opposite polarity in one point. Coefficients characterizing the magnetic response and induced currents are specialized to Quantum Electrodynamics, where the nonlinearity is taken as that determined by the Heisenberg-Euler effective Lagrangian.Comment: The part dealing with magnetically charged responses is removed to be a subject of another paper after revisio

    Noncommutative magnetic moment, fundamental length and lepton size

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    Upper bounds on fundamental length are discussed that follow from the fact that a magnetic moment is inherent in a charged particle in noncommutative (NC) electrodynamics. The strongest result thus obtained for the fundamental lenth is still larger than the estimate of electron or muon size achieved following the Brodsky-Drell and Dehlmet approach to lepton compositeness. This means that NC electrodynamics cannot alone explain the whole existing descrepancy between the theoretical and experimental values of the muon magnetic moment. On the contrary, as measurements and calculations are further improved, the fundamental length estimate based on electron data may go down to match its compositeness radius

    Enhancement of electron spin lifetime in GaAs crystals: the benefits of dichotomous noise

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    The electron spin relaxation process in n-type GaAs crystals driven by a fluctuating electric field is investigated. Two different sources of fluctuations are considered: (i) a symmetric dichotomous noise and (ii) a Gaussian correlated noise. Monte Carlo numerical simulations show, in both cases, an enhancement of the spin relaxation time by increasing the amplitude of the external noise. Moreover, we find that the electron spin lifetime versus the noise correlation time: (i) increases up to a plateau in the case of dichotomous random fluctuations, and (ii) shows a nonmonotonic behaviour with a maximum in the case of bulks subjected to a Gaussian correlated noise.Comment: 6 pages, 3 figure
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