10,358 research outputs found

    The election, God, Advent, and figuring out where the light is

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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.A reflection by Kate Froehlic

    A Microscopic Derivation of the Time-Dependent Hartree-Fock Equation with Coulomb Two-Body Interaction

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    We study the dynamics of a Fermi gas with a Coulomb interaction potential, and show that, in a mean-field limiting regime, the dynamics is described by the Hartree-Fock equation. This extends previous work of Bardos et al. to the case of unbounded interaction potentials. We also express the mean-field limit as a "superhamiltonian" system, and state our main result in terms of a Heisenberg-picture dynamics of observables. This is a Egorov-type theorem

    Lie-Schwinger block-diagonalization and gapped quantum chains

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    We study quantum chains whose Hamiltonians are perturbations by bounded interactions of short range of a Hamiltonian that does not couple the degrees of freedom located at different sites of the chain and has a strictly positive energy gap above its ground-state energy. We prove that, for small values of a coupling constant, the spectral gap of the perturbed Hamiltonian above its ground-state energy is bounded from below by a positive constant uniformly in the length of the chain. In our proof we use a novel method based on local Lie-Schwinger conjugations of the Hamiltonians associated with connected subsets of the chain

    Do We Understand Quantum Mechanics - Finally?

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    After some historical remarks concerning Schroedinger's discovery of wave mechanics, we present a unified formalism for the mathematical description of classical and quantum-mechanical systems, utilizing elements of the theory of operator algebras. We then review some basic aspects of quantum mechanics and, in particular, of its interpretation. We attempt to clarify what Quantum Mechanics tells us about Nature when appropriate experiments are made. We discuss the importance of the mechanisms of "dephasing" and "decoherence" in associating "facts" with possible events and rendering complementary possible events mutually exclusive.Comment: 42 pages, contribution to the Proceedings of a conference in memory of Erwin Schroedinger, Vienna, January 201

    Proton-rich nucleosynthesis and nuclear physics

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    Although the detailed conditions for explosive nucleosynthesis are derived from astrophysical modeling, nuclear physics determines fundamental patterns in abundance yields, not only for equilibrium processes. Focussing on the nu p- and the gamma-process, general nucleosynthesis features within the range of astrophysical models, but (mostly) independent of details in the modelling, are presented. Remaining uncertainties due to uncertain Q-values and reaction rates are discussed
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