804 research outputs found

    General Relativity without paradigm of space-time covariance, and resolution of the problem of time

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    The framework of a theory of gravity from the quantum to the classical regime is presented. The paradigm shift from full spacetime covariance to spatial diffeomorphism invariance, together with clean decomposition of the canonical structure, yield transparent physical dynamics and a resolution of the problem of time. The deep divide between quantum mechanics and conventional canonical formulations of quantum gravity is overcome with a Schr\"{o}dinger equation for quantum geometrodynamics that describes evolution in intrinsic time. Unitary time development with gauge-invariant temporal ordering is also viable. All Kuchar observables become physical; and classical spacetime, with direct correlation between its proper times and intrinsic time intervals, emerges from constructive interference. The framework not only yields a physical Hamiltonian for Einstein's theory, but also prompts natural extensions and improvements towards a well behaved quantum theory of gravity. It is a consistent canonical scheme to discuss Horava-Lifshitz theories with intrinsic time evolution, and of the many possible alternatives that respect 3-covariance (rather than the more restrictive 4-covariance of Einstein's theory), Horava's ``detailed balance" form of the Hamiltonian constraint is essentially pinned down by this framework.Comment: 11 page

    Pathways into Political Party Membership:Case Studies of Hong Kong Youth

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    This article explores and conceptualizes the individual mobilization processes into political party membership of a sample of young people in Hong Kong, a semi-autonomous and semi-democratic region under Chinese sovereignty where political parties are relatively underdeveloped. Based on life history interviews with 23 young party members, I found that the mobilization of young people into party membership comprises three different steps. I also found that not all young party members went through the same order of steps. In total, three orders of steps are identified, which create three different paths into party membership. Lastly, this article found that each mobilization path is shaped by a specific set of macro-, meso-, and individual level influence
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