849 research outputs found
Moving Mirrors and Thermodynamic Paradoxes
Quantum fields responding to "moving mirrors" have been predicted to give
rise to thermodynamic paradoxes. I show that the assumption in such work that
the mirror can be treated as an external field is invalid: the exotic
energy-transfer effects necessary to the paradoxes are well below the scales at
which the model is credible. For a first-quantized point-particle mirror, it
appears that exotic energy-transfers are lost in the quantum uncertainty in the
mirror's state. An accurate accounting of these energies will require a model
which recognizes the mirror's finite reflectivity, and almost certainly a model
which allows for the excitation of internal mirror modes, that is, a
second-quantized model.Comment: 7 pages, Revtex with Latex2
Rights-based reasoning in discussions about lesbian and gay issues: implications for moral educators
Despite a paucity of psychological research exploring the interface between lesbian and gay issues and human rights, a human rights framework has been widely adopted in debates to gain equality for lesbians and gay men. Given this prominence within political discourse of human rights as a framework for the promotion of positive social change for lesbians and gay men, the aim of this study was to explore the extent to which rights-based arguments are employed when talking about lesbian and gay issues in a social context. An analysis of six focus group discussions with students showed that when lesbian and gay issues are discussed, rights-based reasoning is employed intermittently, and in relation to certain issues more so than others. The implications of these findings for moral education aimed at promoting positive social change for lesbians and gay men are discussed.</p
How politics becomes news and news becomes politics. A comparative experimental study of the politics-media relationship
The relationship between the media and politics is close and often characterized by tensions. Politicians often are accused of being led by short-lived media cycles in their actions, thereby losing sight of broader societal interests. At the same time, the media are accused of primarily seeking out conflicts and sensational news which is detrimental to both politics and society. This dissertation provides an empirical test of these claims based on unique data from experimental studies with elected politicians and political journalists in Switzerland and the Netherlands. What media reports trigger politicians to take parliamentary action? And how and when do messages from political parties get picked up by journalists? The answers to these two questions presented in the first part of the book provide the basis for a unique direct comparison of the selection mechanisms politicians and journalists apply in the final part.NWO beurs 452-10-016The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020
`Operational' Energy Conditions
I show that a quantized Klein-Gordon field in Minkowski space obeys an
`operational' weak energy condition: the energy of an isolated device
constructed to measure or trap the energy in a region, plus the energy it
measures or traps, cannot be negative. There are good reasons for thinking that
similar results hold locally for linear quantum fields in curved space-times. A
thought experiment to measure energy density is analyzed in some detail, and
the operational positivity is clearly manifested.
If operational energy conditions do hold for quantum fields, then the
negative energy densities predicted by theory have a will-o'-the-wisp
character: any local attempt to verify a total negative energy density will be
self-defeating on account of quantum measurement difficulties. Similarly,
attempts to drive exotic effects (wormholes, violations of the second law,
etc.) by such densities may be defeated by quantum measurement problems. As an
example, I show that certain attempts to violate the Cosmic Censorship
principle by negative energy densities are defeated.
These quantum measurement limitations are investigated in some detail, and
are shown to indicate that space-time cannot be adequately modeled classically
in negative energy density regimes.Comment: 18 pages, plain Tex, IOP macros. Expanded treatment of measurement
problems for space-time, with implications for Cosmic Censorship as an
example. Accepted by Classical and Quantum Gravit
- …