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pro vyhledávání: '"Adam D. Helfer"'
Autor:
Adam D. Helfer
Chen et al. argued recently that, in Bondi-Sachs space-times, the angular momentum at scri (null infinity) should vary continuously with the position of the cut (but not depend sensitively on its derivatives); they showed that this property was enjoy
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::5987c0a402265c6b07484bf7ddd01018
Autor:
Adam D. Helfer
Publikováno v:
Physical Review D. 104
Twistors appear to provide a satisfactory treatment of angular momentum for gravitationally radiating systems. The approach is manifestly Bondi-Metzner-Sachs (BMS) invariant, and there are no supertranslation ambiguities. The resulting definitions of
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::0df731f243554166539d18281f1be2d9
https://doi.org/10.1103/physrevd.104.104053
https://doi.org/10.1103/physrevd.104.104053
Autor:
Adam D. Helfer
Dray and Streubel proposed a definition of angular momentum in general relativity based on `Bondi-Metzner-Sachs (BMS) charges'. I show here that the natural definition of center of mass in this program has an infinite-dimensional ambiguity. (This see
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::139ec8f60f31c68b33b9f840c2f22936
http://arxiv.org/abs/2105.11623
http://arxiv.org/abs/2105.11623
Autor:
Adam D. Helfer
Publikováno v:
Physical Review D. 102
The Ashtekar-Streubel fluxes give a proposed definition of the angular momentum emitted by an isolated gravitationally radiating system. This was based on identifying a "phase space of radiative modes," independent of any internal degrees of freedom,
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4047638554b1ba8d800895aebff7fc39
https://doi.org/10.1103/physrevd.102.124036
https://doi.org/10.1103/physrevd.102.124036
Autor:
Adam D. Helfer
Publikováno v:
Physical Review
I consider the problem of reconciling "tunneling" approaches to black-hole radiation with the treatment by quantum field theory in curved space-time. It is not possible to do this completely, but using what appears to be the most direct and natural c
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::da3f3a0f5dd7287c2d56836bb597d0e5
https://doi.org/10.1103/physrevd.100.025005
https://doi.org/10.1103/physrevd.100.025005
Autor:
Adam D. Helfer
Gravitational effect of "magnetic type" -- those having a curl-like character over large spheres -- are investigated, for isolated systems. The Bondi-Sachs-Newman-Penrose formalism clarifies a number of points, especially related to radiation memory.
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a4eb15ee89d8c0e0f0540c6552d5ab7d
Autor:
Adam D. Helfer
It has been suggested that dark matter is a superfluid of particles whose masses are on the rough order of $10^{-22}$ eV. Since the occupation numbers are huge, the state is coherent, and the speeds typical of orbital velocities in halos, it has gene
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ab185a9b815104368ad5fb59be533f98
http://arxiv.org/abs/1809.04946
http://arxiv.org/abs/1809.04946
Autor:
Adam D. Helfer
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 430:305-319
One might expect light to be scattered when it passes through a gravitational wave, and might hope that in favourable circumstances these scatterings could be observed on Earth even if the interaction occurs far away. Damour and Esposito-Far\`ese, an
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::747c6b7a182bb29240b96ea2b140cd9b
https://doi.org/10.1093/mnras/sts618
https://doi.org/10.1093/mnras/sts618
Autor:
Adam D. Helfer
Publikováno v:
Nonlinear Analysis: Theory, Methods & Applications. 71:e494-e501
This article is a conceptual discussion, for non-specialists, of what appears to be a satisfactory solution to the problem of treating angular momentum for isolated radiating systems in general relativity. The approach is a development of one suggest
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https://explore.openaire.eu/search/publication?articleId=doi_________::215819c35437a709d08f6b43c461a135
https://doi.org/10.1016/j.na.2008.11.061
https://doi.org/10.1016/j.na.2008.11.061
Autor:
Adam D. Helfer
Publikováno v:
International Journal of Modern Physics D. 13:2299-2305
I reconsider Hawking's analysis of the effects of gravitational collapse on quantum fields, taking into account interactions between the fields. The ultra-high energy vacuum fluctuations, which had been considered to be an awkward peripheral feature
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https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6ed672e4a45ab1d20c8c09ce385b8510
https://doi.org/10.1142/s021827180400636x
https://doi.org/10.1142/s021827180400636x