15,082 research outputs found
How much negative energy does a wormhole need?
It is known that traversible wormholes require negative energy density. We
here argue how much negative energy is needed for wormholes, using a local
analysis which does not assume any symmetry. and in particular allows dynamic
(non-stationary) but non-degenerate wormholes. We find that wormholes require
two constraints on the energy density, given by two independent components of
the Einstein equation.Comment: 6 pages, no figure
HIV/AIDS and Blood Donation Policies: A Comparative Study of Public Health Policies and Individual Rights Norms
Traversable wormholes from massless conformally coupled scalar fields
The massless conformally coupled scalar field is characterized by the
so-called "new improved stress-energy tensor", which is capable of classically
violating the null energy condition. When coupled to Einstein gravity we find a
three-parameter class of exact solutions. These exact solutions include the
Schwarzschild geometry, assorted naked singularities, and a large class of
traversable wormholes.Comment: 11 Pages, plain LaTeX2e, uses graphics.sty, three *.eps figure
Wormholes and negative energy from the gravitationally squeezed vacuum
Minkowski-signature wormhole solutions of the Einstein field equations require the existence of negative energy density in the vicinity of their throats. We point out that the gravitational interaction automatically generates squeezed vacuum states of matter, which by their nature, entail negative energy and, thus, provide a natural source for maintaining this class of wormholes
Broadcasting and CATV: The Beauty and the Bane of Major College Football
Discusses: (1) the existing broadcast arrangements for major college football, (2) the historical forces that have culminated in the current pattern of major college football programming, and (3) the economic implications of the broadcasting of those games. Then explores the potential impact of cable television (CATV) on major college football telecasting
Splitting the Wino Multiplet by Higher-Dimensional Operators in Anomaly Mediation
In a class of AMSB models, the splitting in the Wino multiplet turns out to
be very small, such as the often-quoted 170 MeV in minimal AMSB, which
originates from MSSM loops. Such a small mass gap is potentially a window into
higher scale physics, as it may be sensitive to higher-dimensional operators.
We show that still within AMSB one can get a much larger splitting in the Wino
multiplet--a few GeV--if the scale of the new physics is comparable to the
gravitino mass (which is indeed often the scale of new physics in anomaly
mediation).Comment: 18 pages; v2: references added, matching journal versio
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