91,119 research outputs found
Radiation Pressure Supported Stars in Einstein Gravity: Eternally Collapsing Objects
Even when we consider Newtonian stars, i.e., stars with surface gravitational
redshift, z<< 1, it is well known that, theoretically, it is possible to have
stars, supported against self-gravity, almost entirely by radiation pressure.
However, such Newtonian stars must necessarily be supermassive. We point out
that this requirement for excessive large M, in Newtonian case, is a
consequence of the occurrence of low z<< 1. On the other hand, if we remove
such restrictions, and allow for possible occurrence highly general
relativistic regime, z >> 1, we show that, it is possible to have radiation
pressure supported stars at arbitrary value of M. Since radiation pressure
supported stars necessarily radiate at the Eddington limit, in Einstein
gravity, they are never in strict hydrodynamical equilibrium. Further, it is
believed that sufficiently massive or dense objects undergo continued
gravitational collapse to the Black Hole stage characterized by z =infty. Thus,
late stages of Black Hole formation, by definition, will have, z >> 1, and
hence would be examples of quasi-stable general relativistic RPSSs. This result
is also supported by with our previous finding that that trapped surfaces are
not formed in gravitational collapse and the value of the integration constant
in the vacuum Schwarzschild solution is zero. Hence the supposed observed BHs
are actually ECOs.Comment: Minor chages in proof. Discusses why the observed BHs are actually
ECOs and Chandrasekhar limit is not applicable to the
Field-control, phase-transitions, and life's emergence
Instances of critical-like characteristics in living systems at each
organizational level as well as the spontaneous emergence of computation
(Langton), indicate the relevance of self-organized criticality (SOC). But
extrapolating complex bio-systems to life's origins, brings up a paradox: how
could simple organics--lacking the 'soft matter' response properties of today's
bio-molecules--have dissipated energy from primordial reactions in a controlled
manner for their 'ordering'? Nevertheless, a causal link of life's macroscopic
irreversible dynamics to the microscopic reversible laws of statistical
mechanics is indicated via the 'functional-takeover' of a soft magnetic
scaffold by organics (c.f. Cairns-Smith's 'crystal-scaffold'). A
field-controlled structure offers a mechanism for bootstrapping--bottom-up
assembly with top-down control: its super-paramagnetic components obey
reversible dynamics, but its dissipation of H-field energy for aggregation
breaks time-reversal symmetry. The responsive adjustments of the controlled
(host) mineral system to environmental changes would bring about mutual
coupling between random organic sets supported by it; here the generation of
long-range correlations within organic (guest) networks could include SOC-like
mechanisms. And, such cooperative adjustments enable the selection of the
functional configuration by altering the inorganic network's capacity to assist
a spontaneous process. A non-equilibrium dynamics could now drive the
kinetically-oriented system towards a series of phase-transitions with
appropriate organic replacements 'taking-over' its functions.Comment: 54 pages, pdf fil
Time-reversal and parity conservation for gravitating quarks
The complex mass term of a quark does not violate time-reversal or parity in
gravitational interactions, in spite of an axial anomaly.Comment: 4 pages, to appear in Classical and Quantum Gravit
Axion field induces exact symmetry
While no regularization is consistent with the anomalous chiral symmetry
which occurs for massless fermions, the artificial axion-induced symmetry for
massive fermions is shown here to be consistent with a standard regularization,
even in curved spacetime, so that it can be said to have no anomaly in gauge or
gravitational fields. Implications for theta terms are pointed out.Comment: 5 page
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