13,244 research outputs found
Constraining the tidal charge of brane black holes using their shadows
A constraint on the tidal charge generated within a brane world is shown.
Using the shadow of a rotating black hole in a brane context in order to
describe the M87* parameters recently announced by the Event Horizon Telescope
Collaboration, the deviation from circularity of the reported shadow produces
an upper bound on the bulk's nonlocal effect, which is conceived of as a tidal
charge in the four-dimensional brane induced by the five-dimensional bulk.
Therefore, a deviation from circularity leads to an upper bound
on the tidal charge .Comment: 9 pages, 2 figures, 1 table. V2 with minor changes and new
references. Published in The European Physical Journal
Nietzsche for physicists
One of the most important philosophers in history, the German Friedrich
Nietzsche, is almost ignored by physicists. This author who declared the death
of God in the 19th century was a science enthusiast, especially in the second
period of his work. With the aid of the physical concept of force, Nietzsche
created his concept of will to power. After thinking about energy conservation,
the German philosopher had some inspiration for creating his concept of eternal
recurrence. In this article, some influences of physics on Nietzsche are
pointed out, and the topicality of his epistemological positionthe
perspectivismis discussed. Considering the concept of will to power, I
propose that the perspectivism leads to an interpretation where physics and
science in general are viewed as a game.Comment: 14 pages. Version 3 with improvements, corrections. Accepted in
Philosophia Scientia
Wormholes in de Sitter branes
In this work we present a class of geometries which describes wormholes in a
Randall-Sundrum brane model, focusing on de Sitter backgrounds. Maximal
extensions of the solutions are constructed and their causal structures are
discussed. A perturbative analysis is developed, where matter and gravitational
perturbations are studied. Analytical results for the quasinormal spectra are
obtained and an extensive numerical survey is conducted. Our results indicate
that the wormhole geometries presented are stable.Comment: 10 pages, 7 figure
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