Energy Level Diagrams for Black Hole Orbits (2009)
A spinning black hole with a much smaller black hole companion forms a fundamental gravitational system, like a colossal classical analog to an atom. In an appealing if imperfect analogy to atomic...
Zoom-Whirl Orbits in Black Hole Binaries (2009)
Healy, James, Levin, Janna, Shoemaker, Deirdre
Zoom-whirl behavior has the reputation of being a rare phenomenon. The concern has been that gravitational radiation would drain angular momentum so rapidly that generic orbits would circularize...
Homoclinic Orbits around Spinning Black Holes I: Exact Solution for the Kerr Separatrix (2008)
Under the dissipative effects of gravitational radiation, black hole binaries will transition from an inspiral to a plunge. The separatrix between bound and plunging orbits features prominently in...
Homoclinic Orbits around Spinning Black Holes II: The Phase Space Portrait (2008)
In paper I in this series, we found exact expressions for the equatorial homoclinic orbits: the separatrix between bound and plunging, whirling and not whirling. As a companion to that physical space...
Dynamics of Black Hole Pairs II: Spherical Orbits and the Homoclinic Limit of Zoom-Whirliness (2008)
Grossman, Rebecca, Levin, Janna
Spinning black hole pairs exhibit a range of complicated dynamical behaviors. An interest in eccentric and zoom-whirl orbits has ironically inspired the focus of this paper: the constant radius...
Dynamics of Black Hole Pairs I: Periodic Tables (2008)
Although the orbits of comparable mass, spinning black holes seem to defy simple decoding, we find a means to decipher all such orbits. The dynamics is complicated by extreme perihelion precession...
A Periodic Table for Black Hole Orbits (2008)
Understanding the dynamics around rotating black holes is imperative to the success of the future gravitational wave observatories. Although integrable in principle, test particle orbits in the Kerr...
Dark Energy and Stabilization of Extra Dimensions (2007)
Greene, Brian R., Levin, Janna
We discuss the role Casimir energies may play in addressing issues of moduli stabilization and dark energy. In particular, we examine a (non-supersymmetric) brane world scenario with toroidal extra...
Cosmological Moduli Dynamics (2007)
Greene, Brian, Judes, Simon, Levin, Janna, Watson, Scott, Weltman, Amanda
Low energy effective actions arising from string theory typically contain many scalar fields, some with a very complicated potential and others with no potential at all. The evolution of these...
Chaos and Order in Models of Black Hole Pairs (2006)
Chaos in the orbits of black hole pairs has by now been confirmed by several independent groups. While the chaotic behavior of binary black hole orbits is no longer argued, it remains difficult to...
Missing Lorenz-boosted Circles-in-the-sky (2004)
A topologically finite universe, smaller than the observable horizon, will have circles-in-the-sky: pairs of circles around which the temperature fluctuations in the cosmic microwave background are...
Lyapunov timescales and black hole binaries (2003)
Cornish, Neil J., Levin, Janna
Black holes binaries support unstable orbits at very close separations. In the simplest case of geodesics around a Schwarzschild black hole the orbits, though unstable, are regular. Under...
The Copernican Principle in Compact Spacetimes (2003)
Copernicus realised we were not at the centre of the universe. A universe made finite by topological identifications introduces a new Copernican consideration: while we may not be at the geometric...
A Test of a Test for Chaos (2003)
A simple new binary test for chaos has been proposed by Gottwald and Melbourne. We apply this test successfully to the Henon-Heiles and Lorenz systems, demonstrating its applicability to conservative...
Comment on "Ruling out chaos in compact binary systems" (2002)
Cornish, Neil J., Levin, Janna
In a recent Letter, Schnittman and Rasio argue that they have ruled out chaos in compact binary systems since they find no positive Lyapunov exponents. In stark constrast, we find that the chaos...
Gravitational Waves from Spinning Compact Binaries (2002)
Cornish, Neil J., Levin, Janna
Binary systems of rapidly spinning compact objects, such as black holes or neutron stars, are prime targets for gravitational wave astronomers. The dynamics of these systems can be very complicated...
Topology and the Cosmic Microwave Background (2001)
Nature abhors an infinity. The limits of general relativity are often signaled by infinities: infinite curvature as in the center of a black hole, the infinite energy of the singular big bang. We...
The twin paradox in compact spaces (2001)
Twins travelling at constant relative velocity will each see the other's time dilate leading to the apparent paradox that each twin believes the other ages more slowly. In a finite space, the twins...
The fate of chaotic binaries (2000)
A typical stellar mass black hole with a lighter companion is shown to succumb to a chaotic precession of the orbital plane. As a result, the optimal candidates for the direct detection of...
Gravity Waves, Chaos, and Spinning Compact Binaries (1999)
Spinning compact binaries are shown to be chaotic in the Post-Newtonian expansion of the two body system. Chaos by definition is the extreme sensitivity to initial conditions and a consequent...
Gravity waves from relativistic binaries (1999)
Levin, Janna, O'Reilly, Rachel, Copeland, E. J.
The stability of binary orbits can significantly shape the gravity wave signal which future Earth-based interferometers hope to detect. The inner most stable circular orbit has been of interest as it...
Fractals and Scars on a Compact Octagon (1999)
A finite universe naturally supports chaotic classical motion. An ordered fractal emerges from the chaotic dynamics which we characterize in full for a compact 2-dimensional octagon. In the classical...
Chaos and order in a finite universe (1999)
All inhabitants of this universe, from galaxies to people, are finite. Yet the universe itself is often assumed to be infinite. If instead the universe is topologically finite, then light and matter...
Topological Pattern Formation (1999)
We provide an informal discussion of pattern formation in a finite universe. The global size and shape of the universe is revealed in the pattern of hot and cold spots in the cosmic microwave...
Chaos may make black holes bright (1998)
Black holes cannot be seen directly since they absorb light and emit none, the very quality which earned them their name. We suggest that black holes may be seen indirectly through a chaotic...
Temperature Correlations in a Finite Universe (1998)
Scannapieco, Evan, Levin, Janna, Silk, Joseph
We study the effect of a finite topology on the temperature correlations of the cosmic microwave background in a flat universe. Analytic expressions for the angular power spectrum are given for all...
How the Universe got its Spots (1998)
Levin, Janna, Scannapieco, Evan, De Gasperis, Giancarlo, Silk, Joseph, Barrow, John D.
The universe displays a three-dimensional pattern of hot and cold spots in the radiation remnant from the big bang. The global geometry of the universe can be revealed in the spatial distribution of...
Curing singularities: From the big bang to black holes (1998)
Singular spacetimes are a natural prediction of Einstein's theory. Most memorable are the singular centers of black holes and the big bang. However, dilatonic extensions of Einstein's theory can...
The topology of the universe: the biggest manifold of them all (1998)
Levin, Janna, Scannapieco, Evan, Silk, Joseph
Clues as to the geometry of the universe are encoded in the cosmic background radiation. Hot and cold spots in the primordial radiation may be randomly distributed in an infinite universe while in a...
Is The Universe Infinite Or Is It Just Really Big? (1998)
Levin, Janna, Scannapieco, Evan, Silk, Joseph
The global geometry of the universe is in principle as observable an attribute as local curvature. Previous studies have established that if the universe is wrapped into a flat hypertorus, the...
Chaos in the Einstein-Yang-Mills Equations (1997)
Yang-Mills color fields evolve chaotically in an anisotropically expanding universe. The chaotic behaviour differs from that found in anisotropic Mixmaster universes. The universe isotropizes at late...
Geodesics in Open Universes (1997)
We present the geodesics on homogeneous and isotropic negatively curved spaces in a simple form suitable for application to cosmological problems. We discuss how the patterns in the microwave sky of...
The mixmaster universe: A chaotic Farey tale (1996)
When gravitational fields are at their strongest, the evolution of spacetime is thought to be highly erratic. Over the past decade debate has raged over whether this evolution can be classified as...
Inflation from Extra Dimensions (1994)
A gravity-driven inflation is shown to arise from a simple higher dimensional universe. In vacuum, the shear of $n>1$ contracting dimensions is able to inflate the remaining three spatial dimensions....
Kinetic Inflation in Stringy and Other Cosmologies (1994)
An inflationary epoch driven by the kinetic energy density in a dynamical Planck mass is studied. In the conformally related Einstein frame it is easiest to see the demands of successful inflation...
Gravity-Driven Acceleration of the Cosmic Expansion (1994)
It is shown here that a dynamical Planck mass can drive the scale factor of the universe to accelerate. The negative pressure which drives the cosmic acceleration is identified with the unusual...
Curvature and Flatness in a Brans-Dicke Universe (1993)
Levin, Janna, Freese, Katherine
The evolution of a universe with Brans-Dicke gravity and nonzero curvature is investigated here. We present the equations of motion and their solutions during the radiation dominated era. In a...
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1993.