Toward Saving Nozick from Kripke

Tracking theories of knowledge, though quite popular have been under attack from their inception. Specifically, we have in mind the attacks of Saul Kripke. We don"t think these attacks on tracking theories work. In this paper, we take a step towards rescuing Nozick"s version of the tracking theories of knowledge from the attacks of Kripke

The Life and Times of Extremal Black Holes

Charged extremal black holes cannot fully evaporate through the Hawking effect and are thus long lived. Over their lifetimes, these black holes take part in a variety of astrophysical processes, including many that lead to their eventual destruction. This paper explores the various events that shape the life of extremal black holes and calculates the corresponding time scales.Comment: 9 pages, LaTeX, accepted to General Relativity and Gravitatio

Reply to Gennaro

Last year Charlotte Shreve and I presented an argument that synesthesia contains evidence against higher order thought theories of consciousness. Rocco Gennaro took up the challenge and argued that H.O.T. theories like his could handle the example and dismiss the argument. Below we suggest otherwise. We think the traditional versions of H.O.T. theory are still vulnerable to our argument and we maintain that Gennaro’s version is as well

Magnetic and Gravitational Disk-Star Interactions: An Interdependence of PMS Stellar Rotation Rates and Spin-Orbit Misalignments

The presence of giant gaseous planets that reside in close proximity to their host stars may be a consequence of large-scale radial migration through the proto-planetary nebulae. Within the context of this picture, significant orbital obliquities characteristic of a substantial fraction of such planets can be attributed to external torques that perturb the disks out of alignment with the spin axes of their host stars. Therefore, the acquisition of orbital obliquity exhibits sensitive dependence on the physics of disk-star interactions. Here, we analyze the primordial excitation of spin-orbit misalignment of Sun-like stars, in light of disk-star angular momentum transfer. We begin by calculating the stellar pre-main sequence rotational evolution, accounting for spin-up due to gravitational contraction and accretion as well as spin-down due to magnetic star-disk coupling. We devote particular attention to angular momentum transfer by accretion, and show that while generally subdominant to gravitational contraction, this process is largely controlled by the morphology of the stellar magnetic field (i.e. specific angular momentum accreted by stars with octupole-dominated surface fields is smaller than that accreted by dipole-dominated stars by an order of magnitude). Subsequently, we examine the secular spin-axis dynamics of disk-bearing stars, accounting for the time-evolution of stellar and disk properties and demonstrate that misalignments are preferentially excited in systems where stellar rotation is not overwhelmingly rapid. Moreover, we show that the excitation of spin-orbit misalignment occurs impulsively, through an encounter with a resonance between the stellar precession frequency and the disk-torquing frequency. Cumulatively, the model developed herein opens up a previously unexplored avenue towards understanding star-disk evolution and its consequences in a unified manner.Comment: 18 pages, 7 figures, accepted to Ap