Geomagnetically Trapped Radiation Produced by a High-Altitude Nuclear Explosion on July 9, 1962

Geomagnetically trapped radiation produced by a high altitude nuclear explosio

The Energetic Costs of Cellular Computation

Cells often perform computations in response to environmental cues. A simple example is the classic problem, first considered by Berg and Purcell, of determining the concentration of a chemical ligand in the surrounding media. On general theoretical grounds (Landuer's Principle), it is expected that such computations require cells to consume energy. Here, we explicitly calculate the energetic costs of computing ligand concentration for a simple two-component cellular network that implements a noisy version of the Berg-Purcell strategy. We show that learning about external concentrations necessitates the breaking of detailed balance and consumption of energy, with greater learning requiring more energy. Our calculations suggest that the energetic costs of cellular computation may be an important constraint on networks designed to function in resource poor environments such as the spore germination networks of bacteria.Comment: 9 Pages (including Appendix); 4 Figures; v3 corrects even more typo

Relativistic Effects in Extrasolar Planetary Systems

This paper considers general relativistic (GR) effects in currently observed extrasolar planetary systems. Although GR corrections are small, they can compete with secular interactions in these systems and thereby play an important role. Specifically, some of the observed multiple planet systems are close to secular resonance, where the dynamics is extremely sensitive to GR corrections, and these systems can be used as laboratories to test general relativity. For the three-planet solar system Upsilon Andromedae, secular interaction theory implies an 80% probability of finding the system with its observed orbital elements if GR is correct, compared with only a 2% probability in the absence of GR. In the future, tighter constraints can be obtained with increased temporal coverage.Comment: Accepted for publication in International Journal of Modern Physics D; this paper received ``Honorable Mention'' in the 2006 Essay Competition of the Gravity Research Foundation; 9 pages including 1 figur

Art and Spirit: The Artistic Brain, the Navajo Concept of Hozho, and Kandinsky’s “Inner Necessity”

Most traditional art forms around the planet are an expression of the spiritual dimension of a culture’s cosmology and the spiritual experiences of individuals. Religious art and iconography often reveal the hidden aspects of spirit as glimpsed through the filter of cultural significance. Moreover, traditional art, although often highly abstract, may actually describe sensory experiences derived in alternative states of consciousness (ASC). This article analyzes the often fuzzy concepts of “art” and “spirit” and then operationalizes them in a way that makes them useful for cross-cultural transpersonal research. The fact of the universally abstract nature of traditional art is analyzed and used as a clue to the function of art in expressing and penetrating to the spiritual domain. A “continuum of representational-associational abstraction” model is introduced and described. These concepts are then applied to the author’s experiences with Navajo art and the relation between art and the important Navajo philosophical concept of hozho (which may be understood as “beauty,” “harmony,” “unity”). A perspective on art and spirit is developed that essentially supports Wassily Kandinsky’s contention that abstract art is the expression of an “inner necessity” of spirit. The article argues for a greater sensitivity among researchers and theorists for the sublime nature of spiritual art.be induced by very different means, including contemplative practices and chemical substances, and yet have different after-effects. Taken together, these ideas lead to the cautious conclusion that some psychedelics can induce genuine mystical experiences sometimes in some people, and that the current tendency to label these chemicals as entheogens may be appropriate

Pairing via Index theorem

This work is motivated by a specific point of view: at short distances and high energies the undoped and underdoped cuprates resemble the $\pi$-flux phase of the t-J model. The purpose of this paper is to present a mechanism by which pairing grows out of the doped $\pi$-flux phase. According to this mechanism pairing symmetry is determined by a parameter controlling the quantum tunneling of gauge flux quanta. For zero tunneling the symmetry is $d_{x^2-y^2}+id_{xy}$, while for large tunneling it is $d_{x^2-y^2}$. A zero-temperature critical point separates these two limits