Galactic Punctuated Equilibrium: How to Undermine Carter's Anthropic Argument in Astrobiology

We investigate a new strategy which can defeat the (in)famous Carter's "anthropic" argument against extraterrestrial life and intelligence. In contrast to those already considered by Wilson, Livio, and others, the present approach is based on relaxing hidden uniformitarian assumptions, considering instead a dynamical succession of evolutionary regimes governed by both global (Galaxy-wide) and local (planet- or planetary system-limited) regulation mechanisms. This is in accordance with recent developments in both astrophysics and evolutionary biology. Notably, our increased understanding of the nature of supernovae and gamma-ray bursts, as well as of strong coupling between the Solar System and the Galaxy on one hand, and the theories of "punctuated equilibria" of Eldredge and Gould and "macroevolutionary regimes" of Jablonski, Valentine, et al. on the other, are in full accordance with the regulation- mechanism picture. The application of this particular strategy highlights the limits of application of Carter's argument, and indicates that in the real universe its applicability conditions are not satisfied. We conclude that drawing far-reaching conclusions about the scarcity of extraterrestrial intelligence and the prospects of our efforts to detect it on the basis of this argument is unwarranted.Comment: 3 figures, 26 page

Reversible maps and composites of involutions in groups of piecewise linear homeomorphisms of the real line

An element of a group is reversible if it is conjugate to its own inverse, and it is strongly reversible if it is conjugate to its inverse by an involution. A group element is strongly reversible if and only if it can be expressed as a composite of two involutions. In this paper the reversible maps, the strongly reversible maps, and those maps that can be expressed as a composite of involutions are determined in certain groups of piecewise linear homeomorphisms of the real line

An audio-based personal memory aid

We are developing a wearable device that attempts to alleviate some everyday memory problems. The “memory prosthesis” records audio and contextual information from conversations and provides a suite of retrieval tools (on both the wearable and a personal computer) to help users access forgotten memories in a timely fashion. This paper describes the wearable device, the personal-computer-based retrieval tool, and their supporting technologies. Anecdotal observations based on real-world use and quantitative results based on a controlled memory-retrieval task are reported. Finally, some social, legal, and design challenges of ubiquitous recording and remembering via a personal audio archive are discussed

Quantum Google algorithm

We review the main findings on the ranking capabilities of the recently proposed QuantumPageRank algorithm (G.D. Paparo et al., Sci. Rep. 2, 444 (2012) and G.D. Paparo et al., Sci. Rep. 3, 2773(2013)) applied to large complex networks. The algorithm has been shown to identify unambiguously theunderlying topology of the network and to be capable of clearly highlighting the structure of secondary hubsof networks. Furthermore, it can resolve the degeneracy in importance of the low-lying part of the list ofrankings. Examples of applications include real-world instances from the WWW, which typically display ascale-free network structure and models of hierarchical networks. The quantum algorithm has been shownto display an increased stability with respect to a variation of the damping parameter, present in theGoogle algorithm, and a more clearly pronounced power-law behaviour in the distribution of importanceamong the nodes, as compared to the classical algorithm