No Arabic abstract
The scientific data about the state of our planet, presented at the 2012 (Rio+20) summit, documented that todays human family lives even less sustainably than it did in 1992. The data indicate furthermore that the environmental impacts from our current economic activities are so large, that we are approaching situations where potentially controllable regional problems can easily lead to uncontrollable global disasters. Assuming that (1) the majority of the human family, once adequately informed, wants to achieve a sustainable way of life and (2) that the development towards sustainability roadmap will be based on scientific principles, one must begin with unambiguous and quantifiable definitions of these goals. As will be demonstrated, the well known scientific method to define abstract and complex issues by their negation, satisfies these requirements. Following this new approach, it also becomes possible to decide if proposed and actual policies changes will make our way of life less unsustainable, and thus move us potentially into the direction of sustainability. Furthermore, if potentially dangerous tipping points are to be avoided, the transition roadmap must include some minimal speed requirements. Combining the negation method and the time evolution of that remaining natural capital in different domains, the transition speed for a development towards sustainability can be quantified at local, regional and global scales. The presented ideas allow us to measure the rate of natural capital depletion and the rate of restoration that will be required if humanity is to avoid reaching a sustainable future by a collapse transition.
We present a short overview on the ideas of large extra-dimensions and their implications for the possible production of micro black holes in the next generation particle accelerator at CERN (Geneva, Switzerland) from this year on. In fact, the possibility of black hole production on earth is currently one of the most exciting predictions for the LHC accelerator and would change our current understanding of physics radically. While it is impossible to discuss the models and implications in full detail here, this article is thought to serve as a starting point for the interested physics students with some basic knowledge about general relativity and particle physics.
We review some aspects, especially those we can tackle analytically, of a minimal model of closed economy analogous to the kinetic theory model of ideal gases where the agents exchange wealth amongst themselves such that the total wealth is conserved, and each individual agent saves a fraction (0 < lambda < 1) of wealth before transaction. We are interested in the special case where the fraction lambda is constant for all the agents (global saving propensity) in the closed system. We show by moment calculations that the resulting wealth distribution cannot be the Gamma distribution that was conjectured in Phys. Rev. E 70, 016104 (2004). We also derive a form for the distribution at low wealth, which is a new result.
We present a simple agent-based model to study the development of a bubble and the consequential crash and investigate how their proximate triggering factor might relate to their fundamental mechanism, and vice versa. Our agents invest according to their opinion on future price movements, which is based on three sources of information, (i) public information, i.e. news, (ii) information from their friendship network and (iii) private information. Our bounded rational agents continuously adapt their trading strategy to the current market regime by weighting each of these sources of information in their trading decision according to its recent predicting performance. We find that bubbles originate from a random lucky streak of positive news, which, due to a feedback mechanism of these news on the agents strategies develop into a transient collective herding regime. After this self-amplified exuberance, the price has reached an unsustainable high value, being corrected by a crash, which brings the price even below its fundamental value. These ingredients provide a simple mechanism for the excess volatility documented in financial markets. Paradoxically, it is the attempt for investors to adapt to the current market regime which leads to a dramatic amplification of the price volatility. A positive feedback loop is created by the two dominating mechanisms (adaptation and imitation) which, by reinforcing each other, result in bubbles and crashes. The model offers a simple reconciliation of the two opposite (herding versus fundamental) proposals for the origin of crashes within a single framework and justifies the existence of two populations in the distribution of returns, exemplifying the concept that crashes are qualitatively different from the rest of the price moves.
We show here how to create from digital films using the well-known software Tracker stroboscopic photos in order to analyze different types of movements. The advantage of this procedure is that it is possible to analyze the printed photo or on a computer screen in an intuitive way for the students. After presenting a historical perspective of the use of stroboscopic photos in secondary education we discuss several examples: the movement of a remote control car, an elastic planar collision, the movement of a projectile and also an experiment in electromagnetism, more specifically, the discharge of a capacitor measured using an analog multimeter.
Sicily has played an important role in the development of the new research area named Econophysics. In fact some key ideas supporting this new hybrid discipline were originally formulated in a pioneering work of the Sicilian born physicist Ettore Majorana. The article he wrote was entitled The value of statistical laws in physics and social sciences. I will discuss its origin and history that has been recently discovered in the study of Stefano Roncoroni. This recent study documents the true reasons and motivations that triggered the pioneering work of Majorana. It also shows that the description of this work provided by Edoardo Amaldi was shallow and misleading. In the second part of the talk I will recollect the first years of development of econophysics and in particular the role of the International Workshop on Econophysics and Statistical Finance held in Palermo on 28-30 September 1998 and the setting in 1999 of the Observatory of Complex Systems the research group on Econophysics of Palermo University and Istituto Nazionale di Fisica della Materia.