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The End of Cheap Uranium

Historic data from many countries demonstrate that on average no more than 50-70% of the uranium in a deposit could be mined. An analysis of more recent data from Canada and Australia leads to a mining model with an average deposit extraction lifetime of 10+- 2 years. This simple model provides an accurate description of the extractable amount of uranium for the recent mining operations. Using this model for all larger existing and planned uranium mines up to 2030, a global uranium mining peak of at most 58 +- 4 ktons around the year 2015 is obtained. Thereafter we predict that uranium mine production will decline to at most 54 +- 5 ktons by 2025 and, with the decline steepening, to at most 41 +- 5 ktons around 2030. This amount will not be sufficient to fuel the existing and planned nuclear power plants during the next 10-20 years. In fact, we find that it will be difficult to avoid supply shortages even under a slow 1%/year worldwide nuclear energy phase-out scenario up to 2025. We thus suggest that a worldwide nuclear energy phase-out is in order. If such a slow global phase-out is not voluntarily effected, the end of the present cheap uranium supply situation will be unavoidable. The result will be that some countries will simply be unable to afford sufficient uranium fuel at that point, which implies involuntary and perhaps chaotic nuclear phase-outs in those countries involving brownouts, blackouts, and worse.

physics.soc-ph↗

The Tibetan singing bowl: acoustics and fluid dynamics

We present the results of an experimental investigation of the acoustics and fluid dynamics of Tibetan singing bowls. Their acoustic behavior is rationalized in terms of the related dynamics of standing bells and wine glasses. Striking or rubbing a fluid-filled bowl excites wall vibrations, and concomitant waves at the fluid surface. Acoustic excitation of the bowl's natural vibrational modes allows for a controlled study in which the evolution of the surface waves with increasing forcing amplitude is detailed. Particular attention is given to rationalizing the observed criteria for the onset of edge-induced Faraday waves and droplet generation via surface fracture. Our study indicates that drops may be levitated on the fluid surface, induced to bounce on or skip across the vibrating fluid surface.

physics.flu-dyn↗

Coils and transformers - often used but seldomly explained correctly

The devices coil and transformer are subjects of interest in numerous schoolbooks, in introductory scientific textbooks of physics and engineering, and in laboratory courses at universities. Many descriptions, however, draw a somewhat distorted picture of the underlying physical mechanisms and provide half-knowledge or even clear misconceptions that should not be left uncommented and are therefore studied in detail: (1) Primary and secondary voltage at a transformer have a different sign. (2) Electromagnetic induction is the only mechanism of importance for coils and transformers. (3) The terminal voltage at coils and transformers is compensated by the so-called "induced voltage" (emf), which explains why Kirchhoff's voltage law also applies to coils and transformers. (4) The cores of coils and transformers are used for their ability to store energy. Energy is transported from the primary to the secondary coil within the magnetic core. (5) The stray magnetic and electric fields are sencondary effects not having a major effect on energy transport. (6) The higher the load current, the easier a transformer goes into saturation. (7) The higher the number of turns at the primary coil, the larger the magnetic flux in the core. (8) Transformers with cores having an air gap have a lower coupling factor, because the stray inductivity increases. In the paper, the most important characteristics of coil and transformers are derived directly from Maxwell's equation for idealised conditions, and subsequently, the different misconceptions are discussed and corrected.

physics.pop-ph↗

Quantum magic: A skeptical perspective

Quantum mechanics (QM) has attracted a considerable amount of mysticism, in public opinion and even among academic researches, due to some of its conceptually puzzling features, such as the modification of reality by the observer and entanglement. We argue that many popular "quantum paradoxes" stem from a confusion between mathematical formalism and physics; We demonstrate this by explaining how the paradoxes go away once a different formalism, usually inconvenient to perform calculations, is used. we argue that some modern developments, well-studied in the research literature but generally overlooked by both popular science and teaching-level literature, make quantum mechanics (that is, "canonical" QM, not extensions of it) less conceptually problematic than it looks at first sight. When all this is looked at together, most "conceptual puzzles" of QM are not much different from the well-known paradoxes from probability theory. Consequently, "explanations of QM" involving physical action of consciouses or an infinity of universes are conceptually unnecessary

physics.hist-ph↗

Adiabatic Quantum Computing

Adiabatic Quantum Computing (AQC) is a relatively new subject in the world of quantum computing, let alone Physics. Inspiration for this project has come from recent controversy around D-Wave Systems in British Columbia, Canada, who claim to have built a working AQC which is now commercially available and hope to be distributing a 1024 qubit chip by the end of 2008. Their 16 qubit chip was demonstrated online for the Supercomputing 2007 conference within which a few small problems were solved; although the explanations that journalists and critics received were minimal and very little was divulged in the question and answer session. This 'unconvincing' demonstration has caused physicists and computer scientists to hit back at D-Wave. The aim of this project is to give an introduction to the historic advances in classical and quantum computing and to explore the methods of AQC. Through numerical simulations an algorithm for the Max Independent Set problem is empirically obtained.

physics.pop-ph↗

Special relativity (in Russian)

A modern elementary introduction to special relativity for advanced school children or first-year university students, in Russian. I try to demonstrate that relativity does not contradict common sense; on the contrary, it follows from common sense logically. I discuss Minkowski space-time geometry in some detail. Geometrical approach, with few simple formulas but many pictures, makes results of the theory intuitively obvious.

physics.pop-ph↗

With no Color and Scent: Nanoflowers of Metals and Alloys

Ordered volume submicron surface structures "nanoflowers" - are obtained while growing metal nanowires in porous membranes by means of pulsed current electroplating. These structures occur if the electroplating is continued after the nanowires appear on the membrane surface. Various ordered Ag, Pb, PdNi and PbIn volume structures of complex shape resembling living plant organisms are produced. Some of the structures are formed by spherical and ellipsoidal nanoclusters. Membrane geometry and pulsed current electroplating parameters are the main factors, which determine the shape formation process of these ordered structures at the surface of porous membranes. Choosing the membrane geometry, electrolyte composition and pulsed current electroplating parameters one can deliberately fabricate volume ordered complex shape nano- and submicron structures of various metals and alloys. Such objects can be of interest for fundamental research as well as for applications in catalysis, electronics, optics, medicine, etc.

physics.pop-ph↗

The falling slinky

The slinky, released from rest hanging under its own weight, falls in a peculiar manner. The bottom stays at rest until a wave hits it from above. Two cases -- one unphysical one where the slinky is able to pass through itself, and the other where the coils of the slinky collide creating a shock wave travelling down the slinky -- are analysed. In the former case, the bottom begins to move much later than in the latter.

physics.class-ph↗

Visualising Matter and Cosmologies: A Transhistorical Example

We propose a connection between the visualisation of cosmic matter and structure formation in the Cartesian tradition and that used by contemporary astrophysics. More precisely, we identify cosmological simulations of large scale structure in the Universe with the system of vortices in Descartes physics. This connection operates at different levels of the images: their representational purpose; the theoretical systems behind their use; and, finally, their function and materiality as visual productions. A skilled use of image analysis is necessary to stress the continuities and peculiarities between different epochs and disciplines.

physics.pop-ph↗

Certain Interesting Properties of Action and Its Application Towards Achieving Greater Organization in Complex Systems

The Principle of Least Action has evolved and established itself as the most basic law of physics. This allows us to see how this fundamental law of nature determines the development of the system towards states with less action, i.e., organized states. A system undergoing a natural process is formulated as a game that tends to organize the system in the least possible time. Also, other concepts of game theory are related to their profound physical counterparts. Although no fundamentally new findings are provided, it is quite interesting to see certain important properties of a complex system and their far-reaching consequences.

nlin.AO↗

Exergy - a useful concept for ecology and sustainability

We present the relatively less known thermodynamic concept of exergy in the context of ecology and sustainability. To this end, we first very briefly outline thermodynamics as it arose historically via engineering studies. This enables us to define exergy as available energy. An example of applying the concept of exergy to a simple human process is next described. Then we present an exergy analysis of Earth as a flow system, also concurrently describing other necessary concepts. Finally, we briefly comment on the applicability of exergy analysis to ecology and sustainability. Keywords: exergy - energy - work - thermodynamics - heat transfer - flow processes

physics.pop-ph↗

Principle of Least Action and Theory of Cyclic Evolution

A natural process is defined as an act, by which a system organizes itself with time. Any natural process drives a system to a state of greater organization. Organization is a progressive change, while evolution is expressed in the effects of accumulating marks acquired from contingent encounters. Co-existence of the system in states of maximum organization as well as maximum action forms the core idea of the paper. Major influences have been drawn from the Principle of Least Action. This allows us to see how this most basic law of physics determines the development of the system towards states with less action i.e. organized states. Based on this, it has been proposed, that the development of a system towards states of greater organization is cyclic in nature and thus evolution is a cyclic process.

nlin.AO↗

Mathematics : The Language of Science

The purpose of this essay is to bring out the unique role of Mathematics in providing a base to the diverse sciences which conform to its rigid structure. Of these the physical and economic sciences are so intimately linked with mathematics, that they have become almost a part of its structure under the generic title of Applied Mathematics. But with the progress of time, more and more branches of Science are getting quantified and coming under its ambit. And once a branch of science gets articulated into a mathematical structure, the process goes beyond mere classification and arrangement, and becomes eligible as a candidate for enjoying its predictive powers! Indeed it is this single property of Mathematics which gives it the capacity to predict the nature of evolution in time of the said branch of science. This has been well verified in the domain of physical sciences, but now even biological sciences are slowly feeling its strength, and the list is expanding.

physics.pop-ph↗

Philosophy and problems of the definition of Extraterrestrial Life

When we try to search for extraterrestrial life and intelligence, we have to follow some guidelines. The first step is to clarify what is to be meant by "Life" and "intelligence", i.e. an attempt to define these words. The word "definition" refers to two different situations. First, it means an arbitrary convention. On the other hand it also often designates an attempt to clarify the content of a pre-existing word for which we have some spontaneous preconceptions, whatever their grounds, and to catch an (illusory) "essence" of what is defined. It is then made use of pre-existing plain language words which carry an a priori pre-scientific content likely to introduce some confusion in the reader's mind. The complexity of the problem will be analyzed and we will show that some philosophical prejudice is unavoidable. There are two types of philosophy: "Natural Philosophy", seeking for some essence of things, and "Critical (or analytical) Philosophy", devoted to the analysis of the procedures by which we claim to construct a reality. An extension of Critical Philosophy, Epistemo-Analysis (i.e. the Psycho-Analysis of concepts) is presented and applied to the defintion of Life and to Astrobiology.

physics.hist-ph↗

Regarding how Tycho Brahe noted the absurdity of the Copernican Theory regarding the Bigness of Stars, while the Copernicans appealed to God to answer that absurdity

Tycho Brahe, the most prominent and accomplished astronomer of his era, made measurements of the apparent sizes of the Sun, Moon, stars, and planets. From these he showed that within a geocentric cosmos these bodies were of comparable sizes, with the Sun being the largest body and the Moon the smallest. He further showed that within a heliocentric cosmos, the stars had to be absurdly large - with the smallest star dwarfing even the Sun. (The results of Tycho's calculations are illustrated in this paper.) Various Copernicans responded to this issue of observation and geometry by appealing to the power of God: They argued that giant stars were not absurd because even such giant objects were nothing compared to an infinite God, and that in fact the Copernican stars pointed out the power of God to humankind. Tycho rejected this argument.

physics.hist-ph↗

WorldWide Telescope in Research and Education

The WorldWide Telescope computer program, released to researchers and the public as a free resource in 2008 by Microsoft Research, has changed the way the ever-growing Universe of online astronomical data is viewed and understood. The WWT program can be thought of as a scriptable, interactive, richly visual browser of the multi-wavelength Sky as we see it from Earth, and of the Universe as we would travel within it. In its web API format, WWT is being used as a service to display professional research data. In its desktop format, WWT works in concert (thanks to SAMP and other IVOA standards) with more traditional research applications such as ds9, Aladin and TOPCAT. The WWT Ambassadors Program (founded in 2009) recruits and trains astrophysically-literate volunteers (including retirees) who use WWT as a teaching tool in online, classroom, and informal educational settings. Early quantitative studies of WWTA indicate that student experiences with WWT enhance science learning dramatically. Thanks to the wealth of data it can access, and the growing number of services to which it connects, WWT is now a key linking technology in the Seamless Astronomy environment we seek to offer researchers, teachers, and students alike.

astro-ph.IM↗

Active and Cooperative Learning Paths in the Pigelleto's Summer School of Physics

Since 2006, the Pigelleto's Summer School of Physics is an important appointment for orienting students toward physics. It is organized as a full immersion school on actual topics in physics or in fields rarely pursued in high school, i.e. quantum mechanics, new materials, energy resources. The students, usually forty, are engaged in many activities in laboratory and forced to become active participants. Furthermore, they are encouraged in cooperating in small groups in order to present and share the achieved results. In the last years, the school became a training opportunity for younger teachers which are involved in programming and realization of selected activities. The laboratory activities with students are usually supervised by a young and an expert teacher in order to fix the correct methodology.

physics.ed-ph↗