by Nikodem Poplawski

The AAVSO is an international non-profit organization of variable star observers whose mission is:

to observe and analyze variable stars
to collect and archive observations for worldwide access
to forge strong collaborations between amateur and professional astronomers
to promote scientific research and education using variable star data.

It is argued that it is possible to give operational meaning to free will and the process of making a choice without employing metaphysics.

Follow the adventures in the life of a Welsh astrophysicist sent into exile to a small island in the middle of the ocean. A blog by a scientist that almost certainly won't be about science, but will be very facetious.

GNU Data Language (GDL) is a free/libre/open source incremental compiler compatible with IDL and to some extent with PV-WAVE. Together with its library routines it serves as a tool for data analysis and visualization in such disciplines as astronomy, geosciences and medical imaging. GDL is free software licensed under the GPL. GDL is developed by an international team of volunteers led by Marc Schellens - the project's founder

We have prepared a comprehensive critically evaluated compilation of the most accurate wavelength measurements for classified lines of neutral neon (Ne I) in its natural isotopic abundance. Data from 19 sources spanning the region 256 Å to 54 931 Å are included. Based on this line list we have derived optimized values for the energy levels of neutral neon. Tabular data for 1595 classified lines and 374 energy levels are provided. In addition to the observed wavelengths, we present revised wavelengths calculated from the optimized energy levels for all lines that have been previously recommended for use as secondary wavelength standards. © 2005 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved.

D.E. Neuenschwander: Emmy Noether’s Wonderful Theorem
Johns Hopkins University Press, Baltimore, 2011, 228 pages. Intended for senior undergraduate physics students

Events on the world lines of two theoretical physicists, from the horizon to timelike infinity. A scientifically minded blog with varying amounts of entertainment, distractions, and every day trivialities.

Buses on Quantum Schedules

Astro-ph discussions

Naively applying Hubble's law to a sufficiently distant object gives a receding velocity larger than the speed of light. By discussing a very similar situation in special relativity, we argue that Hubble's law is meaningful only for nearby objects with non-relativistic receding speeds. To support this claim, we note that in a curved spacetime manifold it is not possible to directly compare tangent vectors at different points, and thus there is no natural definition of relative velocity between two spatially separated objects in cosmology. We clarify the geometrical meaning of the Hubble's receding speed v by showing that in a Friedmann-Robertson-Walker spacetime if the four-velocity vector of a comoving object is parallel-transported along the straight line in flat comoving coordinates to the position of a second comoving object, then v/c actually becomes the rapidity of the local Lorentz transformation, which maps the fixed four-velocity vector to the transported one.

xyscan is a tool for scientist in the need to extract data points, i.e. numeric values, from a plot. It allows to scan the plots and extract data points including the size of the error bars (both in x and y). It can handle plots with linear and logarithmic scales. In fact xyscan can be used for extracting numeric values from any kind of 2D technical drawings.

A User’s Guide to the Universe: Surviving the Perils of Black Holes, Time Paradoxes, and Quantum Uncertainty” answers the sorts of the questions that we (as physicists) have been drunkenly asked at cocktail parties, but lacked the wherewithal to coherently answer.

The purpose of this web site is to act as a community knowledge base for performing astronomy research with Python. It provides lists of useful resources, a forum for general discussion, advice, or relevant news items, collecting users' code snippets or scripts, and longer tutorials on specific topics. The topics within these pages are presented in a list view with the ability to sort by date or topic. A traditional "blog" view of the most recently posted topics is visible from the site Home page.

This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant, observational constraints on its magnitude, and the physics of a small (and potentially nonzero) vacuum energy.

This book offers an alternative to other textbooks on the subject, providing a more specific discussion of numerous general relativistic effects for readers who have knowledge of classical mechanics and electrodynamics, including special relativity. Coverage includes in particular gravitational lensing, signal retardation in the gravitational field of the Sun, the Reissner-Nordström solution, selected spin effects, the resonance transformation of an electromagnetic wave into a gravitational one, and the entropy and temperature of black holes. The book includes numerous problems at various levels of difficulty, making it ideal also for independent study by a broad readership of advanced students and researchers.

This book has resulted from a course in the general theory of relativity at the University of Oslo where the author has lectured for more than twenty years. Although the text is designed for master students, it is rather self-contained. Since mathematics courses on differential geometry and tensor calculus usually employ a rather abstract notation different from the component notation used in physical applications, the book introduces not only an introduction to the physical principles of the theory and physical applications of the theory, but also introduces the mathematics which is needed, in particular the calculus of differential forms. Detailed calculations are given of the bending of light, the perihelion precession of Mercury and the predictions for the Hafele-Keating experiment. The Tolman-Oppenheimer-Volkoff equation is deduced and solved for an incompressible fluid to give the internal Schwarzschild solution. Rotating black holes are discussed. ...

This comprehensive compendium combining field theory and particle physics for advanced students and researchers directly links the theory to the experiments. Two main sections cover approaches to field theory and the standard model, rounded off with numerous appendices.

So, why do you talk to your dog about physics?

Lots of reasons, but the main one is that I'm a physics professor. Talking about physics is what I do. Sooner or later I talk to everybody about physics.

iLabs – Immortality Research Laboratories – is a multidisciplinary private research institute in Milan (Italy), working mainly on scientific, technological and philosophical issues related to the extension of human life-span.

This textbook, pitched at the advanced-undergraduate to beginning-graduate level, focuses on mathematical topics of relevance in contemporary physics that are not usually covered in texts at the same level. Its main purpose is to help students appreciate and take advantage of the modern trend of very productive symbiosis between physics and mathematics. Three major areas are covered: (1) linear operators; (2) group representations and Lie algebra representations; (3) topology and differential geometry.

We go through the many considerations involved in fitting a model to data, using as an example the fit of a straight line to a set of points in a two-dimensional plane. Standard weighted least-squares fitting is only appropriate when there is a dimension along which the data points have negligible uncertainties, and another along which all the uncertainties can be described by Gaussians of known variance; these conditions are rarely met in practice. We consider cases of general, heterogeneous, and arbitrarily covariant two-dimensional uncertainties, and situations in which there are bad data (large outliers), unknown uncertainties, and unknown but expected intrinsic scatter in the linear relationship being fit. Above all we emphasize the importance of having a "generative model" for the data, even an approximate one. [...]

"Wald's book is clearly the first textbook on general relativity with a totally modern point of view; and it succeeds very well where others are only partially successful. The book includes full discussions of many problems of current interest which are not treated in any extant book, and all these matters are considered with perception and understanding."—S. Chandrasekhar

Up to date and comprehensive in its coverage, Neutrinos in Particle Physics, Astrophysics and Cosmology reviews the whole landscape of neutrino physics, from state-of-the-art experiments to the latest phenomenological and theoretical developments to future advances.

Quantum mechanics describes strange phenomena far beyond the realm of everyday experience. Computer visualization is sometimes the only method to observe what cannot be seen by any other means.

The purpose of this book is to provide an introduction to the concepts of statistical analysis of data for students at the undergraduate and graduate level, and to provide tools for data reduction and error analysis commonly required in the physical sciences. The presentation is developed from a practical point of view, including enough derivation to justify the results, but emphasizing methods of handling data more than theory. The text provides a variety of numerical and graphical techniques. Computer programs that support these techniques will be available on an accompanying website in both Fortran and C++.

"Geometry and Physics" addresses mathematicians wanting to understand modern physics, and physicists wanting to learn geometry. It gives an introduction to modern quantum field theory and related areas of theoretical high-energy physics from the perspective of Riemannian geometry, and an introduction to modern geometry as needed and utilized in modern physics.

"Astrophysics Updates" is intended to serve the information needs of professional astronomers and postgraduate students about areas of astronomy, astrophysics and cosmology that are rich and active research spheres. Observational methods and the latest results of astronomical research are presented as well as their theoretical foundations and interrelations. The contributed commissioned articles are written by leading exponents in a format that will appeal to professional astronomers and astrophysicists who are interested in topics outside their own specific areas of research. This collection of timely reviews may also attract the interest of advanced amateur astronomers seeking scientifically rigorous coverage.

Welcome to my Galaxy Luminosity Function Engine. You can use the form below to create your own B-band luminosity function (LF) of a volume-limited galaxy population. The assumption is that the shapes of the type-specific LF of ellipticals (E), lenticulars (S0), spirals (Sp), dwarf irregulars (dIrr), and dwarf ellipticals (dE) are invariant of the environment and thus the observed variation of the overall LFs from galaxy clusters to the field has its origin in the different type mixtures (known as the morphology-density relation).

I present an elementary essay on some issues related to nonrelativistic quantum mechanics, which is written in the spirit of extreme simplicity, making it an easy-to-read paper. Moreover, one can find a useful collection of ideas and opinions expressed by many well-known authors in this vast research field

Wichtige Wissenschaftler, die in einer Stadt gewirkt haben, sind gewöhnlichen Reiseführern selten mehr als zwei Sätze wert. Doch auch die Geschichte der Physik ist Kultur, finden die Herausgeber des Buches "The Physical Tourist" - und haben ein knappes Dutzend physikalischer Stadtstreifzüge zusammen gestellt.

The previous edition of this text was the first to provide a quantitative introduction to chaos and nonlinear dynamics at undergraduate level. It was widely praised for the clarity of the writing and for the unique and effective way in which the authors presented the basic ideas. These same qualities characterise this revised and expanded second edition. Interest in chaotic dynamics has grown explosively in recent years. Applications to practically every scientific field have had far-reaching impact. As in the first edition, the authors present all the main features of chaotic dynamics using the damped, driven pendulum as the primary model. This second edition includes additional material on the analysis and characterisation of chaotic data, and applications of chaos. This new edition of Chaotic Dynamics can be used as a text for courses on chaos for physics and engineering students at the second and third year level.

This collection of solved problems corresponds to the standard topics covered in established undergraduate and graduate courses in Quantum Mechanics. Problems are also included on topics of interest which are often absent in the existing literature. Solutions are presented in considerable detail, to enable students to follow each step. The emphasis is on stressing the principles and methods used, allowing students to master new ways of thinking and problem-solving techniques. The problems themselves are longer than those usually encountered in textbooks and consist of a number of questions based around a central theme, highlighting properties and concepts of interest. For undergraduate and graduate students, as well as those involved in teaching Quantum Mechanics, the book can be used as a supplementary text or as an independent self-study tool.

Quantum Mechanics:

An intermediate level course



Richard Fitzpatrick

Professor of Physics

The University of Texas at Austin

Vorlesungsskript Statistische Physik
Prof. Dirk-Gunnar Welsch

We describe a new library (AST) which provides a flexible high-level programming interface for handling world coordinate systems in astronomy and for producing graphical output. It includes, but is not limited to, a wide range of celestial coordinate systems and supports the Digitised Sky Survey plate solutions and the draft FITS WCS proposals amongst other possibilities. AST is portable and environment independent.

In a paper [1] on quantum theory, the Autor had to find a general formula for the surfaces of spheres in n-dimensional complex spaces. Since the focus was then strictly physical, the math has been reduced to a bare minimum.

This Note is the first one of a series exploring the mathematical aspects of the topic in more detail and in a step-by-step manner. It focuses on the evaluation of integrals of products of powers of Cartesian vector components over the volumes of n-dimensional spheres and ellipsoids in real, n-dimensional Euclidean spaces. The integrals tackled here are expressed by means explicit formulae which merit attention on their own.

Rutherford Backscattering (RBS) is based on collisions between atomic nuclei and derives its name from Lord Ernest Rutherford, who in 1911 was the first to present the concept of atoms having nuclei. It involves measuring the number and energy of ions in a beam which backscatter after colliding with atoms in the near-surface region of a sample at which the beam has been targeted.

The OSP Collection provides curriculum resources that engage students in physics, computation, and computer modeling. Computational physics and computer modeling provide students with new ways to understand, describe, explain, and predict physical phenomena.

Physics was the leading science of the twentieth century and the book retraces important discoveries, made between 1895 and 2001, in 100 self-contained Episodes. Each is a short story of the scientists involved, their time and their work. Together, they formed a mosaic of modern physics: formulating relativity and quantum mechanics, finding the constituents of matter and unravelling the forces between them, understanding the working of conductors and semiconductors, discovering and explaining macroscopic quantum effects (superconductivity, superfluidity, quantum Hall effect), developing novel experimental techniques like the Geiger counter and particle accelerators, building revolutionary applications like the transistor and the laser, and observing astonishing features of our cosmos (expanding universe, cosmic background radiation). The text is intended for easy reading.

Russische Seite mit haufenweise "kopierter" Fachliteratur... Hat gerade meinen Tag gerettet, das die Bibliotheken über das verlängerte WE geschlossen sind :-)

I thought it would be fun to try to give a readable account of Unruh effect. It's a surprising phenomenon, and there isn't universal agreement over what exactly the theory predicts, let alone whether the effect has ever been observed. It has important implications for physics and philosophy and may even give a way to test some aspects of quantum gravity in the lab.

The goal of this book is to teach computational scientists how to develop tailored, flexible, and human-efficient working environments built from small programs written in the easy-to-learn, high-level language Python.

The focus is on examples and applications of relevance to computational scientists.

"How to learn math and physics" - the title is deliberately provocative. Everyone has to learn their own way. I don't know how you should learn math and physics. But presumably you came here looking for advice, so I'll give you some.
My advice is aimed at people who are interested in fundamental theoretical physics and the math that goes along with that. (By "fundamental" physics I mean the search for the basic laws concerning matter and the forces of nature.) If you want to do experiments instead of theory, or other kinds physics like condensed matter physics and astrophysics, or math that has nothing to do with physics, my advice will be of limited use. You should still learn the basics I mention here, but after that you'll have to look elsewhere for suggestions.

Written by an international team of experts, this set of tutorial reviews provides a coherent and accessible summary of the current state of supernova research in all of its facets. The newly detected gamma-ray bursts are discussed in this context. While primarily addressing astrophysicists and astronomers, this book will also be of interest to cosmologists and nuclear physicists working on supernova-related issues.

Eine Einführung in die experimentellen und theoretischen Grundlagen der Atomphysik für Studenten der Physik und verwandter naturwissenschaftlicher Fächer.

This book offers a concise introduction to the angular momentum, one of the most fundamental quantities in all of quantum mechanics. Beginning with the quantization of angular momentum, spin angular momentum, and the orbital angular momentum, the author goes on to discuss the Clebsch-Gordan coefficients for a two-component system. After developing the necessary mathematics, specifically spherical tensors and tensor operators, the author then investigates the 3-j, 6-j, and 9-j symbols. Throughout, the author provides practical applications to atomic, molecular, and nuclear physics. These include partial-wave expansions, the emission and absorption of particles, the proton and electron quadrupole moment, matrix element calculation in practice, and the properties of the symmetrical top molecule.