The 2011 Nobel prize in physics has been awarded to S. Perlmutter, A. Riess and B. Schmidt for their path breaking discovery that the rate of expansion of the universe is increasing with time. The trio used Type Ia supernovae (SNe Ia) as standard candles to estimate their luminosity-distances. To appreciate some of the far reaching implications of their work, I have provided an elementary exposition of general theory of relativity, accelerated expansion of the universe, luminosity-distance, SNe Ia and the cosmological constant problem.

The ATLAS3D Project (Cappellari et al. 2011) combines a multi-wavelength survey of a complete sample of 260 early-type galaxies within the local (42Mpc) volume (1.16×105 Mpc3) with numerical simulations and semi-analytic modeling of galaxy formation. This project aims to quantify the global stellar kinematics and dynamics of a statistically significant sample of objects to characterize the class of early-type galaxies, and relate this to their formation and evolution. Combining the stellar populations diagnostics from the multi-wavelength coverage, the ATLAS3D Project will derive the star formation history probing the mass-assembly epochs and timescales. In addition, the project will characterise the different phases of the interstellar medium linking the kinematics of molecular, atomic and ionised gas with the dynamical structure, star formation and environment of the host galaxies.

Welcome to this introduction to newLISP! You'll find newLISP easy to learn and powerful, combining some of the power and elegance of classic LISP with the facilities of a modern scripting language, such as regular expressions, network functions, Unicode support, multitasking, and many others.

Overwhelming collection of old star maps and celestial atlasses.

How was the world created? People have asked this ever since they could ask anything, and answers have come from all sides: from religion, tradition, philosophy, mysticism... and science. While this does not seem like a problem amenable to scientific measurement, it has led scientists to come up with fascinating ideas and observations: the Big Bang, the concept of inflation, the fact that most of the world is made up of dark matter and dark energy which we can not perceive, and more.
Of course scientists cannot claim to know the definitive truth. But we can approach the question from a scientific viewpoint and see what we find out. How do we do that? First, we look to the data. Thanks to modern technology, we have much more information than did people of previous ages who asked the same question. Then we can use scientific methods and techniques to analyze the data, organize them in a coherent way and try and extract an answer. This process and its main findings will be described in the article.

Unix has a huge number of directories and no good way to navigate them. Famous cd command is too simplistic to help when you have over 10K directories in the directory tree. the right way was actually invented in DOS with the advent of NCD and Orthodox managers but Unix is lagging behind and there although both orthodox manager and NCD clones re available they are not widely used.

the opening paragraph of the article Mindless Statistics by Gerd Gigerenzer

When it comes to cable constructions, everything makes a difference. Most (but not all) of these differences are measurable. What is at issue is whether these differences are audible ... or not, when tested properly using a blind A-B test. Sighted tests are at best unreliable, and at worst cause people to believe things that are simply untrue. The vast majority of all cable claims have no basis in reality, and rely on the placebo effect.

The Habitable Sun - One of Herschel, William's Stranger Ideas

Title:
The Habitable Sun - One of Herschel, William's Stranger Ideas
Authors:
Kawaler, S.; Veverka, J.
Publication:
Journal of the Royal Astronomical Society of Canada, Vol. 75, P. 46, 1981
Publication Date:
02/1981
Origin:
KNUDSEN
Comment:
A&AA ID. AAA029.004.032
Bibliographic Code:
1981JRASC..75...46K

Publishing and knowledge production in academia can be significantly improved if aspects of cooperative models developed in software and networking communities are adopted. Open Access movement does that partially, by focusing on the openness of the final result. The most important attributes of the development of the Internet, the Web and their communication-cooperation tools is openness of the entire process of production. The novelty that can take many forms is in the organizational structures, decision making and cooperation. This article argues that journals adopting a form of open-process approach could benefit by increased quality of submissions and publications, faster and more responsive pace of research and by attracting more risk taking and innovative authors. Through clearer structure and visibility of tasks, equally important could be possible internal benefits for journals: recognition of the most important workers and decision making in their hands, easier and improved project management, attracting new volunteers and reducing the impact of counter-productive participants. If these changes were implemented well, such open-process journals would gain readership and reputation. Open-process academic publishing can take procedurally and technologically complex forms. A simple transition model is suggested: how to start with an email list and right cultural safeguards.

The Ship Captain’s Medical Guide is intended primarily for use on ships where no doctor is carried and it is necessary for laymen to assess and treat injuries and to diagnose and treat ill health. The Guide can also be recommended for use in other situations where professional medical advice is not readily available, for example on expeditions.

HPC Techreport
A brief introduction to Python (for scientific computing)

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

A free to download Magazine dedicated to Commodore computers.
Articles and help with production are always wanted please contact me for details

Astrobites is a daily literature journal summarizing new astrophysical research posted to astroph. Astrobites is written by graduate students for undergraduates. Read more about our goals.

Life is unique in nature in complexity and in its drive for self-propagation. We are part of life, implying a human purpose to safeguard and propagate life. For this purpose we may settle the Solar System, and seed with life new solar systems, solar nebulae and star-forming interstellar clouds. Directed panspermia to these targets can carry colonizing cyanobacteria, extremophile microorganisms, and eggs of multicellular rotifers to start higher evolution. The technical requirements for launching, targeting, deceleration and capture, and the probability of success were evaluated. The results show that directed panspermia can be accomplished with present technology. These programs will also serve the drive of life to occupy all habitats, and protect life from various threats, including ultimately the red giant Sun. ...

This is a special collection of problems that were given to select applicants during oral entrance exams to the math department of Moscow State University. These problems were designed to prevent Jews and other undesirables from getting a passing grade. Among problems that were used by the department to blackball unwanted candidate students, these problems are distinguished by having a simple solution that is difficult to find. Using problems with a simple solution protected the administration from extra complaints and appeals. This collection therefore has mathematical as well as historical value.

Perception is a scholarly journal reporting experimental results and theoretical ideas ranging over the fields of human, animal, and machine perception.

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.

new upcoming features in ipython 0.11

In the late 1960s British mathematician John Conway invented a virtual mathematical machine that operates on a two-dimensional array of square cell. Each cell takes two states, live and dead. The cells’ states are updated simultaneously and in discrete time. A dead cell comes to life if it has exactly three live neighbours. A live cell remains alive if two or three of its neighbours are alive, otherwise the cell dies. The Conway’s Game of Life became the most programmed solitary game and the most known cellular automaton. The book brings together results of forty years of study into computational, mathematical, physical and engineering aspects of the Game of Life cellular automata.

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 goal of astrometry is to determine positions and motions of celestial objects such as stars and planets, as well as artificial satellites. Astrometry is the oldest branch of astronomy and until the 19th century all of professional astronomy was astrometry (see ASTROMETRY: HISTORY). One of the main astrometric objectives is to measure angular separations of stars and other celestial objects r...

On the heels of the International Year of Astronomy 2009, celebrating the famed peek into the cosmos through Galileo's first telescope, the question arises: What is next for science education and outreach?

Providing a forum for reflection, for sharing lessons learned, and for shaping resolve, the Astronomical Society of the Pacific (ASP) hosted a conference for astronomy and space science professionals in Millbrae, California from September 12 to 16, 2009. During the conference, participants discussed current education and outreach research and practice and shared perspectives about the future of this field. This conference, the proceedings of which are contained in this volume, was divided into a series of conference strands that each represent an important aspect of this time of contemplation and decision about the future of education and public outreach (EPO) in astronomy:

The Annual Review of Astronomy and Astrophysics, in publication since 1963, covers the significant developments in the field of Astronomy and Astrophysics, including: the sun; solar system and extrasolar planets; stars; the interstellar medium; galaxy and galaxies; active galactic nuclei; cosmology; and instrumentation and techniques, andthe history of the development of new areas of research.

We review our current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang. Modern large telescopes discovered galaxies at redshifts greater than seven, whereas theoretical studies have just reached the degree of sophistication necessary to make meaningful predictions. A crucial ingredient is the feedback exerted by the first generation of stars, through UV radiation, supernova blast waves, and chemical enrichment. The key goal is to derive the signature of the first galaxies to be observed with upcoming or planned next-generation facilities, such as the James Webb Space Telescope or Atacama Large Millimeter Array. From the observational side, ongoing deep-field searches for very high-redshift galaxies begin to provide us with empirical constraints on the nature of the first galaxies.

The transmission rate of communication between radio telescopes on Earth and extraterrestrial intelligence (ETI) has been calculated up to the distances 1000 light years. Phase-shift-keying (PSK) and frequency-shift keying (FSK) modulation schemes are both considered here. It has been demonstrated that M-ary FSK is advantageous in terms of energy. Narrow-band pulses scattered over the spectrum can be the probable signals of ETI and modern SETI spectrum analyzers are well suited to searching for these types of signals. Such signals can be detected using the Hough transform which is a dedicated tool for detecting patterns on an image. The time-frequency plane representing the power output of the spectrum analyzer during the search for ETI gives an image from which the Hough transform (HT) can detect signal patterns with frequency drift.

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.

From the best-selling author of The Elegant Universe and The Fabric of the Cosmos comes his most expansive and accessible book to date—a book that takes on the grandest question: Is ours the only universe?

every day the same again compiles ±500 quirky headlines collected over the last 4 years from institutional sources of information—such as reuters, the guardian, and the new york times—, chapterized and interlaced w/ quotes, vaguely or specifically related. in addition to its lack of purpose, this document casts a modest and diffracted look into the public’s strong curiosity [1] for odd facts and weird news, i.e. familiar topics, but at their margin: bizarre crimes, absurd fights, rare fetishes, extravagances, animal fun facts, curious scientific studies, juridical oddities, et cetera.

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. [...]

For 25 years, 2600: The Hacker Quarterly has given voice to the hacker community in all its manifestations. This collection of letters to the magazine reveals the thoughts and viewpoints of hackers, both white and black hat, as well as hacker wannabes, technophiles, and people concerned about computer security. Insightful and entertaining, the exchanges illustrate 2600's vast readership, from teenage rebels, anarchists, and survivalists to law enforcement, consumer advocates, and worried parents.

Wer als Schüler, Student, Ingenieur oder Wissenschaftler Datenreihen und mathematischen Funktionen darstellen will und über elementare Python-Kenntnisse verfügt, der sollte sich diesen Artikel einmal genauer ansehen.

The Galaxy Zoo citizen science website invites anyone with an Internet connection to participate in research by classifying galaxies from the Sloan Digital Sky Survey. As of April 2009, more than 200,000 volunteers had made more than 100 million galaxy classifications. In this paper, we present results of a pilot study into the motivations and demographics of Galaxy Zoo volunteers, and define a technique to determine motivations from free responses that can be used in larger multiple-choice surveys with similar populations. Our categories form the basis for a future survey, with the goal of determining the prevalence of each motivation

This article describes the assembly of an optical (RGB) all-sky mosaic image with an image scale of 36 arcsec/pixel, a limiting magnitude of approx. 14 mag and an 18 bit dynamic range. Using a portable low-cost system, 70 fields (each covering 40 deg x 27 deg) were imaged over a time span of 21 months from dark-sky locations in South Africa, Texas and Michigan. The fields were photometrically calibrated against standard catalog stars. Using sky background data from the Pioneer 10 and 11 space probes, gradients resulting from artificial light pollution, airglow and zodiacal light were eliminated, while the large-scale galactic and extragalactic background resulting from unresolved sources was preserved. The 648 Megapixel image is a valuable educational tool, being able to fully utilize the resolution and dynamic range of modern full-dome planetarium projection systems.

In celebration of its 50th anniversary, the NRAO hosted a science symposium highlighting the most important questions that can be addressed by astronomers. The universe is a unique laboratory yielding historical data on the creation of the universe, the formation of the first stars and galaxies, the production of the elements, the assembly of molecules and the building blocks of life in interstellar space, how and where planets form, and possible changes in fundamental physical constants on cosmological time scales. This “laboratory” contains black holes, neutron stars, and gravitational radiation for studying extreme gravity and extremely dense matter. It is filled with the mysterious dark energy and dark matter that control the expansion and destiny of the universe, and whole nature is a critical unsolved problem for physics. This symposium brought together leading scientists to address the most important questions in these areas [...]

tIt is well known that interstellar travel is bounded by the finite speed of light, but on very large scales any rocketeer would also need to consider the influence of cosmological expansion on their journey. This paper examines accelerated journeys within the framework of Friedmann- Lemaitre-Robertson-Walker universes, illustrating how the duration of a fixed acceleration sharply divides exploration over interstellar and intergalactic distances. Furthermore, we show how the universal expansion increases the difficulty of intergalactic navigation, with small uncertainties in cosmological parameters resulting in significantly large deviations. This paper also shows that, contrary to simplistic ideas, the motion of any rocketeer is indistinguishable from Newtonian gravity if the acceleration is kept small.

Formulae for the line-of-sight and transverse comoving distances, proper motion distance, angular diameter distance, luminosity distance, k-correction, distance modulus, comoving volume, lookback time, age, and object intersection probability are all given, some with justifications. Some attempt is made to rationalize disparate terminologies, or at least abuse bad usage.

The Net Advance of Physics: COSMOLOGY

The theory, observations, and applications of gravitational lensing constitute one of the most rapidly growing branches of astrophysics. The gravitational deflection of light generated by mass concentrations along a light path produces magnification, multiplicity, and distortion of images and delays photon propagation from one line of sight relative to another. The huge amount of scientific work produced over the last decade on gravitational lensing has clearly revealed its already substantial and wide impact and its potential for future astrophysical applications.

We describe an image analysis supervised learning algorithm that can automatically classify galaxy images. The algorithm is first trained using a manually classified images of elliptical, spiral, and edge-on galaxies. A large set of image features is extracted from each image, and the most informative features are selected using Fisher scores. Test images can then be classified using a simple Weighted Nearest Neighbor rule such that the Fisher scores are used as the feature weights. Experimental results show that galaxy images from Galaxy Zoo can be classified automatically to spiral, elliptical and edge-on galaxies with accuracy of ~90% compared to classifications carried out by the author. Full compilable source code of the algorithm is available for free download, and its general-purpose nature makes it suitable for other uses that involve automatic image analysis of celestial objects.

Astronomy provides a laboratory for extreme physics, a window into environments at extremes of distance, temperature and density that often can't be reproduced in Earth laboratories, or at least not right away. A surprising amount of the science we understand today started out as solutions to problems in astronomy. Some of this science was key in the development of many technologies which we enjoy today. This paper describes some of these connections between astronomy and technology and their history.

We describe a new formula capable of quantitatively characterizing the Hubble sequence of spiral galaxies including grand design and barred spirals. Special shapes such as ring galaxies with inward and outward arms are also described by the analytic continuation of the same formula. The formula is r(φ) =A/log [B tan (φ/2N)] . This function intrinsically generates a bar in a continuous, fixed relationship relative to an arm of arbitrary winding sweep. A is simply a scale parameter while B, together with N, determines the spiral pitch. Roughly, greater N results in tighter winding. Greater B results in greater arm sweep and smaller bar/bulge, while smaller B fits larger bar/bulge with a sharper bar/arm junction. Thus B controls the 'bar/bulge-to-arm' size, while N controls the tightness much like the Hubble scheme. The formula can be recast in a form dependent only on a unique point of turnover angle of pitch – essentially a one-parameter fit [...]

Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA

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

Vorlesungsskript Statistische Physik
Prof. Dirk-Gunnar Welsch

The current form of the Particle properties tables stems directly from a 1957 article in the Annual review of nuclear science, by Gell-Mann and Rosenfeld.

Data on particles were becoming available at an increasing rate, and even before the Annual Review volume was published, Walter H. Barkas and A. H. Rosenfeld decided to make the first update of the table of masses and mean lives. It appeared as Lawrence Radiation Laboratory Report UCRL-8030 (unpublished). Thus 1957 saw the first edition of UCRL-8030: Data for elementary-particle physics.

The first revision of UCRL-8030 was made in 1958, accompanied by a "wallet card".

In 1963, Matts Roos's Tables of elementary particles and resonant states illustrated that it was no longer possible for a single person to compile data critically. Thus, as he saw the Rosenfeld et al.'s computerized draft of the 1964 edition, he suggested combining efforts.

...

Introduction The least square method---a very popular technique---is used to compute estimations of parameters and to fit data. It is one of the oldest techniques of modern statistics as it was first published in 1805 by the French mathematician Legendre in a now classic memoir. But this method is even older because it turned out that, after the publication of Legendre's memoir, Gauss, the famous German mathematician, published another memoir (in 1809) in which he mentioned that he had previously discovered this method and used it as early as 1795.