Gamma Ray Bursts are colossal cosmic explosions: in their death throes, supermassive stars collapsing into a black hole will send out a pair of powerful rays from their poles that carry away most of the energy of this incredibly violent event in a second-long burst of intense radiation, radiating away more energy in the blink of an eye than the Sun will during its entire lifetime of billions of years.

Fortunately for us, these ultraviolent events are incredibly rare and thus most of them happen billions of lightyears away in distant galaxies -- a gamma ray burst in our own galaxy could well mean the end of life on Earth if it was directed our way.

Yesterday, the gamma ray burst GRB 080319B was observed. What is so special about this one is that it has been determined to have happened at a distance of 7.5 billion light years, and yet its optical afterglow was briefly visible with the naked eye!

As most people following physics research at some level or other will have noticed, physicists love symmetries. In fact, it can be and has been said that all of modern theoretical physics is based on a bunch of symmetry principles from which the rest follows.

While that may be a bit overly reductionist (experimental input plays an important part in the construction of a scientific theory after all), it is certainly true that symmetry considerations play a huge role in the building of our theories. But why is that so? The answer is that there are a number of mathematical theorems that link the existence (or absence) of certain symmetries in the mathematical formulation of a theory to physical features of the reality described by that theory: the laws of nature are constrained by symmetry.

Emmy Noether (1882-1935) (from Wikimedia Commons)

The world's fastest civilian supercomputer JUGENE, an IBM BlueGene/P hosted by Germany's national laboratory Forschungszentrum Jülich was officially inaugurated today in the presence of the Ministerpräsident of North-Rhine Westphalia.

IBM's BlueGene technology became available in 2004/2005, and is now the leading system for capability computing applications. A key feature of the BlueGene architecture is its scalability, low power consumption, and good price-performance ratio.

Jülich was one of the early adopters of BlueGene technology: in 2005, Jülich started testing a single BlueGene/L rack with 2,048 processors. It soon became obvious that many applications could be ported to the Blue Gene architecture, and since the BlueGene architecture is well balanced in terms of processor speed, memory latency and network performance, many of these can be success fully scaled up to large numbers of processors. In January 2006, Jüich therefore upgraded its BlueGene/L system to eight racks with a total 16,384 processors using funding from Germany's Helmholtz Association.

In the FY-2008 omnibus spending bill, the US Congress has decided to zero out all funding for ITER, the international fusion reactor to be built in Cadarache, France. While unilateral withdrawal of US funding for international organisations is hardly news (just ask these guys), this still raises a lot of big question marks over many planned international science projects.

Firstly, US withdrawal from ITER makes it a lot less likely that the ILC, the next-generation international particle collider intended to suceed the LHC, will be built in the US. In fact, since US funding for ILC development has been essentially zeroed out as well, and since the British government recently also did a unilateral withdrawal, shutting down its participation in the ILC project, it is becoming increasingly likely that the ILC might never be built, putting the future of experimental particle physics beyond the LHC, and thus our best shot so far at understanding the innermost workings of the universe, into doubt. It might seem a bit premature to worry about the fate of the LHC's successor when the LHC isn't even online yet, but these kinds of projects take very long (as seen with the LHC) and funding problems can doom them.

The often counterintuitive world of quantum mechanics might appear to be the reserve of theoretical physicists pondering the possibility of parallel universes and cutting-edge experimentalists struggling to build unbreakable encryption devices or computers capable of factoring astronomical numbers in a heartbeat. But here is an experiment demonstrating effects of quantum mechanics that everybody can do at home.

Take a CD. Take an incandescent lightbulb (assuming those are still legal where you live), and look at its reflection in the silvery side of the CD. You should see a continuous stripe of rainbow colours (you may have to slant the CD a little to see it properly). Now take a neon-light or energy-saving (compact fluorescent) lightbulb, and look at its reflection in the silvery side of the CD. You should see several separate images of the lightsource, each in a different rainbow colour (again, you may have to slant the CD a little to see it properly). You have just seen quantum mechanics at work.

As everybody knows, Australia is the land of cangaroos, koalas and emus. It is also the country that gave the world the didgeridoo (or didjeridu), which is possibly the world's oldest wind instrument. For those who haven't encountered this bizarre-sounding (at least to classically-trained Western ears) instrument, a didgeridoo (called yidaki, or mago, by its Aboriginal inventors) is a wooden pipe of of 1.2 to 1.5 meters length, which is traditionally made from a tree that has been suitably hollowed out by termites (though mass-produced modern didgeridoos are often hollowed out by hand, or even made from PVC pipes).

It is played using the technique of circular breathing (breathing in through the nose while breathing out through the mouth using the tongue and cheeks to expel the air) while continuously vibrating the player's lips to produce the instrument's typical drone. What most pointedly distinguishes the didgeridoo from Western wind instruments, though, is the role that the player's vocal tract plays, and a team of Australian physicists (who else?) at the University of New South Wales have investigated this using microphones inserted into player's oral cavities.

A recent study by Pablo Gleiser of the Centro Atomico Bariloche in Argentina reveals what most readers will have suspected before: superheroes aren't real. More specifically, their social interactions don't follow the patterns that they would in the real world, and instead are based on dramatic considerations and the rules made by the Comics Magazine Association of America.

To arrive at this startling conclusion, Gleiser studied the collaboration network of the Marvel Universe:

A new paper that appeared on the arXiv preprint repository reports the observation of a new particle with a mass of 4.43 GeV by the BELLE collaboration, an experiment studying heavy quarks in an attempt to understand the origin of CP violation.

The importance of this discovery is that this particle does not appear to be predicted by theory, and thus might be evidence of "new physics", such as particles and interactions beyond the Standard Model of particle physics.

But before jumping up and down, screaming "I always knew it, the Standard Model had to be wrong", let's take a deep breath. The experimentalists themselves don't make any claim that their observation invalidates the Standard Model, and that for a number of excellent reasons.

The new issue of PhysicsWorld is all devoted to questions of energy, which have been a prominent topic on this site, too. There are articles about the most recent developments in nuclear and solar energy, clean coal, hydrogen fuel cells and energy storage.

The article I want to talk about here, though, is unfortunately not available online. It is the "Lateral thought" column entitled "Can an LED really be green?".

Monte Carlo methods are among the most important computational techniques in the toolkit of modern science. Complex problems that are simply intractable with analytical or standard numerical methods are often very amenable to a Monte Carlo treatment. So what are these Monte Carlo methods?

Essentially they are an application of the fact that in Monte Carlo (or any other casino) the bank ultimately always wins at roulette, a mathematical theorem known as the law of large numbers. What this theorem states is that if one makes a large number of observations of the outcome of a random process (such as a coin toss), then the observed average of the individual outcomes will converge to the theoretical expectation value for the outcome of the process being observed. This is of course crucial if one ever wants to obtain any knowledge of random processes from observations their outcome.

A friend of mine recently asked me a question regarding the moon, and I thought it might be good to share the answer with my readers.

The question was whether the fact that Europeans tend to see the face of a man in the moon (with the Mare Imbrium and Mare Serenitatis forming the eyes, and the Mare Nubium and/or Mare Humorum forming the Mouth), whereas Asians tend to see a hare or rabbit (with the Mare Foecunditatis and Mare Nectaris forming the ears), had any astronomical basis.

In a recent post, I explained how the fact that the vacuum in quantum field theory is anything but empty affects physical calculations by means of Feynman diagrams with loops, and specifically how one has to take account of these contributions in lattice field theory via perturbative improvement.

In this post, I want to say some words about the relationship between perturbative improvement and unquenching. To obtain accurate results from lattice QCD simulations, one must include the effects not just of virtual gluons, but also of virtual quarks. Technically, this happens by including a difficult to evaluate mathematical expression known as the "fermionic determinant" that arises from the coupling of the quark fields (which due to the quarks' fermionic nature have to be represented by strange abstract quantities called "Grassmann variables") to the gluon field.

The German physicist, philosopher and peace researcher Carl Friedrich von Weizsäcker has died on 28th April at the age of 94. The brother of former German president Richard von Weizsäcker was born on 28th June 1912.

When we think about the vacuum in classical physics, we think of empty space unoccupied by any matter, through which particles can move unhindered and in which fields are free from any of the non-linear interaction effects which make e.g. electrodynamics in media so much more difficult.

In Quantum Field Theory, the vacuum turns out to be quite different from this inert stage on which things happen; in fact the vacuum itself is a non-linear medium, a foamy bubble bath of virtual particles

I promised there were going to be some interesting posts, and I feel this is one of them. I want to talk about harnessing the power of evolution for the extraction of excited state masses from lattice QCD simulations.

The gauge theory known as Quantum Chromodynamics (QCD) has been enormously successful at describing all known phenomena of the strong interactions that bind quarks into hadrons. However, most of this success has been via numerical simulations of lattice QCD; very little is known about how to treat strongly interacting gauge theories like QCD analytically.

Around the turn of the year, New Scientist had some well-known scientists forecast where science will be in 50 years.

A lot of the predictions are of the kind that people made 50 years ago for today: AIs more intelligent than people, permanent colonies on other planets, immortality drugs, contact with alien civilisations. They haven't come true in the past 50 years, and (exponential growth laws notwithstanding) I see no reason why they should come true in the next 50 years. The other kind of prediction seems much more likely to come true: detection of gravity waves, important discoveries at the LHC, significant progress in neuroscience, solutions for all of the Millennium problems, a firm understanding of dark matter and dark energy, a means to grow human organs in vitro, working quantum computers. And of course, just like nobody 50 years ago predicted the internet or the role of mobile phones in today's world, we should really expect that something completely unexpected will become the leading technology in 50 years.

From the echo on this post on my blog about why we use Fortran for number crunching applications, I gather that many people still associate Fortran with the worst features of the now mostly obsolete FORTRAN 77 standard (fixed source form, implicit typing) and are mostly unaware of the great strides the development of the Fortran standard has made in the past 30 (sic!) years. So I feel that this might be a good opportunity to talk a little about the advanced features that make Fortran 95 so convenient for developping computational physics applications. [Note that in the following Fortran 95 will be referred to simply as "Fortran" for the sake of brevity.]