Content about Physics

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Link of the Week: What are the odds?

Image courtesy Paddy Power

With the Large Hadron Collider started up, Paddy Power — Ireland’s largest online bookmaker — has started offering odds as to what the world’s largest machine will discover, and in what order.
The bookie is offering 11-to-10 odds that dark matter (no longer a dark horse candidate) will be found before black holes. And 8-to-1 odds that black holes will be first.
Dark energy sits at 12-to-1 odds.
And the site says that there is a 100-to-1 chance that the LHC will find God. Not the “god particle” — aka the Higg’s Boson —  but something bigger.
A spokesman for Paddy Power told the UK’s Daily Telegraph that “confirmation of God’s existence would have to be verified by scientists and given by an independent authority before any payouts were made, however.”
 

Blogs of the week - CMS and ATLAS event displays: not just pretty pictures

A CMS event display. Image courtesy of Symmetry Breaking.

Any Very Important Person who wanders through one of the Large Hadron Collider’s control rooms or worldwide remote operations centers is bound to be impressed. The equipment is state-of-the-art. There is a near-constant buzz of activity now that the LHC has started up again. And large monitors display very impressive, technical-looking visualizations of potential events as they are detected.
Unlike Monty Python’s machine that goes bing, however, these displays are rife with meaning. You just need a secret decoder blog post!
That’s what the Symmetry Breaking team has set out to do in a recent series of blog posts. The posts are particularly timely, given CERN's recent announcement of the first attempt at 7 TeV collisions on 30 March. Check them out, and you too can smile knowingly when you see an event display!
A CMS display An ATLAS

Feature - Case Study: Einstein@OSG

A screenshot of the Einstein@Home screensaver. Image courtesy of Einstein@Home.

For over five years, volunteers have been lending their computers’ spare cycles to the Laser Interferometer Gravitational Wave Observatory (LIGO) and GEO-600 projects via the BOINC application Einstein@Home. Now a new application wrapper, dubbed “Einstein@OSG,” brings the application to the Open Science Grid.
Today, although Einstein@OSG has been running for only six months, it is already the top contributor to Einstein@Home, processing about 10 percent of jobs.
“The Grid was perfectly suitable to run an application of this type,” said Robert Engel, lead developer and production coordinator for the Einstein@OSG project. “BOINC would benefit from every single CPU that we would provide for it. Increasing the number of CPUs by 1000 really results in 1000 times more science getting done.”
Getting Einstein@Home to run on a grid wa

Feature - Black holes and their jets

This simulation depicts a black hole with a dipole as a magnetic field. This system is sufficiently orderly to generate gamma ray bursts that travel at relativistic speeds of over 99.9% the speed of light. (To see what happens with a more complex magnetic field, see the next video below!)
The black hole pulls in nearby matter (yellow) and sprays energy back out into the universe in a jet (blue and red) that is held together by the magnetic field (green lines).
The simulation was performed on the Texas Advanced Computing Center resources via TeraGrid, consuming approximately 400 000 service units.
Video courtesy of Jonathan McKinney and Roger Blandford.

Jets of particles streaming from black holes in far-away galaxies operate differently than previously thought, according to a study published recently in Nature.
High above the flat Milky Way galaxy, bright galaxies called blazars dominate the gamma-ray sky, discrete spots on the da

Feature - Cosmic simulation

This video simulates Governato’s new model of the formation of a dwarf galaxy over time. It is the first such simulation to match observations in terms of the mass of stars and dark matter in the galactic core. Video courtesy of Fabio Governato.

Cosmic structure formation theory has passed test after test, predicting how many galaxies will form, where they will form, and what type of galaxy they will be. But for almost 20 years, its predictions about the central mass of dwarf galaxies have been wrong.
“Potentially, this is a very big problem for the model,” said Fabio Governato, a researcher at the University of Washington in Seattle. “It might imply that the dark matter particle that we think is the correct one is not the correct one, or maybe that gravity works differently than we think it does. So this is a very fundamental problem for physics.”
Now, a simulation running on computer resources at NASA Advanced Supercomput

Feature: Grids and clouds - reaching for the next phase

A composite image of the Cat’s Eye Nebula with data from NASA’s Chandra X-ray Observatory (blue) and Hubble Space Telescope (red and purple). This cloud of dust and gas is about 3,000 light-years from Earth. The hybridization of grids and clouds seems considerably closer than that. Image courtesy Smithsonian Astrophysical Observatory

“This is not a replacement technology,” says Ignacio Llorente, “This is the next phase of evolution for grids.”
Llorente coordinates ‘virtual machine’ management  for RESERVOIR, an EC-supported project standing for Resources and Services Virtualization without Barriers, that works to enable deployment and management of complex IT services across different administrative domains. This project began collaborating with EGEE in June 2009 to marry the advantages and practicalities of cloud computing with grid technology.
After starting in February 2

Tweet of the week – Midnight in the LHC control room

The LHC control room at CERN, just before midnight on Friday, 20 November, 2009. Photo courtesy CERN

This week, we honor . . .  the Twitter feed at CERN, which allowed us to follow the progress of the Large Hadron Collider restart from the comfort of home on an extremely dark and foggy evening last Friday, when the beam was captured at close to midnight, Geneva time. (Apparently, we weren’t the only ones paying attention to this event; the LHC “tweets” were one of the top five most popular items in Twitter-land.)
You could sense the building excitement, as the posts came in more and more frequently.  See the sequence below. (The time stamps are approximate.)
2 hours ago“Just one sector to go now!”2 hours ago“We have completed the ring!”1.5 hours ago“We will start injecting the anticlockwise beam in the second ring and then go step–by–step again. New photos w

Feature - Calming the wakefield

A snapshot of a simulation of the wakefield generated by a particle bunch moving through a series of ILC cavities, from three different perspectives. The colors represent the magnitude of the fields, with warmer colors representing the strongest fields.

For the International Linear Collider to run at maximum performance, each of its 27,000 cavities must be designed as precisely as possible.
It is very time consuming and costly, however, to produce physical prototypes, so researchers at SLAC National Accelerator Laboratory decided to use a supercomputer to create and test virtual prototypes of the cavities.
The ILC, which is in its design phase, will use superconducting cavities to accelerate electrons and their antimatter partners, positrons, to nearly the speed of light before colliding them. By studying these collisions, researchers will be able to probe more deeply into the subatomic world.
As particle bunches travel through the accelerator cavities,

Feature - Jamie Shiers on the STEP'09 postmortem

Image courtesy Jamie Shiers 

Recently, CERN conducted the STEP’09 test, a full- scale assessment of all the computing resources which will be used to process experiment data from the Large Hadron Collider. Those computing resources include sites all over the world which are organized into different levels, or “tiers.”
Jamie Shiers leads the grid support group in the IT department at CERN, and is responsible for the coordination of the worldwide LHC Computing Grid (wLCG) service. He organized the postmortem for STEP’09 at CERN. iSGTW caught up with him to find out how it went.
iSGTW: What is the STEP’09 postmortem?
Shiers: It’s the workshop to review the results from the STEP (Scale Testing for the Experiment Program) test. The big difference between STEP and other tests we’ve done is that it’s supposed to emphasize that we are in full production. It’s a test of readines

Feature - Flip-flopping of black hole accretion disks scrutinized

Clues to an astrophysical mystery from Renaissance Computing Institute on Vimeo.

Do whirlpools of gas flip-flop as they are sucked into black holes? According to a new simulation powered by TeraGrid, the answer is “Yes.”
The accretion disk of a black hole forms from gas attracted by the black hole’s massive gravitational pull. For the last 20 years, astrophysicists have debated whether the whirlpool-like motion of the accretion disk will periodically reverse motion, a behavior called ‘flip-flop.’
When flip-flopping first turned up in a 1988 numerical simulation, some scientists argued that it explains recurrent x-ray flares observed by the European X-Ray Observatory in 1985. But in subsequent years, although some simulations showed flip-flop, others did not, casting doubt on the existence of the phenomenon.
“The earlier work was criticized for a wide variety of reasons, but I think the chie

Feature - A solid production demonstration of the CMS role in WLCG

Last fall’s unplanned shutdown of the Large Hadron Collider was a disappointment for physicists around the world. But for organizers of the computing grid supporting the collider’s detectors, it was also an opportunity to keep working hard. For the first two weeks of June, instead of flooding the grid with data from actual particle collisions, experiment collaborators at CERN and remote computing sites in Europe, Asia, and North America joined up to test the ability of the collider’s Worldwide LHC Computing Grid (WLCG) to record, transfer and analyze simulated data in a step-by-step “production demonstration.”
Scientists conducted a series of challenges, collectively called the Scale Test of the Experimental Program 2009 (STEP09). All four LHC experiments participated in the test. For example, at the CMS experiment (see earlier iSGTW story, CMS readies network links for LHC data) they first tested the archivin