jump to navigation

NSBP and SAIP Members on LHC Lead-Lead Collisions November 16, 2010

Posted by ASTRO Section Chair in : Astronomy and Astrophysics (ASTRO), Cosmology, Gravitation, and Relativity (CGR), Mathematical and Computational Physics (MCP) , trackback Bookmark and Share

LHC Achieves Heavy Ion Collisions
On Sunday November 7 at 1 am local time the first heavy ion collisions were observed in the Large Hadron Collider (LHC) near Geneva, Switzerland.  By the following Monday morning the heavy ion beam was stably producing a steady stream of collisions such that the physics analysis could start in earnest.  By the end of the week a sufficient number of events had been observed to reach the first conclusions.

Witnessing this historic event was Dr. Zinhle Buthelezi from South Africa’s iThemba LABS who was on duty in the control room of the ALICE (A Large Ion Collider Experiment) detector at the time of the first collisions.  Other members of the iThemba LABS team, Deon Steyn, Siegie Foertsch, and Zeblon Vilakazi, as well as the team from the University of Cape Town led by Jean Cleymans have also been participating in the ALICE experiment.  More

ALICE, Quark-Gluon Plasmas and the Origin of the Universe
The goal of ALICE is to observe the so-called Quark Gluon Plasma (QGP).  This plasma is partially analogous to the more well-known electronic plasma that results when a gas is so hot that its electrons are liberated from their atomic nuclei.  Like electrons are constituents of atoms, quarks and gluons are constituents of nucleons – protons and neutrons.  They can likewise be “deconfined” from nucleons at high energy densities like those that existed at the very moment of the Big Bang, or can be reproduced in high energy accelerators like the Relativistic Heavy Ion Collider (RHIC) or the LHC.  Thus the results gained from ALICE and RHIC give insights into the state of energy and matter in the first microseconds of the universe, before condensation into neutrons, protons, and subsequently atoms.   More

NSBP Members Clifford Johnson and Stephon Alexander on the ALICE collisions
Experimental Excitement
ALICE – A Cosmologist’s Point of View

Theoretical physicists have studied QGPs using a variety of techniques.  Perhaps the most successful method is due to Dr. Juan Maldacena, a plenary speaker at the 2005 Joint Annual Conference of the National Society of Black Physicists and the National Society of Hispanic Physicists.  The so-called “AdS/CFT correspondence” relates string theory to gauge theories like quantum chromodynamics (QCD) which describes the interactions between quarks and gluons. Professor Jim Gates has commented, “So, the next time someone tells you that string theory is not testable, remind them of the AdS/CFT connection…”  Since then experimental, observational, and theoretical evidence has expanded from particle theory to condensed matter physics.

South African Participation at CERN
In addition to the ALICE experiment, South African physicists are participates in the ATLAS experiment.  Dr. Simon Connell, President-elect of the South African Institute of Physics leads the ATLAS Team at the University of Johannesburg.  “ATLAS is designed to answer some of the most fundamental questions about the nature of the universe, like how and why particles have mass,” he explains.

This past summer South Africa hosted the first biennial African school on fundamental subatomic physics and its applications. More

2010 African Physics School

Courtesy of Brookhaven National Lab

South African participation in particle physics brings many benefits to the country and continent, most notably in information and computing technology (ICT).  SANReN, the grid computing network that allows physicists in South Africa to receive results from the LHC is used by many others in science and business, and this network will by design be extended to everyday consumers and learners.  More

Bookmark and Share

Comments»

1. Clifford V. Johnson - November 16, 2010

Hi,

Thanks for the link. I’d just like to make one or two clarifying remarks about the string theory connection.

(1) Overall, I’d say it is somewhat overstated here. There has been some valuable work done using methods of string theory (see the post or mine linked to in the above, and links within that) but it has been in concert with the central work done by people working in the nuclear physics and particle physics field and using various methods from those disciplines. We’re a player in the game, but the game is hardly all about what we bring to it.

(2) To be fair, Juan Maldacena will be one of the first, I expect, to point out that the work done in this area in bringing string theory methods to this issue and these types of experiments was not done by him. There are several theorists working in the field who made this the focus and took the methods developed by him, and Witten and Gubser, Klebanov and Polyakov (the “AdS/CFT correspondence”) and shaped them in this direction.

(3) The condensed matter applications are really still quite embryonic by comparison. We shall see how work in this area goes, with regards being truly useful for experiments, so I’d not list this among “evidence”.

(4) On the “evidence” issue, I’d use an entirely different word. This is is showing that string theory is _useful_ for issues of real experimental consequence. This should not be conflated with the “evidence for string theory” discussion that takes place in the context of particle physics, cosmology, and so forth. In that regard, we are just as in the dark as we ever were, and must look to future developments in string theory as well as experiments and observation for that matter to be addressed.

For a more balanced view (hard to give in a few lines, I appreciate) about what this is all about, please see the May 2010 special edition of Physics Today. I link to some of the free components of it from my site.

Best,

-cvj

2. Sylvester James Gates - November 17, 2010

I agree with Prof. Johnson’s comments. I was not clear enough at the end of my comment. A more clear comment would have been, “Since then experimental, observational, and theoretical evidence for the applicability of string theory has expanded from particle theory to condensed matter physics.” S.J. Gates