Friday, February 17, 2017

The World at CERN

And now for something completely different...  The main focus of this blog is to discuss issues relating science and reason to Christianity and God.  However, I have spent the last week at CERN attending meetings, talking with people, trying to develop computer code to analyze data, and other such activities.  So I'm going to take this opportunity to talk about how experimental particle physics research is done within large collaborations like those at CERN.

I am a member of the ATLAS collaboration.  ATLAS is the name given to both the detector that we use to analyze data from proton-proton collisions at the Large Hadron Collider and the group of scientists who use the data from that detector to try to understand the fundamental particles and forces in the universe.  There are currently about 5000 scientists from about 180 institutions in 38 countries who are members of the ATLAS collaboration, with 1200 of those scientists being students working toward their Ph.D.  It takes that many people to operate the ATLAS detector and to analyze all of the data that we take with the detector.

I don't know if anyone has ever done a Ph. D. dissertation on the sociology of 5000 physicists working on one project, but I know it would be fascinating.  Although there is a definite management structure, the collaboration is very democratic and somewhat informal.  The members of the collaboration elect a spokesperson from among the 5000 physicists who oversees the operations, but all members of the collaboration are basically equal (except maybe for graduate students 😊).  The collaboration as a whole is able to accomplish a lot because we have a common goal, to "do physics:" to understand new things about the universe and publish our results.  If something needs to be done in the collaboration, no one in management will mandate that another physicist  must work on any particular project.  Instead the management will try to persuade others that it is in the best interests of the collaboration if they work on a certain aspect of the experiment.  The exception to this equal partnership is, of course, graduate students, who tend to have to do projects that their advisor wants them to.  I always tell graduate students that it is very important who you pick as your advisor since that person will dictate much of your life for the next few years.

Within the collaboration, there are groups that build various parts of the detector and make sure they work properly.  There are groups that monitor the detector to assure it runs well and data is efficiently collected.  There are groups that work on processing raw data into a format more useful for analysis.  There are groups that analyze the data and look for new results to publish.  Most physicists have worked in all of these groups at some time in their career and will, at any time, be working among a variety of these tasks.

When it comes to analyzing the data our goal is to find something that is not already known.  Very broadly we do that in two ways.  First, we look directly for new particles or new interactions that have not been discovered before.  This first method is often called "searches."  Second, we make precision measurements of phenomena that we think we already understand to some degree.  If our measurements differ from our predictions, it means that something new must be happening that we don't understand.  As an example, in 2012 we discovered the Higgs Boson by directly searching for it.  Since then, we have been making many measurements of its properties to see if that particle behaves exactly as theoretical calculations predict it should.  If it doesn't behave exactly as expected, then we will have to figure out why and we will learn something new.

Because the collaboration is so large with so many activities, about three times a year we set aside one week which we devote to lots of talks given by people doing various aspects of the work within the collaboration.  By attending these talks, other members of the collaboration get an overview of what is going on throughout the collaboration and what areas need additional manpower.  We call these overview weeks "ATLAS weeks." I try to attend as many of these ATLAS weeks as I can since my university is located 5000 miles from CERN and attending these serves as a valuable resource for me to focus my research efforts.

I don't know if any of this post relates to God or Christianity, but I do find the interactions among people at CERN amazing.  Walking through the halls of CERN, I hear languages from everywhere around the world and I hear English spoken in just about every imaginable accent.  People whose countries don't always get along work side by side.  Palestinians work with Israelis, and Chinese work with Taiwanese.  Even the French and British get along.  This happens because we share a common goal and work together to achieve it.  I'm sure there is a lesson somewhere there for Christians who don't always agree on everything.  This also might be a small picture of what eternity will be like with people from every tribe and nation united together with a common purpose.  Maybe we could take some of these lessons from CERN and make the whole world a better place.  Now that might be something completely different....

The top figure above the text shows the home countries of the ATLAS collaborators. The image above shows an aerial view of the main CERN site.  The third image just above shows a computer image of the ATLAS detector (note the size of people in the image).  All images are copyrighted by CERN.

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