What is a Particle?

For my money, particle physics is just about the coolest thing in the world.  The scientifically curious public evidently thinks it’s pretty cool too, as evidenced by the books and articles aimed at the general public that far outnumber the coverage given to other areas of physics, much to the chagrin of the people who study those fields.

So you’ve probably heard about many concepts about particle physics.  I’m sure you know about atoms, electrons and the nucleus.  Maybe quarks, neutrinos, and the higgs boson sound vaguely familiar.  And the media hype around the LHC startup has been hard to ignore.

In this series of posts, I hope to give you a better understanding of what particle physics is about.  I hope these posts will be of interest to both the novice and the relative expert — anyone who wants to explore the question of just what it is we mean when we talk about a fundamental particle.

ATOMS

Before we talk about particle physics, we have to have a little context.  Let’s start with the universe.

Okay, now let’s zoom in juuust a little bit, down to the level of atoms.  This is where I will begin our discussion of what it means to be a particle.  Atoms were originally posited to be the smallest, “uncuttable” building blocks of all matter, the first candidate for a fundamental particle.  This idea, originally put forth by philosophers such as Democritus, was in opposition to the idea that matter was a continuum that could be divided into smaller pieces ad infinitum.  As chemistry developed and new elements were discovered and isolated, the atomic hypothesis moved from the realm of philosophy and became an essential scientific concept.

However, we’re not all that interested in the development of chemistry.  I want to focus instead on what sort of a mental picture this model gives us.  In other words, just what sort of properties does a “fundamental particle” have in this atomic theory?

LHC Rap Video

You might have seen this already, but it’s just too good not to post:

The vibe is decidedly old school, with straight delivery reminiscent of early rappers like Kurtis Blow or the Sugar Hill Gang.  (In fact, since the rapper is a woman, it actually kind of reminds me of Blondie’s foray into hip hop, if you can call it that.)  And for some reason, they decided to resurrect one of the most annoying samples in hip hop’s history, the “Hoo! Yeah!” from Rob Base’s “It Takes Two.”

Interesting Look into the Guts of the LHC

With the Large Hadron Collider scheduled to inject its first protons sometime in August, there have been plenty of articles written about it. Most of these articles are either aimed at the popular or scholarly levels, with little in between for the interested semi-knowlegeable student.  (And don’t forget the important question of whether tiny black holes produced in the LHC will eat our world.)

Well, John from Cosmic Variance has bridged the gap with an excellent article about his personal involvement with one of the detectors in the CMS experiment.  Even though I am generally not all that into “tech specs” about such experiments, I enjoyed this peek inside the actual life of the LHC.

It’s mind-boggling to think about the size of the LHC project.  Looking at the complexity and care involved in this one component, and extrapolating this to the thousands of other components involved in the experiment really brings you face-to-face with the magnitude of this undertaking.