CERN, the world's largest particle physics laboratory based in Geneva, Switzerland, today announced the discovery of a new fundamental particle, which appears to be the long sought after Higgs boson. They are been very cautious about actually declaring that it is the Higgs particle as described by various theories, as they need many more experiments and data to fully understand all the properties of this new particle.
So what's all the fuss about? Well, even for somebody like me with a formal education in physics, it's really not easy to fully grasp the underlying concepts. In simple terms, the discovery of a Higgs particle allows particle physicists to confirm that their star theory, The Standard Model, is a very good description of how the Universe works. This particular part of the puzzle allows them to better understand why some fundamental particles have no mass (i.e. no "weight", such as the photons that make up light) while others do (like the quarks that make up the protons and neutrons that make up you and me). During the press conference, which I was able to follow live this morning, the CERN Director General, Rolf Heuer, gave a brilliant and insightful analogy into how the whole thing works:
Speaking to the room full of journalists, he said to imagine themselves (the journalists) as representing what's known as the Higgs field. This is a field (a bit of a mysterious field, but let's leave that for another day) that permeates the entire universe. Now, imagine that some regular Joe walks into the room. This person will be able to make his way through room without been bothered. This is analogous to particles with no mass, such as photons, that do not interact with the Higgs field and can therefore reach the ultimate speed: the speed of light. Now imagine that a well-known person (e.g. Peter Higgs, the "father" of the theory) walks into the room and wants to make his way to his seat. Well, the journalists begin to crowd around him and poor Peter finds it difficult to walk very fast. This is analogous to particles with mass (e.g. quarks and electrons) that end up interacting with the Higgs field. It is this interaction that slows them down and it is this "slowing down" that we call mass. Simple, eh? But where does the Higgs boson fit into all this? Well, in physics, all fields are capable of producing their own particles and the Higgs field should be no different. Staying with the analogy of a room full of journalists, imagine that somebody whispers a rumour in to the room (like, "I heard there's free coffee and biscuits after the press conference!"). This rumour will cause many of the journalists to clump together to get more information on this important piece of news. Similarly, the Higgs field can be made to clump together if enough energy is available, and this clump of Higgs field is what we call a particle. By proving the existence of this Higgs particle, physicists at CERN have proved the existence of the Higgs field and the Standard Model theory that predicted its existence!
Right, here's a selection of news and blog articles on the event that I found useful:
A Quantum Leap, (Slate.com) by well-known physicist Lawrence Krauss
Higgs! by the Bad Astronomer, Phil Plait
Happy Birthday, Higgs Boson! by ZapperZ on his blog "Physics and Physicists"
Physicists find new particle, but is it the Higgs? by Matthew Chalmers at Nature.com
Stop calling it "The God Particle"!, by Dave Goldberg over at io9.com