The Higgs Particle and the LHC: A Primer

Today, the Large Hadron Collider (LHC) in Geneva announced, with five sigma certainty (that’s a 99.9999% confidence level) that they have discovered a particle that exists at an energy level consistent with the Higgs particle, according to the Standard Model.

So let me back up. Under the Standard Model, particle physics have theorized that there exists a particle (named the Higgs particle) that indirectly gives mass to all other particles. That is, the Higgs particle gives protons, electrons, everything mass. That’s why it’s nicknamed the “God particle”–because without it, nothing would exist (or so people say when giving a shorthand answer). Now, remember E=mc^2? Einstein described a relationship between energy and mass. The Standard Model predicts that the Higgs particle occurs at 125 GeV, a unit of energy that relates to the mass of the particle.

Okay, so what did the LHC announce? They said they found a particle (again, with 99.9999% confidence) between 125 and 126 GeV. Can they say it’s Higgs for sure? No. Womp womp. All the scientists at the LHC can say is that the model predicts a particle at this energy level, and the LHC experiments found a particle at that level. With more experimentation, they can determine if this particle also possesses the other characteristics the Standard Model says the Higgs particle should possess. If you want a great run down of the physics and today’s announcement, check out Phil Plait’s post on his Bad Astronomy blog. Because, let’s be honest. I’m not a scientist. My understanding of the Standard Model is limited. Any errors or inaccuracies in this piece are mine. Let Phil set you straight.

So why should we care about particle physics experiments in Geneva? Why should millions of dollars and thousands of scientists be working on these issues? Yes, this announcement will probably have zero impact on your July 4th holiday unless you have a few PhDs. But the LHC is answering fundamental questions about energy, mass, and gravity–you know, the building blocks of the universe. These experiments are about exploration and discovery on a very fundamental level. They are a beautiful and wonderful thing. Take some time today and read up on the announcement. Then, (if you’re in the US) when you look up at the stars tonight while waiting for the fireworks, you can be happy humanity knows a bit more about the universe than we did yesterday.