The Higgs Boson: an introduction

The (almost certain) discovery of the last piece of a scientific jigsaw puzzle was announced this week. To understand this event, you have to understand that in science, all laws, theories, and models change over time. People like to think that the laws of physics are like diamonds, hidden out in the universe just waiting for some frontier explorer to trip over them. We like to think that the reason science appears to change is just because our view shifts, like looking through a different facet of a gem, but that there is an immutable core that underlies our belief.

In truth, though, scientific laws are a lot less like diamonds and more like philosophies. Every now and then a catchy idea ("I think therefore I am", "E = mc2") comes along and inspires people. Through debate and consensus forming, this idea becomes part of our worldview, other ideas build on it, and it grows. There is no solid bedrock of Truth that provides a foundation for scientific laws. We regard them as true only as long as they agree with testable observations. When technology improves and new observations are made, laws often get thrown out completely.

So, the Higgs boson is a particle that we wanted to see to test a particular idea called the Standard Model. Scientists used to think that atoms were the smallest building blocks of the universe, but since about 1900 we've known that atoms are in fact made out of smaller building blocks. One idea for what these blocks are and how they fit together is called the Standard Model. The Standard Model predicts that a bunch of particles exist - quarks, fermions, leptons - things that behave weirdly and seemed pretty dubious when first proposed. But scientists went looking for the evidence of these particles and found all of them, except (until this week) the Higgs boson. Many people had thought (or hoped) that the Higgs boson would never be found and we'd have to throw out the Standard Model.

The Higgs boson is a part of the Standard Model that explains why things have mass. The idea for it (how mass connects to the rest of the Standard Model) was proposed in 1964, in three independent publications (including one by the eponymous Higgs). Since then, physicists have been looking for evidence of this particle. Eventually we figured out that if it existed, it was going to take tremendous energy, and thus tremendous money, to detect it. It cost over $13 billion to build the Large Hadron Collider and run CERN long enough to find the particle. The announcement this week is not a huge theoretical advance - it means that an idea we've believed in for over 50 years is still consistent with the data available. 

But it is a triumph in that we now have more confidence in this model of how the universe is put together. More than that, though, this discovery is a triumph of science working. Physicists had this wild, crazy idea, and spent years refining it. Then they developed new technologies and created whole new fields of study in order to test out their idea. The particle itself is neat, but the questions raised and the ideas that we've thought of while looking for it - that's amazing.