Uncovering the Mysteries of Particle Physics
Last Thursday I finally managed to respond to Jenny’s request that I bring my particle physics cupcakes to class (mmmmmmm…cupcakes!)
Since my first post, I have received a few requests for an explanation of what the cupcakes actually represent. Needless to say I have not done a course in theoretical particle physics (yet), but I’m going to give it my best shot.
First and foremost, particle physics is the study of the fundamental building blocks of our universe. The cupcakes represent the Standard Model of Particle Physics, which you can think of as being somewhat equivalent to the Periodic Table of the Elements. It contains the 17 fundamental particles that are believed to govern the laws of nature.
Here’s my version of history: the universe was created, some stuff happened, and then we developed the Standard Model of Particle Physics. So it’s fair to say that the Standard Model represents a giant leap forward in modern science.
So how did it all begin?
We have known for centuries that the elements that make up the stuff in our universe are just atoms with varying numbers of protons. Unfortunately there’s a bit more to it than that.
Since the 1950s, scientists have detected all sorts of weird and wonderful particles entering our atmosphere from outer space. None of them was anything like the elements in the Periodic Table, so they must have been some new type of particle. How exciting! The trouble was that physicists had no idea how they all fitted together.
In the 1970s, some brainiac decided that it might be worth trying to group these particles according to their properties, such as mass and electric charge.
The defining moment came when physicists realised that a lot of these new particles were actually made up of even smaller particles called quarks (which, of course, rhymes with ‘forks’). Quarks come in 6 ‘flavours’** – up, down, charm, strange, top, and bottom. For example, a proton is made from two up quarks and one down quark, and a neutron consists of one up quark and two down quarks.
The next major family of particles is the leptons. The electron is one of the basic leptons, along with the muon and the tau, and they are all negatively charged. The muon and the tau can be created by smashing particles together at the Large Hadron Collider, and they also enter our atmosphere in cosmic ray impacts. Each base lepton has a corresponding neutrino, which are created during nuclear reactions and can travel at almost the speed of light. The neutrinos appear above their matching base leptons in the 4×4 grid.
Now we will take a look at the bosons, the force-carrying particles. My favourite boson (everyone has a favourite boson, right?) is the gluon. The gluon mediates the force that holds atoms together. If you think about it, all those protons inside a nucleus should repel each other because they are all positively charged. The appropriately-named gluon provides the ‘glue’ that holds all the atoms together against this repulsive force. The rest of the bosons mediate the other fundamental forces of nature – the weak force that governs radioactive decay, the electromagnetic force (light & magnetism), and good old gravity.
Finally we arrive at the Higgs boson. Scientists have been able to detect all of the particles in the Standard Model except this one, and they suspect it must be hiding out there somewhere. If it exists, it will almost certainly be detected at the Large Hadron Collider. Physicists hope that the discovery of this elusive particle will help explain the origin of mass, and also why some particles, like photons (particles of light), have no mass at all.
The Large Hadron Collider may uncover some deep dark secrets about the universe that cannot be explained by the Standard Model. These include dark matter, dark energy and even extra dimensions. I’ll fill you in on those another time.
**Physicists do get creative from time to time
This post was written using 100% recycled electrons.