LHC PROJECT SIMULATOR

Scientists assembling one of the elements of an LHC detector

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School science up to 16 covers how mass behaves: forces and motion in physics and the idea of the conservation of mass in chemistry. The ability of matter and energy to be interchanged gets a mention in radioactivity, but it is basically descriptive. The fundamental question "What actually is mass?" doesn't arise.

For more able pupils though, it is a useful question to introduce as a piece of extension. It is a good illustration of how science is a "work in progress" and that some of the most basic questions remain a deep mystery. It also shows how science often operates by developing a model to describe a set of phenomena and then gauging the validity of the model by using it to make a testable prediction. In this case it is the "standard model", which describes the fundamental particles and their interactions. The Higgs boson is a key piece of the jigsaw that is missing, and its discovery would be a big boost in providing evidence to prove the validity of the standard model. Not finding it could mean that our best model of the universe is critically flawed, so the stakes are high.

A good analogy is Mendeleev and the periodic table - each discovery of a new element with properties predicted by the periodic table strengthened the whole concept of ordering elements in that way. Similarly, particle accelerators have revealed the existence of a whole succession of particles that are predicted by the standard model. Finding the heavier particles has required increasingly powerful accelerators, as the mass of the particles that can be made depends on the energy of the collisions. This culminates with the LHC. Although there are already plans for even more powerful accelerators, the maximum energy of the collisions the LHC can produce is more than ten times that of any previous accelerator. This should be plenty enough to produce the Higgs - if the theory is correct.

A common analogy to explain the Higgs mechanism is to imagine a room full of people. A famous person walks in and is mobbed by adoring fans, slowing down their progress. In a similar fashion, particles pick up mass as they move through an all-pervasive Higgs field - a bit like pulling a necklace through a jar of honey.

The search for the Higgs boson has attracted quite a bit of media attention, where it is often dubbed "the God particle" due to its perceived importance as a particle that confers mass on the other particles. For the most part, physicists prefer to avoid this term on the grounds of the confusing messages it conveys.

A popular misconception is that one day a big light will come on at CERN and champagne corks will fly to cheers of "We've found the Higgs!". The reality is rather different. The Higgs won't be detected directly - all that will be measurable will be the "signature" created by its decay products. Analysing the avalanche of data that pours out of the four main experiments at the LHC is an extremely complex business, drawing on global computing resources and the interpretational skills of thousands of particle physicists.

Even if the LHC creates Higgs bosons every day, it will take months to confirm the result. Many physicists would say that the work is particularly satisfying because it is so challenging, and it is a good example of the hard work and meticulous approach that you routinely find in scientific research. Nobody will deny that there is an element of healthy competition between the teams looking for the Higgs, but the whole project also relies on extensive international cooperation and collaboration.