Going after the elusive dark matter
I ghosted a column for the eminent theoretical phycicist John Ellis CBE based on an interview about the Higgs Boson and the discovery of supersymmetry
WORDS: JOHN C SILCOX
ILLUSTRATION: DALE EDWIN MURRAY
What is the universe made of? This is a question humans have been asking themselves since ancient times, and over the years many advances have been made. Physicists such as myself describe all the visible matter in the universe by a theory called the Standard Model. This theory, which was first proposed in the 1960s, uses a handful of particles and a few forces to explain most features of the world we live in, by providing an accurate description of everything visible in the macrocosm.
It is the natural partner of the Big Bang theory: the idea that the universe started with an explosion and hasn’t stopped expanding ever since. This theory was popularised by Stephen Hawking, the world-famous cosmologist whose life is currently the subject of the Oscar-winning film The Theory of Everything. However, the Standard Model doesn’t explain everything. A current estimate is there is as much as six times as much dark matter as the visible matter – which is why my colleagues and I still have a big job to do.
The Large Hadron Collider (LHC) is currently the best tool we have for testing our theories by running large experiments on the fundamental particles. It lies in a 17-mile circular tunnel near Geneva in Switzerland and is the largest single machine ever built. It shoots particles such as protons and nuclei at each other at incredible speeds, and records the results in electronic detectors that work like gigantic digital cameras.
In 2012, the LHC discovered the Higgs boson, the last particle in the Standard Model. The machine has been undergoing improvement work since making this breakthrough in fundamental physics, but in March 2015 it will be turned back on and scientists all around the globe will eagerly work on the results.
This time round, our main focus is that elusive dark matter – the cosmic glue that holds galaxies together. Before you jump the gun, I’m not saying that we will elucidate all the mysteries of life in one fell swoop, but I am confident this new phase in the LHC’s life will further our understanding of the fundamental laws of physics. One particular field of interest is the idea of supersymmetry, or SUSY, which is currently one of the foremost candidates to explain some of the way dark matter works.
SUSY is an area of work I have specialised in for many years, and tries to link the fundamental particles of matter and the forces between them.
If it were possible to prove this idea by an experiment, then not only would we gain a far greater understanding of the way galaxies interact, but also take a giant step towards unifying all the fundamental forces in nature.
If SUSY is a true symmetry of nature, it would open up many exciting new fields of study, and enable us to delve further into the mysterious features of particle physics, solving a number of paradoxes scientists are currently confronted with. The supersymmetric extension of the Standard Model would supersede the Standard Model as the best description of all the matter in the universe.
The discovery of SUSY will provide important answers to the questions about how we exist, although it’s sadly not going to solve all of the world’s problems. Science can answer questions about how, what, where and when, but it will never answer the biggest question of all: why are we here?
Professor John Ellis is a British theoretical physicist. He currently splits his time between King’s College University in London and the European Organisation for Nuclear Research (CERN) in Geneva, Switzerland