17.10.2013

Science and collaboration

The ‘standard model’ has been confirmed, writes Anthony Rose. But it is not only Peter Higgs who should be celebrated

As readers may know, this year’s Nobel Prize in physics was awarded to professors Peter Higgs and François Englert for their theoretical work on what has come to be known as the ‘Higgs mechanism’, following the discovery of the ‘Higgs boson’ in experiments conducted by the European Organisation for Nuclear Research (CERN) at its Large Hadron Collider (LHC) in Switzerland last year.

In order to provide a brief explanation of the work that resulted in this award, and why it is so significant, first a little background will be required. Our current theory of particle physics is the beautiful, if blandly named, ‘standard model’. This provides a unified description of the fundamental particles and interactions that make up the universe, and is one of the most significant achievements of modern science. It has required decades of work from both the theoretical and the experimental physics community to reach the level of precision that exists today, and last year’s discovery of a new boson (elementary particle) using the Atlas and CMS particle detectors, consistent with the long-predicted Higgs boson, could potentially be the missing piece of the standard model puzzle that physicists have been searching for since it was postulated in the 1960s.

The billions of pounds spent on the construction and operation of the LHC and the particle detectors is just the latest episode of a decades-long quest to establish the limitations of this model, which has so far seen its predictions confirmed as correct time and time again.

According to the standard model, there are two types of fundamental particles. The first of these are the particles that make up matter (known as fermions) and the second type mediate the forces we observe in nature (bosons). This theory was first developed in the 1960s, beginning with Sheldon Glashow’s discovery of a way to combine the electromagnetic and weak nuclear force into a single theory of the electroweak interaction. In 1964, realistic models for the breaking of the electroweak symmetry were formulated by Englert and Brout (who died in 2011, and would otherwise be sharing this prize with his long-time colleague), Higgs, and Guralnik, Hagen, and Kibble.

They proposed the existence of a new field that permeates the universe (we now know this as the Higgs field) and put forward the theory that particles acquire mass via their interactions with this field. This is why last year’s discovery of the Higgs boson is so important to the story - to prove that the Higgs field exists we can dump enough energy into it to ‘excite it’, with the resulting (detectable) boson being the excitation of the field. The Higgs mechanism was a comprehensive solution to the problem of how to break the electroweak symmetry, but without experimental evidence it was just the (overwhelmingly) most likely, as there were in fact several alternative candidates.

The most crucial consequence of this symmetry breaking is that it allowed for the photon (the particle associated to the electromagnetic force) to remain massless, while the W and Z bosons (which mediate the weak force) could acquire mass, as required nature. This was a critical development in our understanding of the universe. In 1967 the Higgs mechanism was incorporated into the electroweak theory by Steven Weinberg and Abdus Salam. These two, along with Glashow, shared the 1979 Nobel Prize in physics for their work in the formulation of the standard model. A quick count suggests that following last week’s announcement there are now 16 Nobel Prizes recognising work associated with the development of this theory.

One question that has been raised countless times over the past two years or so, as physicists speculated on when (not if!) the Higgs boson would yield a Nobel Prize, was how the committee was going to split the award. There is a convention for the prize not to be awarded to more than three people, and also to recognise individuals rather than collaborations. The problem with this approach is that it simply does not allow for the prize to accurately reflect the way that fundamental science is often carried out. From the theoretical standpoint, the discovery of the Higgs mechanism was built upon contributions from far more than just Englert and Higgs. It is widely known that there was very important input from physicists such as Philip Anderson, Robert Brout, Gerald Guralnik, Carl Richard Hagen and Tom Kibble. This year’s Nobel Prize, however, does not acknowledge the work of any of these people.

The discovery of the Higgs boson itself was also a phenomenally difficult task, and was the result of hundreds of thousands of hours’ work from those building and operating the LHC and its detectors, and those analysing the data. The discovery required many billions of protons to be accelerated to close to the speed of light, at the highest energies ever achieved in a laboratory, before being caused to collide inside enormous particle detectors. There are around 3,000 physicists working on each of the Atlas and CMS experiments (the two general purpose detectors that dedicated a large fraction of their effort to searching for evidence of the Higgs boson), and several hundred more accelerator physicists who are responsible for the operation of the LHC.

The experimental collaborations do have a spokesperson, and various other past prizes have been given to the person that happened to be in this position at the time of the award, but every paper published is the work of a huge number of people, and the name of every member of the collaboration is actually listed on each one (in some cases the author list is longer than the paper itself!).

The work of Peter Higgs and François Englert was undoubtedly incredibly significant, and it is right that they have been recognised for their important insights into fundamental physics. The award should be considered to represent something much wider than the work of two individuals, however, and instead we should remember that often scientific breakthroughs such as this are the culmination of decades of intellectual effort by a huge number of people. While it may be impossible for any scientific award to accurately reflect the contribution from all of those that have played a part, we should remember that every scientist necessarily builds upon the work, and relies upon the direct or indirect collaboration, of countless others.