On December 3 and 4, CERN held a two-day symposium to celebrate the past fifty years in high-energy particle physics. The event, titled “From the Proton Synchroton to the Large Hadron Collider--50 Years of Nobel Memories in High-Energy Physics,” coincided with the fiftieth anniversary of the PS, the Proton Synchroton; twentieth anniversary of LEP, the Large Electron-Positron collider; and the restart of the LHC. Speakers at the symposium, including thirteen Nobel Laureates, discussed developments in high-energy physics over the last fifty years and what’s to come, from the LHC to linear colliders and beyond.
The first day of the symposium focused largely on accelerator physics, looking back and highlighting the trials and triumphs of particle accelerators and the people who built them. The Proton Synchrotron, or PS, which began operation in 1959, was CERN’s first synchrotron and remains a vital part of the CERN accelerator complex today. LEP, which was the largest accelerator of its time when it began running in 1989, tested theoretical predictions of the Standard Model, set a lower limit for the Higgs Boson’s mass, and established the existence of three types of neutrino.
The long history of the LHC, LEP’s successor, was discussed by Lyndon Evans in his presentation “The LHC Adventure.” He noted, “This machine is a beautiful machine and frankly, it feels more like an old friend than a new machine.”
The formation and scope of CERN as an international organization was also discussed. Guenther Plass mentioned the sixtieth anniversary of Louis de Broglie’s request for an institution that would operate beyond the framework of its member states, and Burton Richter called for greater collaboration in the future. Richter closed his presentation with the opinion that only two places had the potential to host a multibillion dollar linear collider, CERN or China. Richter stressed, however, that CERN would only remain at the forefront by internationalizing further.
Director General Rolf Heuer closed the first day’s talks with a forward look, including LHC upgrades and future colliders such as the ILC or CLIC.
The second day of the symposium focused on the development of the broader field of particle physics, and the development and testing of the Standard Model. By examining the differences between physics as it was in 1959, and particle physics today, the speakers provided a window into not only how much has changed within fifty years but also insight into the process of discovery itself.
In his comparison of old and new physics, Gerardus t’Hooft marveled at the elegance and beauty of nature as revealed in each new discovery. While discussing the standard model, he remarked on how dramatically perspectives in physics have changed with new discoveries: “Could we have expected such a beautiful theory in the 1960s? I think no one could have expected such a grand synthesis.”
Personal experience woven into the presentations created a layered history of scientific progress. Sheldon Glashow focused on the “road to electroweak unification,” incorporating “false starts and bumbling blunders, mostly mine, and a few brilliant insights,” to reveal the importance of both error and success in scientific discovery.
Questions were also generated by looking at the past. David Gross challenged that “Standard Model” was a misnomer and that standard theory would be a more appropriate title. Opinions also varied on the relative relevance of string theory and supersymmetry to future physics discoveries and the LHC. Martinus Veltman focused on the efforts thus far to find the Higgs boson and what steps should be taken if the LHC experiments do not detect the Higgs. A recurring theme in the presentations was a willingness to pursue possibilities and to question everything.
“We really make progress when we recognize good ideas, whether we make them or not,” observed Jim Cronin. This sentiment was palpable in the symposium, as the people who had pursued good ideas shared their stories and offered advice for the future. It was evident that, as CERN looks forward to future physics discoveries with the LHC, the lessons of the past fifty years will not soon be forgotten.
Full video coverage of the symposium is available online at http://cdsweb.cern.ch/record/1227015/. Highlights include:
- Part 1: Guenther Plass’s “The PS Machine: 50 Years of Continuous Evolution,” and Dr. Steve Meyer’s “LEP Operation”
- Part 2: Burton Richter’s “Electron Accelerators at CERN,” Lyndon Evans’ “The LHC Adventure” and Rolf-Dieter Heuer’s “The Future of the CERN Accelerators Complex”
- Part 3: Jim Cronin’s “The Discovery of CP Violation: a Surprise” and Sheldon Glashow’s “Unification: Then and Now”
- Part 4: Martinus Veltman’s “The LHC and the Higgs boson”
- Part 5: Gerardus ‘t Hooft’s “The Unique Beauty of the Subatomic Landscape,” David Gross’ “QCD: Now and Then,” and Steven Weinberg’s “Changing Views of Symmetry”