CERN’s Large Hadron Collider (LHC) in which scientists intend to collide two beams of protons moving circularly in opposite directions was started on the last day of March 2010 in a 27-kilometer-long circular tunnel fifty meters underground near Geneva on the Swiss-French border. The Hadron Collider was first launched on September 10, 2008, but sustained damage after nine days and, following repairs, was re-launched in November 2009.
 The experiment is part of a project in which scientists at CERN were attempting to re-create conditions such as existed at the time of the Big Bang from which, as believed, the universe emerged fourteen billion years ago. The experiment was also to try to learn about the original material and origins of the planets and stars.
The project included making four detectors. The two nine-meter stainless-steel wheels weighing 120 tonnes on one of the detectors were manufactured at Serbia’s Lola plant, while the Vinča Institute participated in the making of the other detector.
We talked with Dragan Popović, Belgrade University Institute for Physics director, about the participation of Serbian scientists in the CERN project and about the project itself.
The Institute for Physics you head for quite a number of years is involved in the CERN project designed to re-create under laboratory conditions the Big Bang. Who from Serbia is included in this project and in what way?
 - Scientists from Serbia are included in two experiments – Atlas and CMS, of the total of four experiments conducted at CERN. Researchers from the Institute for Physics are involved in the Atlas experiment that rallies over 2,000 researchers from around the world, while researchers from the Faculty of Physics and the Vinča Institute are talking part in the CMS experiment. Atlas is one of the four detectors on the circular tunnel through which the proton beams are to be circulated at a speed slightly smaller than the speed of light and in which the collision is to take place. For this gigantic piece of equipment the Institute has made two so-called small wheels. Work on these experiments unfolds through international scientific collaboration – the most extensive ever achieved.
Ordinary people can hardly be expected to grasp and appreciate the goal and essence of many scientific exploits and projects. Concretely speaking, what is the ultimate goal; what is the purpose of this Big Bang experiment?
- One of the major tasks of contemporary physics is to describe laws of nature operating in the smallest distances, i.e. at the highest energies, and endeavor to offer quantitative descriptions of the universe. Today in particle physics we know the attributes of elementary particles and their interactions with energies amounting up to several hundred GeV for distances of 10-16 centimeters. At the same time, dynamic advance of cosmology (observational, first of all), made possible not only qualitative but also quantitative (with solid accuracy) descriptions of evolution of the universe as well as the features of the early and present-day universe. However, a series of unresolved problems in physical cosmology necessitated radical supplementing of the existing views on the laws of nature. In the 1970s, a Standard Model theory was developed in elementary particles physics offering consistent descriptions of the bulk of our knowledge gained thus far about particles and forces affecting them. Despite its great success, the Standard Model is incomplete and there is a whole range of issues it cannot as yet provide answers to. It is believed that only when the Standard Model is expanded can these open questions be solved. Despite variegated theoretical ideas on the Standard Model expansion in particle physics, there is still no single convincing piece of experimental evidence regarding physics beyond the Standard Model. On the other hand, cosmological observations hinting at the existence of dark matter and dark energy point to a new physics existing beyond the Standard Model. The LHC will help physicists provide answers (or at least partly so) to the key unresolved questions in particle physics. Attaining for the first time an overall collision energy measuring 14 TeV (thousands of billions of electron volts) would enable exploring particle physics on the tera-energy scale (TeV scale) and for distances a thousand times smaller than the diameter of a proton. Sound reasons exist supporting physicists’ belief that the new domains hold a new physics that exceeds the boundaries of our knowledge about particles and forces affecting them. Assisted by powerful accelerators we are in a position to produce new particles and uncover symmetries that existed in the early stages of development of the universe. The higher the energy of accelerated particles, the closer we come to recreating the conditions that existed at the offset of the Big Bang. Physicists believe that with as 14 TeV energy is achieved in highly rare and extremely improbable events with specific signature they will be able to reconstruct what happened in the billionth fraction of a second following the Big Bang.
Participation in this project signifies not only recognition of the role of our science and scientists but also implies the possibility for our science to move along with contemporary research and trends on an equal footing with the rest of the world?
- This is an equality-based cooperation involving our nine researchers whose contribution is proportional to the size of our research team engaged on this project.
Tell us something more about your Institute?
- The Institute for Physics was founded jointly by the Serbian government and the University of Belgrade in 1961. Today it boasts 212 employees, and of the 152 researchers 100 hold a doctoral degree. It is noteworthy that half of the overall number of researchers are under the age of forty. The Institute has five centers covering - in terms of research work - the most topical issues in physics. The European Union has recognized and financially assisted four centers of excellence at the Institute. The Institute accounts for ten percent of the country’s overall number of published scientific papers.
Your career, too, is a very interesting one. You graduated from Belgrade University, and as far as we are aware, took a doctoral degree in Japan. You have headed the Institute for a good many years. How do you perceive the future of science in Serbia and that of the Institute?
- Yes, after completing my MA in Belgrade, under a Japanese government scholarship I worked at the Research Institute for Fundamental Physics (Yukawa Hall) in Kyoto University, and took my doctoral degree from the Hiroshima University. On returning home, I became a researcher at the Institute for Physics and today I head this respectable scientific institution. At this time, considering the economic crisis is affecting science as well, we are struggling to maintain the high level of research work that we traditionally cultivated and enjoyed and in this way retain the high position among international scientific institutions thanks to the top researchers we employ and the superb equipment have obtained over a number of years. In all this, the indisputable role was and is that of the Ministry for Science and Technological Development, which supports the Institute’s work.
Getting back to the beginning of the interview, what is the nature of the Institute’s and your involvement as the Big Bang experiment unfolds and how will that affect your future work.
- As the first stage on the LHC is complete, that is beams of protons have been circulated and the work of the detectors tested, what awaits us is to analyze the collision results that will be recorded in the coming years in an effort to discover the missing Higgs boson, to determine why is there more matter than antimatter in the universe, to determine whether there is supersymmetry in nature, to define the number of dimensions of our space-time, to discover the nature of dark matter and dark energy as well as possibly to answer such questions as have not as yet been raised. | 
