The connection between outer space and elementary particles

Text: Sven Titz

Georgi Dvali is a top expert in particle research. At the Ludwig-Maximilians-Universität and the Max Planck Institute of Physics in Munich he is planning to combine cosmology and astrophysics with elementary particle research and, for example, question assumptions about the existence of other spatial dimensions.

Fundamental questions about physics fascinated Georgi Dvali even when he was a schoolboy in Georgia. “I was 11 or 12 years old at the time, and pondering about how the universe came about”, says the researcher. And that is still his favourite topic today. After ten years of research in the USA, Dvali will in future be addressing the fundamental questions of physics in Munich. Dvali is regarded as one of the most creative minds in his field. Hardly anyone else is an expert in several fields and unearths new truths in theoretical physics. On the one hand Dvali focuses on elementary particles, and on the other on cosmology and astrophysics. As part of his Professorship in Munich Dvali intends to analyse, for example, the trial data of the Large Hadron Collider (LHC) particle accelerator in Geneva.

Hunting the Higgs boson

There, at the European Organization for Nuclear Research (CERN), scientists study elementary particles in experiments. To unearth the matter’s innermost secrets, they make particles collide with one another at high speeds. The collisions generate numerous other particles that provide information on the structure of the matter. The experts hope to be able to use the LHC to fi nally prove the existence of a particle that has to exist according to the generally-accepted Standard Model of physics, but which as yet has never been observed, namely, the Higgs boson. It is hoped this boson will explain what gives subatomic elementary particles their mass.

Presumably however, they will make several new discoveries in physics with the LHC in Geneva, speculates Dvali. “We hope, for example, that we will be able to use the machine to test our theories about the existence of other dimensions”, he says. The much-discussed hypothesis states that in the realm of the tiniest particles of all, elementary particles, additional spatial dimensions could open up, i. e., more than the three we are aware of. Dvali develops mathematical models on this subject. He aims to test whether they are realistic or not with the new measurements. Some physicists, including Dvali, also predict the temporary appearance of black holes during the LHC experiments – even if they are only microscopic. These fleeting phenomena are not dangerous, Dvali assures us. “We even find it difficult to keep the black holes alive for long enough to correctly identify them at all”, he says.

Stargazing as theory test

Dvali’s second subject, cosmology and astrophysics, involves unimaginably large distances. With telescopes, we can even observe events which occurred shortly after the Big Bang. Just after this happened, the universe was still considerably smaller than the head of a drawing pin. However, it expanded extremely rapidly. Using telescopes, we can identify a form of radiation in the background of the cosmos that tells us about those very first moments. It is called cosmic microwave background radiation, and it took billions of years to reach us. Background radiation reveals the structure the mini cosmos once had. “For us, the sky is like the projection screen of a gigantic microscope”, says Dvali. He intends to use the observations to see whether his mathematical models of elementary particle physics are correct. For the physics of elementary particles and that of the cosmos are inseparably linked, he says. The processes that took place directly after the Big Bang were presumably governed by laws which also apply to elementary particles. “In many ways”, says Dvali, “the theory of elementary particles can be tested with the help of cosmological and astrophysical observations.”

Dvali also intends to consider the movements of the planets and moons to test and develop his theories further. Experts think, for example, that Einstein’s Theory of Relativity may not be 100 per cent exact. Thus there are tiny gravitational differences from the theory. These should be apparent in our moon’s orbit, for example. In order to measure the differences, mirrors were positioned on the moon. Using the different time it takes for light rays to travel to the moon and back, researchers monitor the lunar orbit with an extraordinary accuracy, which is expected to improve even further in the future. Using the expected data of the improved accuracy measurements, Dvali aims to test this theory in Munich.

Having been invited to Germany, the Georgian especially appreciates “the flexible support of the Alexander von Humboldt Foundation” and the high level of research there. “I think the group in Munich is really exciting”, he says and also hopes to find an answer or two to the fundamental questions he asked himself as a child.