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Srdan Kotus

The main question in my work is whether the fundamental constants of nature are actually constant. Fundamental constants are numbers that are central to any physical theory, but those numbers cannot be calculated within those theories. We assume that these numbers are constants because, so far, we seem to find the same value whenever and wherever we try to measure them. The fine-structure constant is one of these numbers which characterizes the strength of electromagnetic force. There is currently some evidence that the fine-structure constant could vary in spacetime, which could be seen at very large distances.

In my PhD project we conduct an experiment in which we are looking at a cloud of gas between us and a background source of continuum light (quasar) through a spectrograph. When the light passes through gas clouds, only light at very specific colours (wavelengths) which corresponds to specific atoms/ions is absorbed. Through the spectrograph we see this as black stripes on a background rainbow. Among many things that we can infer from these stripes, we can see whether the distance between some of them is different compared to the same stripes measured in laboratory. If that is the case, which has been tentatively shown by my collaborators, than we can infer that the fine-structure constant in those clouds is slightly different from its value in the laboratory. Alternatively, we can check whether some systematic errors may be affecting the measurements.

My project is to look at new spectra taken from some of the largest optical telescopes in the world and see if there is some difference in fine-structure constant and also to search for systematic errors that can occur in these spectra.

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