I am a member of the Fermi-LAT collaboration. Currently I work on data analysis of the Fermi bubbles - these are two large structures stretching up to 10 kpc above and below the Galactic center. They are believed to be related to past activity in or around the supermassive black hole at the center of our Galaxy. Together with Anna Franckowiak we study the energy spectrum and morphology of the Fermi bubbles. If the Fermi bubbles are related to the black hole accretion, then using the Fermi data we can estimate how much matter has been accreted by the black hole in the past several millions of years. Previously I worked on astrophysical and dark matter explanations of the PAMELA positron fraction excess, supersymmetry breaking in string theory, some mathematical properties of the renormalization group in quantum field theories.