[2] In February 2022, he signed an open letter from Russian scientists and science journalists condemning Russia's invasion of Ukraine.

They predicted the pattern of acoustic fluctuations that have been clearly seen by WMAP and other CMB experiments in the microwave sky and in the large-scale distribution of galaxies.

With Yakov B. Zeldovich, at the Moscow Institute of Applied Mathematics, he proposed what is known as the Sunyaev-Zeldovich effect, which is due to electrons associated with gas in galaxy clusters scattering the cosmic microwave background radiation.

He has collaborated in important studies of the early universe, including the recombination of hydrogen and the formation of the cosmic microwave background radiation.

At Garching he is working in the fields of theoretical high energy astrophysics and physical cosmology and participates in the data interpretation of the ESA Planck spacecraft mission.