Silk has written or co-authored more than 500 publications. He has conducted important early work on homogeneities in the cosmic microwave background and how they are influenced by density fluctuations in the matter of the early universe, in particular by a damping effect that bears his name. These were decisive contributions that helped transform cosmology into a high-precision science. He has also made pioneering advances in understanding the nature of dark matter, and explored novel indirect methods for its detection. The latter have inspired very large experiments with new types of telescopes. Silk‘s studies of galaxy formation and his work on the dynamics of mass loss and the feedback mechanisms from star formation and evolution have formed a very significant basis for subsequent work in this important field.