Topical collection: in memory of professor T Padmanabhan

Professor Thanu Padmanabhan contributed significantly to a broad spectrum of topics in astrophysics, cosmology, and classical and quantum aspects of gravitation. In his memory, the Editorial Board of General Relativity and Gravitation invited us to edit a Topical Collection “In Memory of Professor T Padmanabhan”. This collection gives a snapshot of ongoing research in the subjects he worked on.