He is also a member of the Young Academy of the Dutch Royal Academy of Sciences (KNAW). His research focuses on understanding the physics of neutron stars, which are the compact remnants of massive stars that have collapsed in a supernova. Some neutron stars, called `pulsars’, emit radio pulsations like a cosmic lighthouse, and Hessels studies these using the largest radio telescopes in the world. He also uses pulsars as natural laboratories for testing the fundamental laws of particle interactions and gravity.