Complex sentence: A theoretical physicist who has been working in the field of cosmology for 25 years, Vilenkin has written over 150 papers and is responsible for showing that eternal inflation is generic and introducing the idea of quantum creation of the universe from a quantum vacuum.
Split into simpler sentences: A theoretical physicist who has been working in the field of cosmology for 25 years, Vilenkin has written over 150 papers. He also introduced the idea of quantum creation of the universe from a quantum vacuum.