In 1996 he joined the Physics Department of the State University of New York at Stony Brook from which he received his PhD in May 2000, with thesis written under the direction of Peter van Nieuwenhuizen.
From 2000 to 2002 he was a postdoc at the Institute for Advanced Study in Princeton, after which he was an assistant research professor at Brown University until 2006.
Since 2010, Năstase holds a permanent position as assistant professor at IFT-UNESP in Brazil.
Năstase attracted some media attention in 2005[1] by arguing that string theory could be tested by the Relativistic Heavy Ion Collider, through the AdS/CFT correspondence.
[2] He is also known for his work in 2002 with David Berenstein and Juan Maldacena to investigate the duality between strings on pp-wave spacetime and "BMN operators" in supersymmetric Yang–Mills theory.