Given the task definition and input, reply with output. In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Which of these Greeks knows more about physics: Joseph Sifakis or John Iliopoulos?, Context: As of 2007, Greece had the eighth highest percentage of tertiary enrollment in the world (with the percentages for female students being higher than for male) while Greeks of the Diaspora are equally active in the field of education. Hundreds of thousands of Greek students attend western universities every year while the faculty lists of leading Western universities contain a striking number of Greek names. Notable modern Greek scientists of modern times include Dimitrios Galanos, Georgios Papanikolaou (inventor of the Pap test), Nicholas Negroponte, Constantin Carathéodory, Manolis Andronikos, Michael Dertouzos, John Argyris, Panagiotis Kondylis, John Iliopoulos (2007 Dirac Prize for his contributions on the physics of the charm quark, a major contribution to the birth of the Standard Model, the modern theory of Elementary Particles), Joseph Sifakis (2007 Turing Award, the "Nobel Prize" of Computer Science), Christos Papadimitriou (2002 Knuth Prize, 2012 Gödel Prize), Mihalis Yannakakis (2005 Knuth Prize) and Dimitri Nanopoulos.
John Iliopoulos