The Royal Swedish Academy of Sciences has awarded the 1999 Nobel Prize in Physics jointly to

Professor Gerardus ‘t Hooft
and
Professor Emeritus Martinus J.G. Veltman

for “elucidating the quantum structure of electroweak interactions in physics.”

The structure of particle physics is described using the Standard Model. In this model electromagnetic and weak interactions are unified and together called electroweak interactions. It is theoretical studies of these interactions that have been rewarded with the 1999 Nobel Prize in Physics.