Martinus J.G. Veltman, the Dutch theoretical physicist who won the Nobel Prize for major contributions to the standard model of particle physics, which explains the structure and workings of the universe at its most fundamental level, died Jan. 4 at his home in the Netherlands. He was 89.

His death, in Bilthoven, was confirmed on the Nobel Prize website, but no cause was released. He taught for years in his native land and was also a professor emeritus at the University of Michigan.

Dr. Veltman made his most significant contribution in helping clear away mathematical roadblocks to the full flowering of the standard model. His mathematical contributions have been regarded as pointing toward and making possible major and well-publicized advances in physics.

These include discovery of the top quark, regarded as one of the fundamental building blocks of matter, and of the Higgs boson, a subatomic particle sometimes viewed as the key to the structure and even existence of the universe.

Veltman shared the Nobel in physics with another Dutch theoretical physicist, Gerardus 't Hooft, then at Utrecht University in the Netherlands. 'T Hooft studied and did his research under Veltman at Utrecht.

"Without Veltman's and 't Hooft's work, discovery of the top quark would have been impossible," Homer Neal, a physicist at the University of Michigan, said at the time the Nobel was awarded.

"While the concepts behind the Standard Model — the theory that describes the elementary particles and forces in the universe — were well-known in the physics community, their work gave us a way to apply the theory to real-world events. It was of monumental importance to advances of modern physics."

Among the specific developments with which Veltman was credited was an early computer program that helped bridge what had been a daunting and discouraging roadblock in efforts to build the standard model. The obstruction had blocked the path between the concepts underlying the standard model and the ability to use the model to describe existing particles and to predict the existence of new ones.

Known as Schoonschip, the program brought him recognition for enabling computers to operate on the symbols of mathematics, just as they were becoming known for manipulating numerical data.

Its name -— which in Dutch means or suggests a taut, clean ship — implies its usefulness in handling the profusion of terms that bogged down efforts to make calculations on the basis of new theories that tried to blend the understandings of classical and quantum physics.

'T Hooft, Veltman's former student, expressed admiration for his professor's work with computers in a relatively primitive age, when programs were punched mechanically into paper cards.

For Veltman, computers were a means to an end, a tool in the development of theoretical physics. The goal was to probe the mysteries of the universe. "There is nothing more exciting than discovering how nature works," he said.

The Nobel committee cited him and 't Hooft for "elucidating the quantum structure of electroweak interactions in physics."

What this meant, among other things, was devising mathematical methods that made fully possible and practical the unification of quantum theory with two of the four forces of the universe: electromagnetism and the "weak force" that acts between nuclear particles. (The other two forces are the strong nuclear force and gravitation.)

With their computer work, the two 1999 prize winners found ways to develop a mathematical system for unifying the forces that avoided the previous pitfalls. Importantly, it made calculation possible without the values of important terms departing from reality and showing up as infinite. Among physicists, clearing away these troublesome infinities is known as renormalization and is basic in many important areas of research.