PASADENA, Calif. — Experts who consulted on the PBS program "Nova: Building at Ground Zero" openly scoffed at theories such as those presented by Brigham Young University physics professor Steven Jones, which accuse unnamed government agencies of complicity in the destruction of the World Trade Center. (Jones has been placed on paid leave by the university).

Jones insists bombs placed in the towers caused them to collapse, not the planes that hit them. But William Connolly, the director of codes and standards for the state of New Jersey — one of the nation's leading advocates for changing building codes in the wake of the terrorist attacks— insisted such theories are "ridiculous" in response to a question from the Deseret Morning News.

"Number one, why would you bother with the planes if you could bring down the buildings with bombs?" he said. "Second, that whole theory is just utterly inconsistent with the evidence.

"This happened in plain view. The National Institute of Standards and Technology had very detailed pictures analyzing it in a very detailed way. We know exactly what happened and exactly why they fell, and it has nothing to do with bombs."

Leslie Robertson, chief structural engineer of the World Trade Center, echoed those comments. "It's utterly ridiculous," he said.

Larry Klein, who produced both "Building on Ground Zero" (which repeats Sunday at 2 p.m. on Ch. 7) and the Emmy-winning 2002 documentary "Why the Towers Fell," said, "It's always been interesting to me why people need to have those kinds of theories on events like this."

The program includes a minute-by-minute re-creation of what happened to the towers after the planes hit, using data from the National Institute of Standards.

"So I guess I feel that if you see the film, you can't have those theories anymore," Klein said. "But at the same time, I know that those kinds of people — you can't dissuade them."