Over many months, reams of analysis have piled up -- a sometimes competing mix of calculation and deduction that suggests an array of answers to the questions of why and how the steel skeletons of the twin towers suddenly came apart in raging fires on Sept. 11. And with that increased understanding, the storms of emotion surrounding the grim, disturbing questions have quieted some.

But as scientists and engineers have gained these hard-won glimpses into the mechanics of a tragedy, there is one other question that almost all of them have carefully avoided asking: could another building, indeed any building, no matter how stoutly or cleverly built, have stood longer than the twin towers did, let more people escape or perhaps never collapsed?

At a time when public officials across the country are considering sweeping revisions to building codes, and some tenants are struggling to regain confidence in the safety of skyscrapers, many technical experts say there are good reasons they have dealt so gingerly with such a volatile, if perhaps valuable, question. Those experts worry about putting victim families through wrenching what-if thoughts, they want to avoid highlighting new potential targets for terrorists and they are awed by the sheer complexity of actually producing an answer.

It turns out, though, that in little-noticed lectures at academic and professional institutions in the last year, one man, Charles H. Thornton, who is among the world's most renowned engineers, has been both asking and answering that lingering question.