In 1950, at age 24, Kenneth Ford left his graduate studies at Princeton, hopped in a Chevy and drove to New Mexico to help build the world's deadliest weapon.

For two years, he toiled covertly with other physicists. Eventually they unlocked the secrets of the first hydrogen bomb.

Retired in Philadelphia half a century later, Ford wrote it all down. Now he is sparring with the government over whether his memoir reveals nuclear secrets.

His book, Building the H-Bomb: A Personal History, was published March 23, over objections from the Department of Energy that it included descriptive details of the bomb-building project.

After a story in the New York Times outlined the government's concerns, online sales of the book soared before the first print editions even reached the United States.

Ford, 88, didn't expect the attention or the positive feedback that has since flowed in.

"I've never been a public figure in any sense, never had a reason to be in the papers," Ford, who lives in Germantown, said last week. "It's been pleasant, actually, and interesting and surprising."

The Energy Department had asked him to withhold about 10 percent of the information in the book, he said, ostensibly to protect restricted data Ford had access to as a worker with security clearance between 1950 and 1952.

One of the government's concerns, according to Ford, is his discussion of the importance of "thermal equilibrium" to the success of the bomb. During his time on the bomb squad, Ford created calculations on the burning of the fuel that ignited the bomb and its explosive power.

Ford said he viewed the department's request as bureaucratic "overreach." The information, he said, has long been made public by scientists working in and outside the U.S. nuclear program.

Citing its policy not to reveal which nuclear information is considered classified, a spokesperson for the Department of Energy declined to comment on the book's content and referred questions on possible legal action to the Department of Justice.

A spokesperson there also declined comment.

Ford maintains his story is just one of a young scientist working among the world's top physicists.

He said that most of what he remembers from his two years of weapons work is personal, not technical, and that his explanations for theories were drawn mostly from declassified documents and scientific papers.

The book "would no longer be of any interest to anybody if I took out what they wanted me to," Ford said. "We were miles and miles apart."

This is not the first time the government has publicly lost a battle to keep perceived nuclear secrets hidden. In 1979, the Energy Department won a temporary injunction against a Wisconsin magazine that planned to release information about the bomb's design. The government dropped the case when the same information was released elsewhere.

While Ford's former clearance could make him a target for criminal charges, litigation is unlikely because of the public relations battle that would come with it, said Alex Wellerstein, professor at the New Jersey-based Stevens Institute of Technology and a blogger who specializes in nuclear security.

And getting more details about their concerns is unlikely. For the most part, Wellerstein said, the government has maintained a no-comment policy about its reviews of such published information in order to prevent hinting at what it considers secret.

Neither Ford, who had written nine other books on physics and science, nor his Singapore-based publisher said they had been contacted by the government since the book's release.

The publisher, World Scientific, could not provide details on how many copies have been sold online or in print. But sales reached No. 1 on Amazon's Kindle list of bestsellers in the nuclear physics category. And his U.S. editor said that an additional printing has been ordered.

After years spent in higher education, including a stint as president at New Mexico Institute of Mining and Technology, Ford arrived in Philadelphia in the early 1980s to head a private research firm. He retired in 1993 but returned for a time to teach physics part time to students at Germantown Academy and later Germantown Friends School.

Ford now lives with his wife, Joanne, on a quiet, tree-lined block near Wissahickon Valley Park in Northwest Philadelphia. During an interview Tuesday, he recalled how, 10 years after he left to finish his graduate studies, he grew disillusioned with the Vietnam War and publicly stated he would not return to weapons work.

Still, Ford said, he thinks beating the Soviet Union to the hydrogen bomb was a good thing, and he has no regrets.

There was no political motivation in writing the book, he added. Many readers likely don't care why he wrote it.

But the buzz since its release is not hard to understand, according to Wellerstein, the national security blogger.

"There's nothing in modern culture that makes something more interesting," he said, "than the government telling us it's dangerous."