"Before Nolan called, we had sort of given up. We thought this was never going to happen. This story — it's too complicated," Bird says.

It was not until he read Nolan's script, which he described as "brilliant" and a "faithful" adaptation of the book, that Bird began to feel hopeful.

"It did justice to the two main storylines — the scientific triumph that Oppenheimer had in building the weapon, and the tragedy that Oppenheimer was terribly wounded by what happened in 1954," Bird says. That year the United States Atomic Energy Commission investigated Oppenheimer and removed his security clearance.

But the biographer was still skeptical that the film would be a hit with the audiences, citing how most young Americans had never heard of Oppenheimer.

"I assume most Chinese had never heard about him either," he says. "Why would the younger generation go to see a movie about an unknown scientist?"

As it turned out, the film's success has had a knock-on effect on the book. In fact, the effect has been so pronounced that the book has since been published in more foreign languages.

Bird points out that while biographies shed light into a particular person's life, some things in the book are subjective and do not represent the absolute truth.

"Biographers should be the first to admit that what they write is subjective. It's their point of view about a person's life," he explains.

"Our motivation as biographers was to use Oppenheimer's life to convey both the fascination we had with his personal life, and the larger history of what he lived through, and to address some of the big questions like, was the atomic bomb necessary to end the war? How do we think about nuclear weapons today? Can we live with the bomb?"