Christopher Nolan says the movie business is alive and well, a case in point being the mega box office success of his recent directorial Oppenheimer, which he termed the 'most successful film' of his 20-year career.

Oppenheimer, the Cillian Murphy-led biopic of the theoretical physicist J Robert Oppenheimer, has earned 950 million dollars at the worldwide box office which is a rare feat for an R-rated biographical drama based on the life of a scientist.

The filmmaker, one of the strongest proponents of theatrical releases, said it is great to see people flocking back to cinema halls.

"I've just made a three-hour film about Robert Oppenheimer which is R-rated and half in black-and-white and it made a billion dollars. Of course, I think films are doing great. The crazy thing is that it's literally the most successful film I've ever made. I've been doing this for 20 years and in the United Kingdom it's my highest-grossing film. So, I feel great about the state of the movie business, based on my own experience. But also based on seeing other movies break out, seeing audiences come back," Nolan told Empire magazine.

Viewers also thronged to watch Greta Gerwig's Barbie, which released the same as Oppenheimer.

Other Hollywood releases that raked in the moolah include The Super Mario Bros, Spider-Man: Across the Spider-Verse and Guardians of the Galaxy Vol. 3.

"The audience's desire to be surprised, to see something new and to see something they did not know they wanted, that's always been the most powerful force in theatrical film. So, it was wonderful to see that this year," said the filmmaker, also known for the Batman trilogy, Interstellar and Inception.

Nolan said he sneaked into the screenings of Oppenheimer on opening weekend with his producer and wife Emma Thomas and experienced the magic of cinema firsthand.

"Emma and I went into the back of Lincoln Square, which has a giant IMAX screen where you can still play 70mm film. And there were two screens - one five-perf 70mm, one 15-perf - and we went from one to the other. When we walked into the back of the IMAX screen, it was just as the Trinity test was coming to its conclusion. It was absolutely packed. Every seat was filled. To be in the back of that theatre in that moment of silence before the sound washes over the audience, you could hear a pin drop. It was a really remarkable experience. Quite overwhelming, really," he added.

Recently, Nolan said a lot of time and energy went into making the Blu-ray version of Oppenheimer so that fans can own a physical copy of the film that no "evil" streaming service can steal from them.

The Blu-ray version of the film, also starring Matt Damon, Robert Downey Jr, Emily Blunt, and Florence Pugh, was released last month.