It has been 20 years since the release of Titanic, but fans of the movie are still questioning why Jack (Leonardo DiCaprio), could not climb on top of the door on which Rose (Kate Winslet), had been floating after the ship hit an iceberg and sank.

Addressing fans' concerns, director James Cameron recently explained in an interview with Vanity Fair: "The answer is very simple because it says on page 147 [of the script] that Jack dies. Obviously it was an artistic choice, the thing was just big enough to hold her, and not big enough to hold him.

"I think it's all kind of silly, really, that we're having this discussion 20 years later. But it does show that the film was effective in making Jack so endearing to the audience that it hurts them to see him die."

The scene where Jack freezes to death and drowns in the ocean while Rose helplessly watches is one the most tragic in movie history and has troubled fans for years.

Cameron explained how Titanic is about "death and separation". He added: "Had he lived, the ending of the film would have been meaningless."

The filmmaker was always clear about Jack's fate and if not in the water, DiCaprio's character would have met his end in some other way. "Whether it was that, or whether a smoke stack fell on him, he was going down. It's called art, things happen for artistic reasons, not for physics reasons," the director stressed.

James Cameron Kate Winslet
James Cameron and Kate Winslet at the premiere of Titanic 3D in 2012 Getty Images

This is not the first time Cameron has talked about the topic. Earlier this year, he had responded to Mythbusters, a science TV show, where in one of the episodes they had demonstrated how both Jack and Rose could have survived until they were rescued by a lifeboat.

He told Daily Beast in an interview: "Let's really play that out: you're Jack, you're in water that's 28 degrees, your brain is starting to get hypothermia. Mythbusters asks you to now go take off your life vest, take hers off, swim underneath this thing, attach it in some way that it won't just wash out two minutes later—which means you're underwater tying this thing on in 28-degree water, and that's going to take you five to 10 minutes, so by the time you come back up you're already dead. So that wouldn't work.

"His best choice was to keep his upper body out of the water and hope to get pulled out by a boat or something before he died. They're fun guys and I loved doing that show with them, but they're full of s**t."

A Titanic reunion is on the horizon as it was recently revealed Winslet will join Cameron for the Avatar sequels.

Cameron was quoted by Deadline as saying: "Kate and I have been looking for something to do together for 20 years, since our collaboration on Titanic, which was one of the most rewarding of my career. I can't wait to see her bring the character of Ronal to life."