Director Sir Ridley Scott is looking for collaborators to help him document a day in the life of the planet.
The Life in a Day YouTube project invites people to record their lives on 24 July, for a final film to be premiered at the Sundance Film Festival in January.
"It should be personal - it must be personal. That's what we're looking for," says Scott.
"If you want to do what I do, get the camera, get some buddies, you'll put it together that way. If you want to be a filmmaker, nothing should put you off, and nothing should put you down. Just do it."
Scott will produce the film, which will be directed by Kevin Macdonald. Anyone whose film makes it into the final cut will get a credit as co-director, and 20 of the best will be flown to the festivval for the premiere.
"What I want to do is make a film - unlike any film, I think, that's ever been made before, which is to ask thousands of people, everywhere in the world, on a single day, which is the 24th of July this year, to film some aspect of their day and then post that material onto YouTube so that we can use it to make a film that is a record of what it's like to be alive on that one day," says Macdonald.
He says he particularly wants to know what people fear, what people love, and what makes people laugh - and what's in their pockets.
Participants can upload videos between July 24 and July 31, here.
Languages other than English are fine, but trademarks and copyrighted material are to be avoided, and high-resolution footage will be preferred. Clips can be 15 seconds or two hours.
Scott says the inspiration for his film goes back a long way, to the day when he first decided to bunk off school and make a film about his day.
"I thought, what am I going to do? So I thought, oh, I'll just write a day in the life of me, and how I decided not to go to school because I hated school, and I'll take the day off," he says.
"But by having a day off all to myself, I had to hide most of the time with my bicycle, and therefore it was very much a day of internalization narrative about thinking about this and thinking about that, and that got me my first job."
Life in a Day is not entirely original. Back in 1937, an organization called Mass Observation started chronicling the lives of people in Britain through diaries on particular days. The project petered out in the 60s but was revived in 1981 and is still going strong, using a variety of different media.