A Belfast film-maker has posted a video on the internet showing what he says could be evidence of time travelling.
George Clarke from east Belfast has been puzzled for more than a year by a scene in a film which appears to show a woman talking on a mobile phone.
The unusual thing is that the movie was made by Charlie Chaplin in 1928 - long before mobile phones were invented.
In the eight days since George posted the clip on Youtube - more than 1.5m people have viewed the video online.
Even the US talk show host Jay Leno created his own spoof version.
George was checking the extras on a Chaplin DVD box-set and began watching a clip of the 1928 Hollywood premiere of The Circus.
"As I sat back to watch it I realised in the first 30 seconds there's A lady strolling by with her hand up to her ear which looked quite familiar in today's society.
"So I wound it back and watched it again, zoomed it in and slowed it down and got other people in to check it out.
"Everybody had the same reaction - it looks like she's talking on a mobile phone."
He has since showed the clip to a number of people, including the audience of a Belfast film festival. He said no-one has been able to provide an explanation.
Since posting it on Youtube it has had more that 1.5m views and provoked 10,000 comments.
"A mystery like this one, bottom line I don't think we're ever going to find out," George said.
"My initial reaction was that's a mobile phone, they weren't around then, my only explanation - and I'm pretty open-minded about the sci-fi element of things - it was kind of like wow that's somebody that's went back in time."