The video: An Irish filmmaker claims to have discovered proof of time travel: George Clarke says that, while watching the DVD version of Charlie Chaplin's 1928 film The Circus, he spotted a mysterious woman chatting on a cell phone in the disc's "extra footage." (Watch Clarke's wildly popular YouTube explanation below.) The woman, filmed while attending the movie's premiere, appears to be speaking into an object held up to her ear some 45 years before Motorola unveiled the first cell phone in 1973. "The only conclusion that I can come to... sounds absolutely ridiculous," says Clarke. "It's a time traveler." Unsurprisingly not everyone agrees. Here are five alternate theories:

1) It's a hearing aid: The most plausible explanation is that the woman is holding a "big, clunky, old-fashioned, carbon-amplified hearing aid," says Robert Quigley at Geekosystem. The device patented by Siemens in 1924 had to be held to the face, much as a cell phone is today.

2) It's a hoax: Some YouTube users have suggested the shot was digitally inserted into the DVD extras by "a post-production whiz having some fun," says Joal Ryan at E! Online.

3) The woman is merely sensitive or publicity shy: "Perhaps she's holding her hand up to her ear to shield the sun from her eyes," says Suzanne Choney at MSNBC, or to avoid the "camera's gaze."

4) She's adjusting her hat: "If you watch closely she eventually starts to put her hand back down and... it looks like there isn't actually anything in her fist at all," says Jen Chaney at The Washington Post.

5) She's crazy: Maybe she's a "crazy woman who uses a piece of wood to talk to her dead husband," says Monica Bartyzel at Cinematical. And besides: Even if she was a time-traveler with a cell phone, "how would she get reception?"
Watch Clarke's video here (The 1928 footage begins at about 2:30):