- New theory from mathematician explains lack of debris
- Other experts say the crew may have become incapacitated
- If the pilot caused a crash, experts say it could have been suicide
(CNN)It has been 15 months since Malaysia Airlines Flight 370 from Kuala Lumpur to Beijing did an unexplained about-face, flew in the wrong direction and disappeared without a trace with 239 souls on board. In the absence of physical evidence, theories on what happened to the plane continue to proliferate: The crew passed out. It was pilot suicide. Or was it a paranormal event?