Who knows? : Some sightings over the years of "unidentified flying objects"-UFOs-have been accompanied by unexplained physical evidence that deserves serious study, according to an internatioal panel of scientists. In the first independent scientific review of the controversial topic in almost 30 years, directed by Peter Sturrock, a physicist at Stanford University, the panel emphasized that it had found no convincing evidence of extraterrestrial intelligence or any violation of natural laws.