Aliens could be "walking among us" on Earth, Harvard researchers suggest

CAMBRIDGE - Are we alone in the universe? A recent paper from researchers at Harvard University puts an interesting twist on one of humanity's biggest questions.

The paper, which is not affiliated with the university, addresses a resurgent interest in UFOs, known officially as Unidentified Anomalous Phenomena or UAPs by the government. The United States is tracking more than 650 potential UFOs, a Pentagon official said last year.

Harvard researchers Tim Lomas, Brendan Case and Montana Technological University professor Michael Masters put forward a "cryptoterrestrial hypothesis" for the UFOs, theorizing that there's a "concealed earthly explanation" for the sightings. They argue scientists should seriously consider this possibility, alongside explanations that pilots are actually seeing human-made technology or something from an advanced civilization in another part of space. 

"We've seen these cockpit videos so many times ... but what's inside?" Masters said in an interview with CBS News Boston.