Has Earth been visited by aliens? Luis Elizondo, a former Pentagon official, seems to think that this might be the case. The former head of the Advanced Aviation Threat Identification Program (AATIP) recently told CNN that “there is very compelling evidence that we may not be alone.”

Elizondo’s conviction is based on information he claims was uncovered by the AATIP, including observations of aircraft travelling and manoeuvring in ways that appeared to defy the laws of aerodynamics. Elizondo’s comments came shortly after an eerie video of an unidentified flying object was released by the US Department of Defense.

Sure, these claims are coming from a former government official — a seemingly credible source — but they do not sound too different from the claims you hear on late night call-in radio shows.

So, what does the current scientific evidence say? Is the existence of intelligent extraterrestrial life viable?

“We don’t have a lot of evidence either way,” explained Michael Reid, an Associate Professor in the Department of Astronomy and Astrophysics. “We’ve never found any [extraterrestrial life], despite looking — but you could argue we haven’t really looked all that hard.”

In spite of the lack of evidence, Reid doesn’t think we should rule out the possibility of extraterrestrial life just yet. There may be extraterrestrial life forms out there that are not capable or interested in communicating with us: “Maybe there are billions and trillions of planets with bacteria on them, but almost none of them with multicellular life.”

“I tend to think that it’s a really big universe with lots and lots of places for chemistry and biology to develop and take place, but we just don’t have any evidence yet,” said Reid.

Despite Reid’s optimism about the possibility of extraterrestrial life, the recent reports from Elizondo have not had much sway on him.

“If you go on YouTube, you can find decades worth of people spotting mysterious lights in the sky that at least appear to move in ways that are unlikely if they were man-made technology,” said Reid.

Sometimes the observation of these objects is missing context. For example, a nearby object moving relatively slowly could be mistaken for a distant object moving very quickly.

Elliot Meyer, a PhD candidate in the Department of Astronomy & Astrophysics, explained that before any conclusions can be made based on the statements of Elizondo, much more empirical evidence and higher-quality observations are needed.

Meyer put it simply: “It’s a big logical leap to go from this weird thing you’re seeing to ‘it must be aliens.’”

The lack of concrete evidence leaves the whole topic to speculation. Nevertheless, Meyer explained, “[If] you think of the big picture, we as humans have only been looking out there and listening for other life for an extremely brief period of time relative to the age of the universe.”

Maybe it’s just a matter of time.