An astronomy professor at Penn State has put forward a remarkable hypothesis that should sound familiar to UFO enthusiasts and ancient alien advocates.

In a recently-published paper, professor James Wright theorizes that Earth as well as Mars and Venus may have once been inhabited by technologically advanced ETs!

Titled 'Prior Indigenous Technological Species,' the paper proposes that evidence for such civilizations would have been lost to the ravages of time here on Earth and harsh conditions on Mars and Venus.

That said, Wright noted that there could be what he calls 'technosigatures' contained in the geologic record of these planets which would indicate previous unnatural events such as nuclear activity or mining operations.

Beyond that he also proposes that underground installations created by these ETs may still be in existence and, thus, could be discovered in the future.

Additionally, Wright says that the asteroid belt or other areas of space where considerable debris has accumulated could be locations where disused ET craft or probes might be located in the future.

The remarkable paper is not Wright's first foray into the fantastic as he is largely responsible for advancing the 'alien megastructure' theory surrounding the mysterious 'KIC 8462852' star.

As such, cynical observers may say that the professor saw how well that theory captivated the media and has doubled down on the ET idea with his new work.

However, setting aside that critique, it is a testament to how much more open-minded mainstream science has become to various scenarios involving intelligent ETs inhabiting space, which apparently now includes a somewhat less sensational form of the much-maligned 'ancient alien' theory.

Perhaps, in due time, the rogue researchers who advanced such ideas in the past and were marginalized by mainstream science will see their work given a much-deserved second look.

Source: arXiv.org