Non-human intelligence sharing the planet with us is a mundane explanation. It's a completely trivial possibility in the vastly expansive fields of biology and physics. Earth is known to host extremely complex life and is the only known planet to do so. To look for unknown forms of life one need only look at their feet. Bacteria was a previously unknown, extremely expansive form of life on Earth.
We unlocked the secrets of the atom and gained within it the capability of ending all life on earth trivially. Other secrets being locked behind physics isn't a radical speculation. In fact, it's surprising that we haven't really seen any since.
We unlocked the secrets of the atom and gained within it the capability of ending all life on earth trivially. Other secrets being locked behind physics isn't a radical speculation. In fact, it's surprising that we haven't really seen any since.