>What about the strange UFO occurences that pentagon acknowledged, are we getting visits from aliens within our universe or from another universe?
The Pentagon has never acknowledged the existence of extraterrestrial craft, or of UFOs as being anything but hoaxes and misidentified, mundane phenomena.
>but how could Buddha have known that blackholes existed?
He didn't, any more than the Norse knew that wormholes existed when describing the Bifrost bridge or the World Tree. Reading modern scientific meaning into ancient religious ideas is a common way to attempt to validate religion, but doing so does a disservice both to the religion and to science.
The Buddha may have had many insights, but none of them involved the relationship between spacetime and gravity.