To be sure, we were visited before 1947, but why did alien activity explode in 1947? First, we will take note of the more obvious suppositions before I reveal the real reason.
Certainly the advent of rocketry could have been a factor, but why 1947? Rockets carrying men into space were still 20 years away. Perhaps more importantly, humanity still has no knowledge that would let us travel beyond our solar system.
Maybe aliens wanted to witness the breakthrough that would lead to humans colonizing the stars, and they knew that such a breakthrough could occur as little as two years after the first atomic bomb, and suppose it takes them two years to get here.
Of course, the atomic bomb itself is a reason to escalate visitation. Maybe aliens want to prevent nuclear war, or maybe they won’t intervene but want to witness nuclear war first-hand if it happens.
These are pretty well known suppositions, but the wave of visitation really began in 1947 because, in 1945, humanity had indeed made a breakthrough that qualified us to joined the galactic community.
All the tribes of men had been committing atrocities against each other since the dawn of humanity.
Native American tribes did it to each other, and then European tribes did it to Native Americans, but humanity kept evolving …. until …. at some point in 1945 …. all the tribes of men were finally on the same page.
A new spirit had taken root among the tribes of men. It was most often articulated as Never Again.
Aliens began arriving to welcome us into the galactic community, but something happened.
By the time they got here, some European invaders had done it again! And they are still doing it! And humanity is forced to look the other way! Perhaps worse than their own atrocities is that they have given cover to every other atrocity that has occurred since.
The aliens are still here because there is hope.
Some of us are beginning to talk about The Greatest Act of Love in 2000 Years.