I have been a fan of science fiction since the summer of 1956 (58 years ago).My dad took my sister and I to the Majestic theater in downtown Houston. We watched with great fascination the classic science fiction film Earth Vs. The Flying Saucers. Since then I have seen countless movies and television shows about aliens invading our planet. For all of that time I just assumed that a big invasion armada would appear in the skies above our planet. We would have to fight a ferocious battle for the survival of humanity. Then two nights ago I was watching an elaborate show on Netflix. It was a war game with the ex-head of the British Ministry of Defense. It went on for 90 minutes with all sorts of ideas to fight aliens with superior technology and fire power.
Suddenly a light came on inside my brain. With the massive distances between stars it might not be economically feasible even for a very technologically advance alien society to send a huge armada to invade earth. When and if we get a visit from another civilization, I suspect it will be one ship that goes into orbit above our planet. There is a 50% possibility that the visit will be a peaceful one with no sinister ulterior motives. On the other hand there is a 50% probability that the visit will have very evil intentions. If the bad guys park in orbit above us, one of two things will happen as follows:
1) Some alien virus will be introduced that kills the whole human race rapidly. Our infrastructure and wealth would be there for the aliens to take over without firing a shot.
2) Something will happen to fry all of our electronics. All of our weapons will be neutralized.Vast social unrest will follow as people realize they have to live without electricity and all the toys that they are used to. (During the Cold War the Russians had six high-yield nuclear weapons designed to be detonated high above the US. The electromagnetic pulse that followed would fry all electronic devices and rapidly bring the US to its knees.) We would be reduced to almost a Stone Age existence and easy to control.