All joking aside, here's the "sniff test" I use regarding alien visitations to earth - timing.
It took about 4 billion years for life to evolve here from primitive proteins to sentient beings who can wonder if there is sentient life elsewhere.
Along the way, there were numerous mass extinction events, occurring every few hundred million years or so.
If there had been one or 2 less, over the billions of years, maybe dinosaurs would still be ruling the planet and there'd be no sentient beings at all.
If there had been one or 2 more, over the billions of years, maybe man would have evolved 100 million years ago.
Or vice versa.
Assuming that life is possible on other worlds, and that sentient life could evolve (2 rather large suppositions), what are the odds that the timing of that other world's evolution closely matches our own?
I.e., assuming there are other civilizations out there, they are far more likely to be 10 million years behind us, or 100 million years ahead of us, etc.
If behind us, clearly they aren't traveling to visit us.
If that far ahead of us, why do they need shiny metal spaceships that closely resemble our own aircraft? Look at how far human have advanced in the past 200 years - what will human civilization be like 10 million years from now?
Also, when other civilizations reach the point we are at now, I'd have to think that the most common outcome would be total annihilation of themselves & their civilization thru some form of warfare. Do you really think we can avoid destroying ourselves and the planet in the next 100 or 200 years? If so, what are the odds that we don't do so in the next million years?
