Hey fellow astro geek...really nice analysis, but it's full of questionable assumptions. (Also Neil Tyson is a tool.)
One big one is that you're assuming that the alien civ would remain a constant size. But a civ that had practical interstellar travel would begin expanding exponentially. I read a calculation once that said given FTL, a civilization would only take only 10,000 years to totally colonize a galaxy.
Another big assumption is the limited temporal recognition window. Who says they'd only scan or visit once? What if outposts managed sections of the galaxy like a forest service? What if the dinosaurs were interesting enough to set up an automated monitoring station?
Hey fellow astro geek...really nice analysis, but it's full of questionable assumptions. (Also Neil Tyson is a tool.)
One big one is that you're assuming that the alien civ would remain a constant size. But a civ that had practical interstellar travel would begin expanding exponentially. I read a calculation once that said given FTL, a civilization would only take only 10,000 years to totally colonize a galaxy.
Another big assumption is the limited temporal recognition window. Who says they'd only scan or visit once? What if outposts managed sections of the galaxy like a forest service? What if the dinosaurs were interesting enough to set up an automated monitoring station?
It's a mathematical demonstration of odds, man, not a concrete analysis.
The point is that the odds of encountering an alien race is not even a rounding error in the calculation, not that it's completely impossible.
As someone else pointed out, life spontaneously generating is essentially mathematically impossible, yet here we are.
I only bring this up because people get caught up in absurdly low order probabilities and ignore the far more likely answer.