We're pretty close to being capable of launching a Bracewell-von Neumann probe if some billionaire had the urge to do so. But so far as we can tell, the galaxy

We're pretty close to being capable of launching a Bracewell-von Neumann probe if some billionaire had the urge to do so. But so far as we can tell, the galaxy is not already full of self-replicating interstellar probes. Where are they? The uncomfortable implication is that we are the first/only species to get this far.