I find the lack of Bracewell-von Neumann self-replicating probes to be a convincing argument that we are the first technical civilization to at least approach t

I find the lack of Bracewell-von Neumann self-replicating probes to be a convincing argument that we are the first technical civilization to at least approach the level of launching a BvN probe. (In short, the first launch of a BvN probe is basically a permanent phase change of sorts for the galaxy, one that ours has not yet undergone.)