Walt said:

“Carl Sagan was positing a single universe of bilions of civilizations, and the slim to none chance of another civilization arriving at the brief moment of technology capable of communicating across vast distances at the same time we did.”

I suspect Carl Sagan maybe one of the most overrated scientists in human history (he invented nuclear winter and set the stage for global warming) . However Sagan was pretty good at working the entertainment media and the MSM.

It is my own opinion that our galaxy has been traversed by at least one technological civilization (maybe by many). I believe that most F, G, K and maybe even M type stars in our galaxy have planets with biology. Most of these planets are “water worlds” and have only marine life. A small fraction have continents with more complex animals like ourselves (star systems with biology would tend to have gas giants and worlds with complex animals would tend to have very large moons). The small fraction of planets in our galaxy with complex animals would still number in the hundreds of millions. Many of these worlds with complex animals would eventually have a species that evolves into something capable of an advanced technology. If these beings are sufficiently clever they eventually develop an interstellar capability and encounter the more advanced civilizations that had already traversed the galaxy eons ago. That encounter exposes the younger civilization to a culture that is millions of years more advanced in all aspects. The younger civilization is then absorbed by the older one and its unique identity is lost forever. The loss of the younger civilizations unique identity makes it less interesting to the older civilization. Consequently, the older civilization does not go out of its way to reveal itself.