Cryptids

[Anomalocaris]

Once upon a time I calculated that with a travel capability of 10% of lightspeed, it would take us about 2 million years to colonize the galaxy end-to-end. We don't have to break the laws of physics to occupy the galaxy, but it does presume the will to do so.

It also presumes the goals which govern our behavior would be better served by spending available energy on accelerating and deccelerating matter across intersteller space than through more through and efficient exploitation of matter available within a stellar system.

I personally doubt the extensive colonization paradigm of behavior of advanced technological civilizations as I indicated above. I also doubt different advanced technological civilizations would really have much appetite for extensive communication or mutural cultural/technological interchange as depicted in most "science" fiction soaps on TV or big screen because the staggering differences in both basic biology and even more importantly the level of technological development that is likely to exist between different civilizations. Unlike in Star Trek where hundreds of covilizations seem to just by pure chance be within a few hundred years of each other in technology, it is far more likely that first technological civilization other than our own that we encounter is superior to us by a greater margin than we are over trilobites. So on the whole civilizations would prefer to passively listen for evidence of other civilizations rather than ping or probe for these because they would like to know of other civilizations without being found themselves.

I suspect most civilizations would stick to themselves, focus on intensive exploitation of a few system at a time to maximize energy available for productive ends by minimizing energy spent in accelerating and deccelerating mass, and only move on when the system they are on is exhausted to the point of annihilation.

So I think the behavior paradigm for advanced insterstellar civilizations would likely be a slow crawl through the galaxy at the tip of a narrow borrow of completely exploited and utterly demolished stars and planets, like an termite eating its way through the wood of the galaxy, instead of spreading like fungus across a large swath of the galaxy, but leaving widespread but only superficial impression (as we humans do on earth now) everywhere it goes as depicted in space operas. Active communication and interchange between alien technological civilizations would be sporatic at most.