Freeman Dyson (and others) noted in the 1960s the proposed Orion nuclear impulse technology could be stretched sufficiently to someday enable interstellar flight. And not just a sightseeing trip to a nearby star, a colonizing effort carrying 50,000 people, no less.
And once 'we' have a viable colony on a world orbiting a nearby star, realize earth can still send other colonizing ships towards other stars, and the colony will be able to also.
And then you have colonies sending out colonizing ships, etc, etc.
It turns out, that is an exponentiating system, and in less than 10 million years, you have a galaxy colonized from ene to end (so to speak).
So for those positing 'thousands' or 'tens of thousands' of advanced civilizations in our galaxy, it must be realized it only takes a SINGLE instance of a civilization to develop and refine technology humans had in the 1960s to colonize our entire galaxy in less than 1/10 of 1% of the age of the galaxy.
That there is not an outpost, colony, or an entire planet full of 'aliens' in our solar system is very significant.
And once 'we' have a viable colony on a world orbiting a nearby star, realize earth can still send other colonizing ships towards other stars, and the colony will be able to also.
And then you have colonies sending out colonizing ships, etc, etc.
It turns out, that is an exponentiating system, and in less than 10 million years, you have a galaxy colonized from ene to end (so to speak).
So for those positing 'thousands' or 'tens of thousands' of advanced civilizations in our galaxy, it must be realized it only takes a SINGLE instance of a civilization to develop and refine technology humans had in the 1960s to colonize our entire galaxy in less than 1/10 of 1% of the age of the galaxy.
That there is not an outpost, colony, or an entire planet full of 'aliens' in our solar system is very significant.
