Speeds far slower than light are entirely adequate to colonize the galaxy, it just takes time. And realize, once a colony is up and running, it can launch colonizing ships of it's own, and those colonies can do the same. The galaxy can be explored and settled in far less time than it has existed.
The greater the number of advanced civilization one imagines as existing in our galaxy, the more likely it is at least one of them will have the technology and the will to colonize. But, then we should be even more likely to have encountered them, and we have not. It can't be both ways, many civilizations will make for many colonizers, not every advanced civilization will be content to stay home when they don't have to. And it only takes a SINGLE civilization to spread throughout the galaxy.
We already know our galaxy is EXTREMELY different from Star Trek, very, very different. It is not teeming with expansionist aliens of any stripe. And 'not teeming' might extend down to just a mere handful of civilizations, and maybe, just maybe, only us.
The greater the number of advanced civilization one imagines as existing in our galaxy, the more likely it is at least one of them will have the technology and the will to colonize. But, then we should be even more likely to have encountered them, and we have not. It can't be both ways, many civilizations will make for many colonizers, not every advanced civilization will be content to stay home when they don't have to. And it only takes a SINGLE civilization to spread throughout the galaxy.
We already know our galaxy is EXTREMELY different from Star Trek, very, very different. It is not teeming with expansionist aliens of any stripe. And 'not teeming' might extend down to just a mere handful of civilizations, and maybe, just maybe, only us.
