How long would it take for an alien civilization to populate an entire galaxy?
syfy.com
syfy.com
For comparison the fastest we have done is 200 km/sec and that's doing various gravity gymnastics by Parker Solar probe. 1% speed of light is about 3,000 km/sec.
That also came with a lot of gravitational debt very close to the sun. So it is even worse than it sounds.
There was also another thread here: https://news.ycombinator.com/item?id=27526803
This article says the universe is very old, I think this probably is also "bad astronomy".