Yeah, nothing we can fathom can actually travel faster than speed of light. The calculations based on a trip traveling at 1 G accelerating first half of the flight and decelerating the second half is what they are seeming to see as the sweet spot. When you get into time dilation due to special relativity it is just mind boggling. With the exception of a few close places, any were else is a one way ticket bc the amount of time passed here means Earth could be destroyed of at the very least humanity. And the crazy thing is most people do not thing about there is a difference between interstellar and intergalactic travel. If we actually were to travel intergalactic at 1G to the closest galaxy to us, Andromeda, it would take 60 years about the craft and 5,000,000 years will have passed on Earth. So you either set off as nomads really vs explorers. Until there is something unbelievably radical discovered, such as how to not only make a worm hole, but control the start and finish to where you want to go. Then you are talking more like stepping through a doorway bc you have literally folded space-time in half. It’s truely mezmoring when thinking about things like this. The flip side is its almost disheartening and really makes it feel as though we are not meant to go beyond our playground. Sorry for the massive ramble session! :)